CLA formation in oils during hydrogenation process as affected by catalyst types, catalyst contents, hydrogen pressure, and oil species

Abstract

The effects of types and amount of catalysts, hydrogen pressure, and kinds of vegetable oils on the formation of CLA isomers were studied during hydrogenation. CLA isomers were identified by using a silver ion-impregnated high-performance liquid chromatograph and 100-m cyano-capillary column gas chromatograph. A selective catalyst (SP-7) produced a considerably higher content of CLA in soybean oil than nonselective catalysts. The maximal quantity of CLA produced in soybean oil during hydrogenation increased greatly with increasing amount of catalyst. By increasing the amount of selective catalyst from 0.05 to 0.3%, the quantity of total CLA obtained was about 1.9 times higher. Changes in hydrogen pressure also greatly influenced total CLA formed. By decreasing hydrogen pressure from 0.24 to 0.024 MPa, the quantity of CLA obtained was about 1.3 times higher. With different oil species (soybean, cottonseed, and corn oils), the time to reach the maximal quantity of CLA was different under the same hydrogenation conditions. However, the maximal quantity of CLA and proportion of CLA isomers formed were almost identical, regardless of oil species tested, under the same hydrogenation conditions. EXPERIMENTAL PROCEDURESMaterials. Authentic CLA methylesters, stearic acid methylester, oleic acid methylester, linoleic acid methyl ester, linolenic acid methylester, arachidic acid methylester, behenic acid methylester, and heptadecanoic acid methylester were purchased from Sigma Chemical Co. (St. Louis, MO). HPLCgrade hexane and acetonitrile were purchased from Mallinckrodt Specialty Chemicals (Paris, KY). Sodium methoxide in

Conjugated linoleic acid formation by hydrogenation/isomerisation of safflower oil over bifunctional structured catalyst Rh/SBA‐15

“…The formation of these isomers was favoured at low hydrogen pressures (4 psi). Jung et al (2001Jung et al ( , 2002 reported the effect of hydrogen pressure on the quantity of CLAs in hydrogenated soybean oil using selective Ni catalysts. They demonstrated that when the hydrogen pressure increased, the total CLA content in soybean oil decreased.…”

“…Several studies on CLA enrichment of vegetable oils, without the triglycerides hydrolysis, have been carried out in the past few years. Jung et al (2001Jung et al ( , 2002 reported the effects of catalyst type, catalyst amount, reaction temperature, agitation rate, hydrogen pressure and different oils on the quality and quantity of CLAs of hydrogenated soybean oil using a selective Ni catalyst. They concluded that the gas-liquid mass transfer limitation conditions at low hydrogen pressure, low stirring rate, high catalyst content and high reaction temperature favoured the CLA production in vegetable oils during hydrogenation and reached 250 mg g −1 oil.…”

Autoxidation and photooxidation of triacylglycerols containing conjugated linoleic acids

“…Resulting hydrogenated soybean oil was subjected to Ag + -HPLC for isolation and identification of individual CLA isomers. Elution patterns of chromatographic peaks for authentic CLA methyl esters and soybean oil FAME standards were the same as reported previously (11,21,28). The individual Ag + -HPLC peak of hydrogenated soybean oil was identified based on comparison with authentic CLA standards (22,29).…”

“…Hydrogenation conditions were essentially the same as reported by Jung et al (11,21). Hydrogenation was carried out using the commercially available selective catalyst SP-7 (Engelhard) with an amount of 0.3% (w/w) catalyst, a hydrogen pressure of 0.24 MPa, a temperature at 230 o C, and an agitation rate at 300 rpm for 320, 360, and 380 min for soybean, cottonseed, and corn oils, respectively.…”

“…Dairy products (milk, butter, cheese, and yogurt) and meats from ruminant animals reportedly contained large quantities of CLA (approximately 3-8 mg of total CLA/g of fat) (5). Vegetable oils reportedly contained low levels of CLA, ranging from 0.1 mg of CLA/g of oil (coconut oil) to 0.7 mg of CLA/g of oil (safflower oil) (11).…”