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

  • Original Paper
  • Published:
Journal of the American Oil Chemists' Society

Abstract

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.

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Authors and Affiliations

  1. State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, 100091, Beijing, China

    Ye Zhou, Wei Fan & Dong Pei

  2. Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, 210042, Nanjing, China

    Fuxiang Chu

Authors
  1. Ye Zhou
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  2. Wei Fan
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  3. Fuxiang Chu
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  4. Dong Pei
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Correspondence to Dong Pei.

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Zhou, Y., Fan, W., Chu, F. et al. Improvement of the Flavor and Oxidative Stability of Walnut Oil by Microwave Pretreatment. J Am Oil Chem Soc 93, 1563–1572 (2016). https://doi.org/10.1007/s11746-016-2891-9

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  • DOI: https://doi.org/10.1007/s11746-016-2891-9

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