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In this study, varying concentrations of polyunsaturated fatty acids in goat’s milk were obtained by supplementing goat feed rations with maize dried distillers grains with solubles (DDGS). In comparison to the control group, the milk of goats that received DDGS contained about 25% more polyunsaturated fatty acids, 30% more conjugated linoleic acid (CLA), and had more favorable values of the atherogenic and thrombogenic indices. The diverse composition of fatty acids present in the goat’s milk correlated with the olfactory perception of the milk and its volatile compound profile. The level of unsaturated fatty acids significantly affected the odors detected in the processed goat’s milk. The volatile compound profile of the milk was mostly differentiated by the concentrations of aldehydes (hexanal and furfural) and furanones (furaneol), which exceeded their odor threshold values. The total concentration of identified aldehydes was highest in pasteurized milk samples from the goats of the experimental group, as a result of heating. Furfural was found in pasteurized samples of both the control and experimental milk at concentrations exceeding its odor threshold (3 mg·kg−1). Feeding goats with DDGS did not change the animal, cooked, dairy fat, lack of freshness, light-oxidized, or overall dairy flavors of the raw milk. After pasteurization, milk from goats fed with DDGS retained its characteristic animal odor and gained a very intense cooked flavor.

Color is important for the consumer when making a purchase decision. Mare&rsquo, s milk and, thus, fermented mare&rsquo, 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&rsquo, s milk. Herein, we examined the range of color changes in mare&rsquo, s milk and cow&rsquo, s milks adapted to mare&rsquo, s milk composition. These samples were further fermented and stored for 3 weeks at 5 &plusmn, 1 &deg, C. Starter cultures containing Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus were used for fermentation. Mare&rsquo, s milk reached the required pH of 4.5 during fermentation faster (255 min) than cow&rsquo, s milk (300 min). After fermentation, mare&rsquo, s milk compared to cow&rsquo, s milk and adapted cow&rsquo, 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&rsquo, s and other&rsquo, s milks were the same. Mare&rsquo, s milk was furthest from the ideal white (WI) color, with its chrome (C*) being 1.5-times larger than cow&rsquo, s milk. However, fermented mare&rsquo, s milk was darker than the fermented adapted milk and cow&rsquo, s milk by 36% and 58%, respectively. Storage caused a decrease in the WI, C*, and yellowness index (YI). The fermented mare&rsquo, s milk color stability during production and storage was less than that of fermented cow&rsquo, 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&rsquo, s milk. The water holding capacity decreased but was still higher compared to fermented cow&rsquo, s milk.

Camelina sativa cake (CS), a rich source of unsaturated fatty acids, in the case of ruminants may improve the energy value of a diet and also increase the unsaturated fatty acid content in milk. Effects of basal diet (control) and basal diet plus 12 g 100 g −1 of CS in concentrate dry matter on fatty acid composition of goat's milk and kefir made from this milk were examined with particular emphasis on the contents of monoenes and conjugated isomers of linoleic acid. A total of 66 goats of the Polish White Improved breed were divided into two groups – the control and receiving CS. The diets were administered to animals for 30 days. Elevated concentrations of total monounsaturated fatty acids, the effect of an increased levels of monounsaturated fatty acids in the trans configuration as well as an increased content of total polyunsaturated fatty acids resulted from CS supplementation. Total saturated fatty acid concentration was decreased. Milk from CS-supplemented goats and kefir made from this milk were characterized by increased levels of beneficial nutritional factors, including mono- and polyunsaturated fatty acids.

BACKGROUND The composition of bioactive components in dairy products depends on their content in raw milk and the processing conditions. The experimental material consisted of the milk of dairy goats supplemented with 120 g d−1 per head of false flax cake. The aim of the study was to evaluate the quality of kefir produced from goat's milk with a higher content of bioactive components resulting from supplementation of the goats' diet with false flax cake. RESULTS The administration of false flax cake to goats had a positive effect on the fatty acid profile of the raw milk, causing an increase in the proportion of polyunsaturated fatty acids (PUFA), including conjugated linoleic acid (CLA) and n-3 fatty acids. Their increased percentage was detected in the kefir after production as well as after storage. The processing value of the harvested milk did not differ from the qualitative characteristics of milk from goats of the control group. Increasing the proportion of bioactive components in goat's milk did not result in changes in the acidity, texture, colour, flavour, aroma or consistency of the kefir obtained. CONCLUSION Milk and kefir obtained after the administration of false flax cake to goats contain bioactive components (PUFA including CLA, n-3 and monoenic trans fatty acids) in significant amounts. Kefir from experimental goat's milk did not differ in quality from kefir made from the milk of the control group. © 2014 Society of Chemical Industry

This article explored the formation of volatile compounds during the production of kefir from goat and sheep milks with high polyunsaturated fatty acids (PUFA) as a result of feeding animals forage supplemented with maize dried distillers grains with solubles (DDGS). The increased PUFA content of the goat and sheep milks resulted in significant changes to the fermentation process. In particular, apart from an increase in the time taken to ferment sheep milk, fermentation yielded less 2,3-butanedione. The highest quantities of this compound were assayed in kefir produced from goat milk with an increased content of PUFA. An increase of PUFA significantly elevated ethanal synthesis during lactose-alcohol fermentation of sheep milk. Neither the origin of milk (sheep or goat) nor the level of PUFA had any statistical effect on the amount of ethanal assayed during the fermentation of milk and within the finished product. The proportion of l(+)-lactic acid was higher in kefirs produced using goat milk compared with sheep milk and did not depend on the content of PUFA in milk fat. The content of PUFA had a significant effect on the aroma profile of the resulting kefirs. An increase in PUFA content resulted in the loss of whey aroma in goat milk kefirs and the animal odor in sheep milk kefirs, and a creamy aroma became more prevalent in kefirs made from sheep milk.