+44-7897-074717Oumoule Ndiaye, Susan E Duncan, Mady Cisse and Sean F Oâ??Keefe*
There has been a great deal of interest in Roselle (Hibiscus sabdariffa L.), called bissap in Senegal, recently because of consumer demand for nutraceutical products. However, beverages made from hibiscus have short self-lives due to anthocyanin and flavor degradation. The purpose of our study was to examine the impacts of freeze-drying on the anthocyanins and the volatiles compositions of hibiscus extracts. Senegalese hibiscus was extracted with hot and cold water and one part of each extract was freeze-dried. A ratio of 1:15 w/v was used; temperature was 98°C for 30 min for hot extraction and 22°C for 4 hours for cold extraction. The anthocyanins were determined using reversed phase High Performance Liquid Chromatography (HPLC) and the volatiles were measured using headspace-Solid Phase Micro-Extraction and Gas Chromatography-Mass Spectrometry (SPMEGCMS) Freeze-drying had no effect on the anthocyanins in cold extracts. However, a significant difference between the hot extract and its freeze-dried product was observed. Volatile profiles were different between cold and hot extracts and their freeze-dried powders. The results of this study show freeze-dried hibiscus has volatiles and anthocyanins similar to non-dried, suggesting that freeze drying is an option for stabilizing hibiscus.
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