Academic literature on the topic 'Milk concentration permeate'

AbstractThe experiment was conducted to analyse the effect of fermented acid whey permeate on milk yield and composition in the lactating cows. Propionic acid bacteria and their metabolites have been used in the lactating cows feeding over decades, primarily to improve growth performance, feed conversation and milk production efficiency. Two groups of the lactating cows were arranged in the study: control group (n=50) and experimental group (n=50). Experimental group’s animals received 0.5 L of fermented whey permeate daily. Acid whey permeate was inoculated with the freeze-dried PS-4 (Propionibacterium freudenreichii subsp. shermanii, Chr.Hansen, Denmark) starter and fermented anaerobically for 48 hours at 20±2 oC. Fat, protein, lactose and total solids concentration in acid whey permeate and fermented acid whey permeate was analysed by the standard methods, but propionic acid was detected by HPLC. Milk composition and quality indices were determined at the beginning of the study and each month during 6 months period. At the end of the study the feeding of fermented acid whey permeate was stopped, but milk composition and quality data were monitored additionally after one month. Milk fat, protein, lactose, total solids, urea concentration and somatic cell count were analysed by a near infrared spectroscopy.The variability in milk composition and quality data across trial was greater in the experiment group than in the control. Milk fat and somatic cell count were significantly different (p<0.05) than other studied parameters in the experimental group cows’ milk. Milk yield and lactose concentration were tended to increase during feeding of fermented acid whey permeate in the lactating cows without significant differences between control and experimental groups. Fermented acid whey permeate as feed supplement improves energy metabolism for dairy cows which results in the higher milk yield and fat concentration.

This work aimed at evaluating the influence of enzyme concentration, temperature, and reaction time in the lactose hydrolysis process in milk, cheese whey, and whey permeate, using two commercial β-galactosidases of microbial origins. We used Aspergillus oryzae (at temperatures of 10 and 55°C) and Kluyveromyces lactis (at temperatures of 10 and 37°C) β-galactosidases, both in 3, 6, and 9 U/mL concentrations. In the temperature of 10°C, the K. lactis β-galactosidase enzyme is more efficient in the milk, cheese whey, and whey permeate lactose hydrolysis when compared to A. oryzae. However, in the enzyme reaction time and concentration conditions evaluated, 100% lactose hydrolysis was not reached using the K. lactis β-galactosidase. The total lactose hydrolysis in whey and permeate was obtained with the A. oryzae enzyme, when using its optimum temperature (55°C), at the end of a 12 h reaction, regardless of the enzyme concentration used. For the lactose present in milk, this result occurred in the concentrations of 6 and 9 U/mL, with the same time and temperature conditions. The studied parameters in the lactose enzymatic hydrolysis are critical for enabling the application of β-galactosidases in the food industry.

Pasteurized skim milk and retentate (concentrated fivefold or twofold by volume) and permeate from ultrafiltered skim milk were inoculated with Listeria monocytogenes strains California or V7 and incubated at 4, 32, or 40°C. Changes in populations of the pathogen were determined, growth curves were derived, and generation times and maximum populations calculated for each combination of strain, product, and temperature. Both strains grew faster and achieved higher (ca. 1 to 2 orders of magnitude) populations at 4°C in retentate of either concentration than in skim milk. The pathogen grew in permeate at 4°C and attained maximum populations of ca. 106 to 107/ml. Tyndallized samples of skim milk and retentate and permeate from ultrafiltered skim milk were inoculated with the same strains of L. monocytogenes and incubated at 32 or 40°C. Populations achieved by the pathogen at these temperatures, ca. 107 to 108/ml, were similar in skim milk, retentate, and permeate.

SummaryMilk permeate was separated at various temperatures by means of a hollow fibre ultrafiltration unit coupled to a stainless steel heat exchanger. Milk samples conditioned at 4°C were heated to 20, 40, 60, 80, 85 or 90°C prior to ultrafiltration. Ca, P, Mg, Na, K and citrate concentrations were measured in the permeate samples. Ca and P contents of the permeate decreased as the temperature increased. The pH was measured after cooling the permeate to room temperature. Smaller losses of Mg and citrate were also observed with increase in temperature. Na and K levels were not affected. A two-step time-concentration relationship was apparent for the species under study. An initial sharp decrease in concentration occurred in the first minute of holding time and was followed by a slower reaction. The possible occurrence of a two-step mechanism in the heat-induced salt balance changes is discussed. Dicalcium phosphate precipitation is believed to be coupled with tricalcium citrate precipitation upon heating.

