S. Koritala

A novel compound, 7,10-dihydroxy-8(E)-octadecenoic acid from oleic acid by bioconversion

Sixty-two cultures from the Agricultural Research Service (ARS) Culture Collection and 10 cultures isolated from soil and water samples in Illinois were screened for their ability to convert agricultural oils to value-added industrial chemicals. A new compound, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD), was produced from oleic acid at a yield of greater than 60% by bacterial strain PR3 which was isolated from a water sample in Morton, IL. To our knowledge, DOD has not been previously reported. The optimum time, pH and temperature for the production of DOD were 2 days, 7.0, and 30°C, respectively. The production of DOD is unique in that it involves hydroxylation at two positions and rearrangement of the double bond of the substrate molecule.

• %Biochemical Modification of Fats by Microorganisms: A Preliminary Survey

Over 100 different strains of bacteria, actinomycetes, fungi and yeasts were incubated at 28 C for five days in the presence of soybean oil. Some soybean oil was consumed by many microorganisms, and some was also hydrolyzed to free fatty acids.Aspergillus oryzae, two different strains ofAmylomyces rouxii andRhizopus oligosporus hydrolyzed the oil completely (95%). The fatty acids fromAspergillus flavus fermentation contained less linolenic acid than the original soybean oil. Lipase was found intra- and extracellularly when microorganisms were grown in the presence of soybean oil.

Selective hydrogenation of soybean oil: V. A Novel copper catalyst with excellent re-use properties

A procedure for the preparation of highly active copper catalyst by chemisorption of copper-ammonia complex on silica gel is described. This catalyst was highly selective towards the reduction of linolenate in soybean oil. The catalyst was re-used four times with no loss in activity.

Flavor and oxidative stability of hydrogenated and unhydrogenated soybean oils: Effects of antioxidants

Flavor and oxidative stabilities were studied by organoleptic evaluation and chemical analysis of three different samples of soybean oil: unhydrogented (I); hydrogenated with nickel catalyst (II); and hydrogenated with copper-chromium catalyst (III). Analyses for these oils were: I II III iodine Value 138 109 113 Linolenate, % 8.3 3.3 0.4 Each oil was deodorized with the addition of either citric acid alone or citric acid plus BHA and BHT antioxidants. Addition of antioxidants did not improve the flavor stabilities of the oils in accelerated storage tests but did improve the flavor stabilities of II and III in light exposure tests. All three oils that received the same additive treatment had equivalent flavor stability in both accelerated storage and light exposure tests. However, both hydrogenation and antioxidant treatment improved oxidative stability as measured by the Active Oxygen Method. There was good correlation between flavor score and the logarithm of the peroxide value determined at the time of tasting.

High oleic oils by selective hydrogenation of soybean oil

High oleic (monoene) oils were obtained from soybean oil by selective hydrogenation with copper catalysts. A mixture of nickel and copper chromite catalyst had activity suitable for producing the high monoene oils. A new catalyst (copper-on-Cab-O-Sil) prepared in the Laboratory was more active than commercial copper catalysts. Hydrogenated oils contained 61–72% monoenoic and 14–24% dienoic acids, and there was essentially no increase in stearic acid. Thetrans-isomer content of these oils varied between 17% to 32%. Double bonds in the monoene were distributed along the molecule from C6 to C15, but were located preferentially in the C9 position for thecis-monoene and in the C10 and C11 positions for thetrans-monoene. When the iodine value of these high monoene oils was about 90–95, they remained liquid above 28 C. Citric acid treatment reduced the copper content of hydrogenated oils to a level that was comparable to that of the original soybean oil.

Selective hydrogenation of soybean oil. VI. Copper-on-silica gel catalysts

The preparation of copper-on-silica gel catalysts containing 15% and 20% copper is described. These catalysts can be reused three times without appreciable loss of activity. Their activity compares favorably with the highly active 5% copper-on-silica gel catalyst previously reported. Higher copper catalysts are somewhat less selective for the reduction of linolenate in soybean oil than 5% copper-on-silica gel, but these copper catalysts have greater activity, better reuse characteristics, and selectivity comparable to commercial copper-chromite catalysts.

