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Extraction and bioconversion of kaempferol metabolites from cauliflower outer leaves through fungal fermentation

Huynh, Nguyen Thai, Smagghe, Guy, Gonzales, Gerard Bryan, Van Camp, John, Raes, Katleen
Biochemical engineering journal 2016 v.116 pp. 27-33
Aspergillus sojae, bioactive compounds, biotransformation, cauliflower, fungi, kaempferol, leaves, metabolites, phenolic compounds, rutin, solid state fermentation
Cauliflower outer leaves contain bioactive compounds, therefore fermentation could be a strategy to release phenolic compounds and their metabolites and thus increase their valorization potential. This study aimed to evaluate the release and metabolism of different filamentous fungi. The fermentation with Aspergillus sojae was found to extract the highest level of total phenolic compounds (321mg rutin equivalents (RE)/100g fresh weight (FW)) after 1day, which was 3 times higher compared to the unfermented sample (113mg RE/100g FW). The most dominant kaempferol metabolites were kaempferol-3-O-diglucoside in all fermented samples (38–126mg RE/100g FW) and kaempferol-3-O-diglucoside-7-O-glucoside in the unfermented sample (34.8mg RE/100g FW). Furthermore, in all fungal treated samples, the phenolic profile shifted to a profile with less or no carbohydrate moieties at the 3- or 7-carbon position. These results indicate the potential of solid-state fermentation to obtain different phenolic-rich extracts, with a unique profile in phenolic compounds, depending on the fungal strain used.