Rozprawy doktorskie na temat „Dairy powders”

Three types of dried milk (whole, nonfat, and buttermilk) were packaged in a modified atmosphere with a novel palladium-based oxygen removing catalyst and stored for eight weeks at 50°C. Powders stored in air with no catalyst and powders stored with the catalyst in an atmosphere modified to contain 5.7% hydrogen in nitrogen were evaluated by instrumental, chemical, and sensory methods. Hexanal concentrations were measured weekly using solid phase microextraction (SPME) and gas chromatography (GC) to compare the degrees of oxidation in the powders stored with the catalyst to those stored without it. Color changes were also monitored weekly using Hunterâ s L-, a-, and b-values. At the end of the eight-week period, a paired comparison sensory test was used to ascertain if the catalyst had an effect on odor. Anisidine values were also measured at this point to determine levels of oxidation in the powders. No significant difference was found in levels of oxidation between samples packaged with and without the catalyst in the modified atmosphere. At the end of eight weeks, the average hexanal concentration in the whole milk powder stored with the oxygen scavenger was 1.19 ± 0.20 ppm, while the average hexanal concentration in the air-packed whole milk powder was 1.06 ± 0.08 ppm. The average hexanal concentrations for the buttermilk stored with the catalyst and without were 0.84 ± 0.18 and 0.79 ± 0.15 ppm, respectively. In the nonfat milk powder, the sample stored with the catalyst had an average hexanal concentration of 0.91 ± 0.14 ppm and the sample stored in air without the catalyst had an average hexanal concentration of 0.83 ±0.20 ppm. Difference testing by volunteer sensory panelists also revealed no significant differences. It was expected that the milk powders stored with the catalyst in the modified atmosphere would have lower levels of oxidation and off-odors at the end of the eight weeks. However, the treatment ultimately resulted in no chemical or sensory differences. Thus, the catalyst proved ineffective in the given conditions. This could be due to a loss of the hydrogen required for the catalyst to function as time progressed or a lack of significant oxidation under the conditions employed.
Master of Science in Life Sciences

Master of Science
Food Science Institute
Jayendra K. Amamcharla
In recent years, the interest in functional components such as phospholipids (PLs) is increasing as a result of growing awareness of their health benefits. PLs affect several cell functions, such as growth, molecular transport system, memory processing, stress responses, and central nervous system myelination. Many studies have shown that the neutral lipids can be successfully extracted using supercritical carbon dioxide (SCO₂) from different types of foods such as egg, canola, pumpkin seed, fish and dairy powders. It is an alternative method to avoid the use of large quantities organic solvents. The SCO₂ is a safe, environmentally friendly and economical process to extract edible lipids from a variety of matrices. However, a modifier such as ethanol is needed to fractionate PLs due to limited solubility of PLs in SCO₂. The objectives of this study were to optimize the SFE process parameters and to determine the effect of pressure, temperature, and ethanol concentration on the extraction efficiency of PLs from whey protein phospholipid concentrate (WPPC) and buttermilk powder (BMP). Three different batches of WPPC and BMP were obtained from a commercial manufacturer and followed a unique two-step extraction process to isolate PLs from WPPC and BMP. In Step-1, neat supercritical CO₂ was used to remove all the neutral lipids at 414 bar pressure, 60 °C sample temperature, and 5 L/min CO₂ flow rate. The spent solids, the powder left after the first step extraction, were used to extract PLs in the second step. The Step-2 (SCO₂-Ethanol) process was optimized in terms of pressure (350, 414 and 550 bar), temperature (40 °C and 60 °C) and concentration of ethanol (10%, 15% and 20%) as independent factors. All the lipid fractions were analyzed by high performance lipid chromatography (HPLC) and thin layer chromatography (TLC). For WPPC, only ethanol concentration had significant effect (P < 0.05) on the amount of PLs extracted after the Step-2. On the other hand, temperature and ethanol concentration were significantly (P < 0.05) affected the efficiency of SFE for BMP. The optimal processing conditions for WPPC and BMP were 350 bar pressure, 60 °C sample temperature and 15% concentration of ethanol, and 550 bar of pressure, 60 °C sample temperature and 15% concentration of ethanol, respectively. This study allowed obtaining PLs from dairy co-products such as WPPC and BMP as a separate ingredient and this could be useful in nutraceutical and infant formulations as well as different food products formulations.

Les poudres laitières enrichies en matière grasse (MG) suscitent un intérêt croissant d'un point de vue économique et scientifique. Elle représentent une large gamme de produits, qui donnent lieu à de nombreues applications alimentaires parmi lesquelles les laits infantiles, les ingrédients laitiers, l'alimentation animale et les arômes encapsulés. La structure supramoléculaire de la MG dans les poudres enrichies en MG est souvent très complexe et mal connue. Elle confère à la MG des propriétés fonctionnelles de la matrice environnante. Malgré son intérêt, cette thématique n'a que peu été étudiée. De plus, le contrôle des propriétés physico-chimiques des poudres reste empirique dans le domaine industriel. Ainsi, il apparaissait primordial d'étudier les questions scientifiques en lien avec la structure supramoléculaire de la MG dans les poudres laitières, tant pour les communautés académiques qu'industrielles
Fat-filleddairy powders have acquired a growing interest from both an economical and a scientific point of view. They include a large variety of products for numerous food applications such as infant formulae, dairy ingredients, cattle feeding, and ecapsulated flavors. Fat supramolecular structure in fat-filled dairy powders can be very complex and is often poorly understood. It gives specific physicochemical properties to fat, which in turn gives specific functional properties to the surrounding matrix. Despite its interest, there was no exhaustive academic study of the topic at the beginning of this Ph. D. Program. Furthermore, controlling the physicochemical propoerties of these powders was still rather empirical in the industry. Hence, investigating the scientific issues related to fat supramolecular structure in fat-filled dairy powders appearead to be of primary importance for both the academic and industrial communities worldwide. The aims of this Ph. D. Research program were to investigate fat supramolecular structure and properties in fat-filled dairy powders in order (1) to determine adapted chemical compositions and process parameters to orientate fat supramolecular structure in fat-filled dairy powders, (2) to reach a better understanding of the mechanisms of the formation and evolution of fat supramolecular structure and fat physicochemical properties, and finally (3) to control powder physicochemical properties. The strategy was original as the study considered powders manufactured at the laboratory in controlled and industrial-like conditions and as specific methods for lipids were adapted to fat-filled dairy powders

