Effect of the degree of processing on soy oil conjugated linoleic acid yields

Valorization of waste chicken skin for conjugated linoleic acid (CLA) production: optimization using response surface methodology

The valorization of waste chicken skin fat (WCSF) for conjugated linoleic acid (CLA) production was performed by photoisomerization and optimized the process conditions for high CLA production by response surface methodology. The fat extraction yield from waste chicken skin was approximately 52%. The linoleic acid content of the fat obtained from waste chicken skin was increased by the fractionation process approximately 2 times, up to 52%. Optimum iodine amount and processing time for predicted maximum total CLA amount were determined as 0.87% and 116.36 h, respectively. The maximum total CLA amount was predicted and produced experimentally as 32.14% and 29.01%, respectively. Additionally, iodine amount, processing time, and their interaction significantly affected the amount and variety of produced CLA isomers. The results indicated that dominant isomers produced by photoisomerization of WCSF were trans, trans isomers. However, the amount of cis 9, trans 11 and trans 10, cis 12 CLA isomers could be more increased by optimizing the production parameters. The present study indicated that waste chicken skin could be valorized in CLA production by photoisomerization and obtained high value-added product, and also a more economical and faster CLA production could be realized.

Catalytic production of conjugated fatty acids and oils

The reactive double bonds in conjugated vegetable oils are of high interest in industry. Traditionally, conjugated vegetable oils are added to paints, varnishes, and inks to improve their drying properties, while recently there is an increased interest in their use in the production of bioplastics. Besides the industrial applications, also food manufactures are interested in conjugated vegetable oils due to their various positive health effects. While the isomer type is less important for their industrial purposes, the beneficial health effects are mainly associated with the c9,t11, t10,c12 and t9,t11 CLA isomers. The production of CLA-enriched oils as additives in functional foods thus requires a high CLA isomer selectivity. Currently, CLAs are produced by conjugation of oils high in linoleic acid, for example soybean and safflower oil, using homogeneous bases. Although high CLA productivities and very high isomer selectivities are obtained, this process faces many ecological drawbacks. Moreover, CLA-enriched oils can not be produced directly with the homogeneous bases. Literature reports describe many catalytic processes to conjugate linoleic acid, linoleic acid methyl ester, and vegetable oils rich in linoleic acid: biocatalysts, for example enzymes and cells; metal catalysts, for example homogeneous metal complexes and heterogeneous catalysts; and photocatalysts. This Review discusses state-of-the-art catalytic processes in comparison with some new catalytic production routes. For each category of catalytic process, the CLA productivities and the CLA isomer selectivity are compared. Heterogeneous catalysis seems the most attractive approach for CLA production due to its easy recovery process, provided that the competing hydrogenation reaction is limited and the CLA production rate competes with the current homogeneous base catalysis. The most important criteria to obtain high CLA productivity and isomer selectivity are (1) absence of a hydrogen donor, (2) absence of catalyst acidity, (3) high metal dispersion, and (4) highly accessible pore architecture.

Comparative study of high-linoleic acid vegetable oils for the production of conjugated linoleic acid

Conjugated linoleic acid (CLA) is found in small quantities in dairy and beef products. Obtaining optimum dietary CLA levels from these sources requires an increased intake of saturated fat. A 20% CLA soy oil was produced by UV photoisomerization of soy oil linoleic acid (LA), which is naturally low in saturated fat, but no other high-LA vegetable oils have been studied for their potential as CLA-rich oils. The objectives of this research were to (1) compare flax, sunflower, corn, soy, and high-LA safflower oils as sources of CLA-rich vegetable oils using laboratory-scale equipment, (2) compare CLA yields obtained by laboratory-scale and pilot-scale equipment, and (3) compare the oxidative stabilities of laboratory-scale processed oils. High-LA safflower oil produced the most CLA; soy oil produced slightly less, followed by corn, with flax producing very little and sunflower none at all. Minor oil components and turbidity reduced CLA yields, suggesting that oils should be highly refined before CLA production. The pilot-scale system was more effective than the laboratory-scale system due to greater light exposure and larger surface area to volume ratio of the oil samples. The oxidative stabilities of high-LA safflower oil and soy oil were similar before or after irradiation, indicating that these oils are the most suitable for high-CLA production.