Interaction between Methyl Conjugated Linoleate and Model Lipids during Heating and Illumination

• Main Authors: Jung-Fu Chen, 陳仲富
• Other Authors: B. H. Chen
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/39987982848069129602

碩士 === 輔仁大學 === 食品營養學系 === 87 === Conjugated linoleic acid (CLA) belongs to a group of octadecadienoic acids that contain two conjugated double bonds. CLA is present in meats and dairy products of ruminants origin, and is stable under various processing and storage conditions. Several studies have shown that CLA possesses anticarcinogenic properties, however, the mechanism is still unclear. Also, the antioxidant activity of CLA remains controversial. Thus, it is necessary to study the antioxidant activity of CLA towards the various model lipids. In addition, the interaction between CLA and model lipids during heating and illumination remains unknown. The objectives of this study are to: (1) investigate the interaction between methyl conjugated linoleate and model lipids during heating and illumination; (2) compare the stability of methyl conjugated linoleate and model lipids during heating and illumination; and (3) evaluate the antioxidant activity of methyl conjugated linoleate towards the model lipids. Results showed that the optimum conditions for the separation of MCLA and model lipids consisted of a splitless injection system with helium as carrier gas at a flow rate of 1.1 mL/min. Oven temperature was programmed at 50 ℃, held for 1 min, then increased to 180 ℃ at a rate of 20 ℃/min, and held for 30 min. Injector temperature was 200 ℃. Detector temperature was 240 ℃. MS showed the highest stability, followed by MO, ML and MCLA. The stability of each sample could be associated with the degree of unsaturation. Model lipids with high degree of saturation or with low temperature treatment was able to retard the degradation of MCLA. In most cases, MCLA either facilitated degradation of model lipids or had no effect. In other cases, MCLA was able to retard the degradation of model lipids during heating. At 100 and 200 ℃ heating, the effect of MCLA on the degradation of model lipids was not pronounced. However, the degradation rate of model lipids increased with increasing MCLA levels at 150 ℃. The peroxide values of model lipids increased with increasing levels of MCLA at low temperature. At high temperature, the peroxide values of model lipids increased initially and then declined afterwards, and, meanwhile, the addition of MCLA did not show significant influence. The peroxide values of samples under light storage were higher than those under heating, and the addition of MCLA did not show significant effect on the peroxide values of model lipids during illumination. In this study MCLA did not show significant antioxidant ability against lipid oxidation.