As many of the dairy powders manufactured have to travel long distances to reach their customers, both domestically and internationally, there is considerable interest among dairy powder manufacturers to maintain the quality of their products for relatively long storage periods. Dairy powders can have a long shelf life if packaged and stored properly. Vacuum packaging can be an attractive packaging strategy to maintain the quality of dairy powders and provide added value by improving the efficiency of using the storage space; because of the inherent compactness of these products. Vacuum packaged dry dairy ingredients may also have added ease of handling for end users. However, little is known about the impact of vacuum packaging on the physical properties of dry dairy ingredients. The main objective of this study was to determine the effect of vacuum packaging over 12 months storage on particle size, particle density, bulk density, tapped density, flowability, compressibility, color, moisture content, surface morphology, and solubility of six types of dairy powders. In addition, the effect of dairy ingredients type was also assessed. Commercial samples of nonfat dry milk powder, whole milk powder, buttermilk powder, milk protein Isolate, whey protein concentrate#80, and sweet whey powder were repackaged in duplicate using multi-wall foil side gusseted bags under varying degrees of vacuum (1, 0.7, 0.4 bar) and a control with no vacuum, then stored for 3, 6, and 12 months at 25°C and 60% relative humidity. Each powder was sampled and analyzed in duplicate for all the above listed quality attributes, upon receiving the powder and after 3, 6, and 12 months of storage. Moreover, the effect of vacuum packaging on storage space was evaluated comparing three different models; Model (1) represented a 25 kg bag of atmospheric packaged non fat dry milk with the actual dimensions of a commercial 25 kg bag of non fat dry milk. Model (2), a hypothetical model, represented a 25 kg bag of vacuum packaged non fat dry milk with a length and a width equal to those of model (1). Model (3), another hypothetical model, also represented a 25 kg bag of vacuum packaged non fat dry milk with a length equal to half of a pallet width and a width equal to one third of a pallet length, in order to achieve the highest pallet efficiency possible. The pallet used for all three models was considered to be a (48 × 40) pallet. The height of models 2 and 3 was allowed to reflect the bulk reduction effect of vacuum packaging and was determined based on the weight, density and the known dimensions of the bags. It is important to note that the density of models 2 and 3 was assumed to be equal to the density of a small bag of nonfat dry milk. The saved space per bag and pallet efficiency of vacuum packaging and atmospheric packaging were compared using the three models described above. Physical properties analyses of the dairy powders revealed statistically significant effect of vacuum pressure on only color values: L-, a-, and b but none of the other powder quality attributes examined. Powders packaged under vacuum showed a significantly higher mean of L- color value (p-value = 0.003 < 0.01), but significantly lower means of (a- and b-) color values (p-values = 0.005, and 0.001, respectively). This effect was more dramatic in high fat containing powder such as whole milk powder. In fact, vacuum packaged whole milk powders were significantly whiter, less red, and less yellow. It is likely that vacuum packaging has prevented color changes due to lipid oxidation in whole milk powder. Physical properties analyses of the dairy powders also revealed statistically significant increases in the particle density, particle size, bulk density, and tapped density due to the effect of storage time (all p-values = 0.000 < 0.01), statistically significant decreases in the angle of repose and compressibility due to the effect of storage time (p = 0.000 < 0.01) and (p = 0.004 < 0.01), respectively. The physical properties analyses also revealed a statistically significant effect of the powder type on particle density, particle size, bulk density, and tapped density, angle of repose, compressibility, and color values: L-, a-, and b- (all p-values = 0.000 < 0.01). In other words, particle density, particle size, bulk density, and tapped density of the powders increased over the storage time, while angle of repose (AOR) and compressibility decreased over the storage time. The powder type had a significant effect on particle density, particle size, bulk density, tapped density, AOR, compressibility, and color values: L-, a-, and b; however, it did not have any significant effect on solubility and moisture content. In addition, observations of the surface morphology of dairy powders were made using a scanning electron microscope. This evaluation demonstrated the differences in powder particle shape and surface morphology which are believed to be partially responsible for the significant differences observed in the physical properties, due to the effect of powder type. It was shown that vacuum packaging does increase the efficiency of using the storage space by removing the interstitial air and increasing the density of the powder. As described above, the height of model (2) and the length of model (3) both were expectedly shorter compared to those of model (1). Storage space calculations for non fat dry milk were performed based on comparing the volume of the 3 models and showed 15 % saving in storage space per bag and per pallet, due to vacuum packaging. The effect of space saving on the number of bags per pallet was evaluated using CAPE PACK v2.09 software and showed an increase from 45 bags/ pallet in model (1) to 50 bags/ pallet in model (2) and 54 bags/ pallet in model (3). Overall, this study demonstrates the impact of vacuum packaging on physical properties, solubility, and storage properties of dairy powders. The data suggest that the proposed vacuum packaging method may be beneficial to maintain the quality of the powders studied and it results in space savings per unit of dairy powder compared to conventional atmospheric packaging.

Master of Science
Food Science Institute - Animal Sciences & Industry
Jayendra K. Amamcharla
High-protein dairy powders are added to a variety of products to improve nutritional, functional, and sensory properties. To have the intended properties, the powder must be soluble. The solubility is effected by processing storage, and dissolution conditions, as well as the type of powder. Various tests are used to determine solubility, but they are time-consuming and subjective. Literature has shown that ultrasound spectroscopy can characterize the solubility of high-protein dairy powders, but it requires expensive equipment and skilled technicians. An economical alternative is to use an ultrasonic flaw detector, which is commonly used in the construction industry. For this study, an ultrasonic flaw detector based method was developed to characterize the solubility of high protein dairy powders. To evaluate the method, commercially available milk protein concentrate (MPC) was obtained and stored at 25°C and 40°C and stored for four weeks to produce powders with different dissolution properties. To test the powders, a 5% (w/w) concentration of powder was added to water. A focused beam reflectance measurement (FBRM) and solubility index were used as a reference method. After powder addition, data was collected at regular intervals for 1800s. The FBRM and solubility index showed that the powders lost solubility as the storage time and temperature increased. From the ultrasound data, one parameter was extracted from the relative velocity and three parameters were extracted from the attenuation data. A soluble powder had a low relative velocity standard deviation from 900-1800s, high area under the attenuation curve, low peak time, and high peak height. The ultrasonic flaw detector detected differences in solubility before the solubility index. When testing MPC with protein contents ranging from 85% to 90% and at a dissolution temperature of 40°C and 48°C, data from the ultrasonic flaw detector and FBRM showed that the solubility decreased as the protein content increased and increasing the dissolution temperature improved the solubility of the powder. Overall, the ultrasonic flaw detector can characterize the solubility of high-protein dairy powders.

This project has investigated the mechanism of caking of lactose and identified some possible solutions to minimise caking of lactose and dairy powders, additional to those suggested in the literature. A background to lactose and caking is given. The problems of caking are identified and discussed. The project adds information to the knowledge on the polymorphic forms of lactose and their inter-relationships due to moisture sorption and processes such as milling. This information and many others in the literature are used to complete the simplified lactose conversion diagram developed by King [1965] and improved by Walstra, et al. [1999], which has been widely used in the literature as a guide for lactose manufacturing, processing, and storage.

