The Effects of Drying on Physico-Chemical Properties and Antioxidant Capacity of the Brown Alga (Hormosira banksii (Turner) Decaisne)

Abstract

Hormosira banksii is a rich source of polyphenols, which can be utilized in the food or pharmaceutical industries. This study aimed to determine the impact of six drying methods on properties of the alga H. banksii. Our data revealed that drying conditions significantly affected recovery yield, residual moisture, extraction yield, total phenolic content (TPC) as well as antioxidant capacity of H. banksii (P < 0.05). Optimal conditions for oven, vacuum and de-humidification were 40, 50 and 50C, respectively, and microwave power is 840 W. Under optimal conditions, H. banksii prepared by freeze, de-humidification and vacuum had significantly higher levels of TPC, total flavonoid content (TFC) and proanthocyanidins as well as possessing stronger antioxidant capacity in comparison with those prepared by sun, microwave and oven drying methods. As freeze drying is costly and time-consuming, de-humidification (50C, air in and out of 11.1 and 15.4%) and vacuum (50C, 10 psi) were recommended for drying H. banksii Practical Applications Algae possess various antioxidants with potential benefits for health. Drying is considered as a method for preserving materials, transport with low costs and especially first step for extraction, isolation and purification of active compounds. Thus, it is important to investigate the effects of drying conditions on the properties of the dried alga H. banksii. From the findings, the different drying conditions significantly affected the phytochemical profile and antioxidant activity of the dried alga and the optimal drying conditions could be applied for preparation of dried H. banksii for further processing (extraction, fractionation and isolation of bioactive compounds) as well as potential industrial applications (as a reference for drying H. banksii and other algae).