Effect of drying methods on the quality of tiger nuts (Cyperus esculents L.) and its oil

• Published in: Food science & technology 2022-09, Vol.167, p.113827, Article 113827
• Main Authors: Zhang, Zhen-shan, Jia, Hui-jie, Li, Xiao-dan, Liu, Yu-lan, Wei, An-chi, Zhu, Wen-xue
• Format: Article
• Language: English
• Subjects: Bioactive components; Drying methods; Extraction kinetic; Oil quality; Tiger nut
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2022.113827

This study investigated the effect of 4 different drying methods, i.e. sun-drying (SD), oven-drying (OD), microwave-drying (MD) and vacuum-drying (VD) on the color and microstructure of tiger nuts and quality of its oil. The results showed that SD and VD samples had the desirable color. The morphology of starch granules in cells was changed greatly in OD and MD samples. MD sample had the largest oil yield (22.26%), while VD sample showed the highest extraction rate. The oil extraction kinetic can be well described by an exponential model. In respect of oil quality, SD was ideal for retaining carotenoids, phytosterol and unsaturated fatty acids. The oil from MD sample had the highest oxidation degree, but the longest introduction period (53.27 h), while the one from VD sample had the opposite effect. No significant differences were found in acid value and tocols (tocopherols and tocotrienols) profile between all oil samples. Our results provided a guidance for the selection of drying technique based on specific processing purpose. •Fresh tiger nut was dehydrated by four common drying methods.•Extraction kinetic of tiger nut oil in Soxhlet extractor fitted the exponential model.•Drying at high temperature disrupted the microstructure of tiger nuts.•Sun-drying was ideal for retaining color and carotenoids in tiger nuts.•Oil extracted from microwave dried samples had the highest oxidation stability.