This thesis aims to improve the understanding of the factors that determine the performance of baghouses used for milk powder collection. The research focuses specifically on the similarities and differences between milk powder collection and other common baghouse applications. The thesis also aims to demonstrate the value of recent developments in computational fluid dynamics in developing predictive models of baghouse performance. It is hoped that the findings of the thesis may find application in the New Zealand dairy industry, where such baghouses are commonly used to collect milk powder after spray drying. The effect of operating temperature and humidity on the performance of baghouses was investigated by examining both the forward filtration process and pulse cleaning process. Forward filtration was examined in a series of bench scale experiments, then scaled up to the pilot scale to confirm the findings. The effect of humidity on the pulsing performance was then investigated at the pilot scale. The importance of pulse system design was investigated at the pilot scale in a separate set of experiments. Pulse nozzle position, pulse pressure, and pulse duration were varied and the effect on the baghouse pressure differentials was measured. A computational fluid dynamics (CFD) filter model designed for membrane filtration was adapted with some success to simulate a milk powder baghouse. The model was successful in predicting the length of the low pressure zone at the top of the bag, and the general trends in overpressure associated with changes to the pulse system geometry. The model was not successful in predicting the acceleration of the filter bag during the pulse. The model was used to simulate both forward filtration and pulsing, to extend the results of the experimental investigation. The effects of changes in the pulse nozzle height, pulse nozzle diameter, and pulse pressure were simulated, as well as the effect of gravitational settling during forward filtration, to extend the results of the previous experiments. There is a clear opportunity remaining for further work to extend the basic model developed here and to adapt the model to simulate large industrial baghouses. Experiments on the bench scale and pilot scale indicated that increased cohesive forces between particles improve the performance of milk powder baghouses by lowering the resistance of the filter cake during forward filtration and aiding cake removal during pulse cleaning. Under the conditions typical of industrial milk powder baghouses, cohesive forces are governed primarily by liquid bridging between particles, due to melted fat (particularly at high temperatures) and softened lactose (at high humidity levels). As a range of milk powders with different compositions are produced commercially, the relative importance of lactose-based and fat-based cohesion differs between powder types. Cohesion promotes the formation of porous structures in the filter cake, improving the cake permeability. In skim milk powder (SMP), particle cohesion is dominated by softened lactose, and is highly moisture dependent. In the bench scale experiments conducted here, increasing the relative humidity from 6% to 17% decreased the specific cake resistance from 1.69x10⁹ m.kg¯¹ to 8.23X10⁸ m.kg¯¹, and decreased the proportion of powder adhering to the filter from 14% of the total supplied powder to 3%. The combination of these effects decreased the total resistance over the filter from 1.09X10⁹m¯¹ to 1.89X10⁸; m¯¹, an 83% reduction. The low deposition at high humidity suggested that the porous cake structure formed at high humidity levels was fragile, so that deposited particles were prone to subsequent dislodgement, especially in areas where the shear velocity near the filter surface was high. In pilot scale experiments, the porous cake structure formed at high humidity was more easily removed from the filter bag, resulting in more effective pulse cleaning. It was concluded that particle cohesion promoted cake filtration over depth filtration, as particles tended to adhere to the cake surface immediately upon contact. As depth filtered particles are more difficult to remove, the shift toward cake filtration at high humidity improved the pulse cleaning performance. A high-fat milk protein concentrate (MPC) powder was also filtered on the bench scale apparatus. Particle cohesion in the MPC powder was dominated by liquid fat, and showed a clear dependence on temperature but not on humidity. Increasing the temperature from 30°C to 90°C caused the specific cake resistance of the MPC to decrease from 1.06x10⁸ m⁻¹ to 3.94x10⁷m⁻¹, a 63% decrease. The deposition of MPC powder was unaffected by either temperature or humidity. Gravitational settling of particles in large baghouses was found to produce significant variations in the properties of the filter cake throughout the baghouse. Experimental results with the pilot scale baghouse found a strong decreasing trend in the particle size with increasing height in the baghouse, with the mean particle size decreasing from 117 μm at the bottom of the baghouse to only 31 μm near the top of the filter bag. The filter cake thickness also decreased sharply with height. Results from the CFD simulations indicated that in the pilot scale baghouse particles larger than 120 μm in diameter tend to fall out of the air flow and collect in the bottom of the baghouse, instead of depositing on the filter. While industrial baghouses tend to have a higher elutriation velocity than the pilot scale baghouse used in this study, the large size of industrial baghouses provides ample opportunity for particles to segregate on the basis of size. In addition, bench scale results indicated that high air velocities near the filter surface may cause particles to rebound from the filter. This may occur in industrial baghouses in the region near the inlet, where the air velocity is highest. The reverse pressure differential induced in the filter bag by a cleaning pulse was found to increase with distance from the cell plate. Positioning the nozzle too close to the bag opening created a low pressure zone just beneath the cell plate, where the pressure remained lower inside the bag than outside throughout the pulse. This may lead to poor cleaning at the top of the bag. In the pilot scale baghouse, positioning the nozzle at least 0.7 m from the bag opening eliminated the low pressure zone. The optimum distance of 0.7 m is is dependent on the nozzle type and bag diameter, but can be directly applied to recent industrial baghouse designs in the NZ dairy industry, which have the same nozzle type and bag diameter as the pilot scale baghouse. The design of the pulse cleaning system is important in achieving good baghouse performance. Increasing the pulse tank pressure on the pilot scale baghouse from 3.5 bar to 6.5 bar caused a 30% reduction in the forward pressure differential after the pulse, while decreasing the pulse pressure below 3.5 bar caused the pressure differentials to increase indefinitely. Altering the nozzle position had no effect on the overall pressure differentials, but did alter the local acceleration at different points on the filter bag during a pulse. CFD simulations indicated that decreasing the distance between the nozzle and the bag opening from 0.7 m to 0.1 m increased the overpressure at the bottom of the bag from 770 Pa to 3500 Pa, but this was offset by the appearance of the low pressure zone at the top of the bag as mentioned above. CFD simulations indicated that the diameter of the pulse nozzle altered both the mean bag overpressure generated by the pulse, and the distribution of the overpressure over the bag surface, with the low pressure zone at the top of the bag becoming longer at large nozzle diameters. The pulse duration was found to be unimportant, with experiments on the pilot scale baghouse finding that this had no effect on either the overall baghouse pressure differentials or the length of the low pressure zone at the top of the bag. The project has extended the understanding of milk powder baghouse performance by relating the moisture-dependent properties of lactose and the temperature-dependent melting of dairy fats to baghouse performance. The project has also provided a useful design tool in the form of the CFD model. The project demonstrates an opportunity for further CFD research into baghouse design, as the basic model developed here could now be modified to directly simulate large industrial baghouses. It is hoped that the results from this thesis will find application in the New Zealand Dairy Industry.

The proteins found in milk are largely important in the functionality of many dairy products and dairy processes. The casein micelle system in milk is a complex and highly studied system. The micelle is thought to be a sponge like structure containing four caseins, αs1, αs2, β, and κ casein, and bound together with colloidal calcium phosphate. When a chelating agent such as a citrate, phosphate, or polyphosphate are added to milk systems, the CCP is bound to the chelator and removed from the micelle. It has been shown through past research that the use of calcium chelating agents disrupts the calcium phosphate equilibrium and allows for the dissociation of the casein micelle and release of the individual caseins. Once the caseins are disrupted from micellar form and in solution, it may be possible to separate out different casein streams for functional usage in dairy products using common separation techniques. This thesis project seeks to evaluate the feasibility of separating milk treated with calcium chelators using various separation techniques to evaluate the individual casein fractions of this disrupted system. Four separation methods (ultracentrifugation, membrane filtration, heat coagulation, and coagulation based on pH) were employed to separate out the caseins based on selected properties, specifically density, molecular weight, and solubility. In ultracentrifugation, three speeds were tested, the heat coagulation study tested two temperatures, and pH based coagulation tested four different pHs to determine their impact on overall protein levels and individual casein yields. Skim milk powder was reconstituted and chelator was added at 1, 50, or 100 mEq/L treatment level. These samples were then separated using aforementioned techniques, and the supernatant or permeate was analyzed for total protein content, individual casein composition, turbidity, and mean particle size. Analysis of centrifugal separation studies shows the interaction between chelator type, chelator level, and centrifugation speed had a significant impact on the amount of protein released from the casein micelle (p Coagulation trials based on pH were also shown to have a significant interaction between chelator type, chelator level, and sample pH effecting the protein levels and casein composition (p Membrane filtration showed low protein yields in permeate, however trisodium citrate 100 mEq was still shown to have significantly higher permeate % protein levels (p The use of heat based coagulation as an individual casein separation technique for chelated samples is not recommended, as the casein micelle system itself is extremely heat stable, and the use of calcium chelators only increases the heat stability further. Because of the increased heat stability, no coagulum was formed in samples upon heating, and therefore, no separation and analysis could be done. Improving our knowledge of pretreatment of milk prior to separation and the effectiveness of different separation methods on chelated milk products may result in information leading to the ability to separate out milk fractions that provide unique or improved properties for product applications.

