The effects of various drying techniques on physicochemical and nutritional qualities of roselle (Hibiscus sabdariffaL.) calyx

Abdullahi Lema, Abubakar and Hasima Mahmod, Nor and Moneruzzaman Khandaker, Mohamad and Fatihah Hasan Nudin, Nur and Mahmud Dogara, Abdulrahman (2022) The effects of various drying techniques on physicochemical and nutritional qualities of roselle (Hibiscus sabdariffaL.) calyx. PLANT SCIENCE TODAY, 9 (4). pp. 926-933. ISSN 2348-1900

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Abstract

The calyx of the roselle plant (Hibiscus sabdariffa L.) has been extensively studied for its anthocyanins. Roselle calyces are exceedingly perishable, making the process of drying and extracting them without sacrificing quality quite difficult. Similarly, there are several commercial drying procedures available, each with its own set of benefits and drawbacks on nutritional and physicochemical qualities in the final product. The goal of this study was to examine the effects of sun, oven and freeze drying on the physico-chemical and nutritional properties of roselle calyx. The antioxidant (%RSA), total anthocyanin content (TAC) and their HPLC identification, physico-chemical as well as proximate composition were determined. The results showed that freeze drying increased the drying rate significantly and re-tained the antioxidant activity (32 mg/100 g QE) then fresh calyx, sun and oven drying, freeze-dried calyx also have higher TAC (176.9 mg/l) than sun and oven dried calyx, the HPLC analysis revealed two anthocyanidin cyani-dine glucoside and cyanidin sambubioside. phytochemicals and proximate of roselle calyces were higher in freeze-dried than oven and sun drying tech-niques employed. The findings demonstrated that freeze drying the roselle calyces preserve their quality characteristics.

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