Changes in composition and functional properties of dairy products made with altered milk fat.

摘要

Modification of milk fat through the diet is an alternative to produce low saturated fat dairy products that meet closely consumer preferences. The aim of this study was to evaluate functional properties of cream, ice cream and butter oil obtained from milks with modified milk fat composition, and correlate these functional properties with fatty acid and triglyceride composition of milk fat. For that purpose we performed an approaching experiment where we infused into the abomasum of lactating dairy cows, a control and five different sources of long-chain free fatty acids in a 6 by 6 Latin square experimental design. From this experiment we concluded that an increase in polyunsaturated fatty acids with a decrease in palmitic acid in milk fat, strongly affect the functional properties of the dairy products under study, mainly because of the effect of polyunsaturated fatty acids on lowering the melting point of milk fat. Monounsaturated fatty acid modification resulted in a better option towards the improvement of milk fat nutritional quality, while keeping adequate functional attributes in dairy products. We also concluded that not all dairy products have the same requirements for fat composition to provide optimal functionality.; Based on the conclusions from our first experiment we developed an experiment to define the optimal amount of intestinally available oleic acid to produce a milk fat with the highest possible monounsaturated fatty acid content and satisfactory functional characteristics. We infused increasing amounts of high oleic sunflower fatty acids (0, 250, 750, and 1000 g/d) into the abomasum of four lactating dairy cows, in a change-over design. Results led us to conclude that decisions on the optimal amount of oleic acid infusion have to consider animal feeding behavior, nutritional quality of milk fat, and functional properties of targeted dairy products. Products under freezing temperatures, like ice creams, may tolerate higher oleic acid infusion levels than whipping creams or butter oil. Palmitic acid should be present in milk fat composition in at least 20% to keep functional properties for most of the products under study. Changes in 21 triglyceride fractions were statistically correlated to functional attributes.