Degradation of fats and oils by autozidation I : production rates of peroxides and polymer in the autoxidation of oleic acid

HATATE, Yasuo, FURE, Hiroshi, IKARI, Atsushi

Bibliographic Information

Other Title

自動酸化による食品油脂の劣化 (第1報) : オレイン酸の自動酸化における過酸化物及び重合物の生成速度
自動酸化による食品油脂の劣化-1-オレイン酸の自動酸化における過酸化物及び重合物の生成速度
ジドウサンカニヨルショクヒンユシノレッカ 1 オレインサンノ

Search this article

Description

The degradation of fats and oils by autoxidation is characterized by the production of peroxides and polymers. In this study, the autoxidation of oleic acid - a main constituent fatty acid of lipids - was studied as a first step of our kinetic research on the autoxidation of lipids. It was carried out in the following experimental conditions: Reaction temperatures were 40, 100, 125, 150, and 180°C using pure oleic acid as the liquid and air as the gas feed, oxygen volume fractions in gas feed (atmospheric pressure) were 0.0, 0.026, 0.051, 0.11, 0.21, 0.50, and 1.0 [-] using pure oleic acid at 125°C, and initial oleic acid volume fractions in liquid were 0.25, 0.50, and 1.0[-] diluted with tetralin or chlorobenzene using air as gas feed at 125°C. Production rates of peroxides and polymers were determined to obtain the following results: (1) Peroxides are primary products of autoxidation, but unstable at high temperatures, therefore they accumulate with greater ease at lower temperatures, reaching a maximum value of 800 meq/kg at 40°C. At 180°C, they rarely formed. (2) Higher production rates of peroxides were observed at higher oxygen partial pressures. (3) It has been suggested that polymerization is initiated by radicals from the decomposition of peroxides. (4) In the autoxidation with air bubbling, the initial conversion rate of monomer to polymers is described in the temperature range of 40 to 180°C in the following equation: $\frac{dX}{dt}$=0.653*10^4exp(-$\frac{52.5*10^3}{RT}$) percent/s where X is convension [-], t is time [s], R is gas constant (8.314J/mol・deg) and T is temperature [K]. (5) A higher production rate of polymers but a lower polymerization degree was observed at higher oxygen partial pressures.

Journal

The research reports of the Faculty of Engineering, Kagoshima University

The research reports of the Faculty of Engineering, Kagoshima University 26 95-102, 1984-11

鹿児島大学