Essential fatty acids (EFA) are fatty acids that must be obtained from the diet because they can not be biosynthesized by human or animals. Gamma fatty acids contain gamma-linolenic acid (GLA, 18:3n-6) and dihomo-gamma-linolenic acid (DHGLA, 20:3n-6) as intermediate metabolites of linoleic acid (LA, 18:2n-6), which is an EFA found in vegetable oils. GLA is an important essential fatty acid that is required by human and animals to function normally. Recently, studies have indicated that GLA may be an essential component of the cell membrane, as well as an active component of dietary supplements and medicine. GLA must beadministered through the diet because it is converted into DHGLA in the body quickly and completely. DHGLA is a key material involved in the metabolism of LA. GLA is biosysthesized by the rate limiting step of δc6-desaturase, which is an enzyme that desaturates LA, there by allowing it to be converted into DHGLA via chain elongation. In addition, DHGLA exerts bioactive effects via action as a precursor of eicosanoid series 1. Breast milk contains an abundant amount of GLA; however, GLA is also available directly in evening primrose oil, black currant seed oil, borage oil and hemp seed oil. In addition, GLA enriched animal and plant can be produced using biotechnology, and highly pure GLA can be extracted using supercritical fluids, such as supercritical carbon dioxide, which will allow economically feasible production of GLA for use in medicines.

Hemp seed oil and evening primrose oil were incorporated into the diets of laying hens for 5 weeks and the level of gamma fatty acid in the eggs that the treated hens laid was then evaluated. Hens were fed corn-soybean based diets that contained 5% tallow, 5% corn oil (CO), 5% hemp seed oil (HSO), or 5% evening primrose oil (EPO). The hemp seed oil and evening primrose oil influenced the amount of gamma linolenic acid found in the eggs through blood. The level of gamma linolenic acid in the plasma was significantly higher in hens that received the HSO and EPO diets than in those that received the tallow and CO diets. The HSO and EPO diets led to a 1.09% and 4.87% increase in egg gamma linolenic acids, respectively, when compared with eggs produced by hens treated with tallow and CO. Taken together, these data demonstrate that healthy eggs with increased gamma linolenic acids can be generated by minor diet modifications when hemp seed oil or evening primrose oil is included in the hen diet.

This study was conducted to investgate the effect of gamma irradiation on the lipid oxidation, olfactory properties, fatty acid isomer and volatile compound profiles of five different oil sources. Three plant oils, canola oil, corn oil and soy oil, and two animal fat, tallow and fish oil, were irradiated with 0, 5, 10, and 20 kGy level of dose by Co-60 as a radiation source. Lipid oxidation parameters, FFA, POV and TBARS, were determined according to the AACC and AOCS method. Olfactory property of irradiated oil sources was analyzed using electronic nose (FOX3000, AlphaMOS Co., France) with 12 metal oxide sensors and the result was interpreted using principle component analysis program. Fatty acid isomer profiles and volatile compound profiles of irradiated oils were also measured by GC and GC-MS, respectively. Although the free fatty acid level of oil were the highest by high dose level (20 kGy) of irradiation, changes of both TBARS and POV values by gamma irradiation were varied between oil sources and irradiation level of dose. Electronic nose analysis showed a distinct difference among dose levels of irradiation. Although there was no new volatile compound produced by gamma irradiation, amounts of each volatile compounds were increased by irradiation. Only cis isomer, 9c12c15c of linolenic acid was dose-dependently decreased as irradiation level increased but there was no difference among other isomer profiles of linoleic acid and linolenic acid by gamma irradiation. This study showed that changes in physico-chemical properties of both plant and animal oil were remarkable by gamma irradiation. Therefore, a further study should be needed to scrutinize the interaction among lipid oxidation, production of volatile compounds and off-flavor, and isomerization of fatty acid by gamma-irradiation.

Kenaf (Hibiscus cannabinus) is an annual herbaceous plant of the family Malvaceae that has been planted in Africa for more than 4000 years and used as source of fiber, energy and feed stock. Also, kenaf seeds are good source for edible oil used for first class cooking oil and margarine production. The seeds can be used for lubrication, soap, paint and varnishes. This study was carried out to evaluate fatty acids variation among sixteen kenaf germplasm and gamma-ray induced mutants derived from Jinju and Auxu. Linoleic, oleic, and palmitic acid were the predominant fatty acids in all kenaf seed oils. The sixteen accessions showed a wide range of fatty acid compositions, spanning from 28.94 to 43.36% saturated, 56.64 to 71.05% total unsaturated, 15.52 to 46.85% monounsaturated, and 13.56 to 48.97% polyunsaturated fatty acids. The mutant lines derived from Jinju, significantly surpassed parental mean for all the palmitic and oleic acid. Also, the mutant lines derived from Auxu showed broad ranges of variation in oleic and linoleic acid and narrow ranges of variation in stearic and palmitic acid. The relative amount of monounsaturated fatty acids (MUFA) were increased at all the gamma-ray induced mutants. These results will provide a valuable information to assist parental selection of kenaf breeding.