Effects of drying methods on drying characteristics, physicochemical properties and antioxidant capacity of okra

• Published in: Food science & technology 2019-03, Vol.101, p.630-638
• Main Authors: Li, Hongyan, Xie, Long, Ma, Yue, Zhang, Min, Zhao, Yuwei, Zhao, Xiaoyan
• Format: Article
• Language: English
• Subjects: Antioxidant capacity; Drying characteristics; Drying methods; Okra; Physicochemical properties
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2018.11.076

Results of an experimental study were presented and discussed for hot air drying with horizontal cut (HC-HA) or vertical cut (VC-HA) at 55, 60, 65, 70, 75, and 80 °C, respectively, and heat pump drying with HC (HC-HP) or VC (VC-HP) at 40, 50, 60, and 70 °C, respectively, on drying characteristic, colour quality, chemical compositions (vitamin C, chlorophyll, total phenolic and polysaccharide) and antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical scavenging capacity and oxygen radical absorbance capacity (ORAC)) of okra samples. Results showed VC had shorter drying time than that of HC both during HA and HP. The effective moisture diffusivity determined by Weibull distribution function ranged from 0.992 × 10−9 m2/s to 4.409 × 10−9 m2/s for HA, and 1.915 × 10−9 m2/s to 5.291 × 10−9 m2/s for HP. The drying activation was 37.00, and 35.91 kJ/mol for the samples of HC-HA and VC-HA, 29.25, and 21.40 kJ/mol for HC-HP and VC-HP, respectively. A comprehensive evaluation of quality attributes indicated that HP was more suitable for okra drying as it improved drying rate and drying quality compared with HA. The optimal sample quality (higher contents of chemical compositions and better colour quality) was found in okra treated with VC-HP at 50 °C. •The optimal drying condition for okra was given.•The effect of drying conditions on drying characteristics and qualities was investigated.•The comprehensive weighted scoring method was applied to indicators evaluation.