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.

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Colour measuring instruments have become more reliable, smaller and faster than their predecessors at significantly lower costs for the users. This article has been written to provide practical guidelines for technologists, technicians and scientists to better understand colour measurement of dairy products. The results of milk colour measurement are used to determine the health of cows, as well as the quality of the raw material. The measurement of the colour of final dairy products makes it possible to determine their quality and to monitor changes occurring during storage. The article presents the theory of colour evaluation in the CIE L* a* b* space. It specifies what conditions need to be fulfilled while determining the colour and what information should be given when publishing data on colour. The article explains what affects the colour of milk. The article gives examples of studies on the colours of dairy products and practical applications of such studies.

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.

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Cholesterol oxidation products (COPs) have greater biological activity than cholesterol itself. Oxysterols reduce the nutritional value of foods and exhibit a wide range of biological activity, including pro-oxidant, carcinogenic, and cytotoxic properties. The most commonly detected oxysterols in foods are 7α-HC, 7β-HC, a product of their dehydrogenation 7-KC and α-CE, β-CE. The main dietary sources of oxysterols are eggs and egg-derived products, thermally processed milk and milk-based products, fried meat. This study aimed to measure the amount of cholesterol oxidation products in milk powder, egg powder and milk–egg powder during 24 months of storage. The changes in the selected oxysterols (determined by gas chromatography) were recorded. In milk powder, after the production process, the amount of cholesterol was 0.2 g 100 g−1 fat and in egg powder it was 3.4 g 100 g−1. After 6 months of storage, the dominant oxysterol in milk and egg powder was 7α-HC and in milk–egg powder it was 7-KC. After the storage period, oxysterols in powdered milk reached 1.81% of total cholesterol.  The most stable cholesterol was in the milk–egg mixture and its oxidation was the slowest. This study showed the presence of COPs in milk powder, egg powder and milk–egg powder and the effect of storage on cholesterol oxidation.

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.

Streszczenie. W ostatnich latach obserwuje się dynamiczny wzrost produkcji napojów fermentowanych z mleka krowiego i koziego. Dużą popularnością cieszą się napoje o gęstej konsystencji. Celem pracy było wytworzenie metodą termostatową napojów fermentowanych z mleka koziego z użyciem dwóch różnych kultur starterowych firmy Sacco, a także dokonanie oceny sensorycznej i fizyczno-chemicznej otrzymanych napojów. Badania wykonywano bezpośrednio po wyprodukowaniu oraz po 3, 7, 14 i 21 dniach przechowywania w warunkach chłodniczych. Stwierdzono, że proces fermentacji mleka zaszczepionego kulturą zawierająca drożdże był dłuższy niż mleka zaszczepionego kulturą bez drożdży. W czasie chłodniczego przechowywania wzrost kwasowości w napoju z drożdżami był mniejszy. Barwa i tekstura w obu napojach zmieniały się istotnie w czasie przechowywania. Napoje bez drożdży charakteryzowały się mniejszą twardością i rzadszą konsystencją. Napoje różniły się między sobą smakiem, zapachem, konsystencją i homogennością.Słowa kluczowe: mleko kozie, napoje fermentowane, barwa, tekstura Wstęp W ostatnich latach obserwuje się dynamiczny wzrost produkcji mlecznych napojów fermentowanych należących do żywności funkcjonalnej. Coraz więcej pojawia się na rynku napojów mlecznych z udziałem probiotyków, a także wytworzonych z udziałem kultur zagęszczających. Wzrasta również popularność mleka koziego i jego przetworów, gdyż zwiększa się ilość świadomych konsumentów, którzy cenią sobie jego walory