Poor rehydration properties of skim milk powder (SMP) can impact processing efficiency and functionality in finished product applications. Rehydration can be split into four stages: wettability, sinkability, dispersibility, and solubility. Previous work has suggested that chelator addition during SMP manufacture leads to higher solubility compared to SMP without chelators. This study focuses on the addition of ethylene diamine tetraacetic acid (EDTA) or sodium citrate dihydrate (SCD) at concentrations of 5, 10, and 15 mM to skim milk prior to evaporating and spray drying. The objective of this investigation was to determine the effects of the chelator additions on each SMP rehydration property (wettability, sinkability, dispersibility, and solubility) during reconstitution to 10% total solids. SCD 15 mM, SCD 10 mM, and SCD 5 mM did not have a significant effect on wettability as measured by IDF method (p-value 0.3234, 0.6376, and 1.0000, respectively). However, SCD 15 mM, SCD 10 mM, and SCD 5 mM had higher levels of solubility as measured by particle size analysis of reconstituted 10%TS samples (p-value

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior
The idea of uniting acerola pulp, tropical product, whey by-product of the dairy industry, led to this experiment to develop a new product with different properties, rich in ascorbic acid, proteins and minerals out. Thus, this study aimed to obtain drink made in containing acerola pulp powder and whey through drying spray-dryer. First, we evaluated the influence of process conditions (temperature:. 115-186 Â C and air flow rate from 3.57 to 4.43 m3 / min) on the hygroscopicity, degree of caking, moisture, color (L *, a *, b *) solubility, ascorbic acid and total protein powders using an experimental design type central composite (CCRD). The established from the best drying conditions (. 175 Â C and 3.7 m3 / min), an outline Simplex centroid mixtures for obtaining the best formulation of the powder mix was made containing three components: acerola pulp, whey, maltodextrin. Powders produced were analyzed the following parameters: acidity, pH, soluble solids, humidity, water activity, ascorbic acid, reducing and total sugars, lipids, protein, ash, color parameters (L *, a *, b *) , solubility, hygroscopicity, caking grade and carotenoids. The products produced by the spraying process proved to be of high quality and physical condition and satisfactory physico-chemical, the best formulation was the sample with 50: 25: 25% (m / m) of acerola pulp, whey and maltodextrin, respectively. Next, we assessed the stability of these powders during 75 days of storage laminated packaging and vacuum sealed. It was concluded that the storage kept drinking with good physical and physical-chemical characteristics, as well as ascorbic acid source (1 146.13 mg / 100g) and proteins (0.49% m / m).
A ideia de unir polpa de acerola, produto tropical, com soro lÃcteo subproduto da indÃstria de laticÃnios, conduziu a este experimento a desenvolver um novo produto com propriedades diferenciadas, rico em Ãcido ascÃrbico, proteÃnas e sai minerais. Neste sentido, este trabalho teve como objetivo a obtenÃÃo de bebida composta em pà contendo polpa de acerola e soro lÃcteo por meio da secagem em spray-dryer. Primeiramente, avaliou-se a influÃncia das condiÃÃes de processo (temperaturas: 115 a 186 ÂC e vazÃo de ar de 3,57 a 4,43 m3 / min.) sobre a higroscopicidade, grau de caking, umidade, cor (L*, a*, b*) solubilidade, Ãcido ascÃrbico e proteÃnas totais dos pÃs atravÃs de um planejamento experimental do tipo composto central rotacional (DCCR). A partir das melhores condiÃÃes de secagem estabelecida (175 ÂC e 3,7 m3 / min.), foi feito um delineamento de misturas Simplex Centroide para obtenÃÃo da melhor formulaÃÃo da mistura em pà contendo trÃs componentes: polpa de acerola, soro de leite e maltodextrina. Os pÃs produzidos foram analisados nos seguintes parÃmetros: acidez titulÃvel, pH, sÃlidos solÃveis, umidade, atividade de Ãgua, Ãcido ascÃrbico, aÃÃcares redutores e totais, lipÃdeos, proteÃnas, cinzas, parÃmetros de cor (L*, a*, b*), solubilidade, higroscopicidade, grau de caking e carotenoides. Os produtos produzidos pelo processo de aspersÃo mostraram-se com qualidade e condiÃÃes fÃsicas e fÃsico-quÃmicos satisfatÃrias, a melhor formulaÃÃo foi da amostra com 50:25:25% (m/m) de polpa de acerola, soro lÃcteo e maltodextrina, respectivamente. Em seguida, avaliou-se a estabilidade destes pÃs, durante 75 dias de armazenamento em embalagem laminada e selada a vÃcuo. Concluiu-se que o armazenamento manteve a bebida com boas caracterÃsticas fÃsicas e fÃsico-quÃmicas, alÃm de fonte de Ãcido ascÃrbico (1 146,13 mg / 100g) e proteÃnas (0,49% m/m).

Homogeneity of powder blends is an important metric for industrial applications in fortified dairy foods including commercial pediatric nutrition products. Product development practices evaluating physical properties and nutrient stability performance are reliant on blending parameters that deliver a uniform powder at both the pilot and commercial scale. Quantities of individual micronutrients in finished products are particularly critical for formulated infant foods. The two preliminary phases of this study focused on developing a simple, efficient method, specifically for a pilot scale ribbon blender, in which maximum homogeneity in fortified dairy-based powder blends could be reached. In phase one, a red iron oxide pigment powder was mixed throughout a white dairy powder and color homogeneity was measured by comparing L*a*b* color values from powder samples extracted from different areas of the ribbon blender. For phase two, sixteen similar fortified dairy blends were produced with varying ribbon blade shaft rpm, fill level, and blending durations according to a response surface method (RSM). The level of homogeneity of ferrous sulfate in the dairy blend was measured in these fortified mixtures to determine optimal blender parameters. After operating parameters were determined for uniform blending, phase three was enacted using these parameters. A comparison study of nutrient stability in fortified model non-agglomerated powder infant formula (PIF) and agglomerated whey protein concentrate (WPC) powder blends was executed to evaluate the degradative effect of microencapsulated ferrous sulfate (MFS) vs. unencapsulated ferrous sulfate (UFS) in these fortified dairy blends. The nutrient degradation rates of vitamins A, E and C in both PIF and WPC base powder, fortified with either MFS or UFS, were determined and compared during an accelerated eight-week stability study. Using p = 0.05, no statistically significant differences in vitamin degradation rates were observed when comparing independent spray-dried dairy-based blends containing unencapsulated or microencapsulated ferrous sulfate (using an encapsulating composition of 60% stearic acid) during eight weeks of accelerated shelf-life storage conditions (37 °C with a 75% relative humidity, RH). Of note, the degradation rates of vitamins A and E in blends containing PIF and UFS were more rapid than the control and suggestively significantly different (p = 0.07).

