Vitamin E in Human Health by Peter Weber & Marc Birringer & Jeffrey B. Blumberg & Manfred Eggersdorfer & Jan Frank

Author:Peter Weber & Marc Birringer & Jeffrey B. Blumberg & Manfred Eggersdorfer & Jan Frank
Language: eng
Format: epub
ISBN: 9783030053154
Publisher: Springer International Publishing

Roasting

Vegetable Oils

Besides the cooking methods, also the roasting processes before oil extraction can be relevant with regard to tocopherol yields. In the study of Lee et al. [62], α-T in safflower seeds increased progressively with rising temperatures (140–160 °C) and was significantly higher than in unroasted samples. A possible reason could be an improved release of tocopherols due to damaged cell membranes. Oils from roasted mustard seeds showed higher amounts than oils from unroasted samples in the study of Vaidya and Choe [63]. During heating up to 160 °C, vitamin E decreased, but the losses were not as high as in the unroasted mustard seed oil. This finding is not in accordance with the observations made in the study of Shresta and De Meulenaer [64], in which 90 min of roasting mustard seeds at 180 °C caused a loss of 85% in α-T and a decrease of 40% of the γ-homolog. On the other hand, α-T was significantly higher in roasted rapeseeds than in the unroasted samples, but γ-T slightly decreased. Comparing this outcome with that of the study of Siger et al. [65], the results from Shresta and De Meulenaer [64] are contradictory. Here, α-T contents decreased with roasting processes. The decrease of γ-T occurred slower with rising temperature and time, and 15 min of roasting at 180 °C even caused an increase of γ-T compared to unroasted rapeseed oil. The authors assumed that different oil processing techniques (cold pressing vs. solvent extraction) could be the reason for these discrepancies. Another study conducted with sunflower seeds reported a significant decrease of tocopherols due to an increasing microwave roasting time from 5 to 15 min [66]. Other studies, where rapeseeds were roasted between 73 °C and 165 °C, reported no differences in tocopherol content between roasted and non-roasted samples [67–69]. However, no direct comparison between these studies is valid as different seeds and heat treatments were used.

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