In this work, milk protein concentrate (MPC) was made using wide-pore negatively charged ultrafiltration membranes. The charged membranes were used for a six-fold volume concentration of skim milk and subsequent diafiltration to mimic the industrial MPC process. The charged 100 kDa membranes had at least a four-fold higher permeate flux at the same protein recovery as unmodified 30 kDa membranes, which are currently used in the dairy industry to make MPC. By placing a negative charge on the surface of an ultrafiltration membrane, the negatively charged proteins were rejected by electrostatic repulsion and not simply size-based sieving. Mass balance models of concentration and diafiltration were developed and the calculations matched the experimental observations. This is the first study to use wide-pore charged tangential-flow membranes for MPC manufacturing. Additionally, a unique mass balance model was applied, which accurately predicted experimental results.

Concentration of goat milk using cross-flow filtration unit with 10KDa molecular weight cut off (MCWO)-sized ultrafiltration membrane was examined under various operating conditions. The parameters to be optimized are trans-membrane pressure (TMP) and cross-flow velocity. Permeate flux is decreased with time due to fouling of the membrane. The localized membrane fouling may be reduced by increasing the feed flow rate and TMP to mitigate overall membrane fouling. By doing so, the transmission of lactose will also increase. The aim is to produce concentrated goat milk with minimal lactose content and thus high concentration of protein. Spray-drying method is used to convert the concentrated non-lactose milk obtained into milk powder. The milk powder then was characterized in terms of its surface particle, solubility, and nutritional content with the well-commercialized non-lactose milk. This project tackles understanding to minimize the deposition rates of particles on membrane by optimizing the involved parameters and be proved by comparing the yield obtained with well-commercialized non-lactose milk. Keywords:Goat’s milk, lactose intolerance, ultrafiltration, spray dry,membrane, concentration

Ultrafiltration (UF) can be used to concentrate yogurt to produce Greek-style yogurt (GSY) (UF-YOG), but this generates acid whey permeate, which is an environmental issue. However, when UF is applied before fermentation (UF-MILK), a nonacidified whey permeate is generated. For this study, two model GSYs (UF-YOG and UF-MILK) were produced to compare the composition, UF performance, and energy consumption of the two processes. For UF-MILK, skim milk was ultrafiltered with a 30 kDa spiral-wound UF membrane to achieve a 3× volume reduction factor (VRF). The retentate was fermented to a pH of 4.5. The UF-YOG process was the same except that regular yogurt was ultrafiltered. Both GSYs had similar protein (~10%) and solid content (~17%). As expected, lactic acid/lactate was not detected in UF-MILK permeate, while 7.3 g/kg was recovered from the UF-YOG permeate. Permeation flux values (11.6 to 13.3 L m−2 h−1) and total flux decline (47% to 50%) were constant during UF-MILK, whereas drastic decreases in these two membrane performance indicators (average flux: 38.5 to 10.9 L m−2 h−1; total flux decline: 2% to 38%) were calculated for UF-YOG. Moreover, for UF-YOG, UF membrane performance never recovered, even when drastic and repeated cleaning steps were applied. Energy consumption was 1.6 kWh/kg GSY and remained constant for UF-MILK, whereas it increased from 0.6 to 1.5 kWh/kg GSY for UF-YOG. Our results show that, although the composition of GSYs was similar for both processes, the UF step of yogurt concentration affected process efficiency due to drastic and permanent membrane fouling.

SummaryThe heat-induced changes in sait balance between the colloidal phase of milk and its serum were studied using an ultrafiltration technique. Milk permeate was isolated at the heating temperature by means of a hollow fibre ultrafiltration cartridge coupled with a stainless steel heat exchanger unit. The milk samples initially at 4 °C were heated to 20, 40, 60, 80 or 90 °C. Ca, P, Mg and citrate contents of the permeates were determined. The decreases in Ca and P were proportional to the increase in temperature. Smaller losses in Mg and citrate were observed. An initial sharp decrease in concentration occurred within the first seconds of holding time and was followed by a slower and smaller decrease. The possible occurrence of a two-stage mechanism for the heat-induced salt precipitation is discussed. The precipitation of dicalcium phosphate is believed to occur together with some tricalcium citrate precipitation.