Metabolic syndrome (diabetes, hypertension, obesity and hypercholesteremia) increases the risk of high-mortality chronic diseases including chronic kidney disease, which accounts for 50% of end-stage renal disease (ESRD) in the developed world. Over 1/3 of the world’s adult population have metabolic syndrome. Oxidative stress plays a central role in metabolic syndrome pathophysiology. Grape is one of the broadly studied natural anti-oxidants. Literature demonstrates grape antioxidant’s significant protective effects on metabolic syndrome, however, not yet on metabolic syndrome-related kidney disease. This study evaluates the effect of whole grape on kidney disease associated with metabolic syndrome. Material and methods: Preclinical model of metabolic syndrome-related kidney disease, Obese ZSF-1 rats, ingested whole grape powder (5% of daily diet) for 6 months. Blood and urine samples were analyzed monthly to assess renal function parameters including 24-hour urine volumes, proteinuria, and urine protein to creatinine ratio (PCR). Rats’ kidney tissue histopathology and PCR array studies were conducted. In vitro kidney cell death was examined in cultured podocytes using flow cytometry. Results: Here, collective data from 6-month preclinical study showed chronic kidney disease consistent with an early stage diabetic nephropathy picture in both experimental and control groups. Renal function in rats of the experimental group was significantly enhanced compared with those of the control group, indicated by less 24-hour urine volumes (34.79 ± 15.77 mL vs. 55.8 ± 20.27 mL, p = 0.0147) and less proteinuria (8.56 ± 5.71 g vs. 24.01 ± 37.51 g, p = 0.0412) in the experimental group. Urine PCR was significantly lower in the experimental group versus control (3.42 ± 1.289 vs. 9.722 ± 9.156, p = 0.0084). Histopathology and PCR array analysis showed less oxidative stress picture in experimental group versus control. In vitro antioxidant assays showed significantly reduced H2O2-induced cell death in podocytes treated with grape extract versus control. Conclusion: This pilot study indicates that daily intake of whole grape powder has a protective effect on the kidney in obese ZSF-1 rats, suggesting the potential of grape antioxidants as a prevention strategy for reducing kidney disease progression in metabolic syndrome patients. Further investigations are required to support this preliminary study.
Medicine, Faculty of
Graduate

L'agglomération humide est une étape cruciale dans la technologie de mise en forme des poudres de par son fort impact sur la qualité finale des produits élaborés. Malgré son intérêt lors de l'élaboration de nombreux produits (aliment, pharmaceutique, génie civil,…), ainsi que les différents modes technologiques (malaxeurs horizontaux, verticaux, à faible ou fort de taux de cisaillement, lit fluidisé, …), elle reste insuffisamment maîtrisée de par la difficulté à proposer des diagrammes de fonctionnement opérationnels qui couplent les contributions croisées des procédés et des produits. Ce travail de thèse s'inscrit dans cette problématique et porte sur l'étude des mécanismes d'agglomération en lien avec les caractéristiques de la formulation et les paramètres opératoires. L'identification et la représentation du mode d'assemblage des particules au cours de l'opération de mouillage/malaxage est l'un des enjeux central de ce travail. A partir d'expériences menées avec deux types de poudres alimentaires (semoule de blé dur et poudre de lait), l'agglomération est induite soit par contacts humides en malaxeur à faible taux de cisaillement soit par des collisions entre les particules collantes en lit fluidisé. Les mécanismes d'agglomération humide de la semoule de blé dur développés dans un malaxeur à faible cisaillement sont décrits selon un processus de morphogénèse qui corrèle la taille des agglomérats à leur texture via une dimension fractale. L'influence des propriétés physicochimiques des liants liquides sur les mécanismes d'agglomération est étudiée au regard des paramètres du modèle fractal. L'étude fine des distributions des propriétés hydrotexturales et dimensionnelles des structures agglomérées a permis d'identifier leur « règle » d'agencement : association par même classe hydro-texturale et dimensionnelle. Les régimes d'agglomération en fonction du mode d'apport d'eau (débit faible, débit fort) sont étudiés en se basant sur la notion de flux d'atomisation adimensionné. En ce qui concerne l'agglomération de la poudre de lait en lit fluidisé, les mécanismes d'agglomération sont étudiés en suivant l'évolution des tailles et des teneurs en eau des échantillons prélevés durant l'opération de mouillage/séchage et par la suite l'étude de l'impact de certaines conditions opératoires et de formulation sur les propriétés des agglomérats finaux et les régimes d'agglomération. Un lien entre les procédés est discuté et ouvre sur une requalification des régimes d'écoulement granulaire ainsi que de la réactivité de surface des particules
Wet agglomeration is a crucial step in the shaping technology of powders because of its strong impact on the final quality of the elaborated products. Despite its interest in the elaboration of many products (food, pharmaceutical, engineering,...) as well as different technological process (horizontal mixers, vertical, low or high shear rate, fluidized bed, ...), it remains insufficiently mastered due to the difficulty in establishing operating diagrams taking into account, in the same time, products and process contributions. This thesis focuses on the study of the agglomeration mechanisms related to the characteristics of the formulation and process parameters. The identification and representation of the way particles come together during the wetting / mixing operation is one of the central challenges of this work. From experiments with two different food powders (durum wheat semolina and milk powder), agglomeration is induced either by wet contacts in mixer at low shear rate or by collisions between sticky particles in a fluidized bed. Mechanisms of semolina wet agglomeration developed in a low shear mixer are described as a process of morphogenesis that correlates the agglomerates size to their texture via a fractal dimension. The influence of the liquid binder physicochemical properties on the agglomeration mechanisms is studied according to the values taken by the fractal parameters of the model. The detailed study of the distribution of size and textural properties of agglomerated structures make it possible to identify the rule that lead to their layout: the association is mainly possible between structures belonging to the same class concerning their hydro-textural and dimensional characteristics. Agglomeration regimes depending on the mode of water supply (low flow, high flow) are studied based on the notion of dimensionless spray flux. Concerning milk powder agglomeration in a fluidized bed, agglomeration mechanisms are studied by following the evolution of the size and water content of the samples taken during the operation of wetting / drying and thereafter studying the impact of some operational conditions and formulation on the properties of the final agglomerates and agglomeration regimes. A link between the processes (low shear mixer and fluidized bed) is discussed and opens onto a redefinition of granular flow regimes and the surface reactivity of particles

Spray-dried dairy powders are common ingredients in many food and dairy products. Some of the properties of these powders that are important in their storage, handling and final application are expected to be determined by the surface composition of the powder. Therefore, an understanding of the mechanism behind the formation of the surface composition of the powder and the ability to control the surface composition will be very useful in the improvement of product quality and the development of new products. The aim of this thesis was to understand the mechanism behind the formation of the surface composition of industrial spray-dried dairy powders. To achieve this, a comprehensive research on the surface composition of industrial spray-dried dairy powders was undertaken, using electron spectroscopy for chemical analysis (ESCA, also known as X-ray photoelectron spectroscopy (XPS)). This involved the investigation of the effects of the composition of the concentrate before drying, manufacturing processes, processing conditions and storage on the surface composition of the powder. The distribution of milk components (including triglycerides in milk fat) within the powder particles was also investigated to obtain further insight in the processes occurring within the particles during powder production. It was found that the surface composition of industrial spray-dried dairy powders (skim milk powder, whole milk powder, cream powder and whey protein concentrate) is significantly different from the bulk composition. Particularly pronounced was the accumulation of fat on the powder surface, deteriorating several powder properties (flowability, wettability and oxidative stability). The fat content of the powder appeared to be the critical factor in determining the surface composition of the powder. Results showed that there is redistribution of components within the particles during the spray-drying process. A kind of solid/solute segregation seems to occur. Fat and proteins are preferentially accumulated near the surface of the particles whereas lactose in the interior of the particles. It was also observed that there is some fractionation among the different milk fat present in the powders, with the accumulating of high melting triglycerides in the free-fat and even more at the surface of the powders. The redistribution of components was found to be affected to a large extent by the spray-drying conditions employed (feed solids content, drying temperatures and degree of homogenization). The subsequent fluidized bed drying and handling processes appeared to have little effect on the surface composition of the powders. However, during long-term storage, there was a release of encapsulated low-melting triglycerides towards the surface of powder, thereby lowering the melting points of the surface free-fat and the inner free-fat. Based on the findings in this work and theoretical considerations, possible mechanisms behind the formation of the surface composition of industrial spray-dried dairy powders, from powder production, through storage, to its final application, were suggested.

