Academic literature on the topic 'Caking of lactose'

Milk protein concentrate (MPC) is a commercial designation for dairy ingredients with higher protein and lower lactose content than conventional skim milk powder. Lactose in its amorphous form is found in several spray-dried dairy powders. Amorphous lactose is thermodynamically unstable and can mobilize and crystallize over time under adequate temperature and moisture content. Moisture sorption from the air precedes crystallization, enhancing MPC cohesiveness and caking. This increased humidity results in poor rehydration and dispersibility, lower yield during drying, operation problems, difficulties in handling and storage. Moreover, lactose crystallization in MPC can cause Maillard browning reaction and fat oxidation. To avoid this problem, it is necessary to pre-crystallize lactose as alpha-lactose monohydrate, which is non-hygroscopic, before spray drying. Such a procedure is essential in preventing deterioration of MPC resulting from lactose crystallization or chemical reactions. Additionally, the control of this step is important to obtain specified and reproducible powder, in terms of size and crystallization level. There are various reports on the rheology of milk-based products; however, there is a lack of investigation on concentrated systems. Consequently, the objective of the present work is to review basic concepts of lactose crystallization and rheology of milk protein concentrate.

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.

Cette thèse porte sur le problème fondamental du mottage des poudres suite aux mécanismes de transition de phase. Le projet vise à étudier l'impact des facteurs intrinsèques (structure moléculaire des matériaux, propriétés physiques et/ou physicochimiques, etc.) ou des facteurs environnementaux (conditions de stockage ou paramètres de procédé) sur la stabilité de la structure des poudres. Plus précisément, notre étude a mis en évidence le rôle prépondérant du phénomène de cristallisation et des transitions entre les différents polymorphes du lactose. L'accent a été mis sur le rôle des phénomènes de cristallisation et de la transition de phase dans l'apparition du mottage des poudres de lactose. Deux cas ont particulièrement retenu notre attention: (1) des poudres de lactose monohydrate contenant une fraction de particules amorphes et (2) des échantillons de poudre anhydre composés des anomères α et β du lactose. Dans les deux cas, le mottage a été induite par l'exposition des échantillons à l'air humide, soit dans un dispositif de sorption dynamique de vapeur (SPS), soit par des tests accélérés utilisant deux appareils conçus et réalisés dans notre laboratoire (CLAIR & OLAF). Nos résultats ont montré que, dans les deux cas, la principale cause de prise en masse était la formation de lactose monohydrate, qui est la forme la plus stable parmi tous les polymorphes de lactose. Cependant, les mécanismes élémentaires, les étapes limites et la cinétique du processus de transformation étaient différents dans chaque cas. Les paramètres les plus déterminants étaient l’humidité relative et la température alors que la pression n’a pas eu d’effet significatif. La résistance mécanique des échantillons mottés était étroitement liée au taux et à la cinétique de cristallisation. Enfin, des simulations numériques basées sur la méthode des éléments discrets (DEM) de la résistance mécanique des échantillons mottés ont été réalisées. Le modèle permet de décrire le comportement des échantillons mottés soumis à des contraintes mécaniques de compression ou de traction
This PhD study focuses on the fundamental problem of powder caking due to phase transition mechanisms. The project aims to study the impact of intrinsic factors (molecular structure of materials, physical and/or physicochemical properties, etc.) or environmental factors (storage conditions or process parameters) on the stability of the structure of powders. More precisely, our study has highlighted the preponderant role of the crystallization phenomenon and the transitions taking place between the different polymorphs of lactose. Emphasis was placed on the role of crystallization phenomena and phase transition on the advent of lactose powder caking. Two cases attracted particular attention: (1) lactose monohydrate powders containing a fraction of amorphous particles and (2) anhydrous powder samples composed of ð and anomers of lactose. In both cases, the caking was induced by exposure of the samples to moist air, either in a Dynamic Vapor Sorption device (SPS) or in accelerated caking tests using two home-made equipment (CLAIR & OLAF). Our results showed that in both cases, the main cause of caking was the formation of lactose monohydrate, which is the most stable form among all lactose polymorphs. However, the elementary mechanisms, the limiting steps and the kinetics of the transformation process were different in each case. The more influencing parameters were the relative humidity and the temperature whereas the pressure has no significant effect. The yield stress of caked samples was closely linked with crystallization extent and kinetics. Finally, numerical simulations based on Discrete Element Method (DEM) of mechanical resistance of caked samples were performed using the "beam model". The model allows describing the behavior of the caked samples subjected to compressive or tractive mechanical stresses

