Investigation of caking by fat bridging in aged infant formula

Mechanistic insights into the changes of biological activity and physicochemical characteristics in Lacticaseibacillus paracasei fortified milk powder during storage

To clarify the change mechanism of biological activity and physicochemical characteristics in Lacticaseibacillus paracasei JY025 fortified milk powder (LFMP) during storage, morphological observation, JY025 survival, storage stability, and metabolomics of LFMP were determined during the storage period in this study. The results showed that the LFMP had a higher survival rate of JY025 compared with the bacterial powder of JY025 (LBP) during storage, which suggested that milk powder matrix could reduce strain JY025 mortality under prolonged storage in the LFMP samples. The fortification of strain JY025 also affected the stability of milk powder during the storage period. There was lower water activity and higher glass transition temperature in LFMP samples compared with blank control milk powder (BCMP) during storage. Moreover, the metabolomics results of LFMP indicated that vitamin degradation, Maillard reaction, lipid oxidation, tricarboxylic acid cycle, and lactobacilli metabolism are interrelated and influence each other to create complicated metabolism networks.

Milk fat globule membrane regulates the physicochemical properties and surface composition of infant formula powders by improving the stability of the emulsion

The milk fat globules in infant formula (IF) are encapsulated by a component known as milk fat globule membrane (MFGM). However, it is currently unclear whether the improved emulsion stability of MFGM can have a profound effect on the finished IF. Therefore, this study investigated the effects of MFGM on the particle size, stability, rheology, and microstructure of emulsions prepared by dairy ingredients via wet mixing. Further, IF were processed using such emulsions, the physicochemical properties, surface composition of the powders were examined. The results showed that MFGM reduced the particle size of the emulsion, increased the viscosity, and improved the microstructure of the MFGM. Furthermore, MFGM reduced the moisture content of the powder, increased the glass transition temperature, and reduced the presence of surface fat. In conclusion, the addition of MFGM enhance the finished powder stability by improving the emulsion stability prepared during IF manufacturing.

Effects of different reducing carbohydrate types on the physicochemical characteristics of infant formula food stored for special medical purposes

The formula of food for special medical purpose has a direct impact on physicochemical stability, especially in hot climes and high temperature transport storage environments. An accelerated test (50 °C for 7 weeks) was used to analyze the mechanism of the physicochemical instability of formula A with lactose and maltodextrin, and formula B with maltodextrin. Deep dents and wrinkles were observed on the surface of the formula B, and more fat globules covered the surface of formula A particles after storage for a long time. Significantly higher amounts of furosine and Nε-carboxymethl-l-lysine (CML) were formed and the loss of available lysine was greater in formula A than in formula B. No significant difference was observed in lipid oxidation indicators between the two formulas. The results of this research demonstrated lactose was more active than maltodextrin and led to physicochemical instability.

Rapidly evaluating the caking tendency of sugar alcohols by developing a crystal bridge growth model: A case study of xylitol

Caking of crystalline sugar alcohols is a deleterious and undesired agglomeration process during storage in the food industry. Compared with the time-consuming and labor-intensive conventional caking assessment methods, this work develops a rapid methodology for evaluation of the critical caking cycle of xylitol with over 85% time-saving and 90% labor-saving while guaranteeing the precision accuracy. By developing a Caking-Hygroscopicity-Particle size crystal bridge growth model, the correlation and quantitative relationships among hygroscopic properties, particle size and the critical caking cycle are firstly established and confirmed, which can greatly simplify the most time-consuming and laborious experiments of water sorption measurements and caking tests. Besides, the knowledge obtained can help guide the rapid selection of storage humidity conditions and appropriate particle size distributions for maintaining the desired properties and competitive marketability of crystalline sugar alcohols.

Understanding the factors affecting the surface chemical composition of dairy powders: a systematic review

Dairy powder, with abundant chemical components such as protein, fat, and lactose possessing diverse physical and chemical structures, can exhibit a surface composition distinct from its bulk content during the conversion of liquid milk into dry powder. Surface chemical composition is a significant parameter in the dairy industry, as it is directly associated with the techno-functional properties of dairy powder products. The current work provides an overview of the factors influencing the surface composition of dairy powders such as the bulk composition of raw milk (animal source and formulation), liquid dairy processing (homogenization, thermal treatment, and evaporation), the drying process (drying methods as well as operating conditions during the most commonly used spray drying), and storage conditions (temperature, relative humidity, and duration). The underlying mechanisms involved in the variations of particle surface composition include the mechanical properties of emulsion, milk fat globules redistribution caused by mechanical forces, adsorption competition and interactions of ingredients at the water/air interface, dehydration-induced alterations in particle structure, corresponding solid/solutes segregation differentiation during spray drying, and lactose crystallization-induced increase in surface fat during storage. Additionally, future research is suggested to explore the effects of emerging processing technologies on the surface composition modification of dairy powders.

Elucidating the physicochemical properties and surface composition of goat milk-based infant formula powders

This study investigated the characteristics of cow milk-based, goat milk-based, and mixed-based (using goat milk and cow whey powder)infant formulas (IF) with different sources of casein and whey protein, aiming to construct the properties of powders prepared using goat milk. Goat milk-based IF have different water activity, color, and glass transition temperature than other IF, whereas the crystallinity and solubility were similar. SDS-PAGE pattern showed that goat milk-based and mixed-based IF contained higher β-casein, while cow milk-based IF contained higher α_s1-casein. The differentials of casein affected the powder surface composition and free fat levels. Goat milk-based IF reduces the surface fat content and free fat levels of the particles. Further analysis showed that the surface of the particles was predominantly filled with saturated fatty acids. Our findings revealed that due to the different casein, goat milk-based IF have favorable characteristics and surface composition, thus promoting its particle stability.

