engleski

Nutritional lipid quality indices in milk of different animals

The components of milk provide valuable nutrients for the human body. Milk fat is one of the most complex natural fats that consist of approximately 400–500 fatty acids (FAs). According to the number of double bonds, the FA are classified in saturated fatty acids (SFA), monounsaturated fatty acid (MUFA), and polyunsaturated fatty acid (PUFA), where sum of MUFA and PUFA are total unsaturated FAs (UFA). The aim of the study was to evaluate the nutritional lipid quality indices in milk of different animals. Milk samples were collected from Croatian Lipizzan mares (N = 17), Simmental cows (N = 15), Istrian donkey jennies (N = 30) and Saanen goats (N = 15). Total lipids from the milk samples were extracted and the analysis of methyl esters of FAs was performed using gas chromatography. Indices of concern were: the PUFA/SFA, the hypocholesterolemic/ hypercholesterolemic index (h/H = [(C 18:1+PUFA)/(C14:0+C16:0)]), index of atherogenicity (AI = (C12:0+4*C14:0+C16:0)/UFA), the index of thrombogenicity (TI = C14:0+C16:0+C18:0)/[(0.5*MUFA)+(0.5*n-6)+ (3*n-3)+ (n-3/n-6)]), and the peroxidation index (PI = (monoenoic acid*0.025)+ (dienoic acid*1)+(trienoic acid* 2)+(tetraenoic acid*4). Mare’s milk showed the highest PUFA/SFA index, while cow’s milk had the lowest ratio. The h/H index was the highest in mare’s milk ; mean values were calculated for goat’s and donkey’s milk, while the lowest index was found in cow’s milk. The higher concentration of C12:0, C14:0, and C16:0 in cow’s milk can increase the cholesterol concentration in serum by inhibiting the activity of low-density lipoprotein receptors. The AI as well as TI were the lowest in mare’s milk, mean values were calculated for goat’s and donkey’s milk, while the highest index was found in cow’s milk. These indices depend on the SFA concentration due to C12:0, C14:0, and C16:0 favour the adhesion of lipids to cells of the circulatory and immunological systems and have pro-thrombogenic effect in blood vessels. Mare’s, donkey’s, and goat’s milk had n-6/n-3 ratio below 4.0, which is recommended level by the World Health Organisation ; while in cow’s milk it was 4.54. In mare’s milk PI was 41, which compared to PI values for donkey’s (19), goat’s (10) and cow’s milk (3.4), makes it very sensitive to oxidation. Based on results it can be concluded that mare’s milk has the most favourable nutritional lipid quality indices, but due to high PI, it is recommended to be cooled down quickly, and when fresh, to be used within 6–9 hours after milking.

milk ; nutritional quality indices ; fatty acids

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