To reduce the melting point of a tallow-rapeseed oil mixture, the triglyceride composition of the mixture was altered by enzymatic interesterification in a solvent-free system. The interesterification and hydrolysis were followed by melting point profiles and by free fatty acid determinations. The degree of hydrolysis was linearly related to the initial water content of the reaction mixture. The rate of the interesterification reaction was influenced by the amount of enzyme but not much by temperature between 50 and 70~ The melting point reduction achieved by interesterification depended on the mass fractions of the substrates: the lower the mass fraction of tallow, the larger the reduction of the melting point.

The efficacy of water, chlorinated water (100 ppm), peracetic acid solution (0.05%), and commercial citric acid-based produce wash (0.25%) to reduce the population of Listeria monocytogenes on precut lettuce was tested. Samples were inoculated with a mixture of equal amounts of five L. monocytogenes strains at a level of 4.7 log CFU/g, and analyzed on the day of washing and after 3 and 6 days of storage at 6 degrees C. Sanitizer reduced the number of L. monocytogenes at maximum 1.7 log CFU/g and number of L. monocytogenes reached the inoculation level during 6 days of storage. Thus, disinfectants do not eliminate L. monocytogenes on precut lettuce and cannot be solely relied on in producing precut lettuce safely. The inoculated L. monocytogenes strains were recovered at different rates after 6 days of storage; one of these strains was not recovered at all. Thus, strain-specific differences exist in the ability of L. monocytogenes to survive the washing treatments of the lettuce.

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Byl? F o r s s e l l , R. K e r v i n e n , M . A I k i o a n d K . P o u t a n e n *Polar lipids of crude oat oil were investigated. Oat oil was separated from oats by extraction with isopropanol. Polar Iipids were fractionated from crude oil by supercritical CO2-extraction, by ultrafiltration in hexane and by water degumming. The polar fraction from C02-extraction had the highest phospholipid and lowest tocopherol content. The polar fractions made by different methods possessed similar antioxidative properties. However, the polar lipids from oats were more powerful antioxidants than those made from soybean or rapeseed oil. Fat Sci. Technol. 94.lahrgang Nr.9 1992 PERCENT LECITHIN ADDED Fat sd.Technol. 94. Jabgang Nr.9 1992 * T.S. Kahlon, Cereal Foods World, 34,872 [1989].Cooperation of the following colleagues at VTT is gratefully acknowledged: Mr. 0. Aaltonen for valuable discussions, Ms. A . Rtisgnen for performing the lipid class analysis, Ms. Z Lup: Forssell, M. Cetin, G, Wirtanen and y Malkki, Fat sci.

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