**1. Introduction**

It has been recognized that components of foods can be contributing factors in human health and disease prevention. Based on the potential benefits to long-term human health there is interest in developing sustainable nutritional strategies for reducing saturated and increasing specific unsaturated fatty acids in ruminant milk. Despite the lower scale of milk production from goats compared with cows in Europe, there is an increasing interest in goat milk due to inherent species-specific biochemical properties that contribute to nutritional quality. Goat milk has been identified as a viable alternative for consumers that are sensitive or develop allergic reactions to bovine milk.

## **1.1. Synthesis and composition of goat milk fat**

Fat composition in goat milk is one of the most important components of the technological, nutritional or dietetic quality of goat milk. Milk fat content in goat milk is high after parturition and then decreases during the major part of lactation. This is related to at least two phenomena: a dilution effect due to the increase in milk volume until the lactation peak, and a decrease in fat mobilization that decreases the availability of plasma non-esterified fatty acids, especially C18:0 and C18:1, for mammary lipid synthesis (Chilliard et al., 2003). Even that, total solids, fat, crude protein, lactose, and ash contents of goat milk are almost similar to cow milk, there are important differences in the individual fatty acids and casein fractions and fat globule sizes. Fat globules of goat milk are smaller in size and do not coalesce upon cooling because of lack of agglutinin, which is responsible for the aggregation of fat globules in cow milk.

Goat milk fat is composed primarily of triglycerids (or triacylglycerides) (in 98%) and in a small part from phospholipids and sterols. Triglycerids are synthesized on the outer surface of the smooth endoplasmic reticulum of the milk alveolar cells from precursor substances: fatty acids and glycerol. They are forming larger globules, which are travelling to the margin of cell. At the beginning, they attach to the membrane and they pass through. Then,

© 2012 Kompan and Komprej, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Kompan and Komprej, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

they are eliminated from the cell as fat globules of the milk. The synthesis is endogenous in a large extent, where the presence of the conjugated linoleic acid plays an important role (Hurley, 2009).

Fatty acids in goat milk are synthesized in epithelial cells of the mammary gland de novo or they are passing over from the blood (Chilliard et al., 2003). Two coenzymes have a major role in the synthesis of fatty acids in goat milk: acetyl-coenzyme A-carboxylase, which participates in the synthesis of fatty acids de novo and fatty acid synthase, which is a complex of enzymatic active substances and is responsible for the extension (elongation) of the fatty acid chain (Hurley, 2009). Fatty acids of exogenous origin are presented via the circulation to mammary epithelial cells either in the form of non-esterified fatty acids or esterified as the acyl groups of the triacylglycerol component of lipoprotein particles. In the mammary gland of ruminant animals, short and medium chain saturated fatty acids are the major products of de novo lipogenesis whereas plasma lipids contribute longer chain and mono unsaturated species. The acetate is the precursor of fatty acids synthesis in ruminants, while in monogastric animals, the precursor is glucose (Clegg et al., 2001).
