Kombucha fermentation of African mustard (Brassica tournefortii) leaves: Chemical composition and bioactivity

Abstract

Brassica tournefortii is an edible vegetable formerly consumed by North African populations. Nowadays, this plant has been neglected and is less used. The present study aims to give an extra nutraceutical value to B. tournefortii using a 2-wk kombucha fermentation process. At the end of incubation, fermented and unfermented (control) B. tournefortii aqueous extracts were successively fractionated with ethyl acetate (EtOAc) and n-butanol to measure their chemical composition and bioactivity. Results showed that kombucha fermentation significantly increased total phenolic content, with the highest amounts in the EtOAc fraction. The antioxidant potential of B. tournefortii leaves was improved by fermentation of EtOAc extracts and conversely lowered in aqueous ones. Anti-acetylcholinesterase activity was increased with fermentation to reach ∼8-fold higher value in B. tournefortii EtOAc and aqueous extracts relative to unfermented samples. Kombucha fermentation was found to reduce cytotoxicity and xanthine oxidase inhibitory effects of B. tournefortii leaves. The findings suggested that fermentation is a promising, simple and safe bioprocess that could improve the food proprieties of less-used edible plants.

Kombucha fermentation of six medicinal herbs: Chemical profile and biological activity

“…These results were in accordance to literature data obtained for yarrow extracts [10]. Similar changes in pH values were established for kombucha fermentation of African mustard leaves [29]. In this experiment pH decreased from initial value of 7 to final value of 3, after 14 days of the fermentation process [29].…”

“…Similar changes in pH values were established for kombucha fermentation of African mustard leaves [29]. In this experiment pH decreased from initial value of 7 to final value of 3, after 14 days of the fermentation process [29]. Total acidity is also an usual parameter of kombucha fermentation that indicates the metabolic activity of used starter [1,6].…”

“…The highest value measured in this investigation approximately corresponded to the lowest values given in literature [10]. Previous data suggested that the highest total phenolic content was found in the ethyl acetate fraction of the kombucha fermented African mustard leaves [29] in com-parison to n-butanol and aqueous extract of the same sample.…”

“…The lowest value had sample SN10 (0.55%) and the highest sample P0 (81.81%). Some authors found that antioxidant capacity of ethyl--acetate, n-butanol and aqueous extracts of initial substrate and kombucha products with African mustard leaves had low ability of DPPH radical neutralization [29].…”

Metabolome-microbiome signatures in the fermented beverage, Kombucha

“…Thus, the production of important compounds is directly related to the specific microbiota and the cross-feeding between them. In addition to the composition of the pellicle, the factors that will dictate the growth and activity of kombucha consortia include the substrate (Ayed et al, 2016;Četojević-Simin et al, 2012;Hoon et al, 2014;Rahmani et al, 2019; ⁎ Corresponding author. E-mail address: sandra.beaufort@ensiacet.fr (S. Beaufort).…”