The objective of this study was to determine the antimicrobial activity of pepsin-digested lactoferrin added to carrot juice and filtrates prepared from carrot juice. Lactoferrin isolated from raw skim milk was digested by pepsin for 4 h at pH 3. The digest of lactoferrin was lyophilized, and the antimicrobial activity of the digests was determined in peptone-yeast-glucose broth, carrot juice, permeate from carrot juice, and the dialysate of carrot juice permeate using Esherichia coli (American Type Culture Collection strain 35343) as the test organism. Growth of E. coli and the inhibitory effect of the peptide were greater in peptone-yeast-glucose broth at pH 7 than at pH 4. The peptic digest of lactoferrin did not have antimicrobial properties in carrot juice at concentrations of less than 10 mg/ml of juice. Carrot juice was filtered through a membrane with a molecular weight rejection of 10,000 or 500 Da, and the permeate was dialyzed against distilled water. Growth of E. coli was delayed in the filtrate by 5 mg but not by 1 mg of the peptic digest of lactoferrin per ml of filtrate. Bacterial counts of the control and experimental samples were not significantly different after 24 h of incubation. The peptic digest of lactoferrin at a concentration of 5 mg of digest per ml of dialysate was bacteriostatic toward E. coli after 24 h of incubation at 23°C. Dialysis of permeate caused a percentage reduction in cation concentration in the permeate ranging from 69.23% (Co) to 99.32% (Na). The antimicrobial activity of lactoferrin added to carrot juice was probably inhibited by cations.

The development of processes for the preparation of prebiotic compounds, namely inulin from tubers of Jerusalem artichoke (JA-Helianthus tuberosus L.), and lactulose from milk concentration permeate (MCP) was examined. Inulin was extracted from the whole JA tubers using hydrothermal extraction process, followed by clarification and concentration. The concentrate was fractionated using two different procedures i.e. ethanol fractionation and cold precipitation (+4 and/or -24C) into high- and low-molecular-weight components. The most satisfactory method was cold fractionation wherein the insoluble heavier inulin fractions were found to settle to the bottom and were separated and spray-dried to obtain inulin powder. Lactose in MCP was isomerised into lactulose using carbonate-based catalysts (oyster shell and egg shell powders) followed by clarification and concentration. The high-performance liquid chromatography with refractive index detector (HPLC-RID) chr omatograms and changes in pH and colour values confirmed the conversion of lactose into lactulose and decomposition of lactulose into by-products. The results obtained showed the suitability of oyster shell powder for lactose isomerisation in lieu of egg shell powder. For preparing lactulose-enriched MCP with acceptable lactulose yield of 22%, the optimum reaction conditions were found to be catalyst loading of 12 mg per mL of MCP and isomerisation time of 120 min at 96C. The resulting products i.e. JAI concentrate and powder and lactulose-enriched MCP syrup (40B) were tested for their prebiotic power in media broth and in fermented milk models. Prebiotic properties of these compounds were observed as supplementation levels increased from 0-2% to 3-4%. Based on the growth and acidification abilities of the probiotic strains tested, the combination of Lactobacillus casei LC-01 with JAI, and Lactobacillus acidophilus LA-5 with lactulose-enriched MCP syrup were found to be the best for development of synbiotic yoghurt. The prebiotic effect of JAIP was then compared with the two commercial chicory inulin products (Raftiline GR and Raftilose P95). Probiotic yoghurts supplemented with 4% inulin powders were prepared from reconstituted skim milk using mixed cultures of Lactobacillus casei LC-01, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (1:0.5:0.5, w/w). The survival and acidifying activity of probiotic and lactic acid cultures were investiga ted during the shelf life of 28 days at 4C. Incorporation of JAIP and chicory inulins resulted in a significant improvement in viability of LC-01 compared with non-supplemented yoghurt, maintaining more than 107 CFU g-1 throughout storage time. Additionally, the suitability of JAIP as fat replacer was determined in a set of fat-free yoghurt in comparison to three commercial chicory inulin products. Results of large deformation tests revealed that the firmness of JAIP-supplemented yoghurt was reduced to a similar level as the full-fat control yoghurt. However, small deformation results showed that the JAIP could not fully mimic milk fat to the same extent as Raftiline HP with an average DP of 23. The rheological effects of JAIP addition were comparable to those of short-chain (Raftilose P95 with an average DP of 4) and medium-chain inulins (Raftiline® GR with an average DP of 12).