Fatty acid composition milk fats, bovine

In terms of composition, Table 7.5 shows that milk fat consists primarily of triglycerides with small amounts of di- and monoglycerides, phospholipids, sterols such as cholesterol, carotenoids, fat-soluble vitamins A, D, E, and K, and some traces of free fatty acids (Renner 1983 Christie 1983). The fatty acid composition of bovine milk fat is characterized by a high proportion of saturated fatty acids (60 to 70%), appreciable amounts of monounsaturated fatty acids (25 to 35%), and small amounts of polyunsaturated fatty acids (4%) (Lampert 1975). Milk fat... 

The complex lipids in milk fat are comprised of the phosphoglycerides, phosphatidyl choline, phosphatidyl serine, phosphatidyl ethanolamine, phosphatidylinositol and plasmalogens. Also, the non-glyceride phospholipid, sphingomyelin, occurs in important amounts (Jensen, 2002). Bitman and Wood (1990) described the distribution of phospholipid classes in bovine milk and their fatty acid composition. The phospholipids comprise about 1% and cholesterol 0.4—0.5% of the total milk fat. These occur almost completely in the milk fat globule membrane. 

The major differences between the lipids of bovine and human milk are in fatty acid composition and triacylglycerol structure. Bovine milk contains substantial quantities of C4 o-Ci0 o, about 2% Cis 2 and almost no other long-chain polyunsaturated fatty acids. The fatty acid composition is not altered by ordinary changes in diet. Human milk contains very little C4 o-C10 o, 10-14%i (w/w of fat) Ci8 2, and small quantities of other polyunsaturates. The triacylglycerol structure differs, with much of the sn-2 position in human milk lipids occupied by C16 0 and the sn-2 position of bovine milk-fat occupied by C4 o-Ci0 o-... 

Few compilations of the extensive fatty acid distributions in butter fat have been made since Iverson et al. (17) reported quantitative data on 82 fatty acids that were detected by means of urea fractionation and gas-liquid chromatography (GLC) (Table 6). Table 7 provides the fatty acid composition of bovine milk lipids. 

Diets. Bovine-based nonfat powdered milk was purchased from Pet-Ag (Hampshire, IL). Fat blends which constituted 47% of total dietary energy were composed of a base fat free of LC-PUFA (currently used in Enfanul, Mead-Johnson Nutri-tionals, Evansville, IN) and of LC-PUFA fats derived from DHA and AA single-cell oils (DHASCO and ARASCO). They were mixed together initially at a DHA/AA ratio of 1 2. Specific amounts of this LC-PUFA mixture were then incorporated into the base fat to obtain DHA and AA levels corresponding to 1 (Diet 1), 2 (Diet 2) and 5 (Diet 5) times the amount provided in term infant formulas in the United States. Diet 0 was the control formula it contained only the base fat and was free of LC-PUFA. Amounts of DHA/AA in Diets 1,2 and 5 were 17 mg/34 mg, 34 mg/68 mg and 85 mg/170 mg per 100 kcal, respectively. The fatty acid composition of the four formulas is presented in Figure 1. 

Table 11.4 Averaged composition of the major fatty acids in bovine milk fat (adapted from Jensen, 2000 297).

The composition and structure of bovine milk fat have been reviewed extensively. There are early reviews by Morrison (1970), Christie (1978, 1995), Jensen and Clark (1988), and Jensen and Newberg (1995) recent articles include a comprehensive review of recent research by Jensen (2002) and two book chapters by Vanhoutte and Huyghebaert (2003), and Zegarska (2003). Bovine milk lipids are similar to the milk lipids of other species as they are largely composed of triacylglycerols however, there are also minor amounts of diacyl-glycerols, monoacylglycerols, free (unesterified) fatty acids, phospholipids and... 

Among the biological lipids, few exceed bovine milk fat in the complexity of fatty acids present and triacylglycerol (TAG) structure. This, together with its importance commercially as a human food, has generated very large data bases on the synthesis and composition of milk fat. In spite of this, Jensen (2002) lamented the paucity of new information on the content of trace fatty acids and complex lipids in milk fat. 

Bovine milk fat has been reported to contain 400 or more fatty acids (1). Caprine and ovine milk fats have not been as extensively examined but could be assumed to contain a similar number of fatty acids since the ruminal processes are similar in these two species. Humans have been consuming these fatty acids in meat and milk products since prehistory when ruminant species became food sources for mankind. The variety and chemical composition of milk lipids is truly amazing. Within the last hundred years many lipid classes, individual fatty acids, and isomeric fatty acids have been identified as analytical capabilities increased. Recent advances in technology have allowed the identification and characterization of specific isomers of fatty acids present in milk fat that contain single cis or trans double bonds (monoenes) and conjugated double bonds (CLA) with none, one, or two trans bonds. These techniques of gas chromatography and HPLC with silver ion columns are described in Volumes 1 and 2 of this series. 

Bovine milk fat contains a number of unique fatty acids, some of which have been linked to specific health-promoting properties. Modifying the chanical composition and structure of the milk can further enhance these properties. One fatty add found in relative abundance in milk fat is conjugated linoleic add (CLA), which continues to receive considerable attention because of its assodation with such potential beneficial effects on health as anticarcinogenic, antiatherogenic, and antidiabetogenic activities [see (1) for review]. Recent human studies have demonstrated the link between dietary CLA intakes and risk of breast cancer in postmenopausal women (2). 

Bovine milk fat is made up of 97-98 (wt% of total lipids) triacylglycerols accompanied by much smaller amounts of diacylglycerols (0.36%) and monoacylglyc-erols (0.03%), free cholesterol (0.31%), trace amounts of cholesteryl esters, phospholipids (0.60%), and minor amounts of free fatty acids. For reviews of the composition of bovine milk lipids, the reader is referred to Christie (4) and Jensen and Clarke (5). More than 400 fatty acids have been identified in milk fat, although it is generally accepted that 15 major and 12 minor fatty acids dominate the fatty acid spectrum. The major fatty acids found in milk are long chain (Cj. , myristic Ci6-o. palmitic Cjg., stearic Cjg.j, oleic) and the minor fatty acids are short chain... 

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