Sequential hydrothermal extraction chemistry for recovering bioactives from potato peels

Abstract

Sequential Hydrothermal Extraction (SeqHTE) provides a versatile platform to produce phytochemicals from potato peels. However, there is a lack of understanding of the SeqHTE reaction mechanisms and pathways. In this study, the chemistry of SeqHTE for the recovery of valuable bioactives from peels was investigated. The slightly more polar conditions of the first stage of SeqHTE favored the retrieval of free form polyphenols and extraction of polysaccharides and glycoalkaloids. In contrast, the second stage displayed preferential recovery of bound-type polyphenols and extraction of solanidine. The acid-catalyzed acyl bimolecular and the unimolecular nucleophilic substitution reaction mechanisms were identified. Additionally, the kinetics indicated that the ideal conditions to enhance bioactive recovery while reducing degradation were a temperature range from 140 ℃ to 160 ℃ and 170–190 ℃ for the first and second stage, respectively. The results demonstrated that SeqHTE offers a suitable environment to break down the peels for the recovery of structurally diverse bioactives.