Effect of honeydew honey addition on the water activity and water holding capacity of kefir in the context of its sensory acceptability.

The aim of the research was to check how the addition of honeydew honey and various compositions of starter cultures affects the water holding capacity, water activity, color, syneresis and consistency of the obtained kefir in the context of its sensory acceptability. In this research, 2.5% and 5% (w/w) honeydew honey was added to the samples of model kefir (K) and commercial kefir (K13). Kefirs differed by the type of used starter cultures and conditions of production. The addition of honeydew honey to kefir resulted in increased water holding capacity and a reduction in water activity. Honeydew honey kefir was characterized by the following flavor: astringent, fruity, pungent and waxy. As the honey content increased, the taste and waxy flavor became sweeter. In the sensory assessment, the attributes of texture and mouthfeel, creaminess, density and firmness, do not change because of the honey amount or storage time of the samples. The use of different starter cultures in kefir production with the addition of honeydew honey impacted texture parameters, resulting in up to a 4.8-fold increased viscosity index.

Color Stability of Fermented Mare's Milk and a Fermented Beverage from Cow's Milk Adapted to Mare's Milk Composition.

Color is important for the consumer when making a purchase decision. Mare's milk and, thus, fermented mare's milk is little known to consumers. Thus, it is worth presenting research showing the extent of color change during the production and storage of mare's milk. Herein, we examined the range of color changes in mare's milk and cow's milks adapted to mare's milk composition. These samples were further fermented and stored for 3 weeks at 5 ± 1 °C. Starter cultures containing Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus were used for fermentation. Mare's milk reached the required pH of 4.5 during fermentation faster (255 min) than cow's milk (300 min). After fermentation, mare's milk compared to cow's milk and adapted cow's milk had lower titratable acidity (0.75%) and firmness (145. 6 |(g∙s)|). The water holding capacity (95.6%) and number of Lactobacillus (7.71 log CFU/mL) and Streptocococcus (7.20 log CFU/mL) in mare's and other's milks were the same. Mare's milk was furthest from the ideal white (WI) color, with its chrome (C*) being 1.5-times larger than cow's milk. However, fermented mare's milk was darker than the fermented adapted milk and cow's milk by 36% and 58%, respectively. Storage caused a decrease in the WI, C*, and yellowness index (YI). The fermented mare's milk color stability during production and storage was less than that of fermented cow's milk. After 3 weeks storage, it was observed that the titratable acidity increased to 1.05%, and the pH decreased to 4.3 in fermented mare's milk. The water holding capacity decreased but was still higher compared to fermented cow's milk.

Kinetics of lactose hydrolysis and galactooligosaccharides formation in beverages based on goat's milk and its permeate.

The aim of this work was the analysis of galactooligosaccharides (GOS) formation in a model mixture of goat's milk and its permeate from microfiltration and further concentration by ultrafiltration based on the hydrolysis and transgalactosylation of lactose under various temperature and time regimes. These reactions were catalyzed by a ß-galactosidase from Kluyveromyces lactis. Simultaneous hydrolysis and transgalactosylation of the milk lactose was carried out at 37, 40, and 43 °C for 6 h. The maximum GOS content in the mixture was obtained at 37 °C after 20 min. It was 6.9% of the total sugars and the degree of lactose hydrolysis was 13.3%. This was about 10% more GOS than in milk. The mixture containing GOS had a faster maximum acidification rate, 33% greater than before transgalactosylation.