This project has investigated the mechanism of caking of lactose and identified some possible solutions to minimise caking of lactose and dairy powders, additional to those suggested in the literature. A background to lactose and caking is given. The problems of caking are identified and discussed. The project adds information to the knowledge on the polymorphic forms of lactose and their inter-relationships due to moisture sorption and processes such as milling. This information and many others in the literature are used to complete the simplified lactose conversion diagram developed by King [1965] and improved by Walstra, et al. [1999], which has been widely used in the literature as a guide for lactose manufacturing, processing, and storage.
Doctor of Philosophy (PhD)

Thermophilic spore-forming bacteria such as Geobacillus spp. are common contaminants of milk powder processing plants. Their spores can remain viable throughout the entire dairy powder industrial process, including pasteurisation (72 °C for 15s) and the even hotter evaporator sections. Geobacillus spp. can form biofilms in dairy processing equipment that, over extended run times (e.g., >16 h), can deposit unacceptably high spore loads in end-product. While not dangerous to human health, this potentially leads to quality defects and price reductions, requiring that the process be stopped and the plant fully cleaned. The objective of this study was to: a. investigate the kinetics of Geobacillus growth, biofilm development and spore formation as a function of temperature and water activity, b. to develop an understanding of how these factors influence thermophile attachment and biofilm formation on stainless steel and affect the time before spore release into milk being processed into milk powder, and, based on this knowledge, c. explore options to extend run times of dairy powder plants Growth studies were undertaken, and a stainless-steel, laboratory bench-scale flow-through reactor was built and used, to investigate: 1. The effect of temperature (45 to 75 °C), media composition and water activity (0.959 to 0.992) on growth rates of 16 Geobacillus spp. originally isolated from milk powder processing plants; 2. the kinetics of attachment, biofilm formation and eventual release of new spores from spores inoculated into the flow-through reactor system via milk and with regard to spore inoculum levels, milk flow rates and temperature; 3. the effect on Geobacillus spp. growth of temperature step changes in the flow-through-system, and 4. the potential to disperse biofilms on stainless steel surfaces in the flow-through reactor using exogenously provided nitric oxide (NO). Growth rates of the 16 strains of Geobacillus spp. were modelled as function of temperature using a four-parameter square-root (‘Ratkowsky’) model. The model was developed to predict the growth of Geobacillus spp. under time-varying temperature conditions and to identify temperatures optimal for growth and biofilm formation. Over 300 growth curves were generated at temperatures in the range 45 to 75 °C, using different incubation methods, enumeration methods and growth media, although not all data sets were used because many were deemed to be unreliable due to insufficient or erratic growth of the spore-forming thermophiles under apparently well-controlled growth conditions, a phenomenon reported anecdotally by others. The studies showed that growth occurred in the temperature range 45 to ~70 °C with fastest growth occurring at ~60 °C. Consistent with published reports the generation time at 60 °C was estimated to be ~ 22 – 25 min. Studies at different water activities (a\(_w\)) suggested that the minimum water activity for growth was ~0.975. The results also showed that growth rate variability of all 16 strains is large compared to growth rate variability reported for non-spore forming cells. Nonetheless, no strain had growth rates that were systematically different to that of the pooled data. Growth rates observed for G. stearothermophilus W14 were representative of the average response of all strains and this strain was selected for use in subsequent studies. Growth rate data of G. stearothermophilus strain W14 under either anaerobic (100% N\(_2\)) or aerobic (20% O\(_2\)) conditions were also generated using a bioreactor (fermenter apparatus) at 55 °C, 60 °C, 65 °C, and 70 °C. The bioreactor was employed mainly to enable a comparison of aerobic and anaerobic growth rates by reliably producing anaerobic conditions. G. stearothermophilus strain W14 showed fastest growth at ~60 °C in anaerobic conditions with a doubling time of 26 min for vegetative cells, which was similar to growth rates under analogous aerobic conditions. The kinetics of cell and spore attachment to stainless steel were studied by inoculating the flow-through system with spores of G. stearothermophilus W14 in the milk flowing through the system and monitoring the change over time in vegetative cells and spores in the milk leaving the system (i.e., the ‘effluent’). Studies were conducted at temperatures from 45 to 70 °C. At near optimal temperatures (i.e., 60 – 65 °C) viable cell and spores counts initially decreased in the milk effluent but began to increase consistently after 3-6 h indicating attachment, germination and proliferation of cells and production of spores. Different milk flow rates applied to the system (5, 10, 20, 40 mL/min) showed no significant differences in the time for the generation of vegetative cells or spores. Spore inocula, fed into the system as pulses (1 h) or continuously added (usually for ~24 h but up to 40 h in some experiments), showed significant differences in the time to attachment and detectable proliferation, and as a function of temperature. In the pulsed system, the spore counts increased above the inoculum level after ~8 h of milk flow at near optimal temperatures, whereas in the continuous system levels in the effluent milk increased after ~4 h. In the pulsed system, a lower spore inoculum fed to the system (<10\(^2\) CFU/mL), resulted in a longer time before spore counts increased in the effluent (>8 h). Swabbing internal surfaces of the flow-through equipment at the end of “runs” at 45 °C showed early stage biofilm growth (>10\(^3\) CFU/cm\(^2\)) whereas runs at 65 °C showed high counts (>10\(^8\) log CFU/cm\(^2\)). The flow-through system was a useful way to study, under ‘commercially-relevant’ conditions, the attachment, growth and sporulation of thermophilic spore formers on warm stainless steel surfaces in milk powder plants and provided a system to study potential interventions against biofilm formation by thermophilic spore-forming bacteria. Based on Knight et al. (2004), who reported a method to minimise biofilm build up using temperature cycling to interrupt the growth cycle of non-spore forming bacteria in whole milk processing, temperature cycling studies were undertaken using the flow-through system to evaluate whether powder plant run times could be extended using the same approach. A number of experiments were conducted with temperature of the system altered systematically during the “run”. In some runs, there was reduced attachment and outgrowth of thermophilic spore-forming bacteria, suggesting that temperature cycling could extend run times if applied at the sites of most rapid attachment, growth and biofilm formation. The result showed that the temperature cycling should include temperatures near the limits of the temperature growth range of G. stearothermophilus to be able to significantly retard growth. Together with the temperature model, these data can be used as a foundation to estimate the expected benefits of manipulation of temperatures of milk powder processes. Nitric oxide (NO) has been reported to disrupt bacterial biofilms. Its potential for use to disrupt G. stearothermophilus biofilms in milk processing equipment was also studied using the flow-through system. At realistic and commercially relevant levels, NO did not significantly delay the time for unacceptable spore levels to occur in the milk effluent, although there was evidence of a reduction in final spore loads. However, recent studies have suggested that NO, while effective against Gram-negative biofilms, will not be ineffective against spore-forming Gram-positive bacterial biofilms. In short, the application of NO to extend run times is not supported, however, by the results of this study. Considering the ecology and physiology of G. stearothermophilus, and related species, the results of this study have reinforced that thermophile contamination during dairy powder processing will likely continue to be a difficult problem to address. This is because of the ability of spores to survive processing and cleaning, the rapid growth rate of the microorganism, its ability to form biofilms, and the inevitable production of spores in biofilms. Cell differentiation, including spore-formation, occurs through quorum sensing (QS) mechanisms and appears to be a ‘bet-hedging’ mechanism. It is concluded that thorough sanitation procedures will still be required at the end of each processing session to minimise residual fouling on stainless steel because the time to unacceptable spore loads also depends on initial contamination levels. While temperature cycling produced some effects, under some circumstances, further research is required to determine whether this approach can be manipulated and optimised to achieve commercially significant extension of powder plant run times.

