Hydrolysis of fats and oils with moist oat caryopses |
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Authors: | Shantilal Parmar E G Hammond |
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Affiliation: | (1) Center for Crops Utilization Research, Iowa State University, 50011 Ames, Iowa;(2) Department of Food Science and Human Nutrition, Iowa State University, 3385 Food Sciences Building, 50011 Ames, IA |
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Abstract: | To improve the economic feasibility of hydrolyzing fats and oils with moist oat caryopses, various factors affecting the efficiency
of the process were studied. Caryopses produced with an impact-type dehuller exhibited greater lipase activity than those
produced by a wringer-type dehuller. Abrasion of oat caryopses against each other in a fluidized bed released particles rich
in lipase. Such lipase concentrates could be added to moist caryopsis reactors to speed fat hydrolysis. Beef tallow, lard,
soybean oil and crambe oil were hydrolyzed more efficiently than corn oil, castor oil and milk fat. The poor hydrolysis of
castor oil was attributed to the formation of esters with the hydroxy group of ricinoleic acid, and the hydrolysis of castor
oil was increased by dilution of the substrate with hexane. Diglycerides inhibited the hydrolysis and accounted for the slower
hydrolysis of corn oil. Hydrolysis of milk fat by moist oat caryopses resulted in preferential hydrolysis of C6 to C10 acids. Erucic acid was released from crambe oil at significantly slower rates than the other acyl groups. High conversions
of fats and oils to free fatty acids could be attained by (i) exposing the fats and oils to two to three lots of moist caryopses,
(ii) the use of special oat varieties with elevated lipase content, (iii) the addition of oat lipase concentrates to moist
caryopsis reactors, and (iv) dilution of the substrate with hexane. Estimates of the cost of producing free fatty acids with
these processes indicated that the first three should be profitable. Growth ofClostridium sporogenes spores could not be demonstrated in caryopsis reactors. During the incubation of moist oat caryopses immersed in oil, the
free fatty acid content of the internal caryopsis lipid increased only slightly, but there were changes in its fatty acid
composition. |
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Keywords: | Fat hydrolysis lipase oats |
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