Improvement of the Flavor and Oxidative Stability of Walnut Oil by Microwave Pretreatment

作   者：Ye Zhou,Wei Fan, Fuxiang Chu, Dong Pei
期刊名称：Journal of the American Oil Chemists' Society
影响因子：1.421
卷 期 号：
页     码：
关键词：Walnuts · Microwave · Flavor · Oxidative stability
论文摘要：
Walnut oil is in great demand due to its high
nutritional value. However, it is easily oxidized and often
loses its typical flavor. This study focused on the role of
microwave pretreatment in improving the flavor and oxidative
stability of walnut oil, and also investigated the effects
of microwave pretreatment on unsaturated fatty acids
(oleic, palmitoleic, linoleic, and linolenic acids) and antioxidant
components (tocopherols and phytosterols). The
results indicate that microwave pretreatment is effective
in generating pyrazine compounds. The typical ‘roasted’
flavor was present when pretreatment for 2 min or more
was applied. Meanwhile, compared with the control sample,
only the highly treated sample (microwave-pretreated
for 4 min) showed higher oxidative stability. Only small
changes were found in the composition of the unsaturated
fatty acids, while the levels of tocopherols and phytosterols
significantly decreased with increasing duration of
microwave treatment (P < 0.05). the results suggest that
the Maillard reaction caused the improvement of oxidative
stability, since this reaction can also generate antioxidant
products (melanoidins) in addition to pyrazines. Moreover,
microwave pretreatment was found to be effective for
enhancing the oil yield during pressing. Therefore, despite
its adverse effects on tocopherols and phytosterols, microwave
pretreatment could be used to improve the flavor and
oxidative stability of walnut oil.