Linalyl oleate as a frying oil autoxidation inhibitor

Abstract

Linalyl oleate (LO), an interesterification product of linalyl acetate (LA) and methyl oleate catalyzed with sodium methoxide, was studied to determine its effectiveness in retarding oxidative changes in soybean oil heated continuously at 180 ± 5°C for 32 h. The identity of LO was established by GC-MS and NMR. LO was tested at levels of 0.05 and 0.1% and compared with the more commonly used synthetic autoxidation inhibitor* methyl silicone (MS) at levels of 5 and 10 ppm. FA changes and conjugated dienoic acid formation were monitored. First-order kinetic equations were used to model the decreases in linoleate (18:2)/palmitate and linolenate (18:3)/palmitate ratios. Plots of the data show an inflection point at ~11 h. Oils with either level of MS and LO had lower reaction rate constants before the inflection points, and lower conjugated diene values and higher 18:2 and 18:3 percentages at the end of the 32-h heating period than did oil without additives and with LA.

Frying Performance of No‐trans, Low‐Linolenic Acid Soybean Oils

“…This same tendency was reported by Onal-Ulusoy [9] for soybean oil heated at frying temperatures. After approximately day 9, the changes in the percentages of each fatty acid reached a plateau, probably because of an equilibrium between the degradation and the turnover rates of the oils ( Table 2).…”

“…They were familiarized with the frying setup and trained to use the scoring sheet provided for them. They visited the frying operation on days 2, 5,9,11,14,16,19,21, and 23 and at each visit were asked to independently judge the unidentified oils for their need to be changed, based on their expert judgment as to when they would typically change the oil during normal use. Frying continued until all the chefs agreed that the oils (both replicates) needed to be changed (day 23).…”

“…The FAME were obtained by using the method described by Hammond [8] and analyzed with an HP5890GC chromatograph. The chromatography conditions were similar to those described by Onal-Ulusoy et al [9]. Based on FAME composition, oxidizability was calculated [10].…”

“…The FFA concentration expressed as oleic acid was determined on the fresh oils and on days 2, 5, 6,9,11,14,16,19,21, and 23 by titration following AOCS official method Ca 5a-40 [11] as modified by Rukunudin et al [12].…”

Stability of Silica‐ and Enzyme‐Treated Palm Oil Under Deep Frying Conditions

“…It is postulated that the unstable C18:2 was more likely to degrade into the more stable C18:1 during frying of HTAG (system III). This same tendency was reported by Onal‐Ulusoy and others () and Gerde and others () for soybean oil heated at frying temperatures. The percentage of the unstable :3 and 18:2 decreased at the beginning, while the percentage of the more stable :1, 18:0, and 16:0 acids increased.…”