Fatty acid specificity, acidolysis

The temperature optimum for interesterification is 85°C or higher, and the half-life in continuous acidolysis of spy bean oil with lauric acid at 60°C is above 2500 h. The non-specificity makes the catalyst useful in random interesterification of different fats. The catalyst has some saturated fatty acid specificity. Two lipase components (A and B) were purified. Lipase A is important for interesterification, and Lipase B is important in ester synthesis. 

The fatty acid specificity in the acidolysis reaction has been examined (Table IV). 

This fatty acid specificity may lead to the assumption that the activity in acidolysis of polyunsaturated fatty acids would be negligible. We have tested the incorporation of polyunsaturated fatty acids isolated from menhaden oil into trilaurin, and found that both immobilized Lipase A and the immobilized crude enzyme are quite active, and more active than the immobilized Mucor miehei lipase (Lipozyme). 

The uses cited by Coleman and Macrae (1980) for the lipase catalysed reaction are examples of acidolysis and transesterification. Acidolysis is illustrated by the increase in l(3)-palmitoyl-3(l)-stearoyl-2-olein (POSt) resulting from the reaction of palm oil mid-fraction with stearic acid in the presence of a 1,3-specific enzyme, and by the increase in the content of linoleic acid in olive oil when that oil is reacted with linoleic acid in the presence of an enzyme with fatty acid specificity. An example of transesterification is shown by the increase in POSt triglycerides when a 1,3-specific enzyme is used to catalyse the interesterification of shea butter and palm oil mid-fraction. 

Shimada, Y, Sugihara, A, Nakano, H, Nagao, T, Suenaga, M, Nakai, S and Tominaga, Y (1997b) Fatty acid specificity of Rhizopus delemar lipase in acidolysis. J. Ferment. Bioeng., 83, 321-327. 

The activities in acidolysis of tricaprin with different fatty acids were measured in separate experiments, each performed like the assay for batch interesterification units. It is observed that the enzyme has seme specificity towards saturated fatty acids. This kind of specificity is unique, and has not previously been described. 

Human milk lipids are unique in that they contain predominantly palmitate at the sn-2 position. To produce an infant formula whose lipids resemble those of mothers milk, Yang et al. (84) employed Rhizomucor miehei lipase to catalyze the acidolysis of lard, which is rich in 2-palmitoyl acylglycerols, with soybean fatty acids. As the enzyme had tight specificity for reaction at the sn- and sn-3 positions of the... 

Enzyme-catalyzed reactions are used to produce human mUkfat substitutes for use in infant formulas (46-48). Acidolysis reaction of a mixture of tripalmitin and unsaturated fatty acids using a i -l,3-specific lipase as a biocatalyst afforded TAGs derived entirely from vegetable oils rich in 2-position palmitate with unsaturated fatty acyl groups in the sn- and sn-3 positions (44). These TAGs closely mimic the fatty acid distribution found in human mUkfat, and, when used in infant formula instead of conventional fats, the presence of palmitate in the sn-2 position of the TAGs improved digestibility of the fat and absorption of other important nutrients such as calcium (46, 49). 

Stmctured lipids possessing n-3 PUFAs, such as EPA and DHA, located at mid position, with MCFAs at the end positions, have gained considerable attention as nutritional and health supplements. These TAGs provide rapid delivery of energy via oxidation of the MCFAs and, at the same time, supply metabolically functional fatty acids in the same molecule. Senanayake and Shahidi (51) used an immobilized in-1,3-specific lipase from Mucor miehei to incorporate capric acid into seal blubber oil containing EPA and DHA. On enzyme-catalyzed acidolysis, a stmctured lipid containing 27.1% capric acid, 2.3% EPA, and 7.6% DHA was achieved. Lipase from Mucor miehei incorporated capric acid predominantly at the in-1,3 positions of the stmctured lipid. 

Enzymatically catalysed acidolysis using specific sn-l,3-Hpases is used for the preparation of dietetically important strudured triacylglycerols of the MUM-type (Figure 3.81) that contain unsaturated (U) essential fatty acids in the outer sn-1,3 positions and medium-chain (M) fatty acids (caprylic or capric) in the sn-2 position. 

Specific plant oils have been used as starting materials to obtain sTAG rich in n-3 PUFA and/or GLA. Acidolysis with medium-chain fatty acids and... 

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