Jeom Sig Lee

Synthesis of Phytosteryl Ester Containing Pinolenic Acid in a Solvent-Free System Using Immobilized Candida rugosa Lipase

Phytosteryl ester synthesized with pinolenic acid (PLA) from pine nut oil is expected to have features of both phytosterol and PLA. In this study, lipase from Candida rugosa (CRL) was immobilized and then used to optimize conditions for synthesis of phytosteryl ester containing PLA. Lewatit VP OC 1600, a macroporous hydrophobic resin, was selected as the best carrier, and the optimum condition for the immobilization of CRL was established. With immobilized CRL prepared, synthesis of phytosteryl ester with fatty acid from pine nut oil was carried out. Parameters investigated were temperature, molar ratio (phytosterol to fatty acid), enzyme loading, and vacuum. Optimum conditions for synthesis of phytosteryl ester were a temperature of 60 °C, molar ratio of 1:4, enzyme loading of 10% (based on the total weight of the substrate), and pressure of 80 kPa. The maximum conversion of phytosteryl ester was ca. 93 mol % at the optimum condition.

Impact of Roasting on the Chemical Composition and Oxidative Stability of Perilla Oil

The impact of roasting was observed with regard to certain changes in the chemical components and oxidative stability of oil expelled from the roasted perilla seeds. The roasting times were established differently at each roasting temperature of 180, 200, and 220 °C. Trans fatty acids in perilla oil were detected, and the level detected increased as the roasting time increased. Moreover, the roasting of perilla seed led to an increase of 4 tocopherols, α-, β-, γ-, and δ-tocopherol, as well as phosphorus in the oil. The oxidative stability of the oils obtained after roasting increased during 60 d of storage at 60 °C. The rate of decrease of tocopherol in the oil from unroasted perilla seed was faster than that of the tocopherol in the oils from roasted perilla seeds during storage.

Preparation of highly purified pinolenic acid from pine nut oil using a combination of enzymatic esterification and urea complexation

Pinolenic acid (PLA) is a polyunsaturated fatty acid of plant origin. PLA has been successfully enriched according to a two-step process involving lipase-catalysed esterification and urea complexation. For the first step, the fatty acids present in pine nut oil were selectively esterified with lauryl alcohol using Candida rugosa lipase. Under the optimum conditions of 0.1% enzyme loading, 10% additional water, and 15 °C, PLA was enriched up to 43 mol% from an initial value of 13 mol% in the pine nut oil. For the second step, the PLA-enriched fraction from the first step was subjected to a urea complexation process. In this way, PLA enrichments with purities greater than 95 mol% were obtained at urea to fatty acid ratios greater than 3:1 (wt/wt), and 100% pure PLA was produced at a urea to fatty acid ratio of 5:1 with an 8.7 mol% yield.

Changes in lipid substances in rice during grain development

Lipid substances, such as fatty acids, γ-oryzanol, policosanols, and tocol (tocopherol+tocotrienol), were investigated in two rice cultivars, Ilpum and Dasan, during rice development. In both cultivars, the lipid extract level decreased steadily after it reached its maximum level. Additionally, there were differences in the fatty acid composition, depending on the rice developmental stage, between the two cultivars. The γ-oryzanol level increased during rice development, and there were differences in the composition of γ-oryzanol between the two cultivars. The levels of policosanols drastically decreased during the early stage of rice development in the two cultivars. The total tocol level showed a downward trend during rice development. The predominant tocol isomer in Ilpum was α-tocopherol during rice development. In Dasan, the predominant tocol isomer was α-tocopherol at the early stage, but γ-tocotrienol at the later stage. This study provided information on the levels and composition of lipid substances, such as fatty acids, γ-oryzanol, policosanols, and tocol during rice development.

Antioxidant activities and contents of phytochemicals in methanolic extracts of specialty rice cultivars in Korea

Rice is an important agricultural commodity and a major staple food in Asian diets. The aims of this study were to investigate the antioxidant activities and phytochemical contents of methanolic extracts from specialty rice cultivars and to determine if there is any correlation between antioxidant activity and phytochemical content. Our results indicate that methanolic extracts from different rice cultivars contain different levels of phenolics, anthocyanin, carotenoids, γ-oryzanol, and vitamin E. Black rice cultivars such as ‘Heugkwang’, ‘Heugseol’, and ‘Heugjinju’ contained higher phytochemical contents compared to other cultivars. In contrast, the cultivars ‘Segyejinmi’, ‘Cheonseok’, ‘Hanareum’, and ‘Dasan 1’ contained significantly higher levels of γ-tocotrienol compared with other cultivars. The black rice cultivars also showed higher antioxidant activities. Phenolic content was positively correlated with DPPH and ABTS radical scavenging activities and reducing power. The results could have a direct impact on rice consumption by enhancing consumer awareness of health benefits of the rice.