Physicochemical properties of skim milk powder dispersions after acidification to pH 2.4–3.0 and heating

Process-Induced Molecular-Level Protein-Carbohydrate-Polyphenol Interactions in Milk-Tea Blends: A Review

The rapid increase in the production of powdered milk-tea blends is driven by a growing awareness of the presence of highly nutritious bioactive compounds and consumer demand for convenient beverages. However, the lack of literature on the impact of heat-induced component interactions during processing hinders the production of high-quality milk-tea powders. The production process of milk-tea powder blends includes the key steps of pasteurization, evaporation, and spray drying. Controlling heat-induced interactions, such as protein-protein, protein-carbohydrate, protein-polyphenol, carbohydrate-polyphenol, and carbohydrate-polyphenol, during pasteurization, concentration, and evaporation is essential for producing a high-quality milk-tea powder with favorable physical, structural, rheological, sensory, and nutritional qualities. Adjusting production parameters, such as the type and the composition of ingredients, processing methods, and processing conditions, is a great way to modify these interactions between components in the formulation, and thereby, provide improved properties and storage stability for the final product. Therefore, this review comprehensively discusses how molecular-level interactions among proteins, carbohydrates, and polyphenols are affected by various unit operations during the production of milk-tea powders.

Physical and sensory properties of lemon-flavored acidic beverages formulated with nonfat dry milk during storage

Sensory and physical properties of 2 lemon-flavored beverages with 5% and 7.5% wt/wt nonfat dry milk (NFDM) at pH 2.5 were studied during storage. The 2 beverages had similar volatile compounds, but the 5% NFDM had higher aroma and lemon flavor, with a preferred appearance by consumers due to the lower turbidity and viscosity. After 28 d of storage at 4°C, lemon flavor decreased in the 5% NFDM beverage but was still more intense than the 7.5% one. During 70 d of storage, no microorganisms were detected, and the beverages were more stable when stored at 4°C than at room temperature according to changes of physical properties measured for appearance, turbidity, color, particle size, zeta potential, rheological properties, and transmission electron microscopy morphology. Findings of the present study suggest that NFDM may be used at 5% wt/wt to produce stable acidic dairy beverages with low turbidity when stored at 4°C.

Gluconic acid as a chelator to improve clarity of skim milk powder dispersions at pH 3.0

Clear acidic protein beverages have a niche market. Acidification of skim milk powder (SMP) dispersions to pH 3.0 using citric acid (CA) lowers turbidity but the dispersion remains translucent. The present study aimed at comparing physicochemical properties of 5% w/v SMP dispersions acidified to pH 3.0 using chelating gluconic acid (GA) and CA and non-chelating hydrochloric acid. GA was the most effective in reducing the dispersion turbidity to 394 NTU at pH 3.0, which was further reduced to 248 NTU after heating at 90 °C for 2 min resulting in transparent dispersions. The better chelating ability of GA than CA was supported by the higher extent of dissolved CCP in serum phase. The aggregation of dissociated caseins was not observed for the GA treatment based on transmission electron microscopy. The findings from this study may be used to produce clear casein-based protein beverages.