Air-suspension particle coating is a process by which thin coatings are applied to powder particles. The coatings can be formulated to act as permeable barriers to increase powder shelf-life or to impart controlled release character. The ultimate objective of a coating operation is to produce individual particles, each with a well-controlled, even coating. This project was focused on the air-suspension coating of fine powders of ~100 µm in diameter for the dairy industry. Despite the widespread use of the technology in the pharmaceutical industry, its use in the food industry has been limited. Little is known about the fundamental mechanisms, and so published work to date is product and equipment specific and is statistical in the way the experimental design and analysis has been approached. This 'black box' approach is time consuming and costly. Better methods based on an understanding of the physical and chemical mechanisms are needed to deal with the numerous products and constantly changing formulations typical of the dairy industry. This thesis proposes a new approach to air-suspension particle coating research. The basis of this 'micro-level process approach', is to deconvolute the complex coating process into smaller manageable parts based on classical physical phenomena for which descriptions already exist. The thesis identifies and develops an understanding of the key micro-level processes controlling coated product quality and process performance. Four were selected for further study: drying, droplet impact and spreading, and stickiness which encompasses the two key micro-level processes of droplet impact and adherence and inter-particle agglomeration. They were studied separately to deconvolute the variable effects and interactions. Kinetic data were collected for the drying droplets containing maltodextrins, whey protein isolate and gum arabic. A mathematical model, based on 'ideal shrinkage' was developed to predict the drying kinetics of single droplets with particular interest in the development of the surface glass transition temperature. The model accurately predicted the kinetics until significant morphological changes occurred in the droplet. To better predict the kinetics late in the drying process, the droplet radius was set to be constant at a time based on the surface proximity to the surface glass transition temperature (critical X concept). This was done to arrest droplet shrinkage in line with experimental observations and to more accurately depict the drying of high molecular weight, amorphous glass forming polymers. After this point, a new flexible calculation scheme was used to better predict the variation in internal droplet structure as either a dense, 'collapsed shell' structure or a 'dense skin-porous crumb' structure. Further study should focus on the surface and internal droplet structure (porosity and mechanical integrity) development during drying, particularly the conditions leading to the arresting of the droplet radius and the subsequent rate of skin thickness progression. The critical X concept was used to make industrial-scale predictions of the optimum drying conditions that ensure maximum droplet impact and adherence efficiency and minimum inter-particle agglomeration in a Würster-style coating operation. This enabled the prediction of two key design parameters, the nozzle distance from the powder impact point and the Würster insert height. The span in design parameters showed that there is significant opportunity for design optimisation based on the critical X concept. A probe tack test was used to map the level of stickiness of droplets of different coating materials as they dried. As skin formation progressed, the stickiness passed through a maximum, in most cases to arrive at a point at which the droplet was no longer sticky at all (non-adhesive state). The maximum point of stickiness represents the ideal state to ensure successful droplet-substrate impact and adherence. The minimum point of stickiness represents the ideal state to prevent unwanted inter-particle agglomeration. The time interval between the onset of stickiness and the non-adhesive state was particularly dependent on the addition of plasticisers, but also on the formulation and the drying air conditions. Future work should look to establish a possible relationship between the surface glass transition temperature and the probe tack test stickiness measurements. The impact and spreading of droplets containing maltodextrin DE5 on to solid anhydrous milkfat was studied using a high speed video camera. It was found that the final spread diameter was able to be fixed close to the maximum spread diameter by using surfactants, thus avoiding significant recoil. Because existing literature focuses on predicting the maximum spread diameter, this work defines a need for adequate prediction methods for the final spread diameter, as this is the significant parameter in coating applications. Formulation and operating guidelines were established to independently optimise each micro-level process. These were used in a series of population based coating experiments in a pilot-scale Würster coater. This study highlighted the limited flexibility of the standard 'off-the-shelf' Würster coating apparatus for the coating of fine sized dairy powders. Because of this, the validation of the guidelines were inconclusive and optimisation could not be carried out. Further validation work is required on a custom-built apparatus for dairy powders. This work has advanced the fundamental knowledge of the coating process and is independent of material, equipment and scale. This knowledge, based on physical and chemical mechanisms, can be used to develop coating formulations and identify optimum process conditions for successful coating in less time and at less expense than is current practice. The next step is to put the guidelines into practice and craft the engineering of a continuous coating apparatus for dairy powder applications.

