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Pretreatment of ultrasound combined vacuum enhances the convective drying efficiency and physicochemical properties of okra (Abelmoschus esculentus)

Wang, Hua, Zhao, Qing-Sheng, Wang, Xiao-Dong, Hong, Zhong-dong, Zhao, Bing
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2019 v.112 pp. 108201
Abelmoschus esculentus, antioxidant activity, bioactive compounds, color, drying, energy use and consumption, industrialization, liquids, models, okra, rehydration, response surface methodology, ultrasonics
Ultrasonic pretreatment has been widely studied in food dehydration and drying utilization, which have been chiefly used in liquid medium. The sample slices of okra were performed using ultrasonic combined vacuum pre-treatment (UVP) prior to convective drying. The effects of UVP on drying efficiency and physicochemical properties of okra were studied. Based on Box-Behnken-Design, the optimum pre-treatment combination of ultrasound power level (250 W), sample thickness (0.5 cm) and ultrasonic duration (15 min) was obtained by response surface methodology (RSM). The experimental data from subsequent convective drying were well in close agreement with the Logarithmic model. The physicochemical properties of UVP okra slices at optimum pre-treatment conditions, including of colour, contents of several bioactive substances, antioxidant activity and rehydration potential, were predominately better than those of the control group. In conclusion, UVP can effectively improve the convective drying efficiency of okra, reduce energy consumption, and maintain the physicochemical properties of okra, which can be widely used in the industrialization of okra drying.