Selective hydrogenation of soybean oil: X. Ultra high pressure and low pressure1

Soybean oil was partially hydrogenated with copper-chromite catalyst at 170 C and up to 30,000 psig hydrogen pressure. Catalyst activity increased with increase in pressure up to 15,000 psig. The linolenate selectivity (SLn) of the reaction remained essentially unchanged over 50–1000 psig pressure range. A SLn of 5.5 to 5.6 was achieved at 15,000 to 30,000 psig pressure range. This value is somewhat lower than the selectivity at 50–1000 psig, but much higher than that obtained with nickel catalysts. Geometric isomerization increased as pressure increased up to 200 psig; above this pressure, the percenttrans remained the same up to 500 psig.trans Isomer content decreased when the pressure was increased to 30,000 psig. cis,trans Isomerization of linoleate was greater at 1000 psig and 15,000 psig than at 50 psig. At 15,000 psig, part of the linoleate in soybean oil was hydrogenated directly without prior conjugation, whereas at low pressures, all of the double bonds first conjugate prior to hydrogenation. This difference in mechanism might explain the lower selectivities obtained at high pressures. Conjugated diene isomers were found in the products up to 200 psig. Above this pressure conjugated diene was not measurable. No significant differences were found in the double bond distribution oftrans monoenes even though the amount oftrans monoene formed decreased as pressure was increased to 30,000 psig.

Selective hydrogenation of soybean oil: VII. Poisons and inhibitors for copper catalysts

Hydrogenation rates for the catalytic reduction of soybean oil with a copper-on-silica catalyst increased when the oil was re-refined and bleached in the laboratory. Purification of the re-refined and bleached oil by passage through alumina further enhanced hydrogenation rates. Since these observations suggested that poisons were present in the oil, the effect of minor components of soybean oil upon the activity of copper catalysts was investigated. Free fatty acids, monoglycerides, β-carotene, phosphoric acid, sodium soaps, phosphatides, glycerine, choline, ethanolamine, water, pheophytin, and pyrrole all reduced hydrogenation rates when added to the oil. Organic sulfur added to the oil was a more effective catalyst inhibitor than inorganic sulfur added to the gas. Catalyst activity was affected adversely when iron was added to the oil as a soap or when deposited on the catalyst during its preparation. Squalene, copper soaps, and carbon monoxide had no influence on the activity of the catalyst. Aging of soybean oil also had no effect. There was no significant change in either selectivity or formation oftrans or conjugated diene isomer when these additives were added to the oil.

Selective hydrogenation of soybean oil with sodium borohydride-reduced catalysts

The reaction of metallic salts in aqueous solution with sodium borohydride produces finely divided metals that are catalytically active for hydrogenation. Salts of nickel, cobalt, palladium and platinum give active catalysts for the selective hydrogenation of soybean oil. Iron and silver salts, when reduced with sodium borohydride, show no activity at 200C and atmospheric hydrogen pressure. The cobalt catalyst produces the least amount of stearate. Incorporation of palladium, platinum, copper or chromium up to 2% enhance the activity of the nickel catalyst. Copper and chromium salts, when reduced together, form catalysts that hydrogenate linolenyl groups in soybean oil seven times more rapidly than linoleyl groups. No stearate formation is observed with these binary catalysts.

Hydrogenation of unsaturated fatty esters with copper-chromite catalyst: Kinetics, mechanism and isomerization

Hydrogenation of linolenate with copper chromite produced a large amount of conjugated diene and minor amounts of nonconjugatable dienes. The double bonds in conjugated dienes and monoenes were scrambled all along the chain. This product distribution can be explained if it is assumed that conjugation of the double bonds is followed by hydrogenation. In competitive hydrogenation, fatty esters with conjugated double bonds were reduced preferentially over fatty esters with methylene-interrupted double bonds. Isomerization of conjugated double bonds (geometric and positional) occurred more rapidly than reduction. Reduction of conjugated double bonds in the presence of deuterium resulted in a majority of the products containing no deuterium. Most of the added deuterium was incorporated into the unreacted material. Mechanisms are proposed to account for the products formed during the hydrogenation of linolenate, linoleate and their isomers.