Effect of water activity on the functional, colloidal, physical, and microstructural properties of infant formula powder

We report on the physicochemical changes of infant formula (IF) powder and its macronutrients (lactose, fat, and proteins) under given storage conditions. Colloidal (particle size distribution, emulsion stability and sedimentation), morphological (scanning electron microscopy), thermal (differential scanning calorimetry), structural (synchrotron X-ray diffraction) as well as surface and chemical (X-ray photoelectron and Fourier transform infrared spectroscopies) data were used to elucidate the main cause-effect relationships for microstructural, functional, and other properties of the IF powder. The wetting behavior of the powder was found to be significantly affected by water activity (a_w) during storage (a_w in the range between 0.24 and 0.42). At the highest a_w (a_w = 0.42), lactose crystallization and fat migration took place, leading to changes on the surface of the particles that reduced powder wettability. We propose possible mechanisms to explain the observations, associated with changes in protein conformation. Interestingly, no major changes in the pH and colloidal characteristics, including particle size and distribution, stability, and sedimentation were observed in the reconstituted IF powder upon storage for 6 weeks. The results indicated a negligible contribution from possible Maillard reactions. We propose leading microstructural and wetting characterization to troubleshoot changes in the quality of IF powder, most relevant from the perspective of reconstitution after storage.

Inter-relationship between lactose crystallization and surface free fat during storage of infant formula

Inter-relationship between lactose crystallization (LC), the amount and composition of surface free fat (SFF); and their effect on physico-chemical properties of infant formula (IF) containing hydrolyzed and intact (non-hydrolyzed) whey protein in their composition were investigated at two temperatures (25 and 45 °C) and five RH (11-65%) conditions. Results varied with compositional variation of IF. LC increased exponentially with SFF in non-hydrolyzed IF powders. IF composition influenced LC and caused selective migration of triglycerides, resulting in higher proportion of unsaturated fats in SFF of powders with large lactose crystals and vice-versa. Increase in SFF with increased proportion of saturated fats in their composition, resulted in reduced wettability of powders. Overall, IF composition affects LC which influences the amount and type of fat migration to particle surface resulting in varying wettability of IF powders.

Effect of storage conditions on the physicochemical properties of infant milk formula powders containing different lactose-to-maltodextrin ratios

This study investigated the effect of storage parameters on the physicochemical changes of spray-dried infant milk formula (IMF) powders prepared with various lactose-to-maltodextrin (L:M) ratios (L:M 100:0, L:M 85:15 and L:M 70:30). Powders were characterized during 180 days of storage at 22 and 40 °C and relative humidity (RH) of 11, 23 and 54%. IMF powders were found mostly stable at both temperatures up to 23RH. Deteriorative physicochemical changes were observed at 54RH which were more rapid at 40 °C than at 22 °C. Increasing temperature and RH during storage decreased the glass transition temperature (T_g) to <0 °C and solubility to <25%, while crystallinity increased to >40%. Surface fat content, degree of aggregation and caking increased during storage. Increased surface fat was accompanied by a decrease in surface protein and carbohydrate contents. Incorporation of maltodextrin increased the T_g, decreased the crystallinity and improved the stability of powders.

Physicochemical properties and surface composition of infant formula powders

Compositional difference in infant formula (IF) tends to influence its functionality and storage behaviour. The aim was to study the composition and physico-chemical properties of different stages of two commercial IF (A and B). Lactose crystallization measured by X-ray diffraction ranged between 2 and 32 % and was observed to decrease with increasing IF stages, which directly correlates with their composition. Scanning electron microscopy confirmed the presence of crystalline lactose which significantly (p < 0.05) increased the powder particle size. On the contrary, a negative correlation was observed between surface fat and lactose crystallization in all samples. Bulk and surface-free fat composition was significantly (p < 0.05) different for all samples. Surface free-fat analysis showed restricted presence (5-10% of surface fat) of unsaturated fatty acids (C18:1 and C18:2) in IF with higher crystalline lactose as opposed to >40% in others, suggesting a possible role of lactose crystallization in preferential migration of triglycerides to particle surface.

Effects of Protein-Derived Amino Acid Modification Products Present in Infant Formula on Metabolic Function, Oxidative Stress, and Intestinal Permeability in Cell Models

Proteins present in infant formulas are modified by oxidation and glycation during processing. Modified amino acid residues released from proteins may be absorbed in the gastrointestinal tract, and pose a health risk to infants. In this study, the markers of glycation furosine (1.7-3.5 μg per milligram of protein) and N^ε-(carboxymethyl)lysine (28-81 ng per milligram of protein) were quantitated in infant formulas. The effects of these species, and other amino acid modifications, at the levels detected in infant formulas, on 3T3-L1 (murine preadipocyte) and Caco-2 (human intestinal epithelial) cells were assessed. Incubation of 3T3-L1 cells for 48 h with amino acid side chain oxidation and glycation products (1 and 10 μM) resulted in a loss (up to 40%, p < 0.05) of cell thiols and decreased metabolic activity compared with those of the controls. In contrast, Caco-2 cells showed a stimulation (10-50%, p < 0.05) of cellular metabolism on exposure to these products for 24 or 48 h. A 28% ( p < 0.05) increase in protein carbonyls was detected upon incubation with 200 μM modified amino acids for 48 h, although no alteration in transepithelial electrical resistance was detected. Oxidation products were detected in the basolateral compartments of Caco-2 monolayers when modified amino acids were applied to the apical side, consistent with limited permeability (up to 3.4%) across the monolayer. These data indicate that modified amino acids present in infant formulas can induce effects on different cell types, with evidence of bioavailability and induction of cellular stress. This may lead to potential health risks for infants consistently exposed to high levels of infant formulas.