Subcritical Water Extraction of Phenolic-Rich Product from Defatted Roselle Seed

The Potential of Roselle (<i>Hibiscus sabdariffa</i>) Plant in Industrial Applications: A Promising Source of Functional Compounds

“…As expected, Cissouma et al 22) and Tran-Thi et al 21) reported TPC for defatted dried roselle seed that was lower than that of Mohd-Esa et al 19) . Interestingly, the two former studies used roselle seed from foreign lands whereas the latter study used roselle seed originating from Malaysia.…”

“…A similar type of inverse relationship was also noted in the study of Mohd-Esa et al 19) , whereby extraction of phenolic compounds in roselle plants was more efficient using a relatively less polar solvent. As the polarity of the extraction solvent decreased further particularly when methanol was used such as that in the study of Tran-Thi et al 21) , the TPC of defatted dried roselle seed was found in the range of 2.06 to 3.57 mg GAE/g seed, depending on the solvents used for defatting the dried seed (hexane, methanol followed by hexane, or petroleum ether) .…”

“…The major phenolic compounds in defatted roselle seed were p-coumaric acid and ferulic acid 21) . The researchers utilized methanol and subcritical water (low-polarity water) for phenolic compound extraction.…”

Microwave Assisted Extraction of Defatted Roselle (Hibiscus sabdariffa L.) Seed at Subcritical Conditions with Statistical Analysis

“…Roselle calyces have been long recognized as a source of antioxidants, but roselle seed extract was scientifically proven to possess the highest antioxidant content among the extracts of other parts of a roselle plant, including calyces, stems, and leaves [1]. However, the total phenolic content (TPC) of roselle seed extract varied greatly as reported in several works [2][3][4]. The variation could be related to the difference in the solvent selection or the method used.…”

“…The improvement in extraction practice and technology aptitude actually helps to increase the phenolic content extracted from roselle seed. Using subcritical water at the optimum conditions, the phenolic content of roselle seed extract could be increased up to 12 times (56.72 mg GAE/g extract) [4].…”