Abstract
Several studies have reported that lactic acid bacteria may increase the production of free fatty acids by lipolysis of milk fat, though no studies have been found in the literature showing the effect of kefir grains on the composition of fatty acids in milk. In this study the influence of kefir grains from different origins [Rio de Janeiro (AR), Viçosa (AV) e Lavras (AD)], different time of storage, and different fat content on the fatty acid content of cow milk after fermentation was investigated. Fatty acid composition was determined by gas chromatography. Values were considered significantly different when p<0.05. The highest palmitic acid content, which is antimutagenic compost, was seen in AV grain (36.6g/100g fatty acids), which may have contributed to increasing the antimutagenic potential in fermented milk. Higher monounsaturated fatty acid (25.8g/100g fatty acids) and lower saturated fatty acid (72.7g/100g fatty acids) contents were observed in AV, when compared to other grains, due to higher Δ9-desaturase activity (0.31) that improves the nutritional quality of lipids. Higher oleic acid (25.0g/100g fatty acids) and monounsaturated fatty acid (28.2g/100g fatty acids) and lower saturated fatty acid (67.2g/100g fatty acids) contents were found in stored kefir relatively to fermented kefir leading to possible increase of antimutagenic and anticarcinogenic potential and improvement of nutritional quality of lipids in storage milk. Only high-lipidic matrix displayed increase polyunsaturated fatty acids after fermentation. These findings open up new areas of study related to optimizing desaturase activity during fermentation in order to obtaining a fermented product with higher nutritional lipid quality.
Highlights
Kefir grains are a starter culture used for producing kefir beverage, obtained by fermenting milk with kefir grains
Grains AV and AD were kindly provided by researchers from Brazilian universities (Universidade Federal de Lavras-UFLA and Universidade Federal de Viçosa-UFV), whereas the third grain (AR) belonged to a family that traditionally cultivated the kefir grain in private household for self-consumption
Greater values of HH indicate better nutritional quality [32]. Another indicator of nutritional quality is the polyunsaturated fatty acids (PUFA)/SFA ratio which is recommended to be above 0.4 by health guidelines in order to prevent an excess of saturated fatty acids with a detrimental effect on the LDL cholesterol plasmatic level [33]
Summary
Kefir grains are a starter culture used for producing kefir beverage, obtained by fermenting milk with kefir grains. Kefir Grains Change Fatty Acid Profile in Milk pathogens, enhancement of the intestinal barrier and modulation of the immune response. These health benefits have been observed both in vitro and in vivo experiments [2, 3]. Fatty acids such as butyric acid (4:0), oleic acid (18:1n9), palmitic acid (16:0) and conjugated linoleic acid, which have shown antimutagenic and/or anticarcinogenic properties, may be altered in their proportions by fermentation [4,5,6,7]. Epidemiological studies have shown that consumption of fermented dairy products can reduce the risk of colorectal cancer [9, 10]
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