Research of content of oleic acid trans-isomers in the fat phase of milk and confectionary products

Abstract

The object of the research were rennet cheeses, cottage cheese, sour cream, butter, cream, condensed milk, pasteurized and whole milk. A method of capillary gas chromatography was used for identification and quantification of fatty compounds in products.High consumption of trans isomers present in certain fats of industrial origin, adversely affects human health. There is an evidence that the profile of acid C18:1 trans-isomers differs depending on their origin – bacterial hydrogenation or industrial hydrogenation. However, at present the data on the content of C18:1 trans isomers and the availability of their forms in different foods is quite limited.It was shown that the characteristic for milk fat short-chain acids slightly vary depending on the type of dairy product and very different from animal or vegetable fats especially in the range of C4:0 – C12:0 and C18:2 acids.The total content of C 18:1 acid trans-isomers in the studied dairy products ranged from1.84 to 6.67%; in some samples of milk containing products it was 27-35%. The idea of research importance of not only the total content of C 18:1 trans-isomers, but its specific isomeric forms is based on the fact that trans-isomers can damage cells in brain and peripheral nervous system, which increases the risk of multiple sclerosis, Parkinson’s and Alzheimer’s diseases.It was shown that in milk fat of the studied products isomer C 18:1 T11 was dominant, which was 30-60% of all the identified trans-isomers and to 6,34 % of all the identified fatty acids, and in milk containing products – C 18:1 T9 isomer, the level of which in fat phase was dependent on the type of vegetable oil substitute and its mass fraction in fat phase. On the basis of the data presented it was proposed to add methyl esters t9/t11 C18:1 mass fractions ratio as an additional indicator of fat phase naturalness, including trans-isomers nature. For dairy cow fat it was 0,14-0,36, and for milk containing products – 0,43-1,65.A monitoring of trans-isomers content in domestic dairy products was conducted. According to the data obtained trans-isomer content ranged from 1,84% to 6,67%, that meets normative documents requirements. The differences between trans-isomeric composition of natural milk fat and fats of industrial production were detected. A calculation of the ratio of oleic acid t9/t11-isomers was proposed as additional characteristic of trans-isomers naturalness in fat phase of dairy and confectionary products.