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Title: LIPASE-CATALYZED REACTIONS IN ORGANIC AND SUPERCRITICAL SOLVENTS: APPLICATION TO FAT SOLUBLE VITAMIN DETERMINATION IN MILK POWDER AND FORMULA

Author
item TURNER, CHARLOTTA - LUND UNIVERSITY, SWEDEN
item PERSSON, MATTIAS - LUND UNIVERSITY, SWEDEN
item MATHIASSON, LENNART - LUND UNIVERSITY, SWEDEN
item ADLERCREUTZ, PATRICK - LUND UNIVERSITY, SWEDEN
item King, Jerry

Submitted to: Enzyme and Microbial Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: The determination of vitamin content in various foods is of importance to meet human nutritional requirements and labeling laws. Analytical determination of vitamin content is difficult due to their low levels in foodstuffs and sensitivity to degradation due to exposure to oxygen or light. In this study, extraction of vitamin A and E from milk and infant formula was accomplished using high pressure carbon dioxide as the solvent aided by inclusion of an enzyme in the extraction cell to facilitate hydrolysis of the vitamin A moiety. Eight different types of enzymes were tested with respect to their hydrolytic efficiency and three were found satisfactory in the presence of high pressure carbon dioxide. The derived values of vitamin A content matched very well with those levels certified in standard materials (milk and infant formula). The described method and evaluation of enzyme action permits a substantial reduction in analysis time and associated chemicals and solvents used in conventional vitamin assays in foods. The results of this research will be applicable to industrial food analysis and in support of regulatory agency certification.

Technical Abstract: The aid of this study was to thoroughly investigate the possibility of using enzyme catalyzed hydrolysis of ester bonds in vitamin A and E esters to facilitate their determination in different food formulas. Two vitamin esters, retinyl palmitate and alpha-tocopheryl acetate were used as model compounds and two food formulas, milk powder and infant formula, were used as model matrices. Six lipases and one esterase were investigated in the solvents di-isopropyl ether, hexane and supercritical carbon dioxide. Three of the enzyme preparations, lipases from Candida antarctica (Novozyme 435), Rhizomucor miehei and Pseudomonas cepcacia, showed considerably higher activity toward retinyl palmitate than the other four enzyme preparations. There was no observed activity with alpha-tocopheryl acetate using any of the enzymes. Novozyme 435 showed highest activity in supercritical fluid and generally larger tolerance to variations of the investigated parameters. Using this enzyme preparation in supercritical carbon dioxide containing 3 vol% ethanol and 1.15 vol% water at 366 bar and 80 deg C, quantitative conversion was obtained of retinyl palmitate to retinol. These conditions were then used for simultaneous lipase-catalyzed reaction and extraction of vitamin A and E from milk powder and infant formula. The developed supercritical fluid extraction method using immobilized Candida antarctica was friendlier to the oxidation prone vitamins A and E, giving recoveries of 100-140%, when compared to results obtained with the same samples using extraction methodologies based on alkaline saponification.