Effect of Drying Methods on Chemical Composition and Bioactivity of Water Extract from Hibiscus

Effect of Drying Methods on Chemical Composition and Bioactivity of Water Extract from Hibiscus

Hibiscus sabdariffa L.also known as Roselle . Widely grown in tropical and subtropical areas in China East, Guangxi, Yunnan, Fujian, Taiwan and other areas are cultivated and with production scale.

Hibiscus calyx can be used as medicine and food. It is rich in VC, VE, amino acids, phenolic acids, flavonoids, anthocyanins and other nutrients.

Hibiscus has pharmacological effects of anti-cancer, anti hyperglycemia, anti lipid, anti-inflammatory and improving digestive system.Because of its unique flavor and color,it is widely used to make beverages, preserved fruits, fruit juices, soft drinks, wine and other products and becaome popular with consumers.

Water extract from Hibiscus has high market value and wide application range. The active ingredients in Hibiscus extract such as polyphenols, flavonoids, anthocyanins, etc. are easily denatured or inactivated during their processing and storage. Drying is one of the main processes that affect its activity.

This experiment compares the effects of freeze drying, hot air drying and spray drying at different drying temperatures on the content of active ingredients and antioxidant activity in Water extract from Hibiscus. To find a drying method which is more conducive to reducing the inactivation and denaturation of active ingredients.It provides a reference for the production of rose eggplant products, efficient utilization of active substances and follow-up research in the future.

The contents of flavonoids, polyphenols, anthocyanidins and polysaccharides from AER from freeze-dried samples were (85.24 ± 1.51) μg/mL, (188.88 ± 0.95) μg/mL, (6.51 ± 0.05) μg/mL, (0.850 ± 0.043) mg/mL, respectively. The antioxidant activity showed that the radical scavenging activity against ABTS+• and NO2－ and the reducing power were (28.92 ± 1.25)%, (84.78 ± 4.24)% and 0.713 ± 0.001, respectively, for freeze-drying samples which were higher than those of spray dried and hot air-dried samples. The efficacy of spray drying was shown to be better than that of hot air-drying. Considering the active components and antioxidant activity, the best method to dry AER was freeze-drying followed by spray drying and hot air-drying. Drying temperature and method demonstrated significant impact on the active constituents and antioxidant ability.