L’augmentation de la demande en lait infantile génère une forte croissance de la production mondiale de lactose. En raison d’exigences accrues sur la qualité du produit, le mottage, ou prise en masse spontanée de la poudre, est une non-conformité pouvant s’avérer très coûteuse. En utilisant une approche procédé – produit, ce projet vise à identifier les paramètres critiques et comprendre les mécanismes de mottage du lactose, pour donner les moyens aux industriels de prévenir le mottage. Les résultats obtenus sur des poudres produites à l’échelle pilote montrent le rôle déterminant des impuretés (i.e. composés autres que le lactose) et de la granulométrie. En effet, les impuretés renforcent l’hygroscopicité et le mottage. De plus, en augmentant la teneur en impuretés, la surface spécifique et le nombre de points de contact, une diminution de la taille des particules et une hétérogénéité de tailles accrue intensifient le mottage. L’analyse des poudres commerciales a confirmé ces résultatUn autre résultat marquant de ce travail est le développement d’un test de mottage accéléré, qui permet de classer des poudres de lactose en fonction de leur tendance au mottage en moins d’une journée, après un stockage à 50°C et 60% d’HR. Un test similaire implémenté sur chaque site de production permettrait l’identification rapide des lots à risque avant expédition. Grâce à la meilleure compréhension des mécanismes de mottage fourni par ce travail, les industriels peuvent cibler les étapes critiques du procédé à optimiser pour prévenir le mottage du lactose
Driven by the growth in the infant formula market, lactose production is increasing worldwide, and the requirements for the product quality are becoming stricter. Caking, or the unwanted agglomeration of lactose powder particles, is synonym of poor quality for the customers and should therefore be prevented to avoid large economic loss. Focusing on the process–product relationship, this PhD project aimed at finding the critical parameters and understanding the caking mechanisms in lactose powder in order to establish means to limit caking. In samples from pilot production, impurities (i.e. non-lactose components) were shown to increase moisture sorption and caking. The particle size distribution of the powder also exhibited a large effect on caking. Indeed, smaller particles and a broader distribution were characterized by enhanced moisture sorption and stronger caking, which were explained by a larger impurity content and surface area and more contact points.Analyses on the commercial powder confirmed these results and revealed the instability of the water activity during storage of the powder after drying, which was linked to caking in the bags. This PhD project also addressed an essential need in the dairy industry, i.e. the development of an accelerated caking test. Samples from different production sites were discriminated in terms of caking in less than a day, using appropriate test conditions (50°C and 60% RH). A similar test implemented at all sites would highlight batches with a high caking tendency before shipment to the customers. The better understanding of th

Lactose is used in many food/pharmaceutical products, despite powders containing amorphous lactose being difficult to handle because they tend to be sticky and are prone to crystallization and powder caking. There is therefore a market for lactose powder with improved functionality to facilitate powder handling. The aim of the proposed project was to produce a value-added, free-flowing and non-caking lactose powder that can be easily blended into other dairy products, such as dry-powder soups or drinks, and non-dairy products such as chocolate bars. The principle of particle coating during spray drying (in-situ coating), which exploits the phenomenon of solute segregation of different components within the drying droplet, was used for the purpose of producing such powders. In this work, spray-dried lactose powders containing low concentrations of edible additives, such as proteins, polymers or fat, were produced in order to investigate the ability of these additives to accumulate at the droplet surface during drying to form a coating that improves powder functional properties and limits powder caking. This thesis presents the results of the trials necessary to develop these coated powder by the use of an

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)