2008年三鹿三聚氰胺毒奶粉事件震驚國內外，該事件導致六名嬰兒腎結石死亡，逾三萬嬰幼兒從此生活在各種腎疾病的陰霾之下。此後奶產品安全問題尋出不窮，對國內奶產業造成嚴重的負面影響，令消費者對整個國內奶產業信心下降。事實上，在很多奶產品安全的危機中，遭受質疑的企業組織最後均被政府的檢測結果證實是無辜的。在危機中，組織的形象受到威脅，組織需通過不同的方法進行自我辯護。現存的文獻提出，危機溝通策略和組織對責任承擔的態度是兩個影響公眾對組織信心和媒體報導語調的重要因素。組織類型（國有或外資）也會影響公眾對組織的信心和媒體報導語調。過往研究也發現，公眾對組織的信心與媒體報導語調之間存在正相關的聯繫。此研究通過對兩個犯行危機情景的案例研究（2009多美滋危機事件和2010聖元危機事件），目的在於評估危機溝通策略的效用，同時也探討在不同的階段中危機溝通策略、組織責任承擔、組織類型、公眾對組織的信心和媒體報導語調之間的關係。研究成果發現文獻建議之在不同階段的最佳策略和組織責任承擔對公眾對組織的信心和媒體報導語調均無重要影響。然而，使用越少藉口和越多提供信息策略的組織贏得更多公眾信心，從而提升正面媒體報導。研究也發現，外企在第一和第二階段報導更正面，但最後國企反而取得正面的媒體報導。另外，組織類型與階段對組織選取策略與組織責任承擔均有影響。本研究結果顯示西方危機處理理論在低信任度社會如中國等未必適用。研究一方面透過更複雜的情境角度，進一步加深對現有危機傳播文獻的理解，例如引入不同階段的概念來評估危機管理的成效，另一方面也為在低信任社會中的奶產業企業提供有效的危機管理建議。
Sanlu Melamine-contaminated Milk Scandal, the frequent outbreak of dairy product safety crises had a severe impact on the domestic dairy industry, resulting in a general loss of the consumers' confidence in the entire domestic dairy industry. In fact, in many crises the crisis-ridden organizations were eventually proven innocent by governmental departments. During a crisis, an organization's image is threatened, so that various communicative entities are used to defend this image. Based on the existing literature, this study aims at evaluating the effectiveness of crisis communicative strategies (CCSs) as well as investigating the relationships among CCSs, organization responsibility acceptance, organization ownership type (domestically owned or foreign-invested), confidence in organization and media coverage in different stages during the crisis by comparing the Dumex case in 2009 and the Synutra case in 2010. The results found that the posited optimal CCS in a particular stage and organization responsibility acceptance generally did not have significant effects on confidence in organization or media image coverage. However, the findings revealed that the less excuses and the more information providing strategies were employed, the higher the stakeholders' confidence in organization would be, which in turn significantly increased the positive image coverage. Certain CCSs, i.e., diversion, no response, also showed significant direct effects on media coverage. Moreover, foreign-invested organization appeared to enjoy favorable image coverage in Stage 1 and Stage 2, but domestically owned organization surpassed it in the last stage. Organization ownership type and stages also had significant impacts on the choices of CCSs and degree of organization responsibility acceptance. Stage was also a significant negative predictor of confidence in organization but not for media coverage. This study on one hand revealed that the western crisis management theory might not be accommodative to the low-trust context in mainland China and thus theoretically further the understanding of existing crisis communication literature in a more complex contextual perspective through integrating stages as a significant time factor into the evaluation of crisis management. On the other hand it also pragmatically provides useful suggestions on effective crisis strategic management to dairy corporate in low-trust societies.
Detailed summary in vernacular field only.
Huang, Peiyi.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references (leaves 159-177).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts also in Chinese; appendixes in Chinese.
ABSTRACT (English version) --- p.i
ABSTRACT (Chinese version) --- p.iii
ACKNOWLEDGEMENT --- p.v
TABLE OF CONTENTS --- p.ix
Chapter 1. --- INTRODUCTION --- p.1
Chapter 2. --- CONCEPTUALIZATION --- p.9
Chapter 2.1 --- Crisis Management --- p.9
Crisis --- p.9
Crisis Management --- p.11
Chapter 2.2 --- Outcome: Media Image Coverage --- p.14
Chapter 2.3 --- Time Factor: Stages --- p.16
Chapter 2.4 --- Strategic Factors --- p.20
Crisis Communicative Strategies (CCSs) --- p.20
Organization Responsibility Acceptance --- p.46
Chapter 2.5 --- Organizational Factor: Organization Ownership Type --- p.50
Chapter 2.6 --- Mediator: Confidence in Organization --- p.52
Chapter 2.7 --- Research Framework, Hypotheses and Research Questions --- p.55
Chapter 3. --- METHODOLOGY --- p.58
Chapter 3.1 --- Case Selection --- p.58
Case --- p.58
Design --- p.61
Chapter 3.2 --- Content Analysis --- p.65
Data Collection --- p.65
Data Coding --- p.67
Inter-coder Reliability --- p.70
Chapter 4. --- RESULTS --- p.71
Chapter 4.1 --- Basic Sample Information --- p.71
Chapter 4.2 --- Hypothesis Tests of Two Individual Cases --- p.71
Case 1 (Dumex) --- p.73
Chapter tCase 2 (Synutra) --- p.86
Chapter 4.3 --- The Overall Results of Cases and Research Questions --- p.91
Media Valance --- p.92
Research Question 1 --- p.95
Research Question 2 --- p.99
Research Question 3 --- p.107
Chapter 4.4 --- Summary of the Findings --- p.116
Chapter 5. --- DISCUSSIONS AND IMPLICATIONS --- p.126
Chapter 5.1 --- Stage as A Complex Concept --- p.126
Controlling Other Dangers in a Dynamics Crisis --- p.127
The Role of Governmental Intervention in a Low-trust Society --- p.129
Chapter 5.2 --- Effects of CCSs on Media Image Coverage inLow-trust Society --- p.132
Chapter 5.3 --- Mediating Effects of Confidence in Organization --- p.139
Chapter 5.4 --- Suggestions of Applications of CCSs in Low-trust Society --- p.141
Chapter 5.5 --- Limit Predictive Power of Organization Responsibility Acceptance --- p.148
Chapter 5.6 --- Effects of Organization Ownership Type --- p.150
Chapter 6. --- LIMITATIONS AND FUTURE RESEARCH DIRECTIONS --- p.154
Chapter 7. --- REFERENCES --- p.159
Chapter 8. --- APPENDIXES --- p.178

Master of Science
Food Science Institute
Jayendra K. Amamcharla
Fouling and biofilm formation on stainless-steel (SS) surfaces can be sources for cross-contamination and pose a great threat to the public health and food quality. The dairy industry needs an intervention strategy focusing on technologies discouraging the biofilm attachment and developing a sustainable eco-friendly approach for biofilm removal from the dairy processing surfaces. Since fouling encourages the attachment of bacteria to the SS surfaces, it becomes important to study the ways of reducing the fouling. The bacterial attachment to the fouled SS surfaces can be prevented by modifying the SS surface properties by chemical (using coatings) or mechanical methods. On the other hand, the degree of fouling can also be reduced by using good quality raw materials. The objective-1 of the study was focused on understanding the relationship between effect of milk protein concentrate (MPC80) solubility characteristics and fouling on SS surfaces during thermal processing. The powders were stored at different temperatures (25 ºC and 40 ºC) for 2 weeks to generate powders with different dissolution characteristics. Fouling characteristics of reconstituted MPC80 powder were studied using a custom-built benchtop plate heat exchanger. Exposing the MPC80 powder to a higher temperature during storage (40 ºC) significantly decreased the solubility and increased the amount of foulant on SS coupons (P < 0.05). Microscopic investigations (scanning electron microscopy and laser scanning confocal microscopy) of resulting fouled layers revealed heterogeneous fouling layers of varying tomographies, consisting of lipids, proteins, and calcium. In the second study, the efficacy of Micro- and Nano-bubble aqueous ozone (MNAO) as a disinfectant was studied in removal of Bacillus cereus and Bacillus licheniformis biofilm from the SS surface. For the Bacillus cereus biofilm removal, a log reduction of only 0.68 cfu/cm2 was observed after the de-ionized water wash. Whereas both MNAO and cleaning-in-place (CIP) treatments significantly reduced the bacterial counts by 2.43 and 2.88 log10 cfu/cm2, respectively. On the other hand, for the Bacillus licheniformis biofilm removal from SS surfaces, a significant log reduction observed was 1.45, 3.03, 2.92 log10 cfu/cm2, respectively after de-ionzed water, MNAO, and CIP treatments. Thus, it was observed that MNAO has great potential for removal of Bacillus cereus and Bacillus licheniformis biofilms from the SS surface, and can be used in the dairy industry as an effective sanitizer/disinfectant

Owing to growing markets for Greek yoghurts and soft cheeses, dairy industry generates huge quantity of acid whey creating a significant environmental problem globally. This by-product cannot be simply disposed of due to its toxicity during decomposition, robbing oxygen from rivers and streams creating health and environmental concerns. Currently, there is no solution to acid whey waste, but it seems the behaviour of lactose in presence of LA and Ca in acid whey restricts its further processability due to the failure of lactose to crystallize which thus remains in its amorphous form during concentration and further processing, including spray drying. Hence, the present study aims at fundamentally understand the concentration and crystallisation behaviour of lactose and its interactions with other constituents of acid whey especially LA and Ca. A model based study was thus implemented with varying concentrations of Ca (0.12, 0.072 or 0.035% w/w) and LA (0.05, 0.2, 0.4 or 1% w/w) in establishing behaviour of lactose during concentration up to 50% (w/w). Different concentrations of LA and Ca were selected to imitate the concentrations originally present in acid whey, nanofiltered retentates and sweet whey. Furthermore, the crystallization nature of freeze dried lactose in presence of LA and/or Ca were investigated. Differential scanning colorimetry (DSC) was used to determine the phase transitions while, fourier transform infrared spectroscopy (FTIR) was used to determine the structural changes and screens the molecular vibrations shown by various compounds.