Degradation of potato pulp glycoalkaloids by cultivation of Pleurotus pulmonarius and Flammulina velutipes

Submerged fermentation of potato pulp, a by-product of the starch industry, by the edible Basidiomycota Flammulina velutipes and Pleurotus pulmonarius yielded fermentates with estimated fungal contents of up to 92 ± 12% and 56 ± 5%, respectively. As potato pulp contains the toxic glycoalkaloids α-solanine and α-chaconine as well as solanidine, their contents were determined in the fermentates and the culture supernatants after the end of cultivation. The analytes bioaccumulated in the pellets in the beginning of the fermentation with F. velutipes, but decreased to 161 ± 12 µg/g α-solanine, 247 ± 25 µg/g α-chaconine and 3 ± 1 µg/g solanidine on cultivation day 9. The overall content (sum of pellet and supernatant) showed a reduction of approx. 52% for α-solanine, 28% for α-chaconine and 94% for solanidine for fermentates with F. velutipes. A decrease of all analyte concentrations was observed after fermentation with P. pulmonarius, and no α-solanine or α-chaconine could be determined from cultivation day 3 onwards in the supernatant and from day 7 on in the pellet. The solanidine content in the pellets decreased to 2 ± 1 µg/g on cultivation day 9.