Influence of three drying methods on physicochemical properties of okra (Abelmoschus esculentus L.) powder

Abstract

The different drying methods significantly affected the physicochemical properties of okra powder including its color value (L* a* b*). The okra powder from freeze-drying method exhibited the highest viscosity value (7,961.00 ± 34.83 cP). It also exhibited the highest TPC (1,871.61 ± 28.68 mg GAE/100 g dried sample), TFC (168.07 ± 13.10 mg CE/100 g dried sample), and high antioxidant activities as measured by the DPPH, FRAP, and ABTS assay (89.72 ± 0.72, 1,853.60 ± 61.54, and 646.93 ± 54.48 mg TE/100 g dried sample, respectively). However, the okra powder from the microwave vacuum drying using powder at 1,800 W provided the highest methoxyl content (6.88 ± 0.66%) and the hot air drying (50°C) provided okra powder with the highest total chlorophyll content (1,232.48 ± 3.79 μg/g DW). These results of different drying processes on okra fruit can be applied as a food ingredient to deliver the desirable properties for food product. Novelty impact statement: Six drying methods are compared for drying of okra fruit (Abelmoschus esculentus L.). It is revealed that freeze-drying is the good quality of okra powder in term of phenolic content, flavonoid content, and antioxidant activities. Furthermore, the freeze-drying also provides the lowest methoxyl content which can be applied to create the low calorie confectionery product except it is the most expensive method. Howsoever, the highest total chlorophyll content can be expected from hot air drying which employed much shorter drying time and lower power consumption.