Effect of Hot Air Drying Variables on Phytochemicals and Antioxidant Capacity of Jew's Mallow (Corchorus olitorius L.) Leaves

Document Type : Original Article

Authors

1 Food Technology Department, Faculty of Agriculture, Suez Canal University, 41522, Ismailia, Egypt

2 Food Technology Department, Faculty of Agriculture, Suez Canal University, 41522, Ismailia, Egyp

Abstract

Jew's mallow (Corchorus olitarius L.) is an important vegetable in Egypt. Fresh or dried Jew's mallow leaves
have a wide use and is great demand for domestic as well as export markets. The effects of hot air drying variables
including: air temperature (50, 60 and 70 ºC), air velocity (0.2, 0.4 and 0.6 m/ s) and trays load (125 – 500 g/ 0.22 m2)
on the antioxidant capacity and some phytochemicals content of Jew's mallow leaves were studied. The fresh Jew's
mallow leaves exhibited high antioxidant activity (52.29% and 139.55 μmol trolox/ g dry weight, measured by DPPH
and ABTS assays, respectively). The leaves had high contents of chlorophyll a and b (649.4 and 317.4 mg/ 100 g), total
phenolics (16.54 mg GAE/ g) and total flavonoids (117.88 mg quercetin equivalent/ g). Drying process resulted in
drastic decreases in all studied properties except the β-carotene content. Antioxidant activity and phytochemicals
compounds contents decreased as air drying temperature and velocity decreased, relating to long drying times. Drying
at 60 ºC and air velocity 0.6 m/ s had the lowest negative effect on the leaves antioxidant activity. Leaves dried at the
highest trays load (500 g/ 0.22 m2) also, showed the highest antioxidant activity and phytochemicals contents.

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