Principles of lactose crystallization and rheology of milk protein concentrate

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.

Naturally Occurring Glycosidases in Milk from Native Cattle Breeds: Activity and Consequences on Free and Protein Bound-Glycans

Little is known about the extent of variation and activity of naturally occurring milk glycosidases and their potential to degrade milk glycans. A multi-omics approach was used to investigate the relationship between glycosidases and important bioactive compounds such as free oligosaccharides and O-linked glycans in bovine milk. Using 4-methylumbelliferone (4-MU) assays activities of eight indigenous glycosidases were determined, and by mass spectrometry and 1H NMR spectroscopy various substrates and metabolite products were quantified in a subset of milk samples from eight native North European cattle breeds. The results showed a clear variation in glycosidase activities among the native breeds. Interestingly, negative correlations between some glycosidases including β-galactosidase, N-acetyl-β-d-glucosaminidase, certain oligosaccharide isomers as well as O-linked glycans of κ-casein were revealed. Further, a positive correlation was found for free fucose content and α-fucosidase activity (r = 0.37, p-value < 0.001) indicating cleavage of fucosylated glycans in milk at room temperature. The results obtained suggest that milk glycosidases might partially degrade valuable glycans, which would result in lower recovery of glycans and thus represent a loss for the dairy ingredients industry if these activities are pronounced.

Functional sour cream product

Among the diverse assortment of dairy products, sour cream occupies a leading position in terms of production. Despite the current economic situation, sour cream production increased by 3.4% compared to the previous year. The lack of raw milk, as well as the increased demand for healthy food products have led to the creation of a new group of sour cream products, which are supplemented with non-dairy ingredients - fortifiers. Due to the components of plant origin, it is possible to adjust the properties of the product, to give it a functional orientation. The authors proposed a method for the production of a sour cream product with the addition of wheat flakes and peach puree. The sour cream product was produced according to the traditional technological scheme. A feature of the technology is the introduction of plant components into the fermented product. The choice of the optimal dosage of wheat flakes and peach puree was carried out in accordance with the combination of the taste of the filler and the product, the indicators of the consistency and color of the sour cream product. The optimal dosages of the introduced components have been selected experimentally. An assessment of the quality indicators of the finished product has been carried out. The water-holding capacity of samples of sour cream products has been studied. By the amount of whey, you can judge the ability of dietary fiber to swell. The smaller the volume of whey, the more the dietary fiber absorbs moisture, which has a positive effect on the shelf life of the product. The viscosity was determined on a vibration viscometer in samples of samples with an undisturbed, damaged and restored clot. It was found that the sour cream product has the best moisture-absorbing ability, a fairly thick consistency, and after mixing it well restores the structure. It has been determined that the use of plant materials has a beneficial effect on the quality of the product.

Influence of Emulsifiers and Dairy Ingredients on Manufacturing, Microstructure, and Physical Properties of Butter

The influence of emulsifiers and dairy solids on churning and physical attributes of butter was investigated. Commercial dairy cream was blended with each of the ingredients (0.5%, w/w) separately, aged overnight (10 °C), and churned (10 °C) into butter. The employed additives showed a distinctive impact on the macroscopic properties of butter without largely affecting the melting behavior. In fresh butter, polyglycerol polyricinoleate (PGPR) emulsifier having dominated hydrophobic moieties significantly (p < 0.05) enhanced the softness. Among dairy solids, sodium caseinate (SC) was the most effective in reducing the solid fat fraction, hardness, and elastic modulus (G’), while whey protein isolate (WPI) and whole milk powder (WMP) produced significantly harder, stiffer, and more adhesive butter texture. As per tribological analysis, PGPR, Tween 80, and SC lowered the friction-coefficient of butter, indicating an improved lubrication property of the microstructure. The extent of butter-setting during 28 days of storage (5 °C) varied among the samples, and in specific, appeared to be delayed in presence of WPI, WMP, and buttermilk solids. The findings of the study highlighted the potential of using applied emulsifiers and dairy-derived ingredients in modifying the physical functionality of butter and butter-like churned emulsions in addition to a conventional cream-ageing process.

Determination of Lactose Concentration in Low-Lactose and Lactose-Free Milk, Milk Products, and Products Containing Dairy Ingredients: Single Laboratory Validation of an Enzymatic Method, First Action Method 2020.08

Background The AOAC Stakeholder Panel on Strategic Food Analytical Methods issued a call for methods for the measurement of lactose in low-lactose and lactose-free products under SMPR 2018.009 (1). Megazyme’s Lactose Assay Kit (K-LOLAC) was developed specifically to address the need for accurate enzymatic testing in lactose-free samples. Objective The Lactose Assay (K-LOLAC) was validated for measurement of lactose in low-lactose and lactose-free milk, milk products, and products containing dairy ingredients. A single-laboratory validation of the method is reported. Method The Lactose Assay (K-LOLAC) is an accurate and sensitive enzymatic method for the rapid measurement of lactose in low-lactose or lactose-free products. Validation analysis was performed on a sample set of 36 commercial food and beverage products and a set of 10 certified reference materials. Parameters examined during the validation included working range and linear range, selectivity, LOD, LOQ, trueness (bias), precision (repeatability and intermediate precision), robustness and stability. Results For all samples tested within the lower range (10–100 mg/100 g or mL), recoveries varied from 93.21–114.10%. Recoveries obtained for samples in the higher range (&gt;100 mg/100 g or mL) varied from 94.44–108.28%. All materials had repeatability relative standard deviations (RSDr and RSDir) of &lt; 9%. Conclusions The commercial Lactose Assay Kit (K-LOLAC) as developed by Megazyme meets the requirements set out under SMPR 2018.009. Highlights The Lactose Assay (K-LOLAC) is a robust, quick and easy method for analysis of lactose in foodstuffs and beverages.