Freezing point and other technological properties of milk of the Polish Coldblood horse breed.

Mare milk is a valued and sought-after raw material for the production of innovative dairy products. The high demand, low supply, high price, and lack of accurate characterization of the milk of a given horse breed may provoke its deliberate fraudulent dilution. The aim of this work was to analyze the freezing point against a background of various selected technological parameters of Polish Coldblood mare milk. Research was carried out on multiparous Polish Coldblood mares from 5 to 8 yr of age with live weights between 618 and 851 kg. Their milk was tested on d 1, 3, and 7 postpartum and once a month for the next 9 mo of lactation (n = 52). Milk from 13 mares, taken daily in mo 4 of lactation, was collected for the dilution study (n = 403). The basic composition of the milk was as follows: solids-not-fat, 84.4 g/kg, fat 15.1 g/kg, lactose 65.3 g/kg, and total protein 24.2 g/kg (made up of casein, 14.6 g/kg, and whey protein, 9.5 g/kg). The dominant amino acids were glutamic acid, proline, leucine, and aspartic acid. The mean freezing point during a 9-mo lactation was -0.557°C (coefficient of variation = -2.787; 5th to 95th percentile: -0.563 to -0.550°C). Based on our analysis, we adopted -0.550°C (from 3 to 6 mo) as the reference value for milk from the Polish Coldblood horse. Analysis of the model of changes in freezing point, after dilution, using the coefficient of determination and Akaike's information criterion, showed that a linear model could be recommended (y = 79.35 + 144.35x). Addition of 1% water increased the freezing point of Polish Coldblood mare milk by 0.0069°C.

Formation of volatile compounds in kefir made of goat and sheep milk with high polyunsaturated fatty acid content.

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.