Fermentation with Edible <i>Rhizopus</i> Strains to Enhance the Bioactive Potential of Hull-Less Pumpkin Oil Cake

• Main Authors: Anna Starzyńska-Janiszewska, Robert Duliński, Bożena Stodolak
• Format: Article
• Language: English
• Published: MDPI AG 2020-12-01
• Series: Molecules
• Subjects: antioxidant potential; inositol phosphates; tempe-type fermentation; hull-less pumpkin oil cake; agro-industrial by-products
• Online Access: https://www.mdpi.com/1420-3049/25/24/5782

Solid-state fermentation with food-grade fungal strains can be applied to enhance the bioactive parameters of agro-industrial by-products. Tempe-type fermentation can be adapted to various substrates, but the key factor is the appropriate strain selection. The aim of this study was to compare the potential of <i>Rhizopus</i> strains for obtaining products of improved antioxidant activity from pumpkin oil cake. For this purpose, substances reacting with the Folin-Ciocalteu reagent, with free radical scavenging potential, as well as reducing power were assessed. The effect of the fermentation on the phytate level and inositol phosphate profile in the material was also monitored. The fermentation resulted in the significant enhancement of the antioxidant potential of pumpkin oil cake in the case of all the strains tested, but the most efficient one was <i>R. oligosporus</i> ATCC 64063. During the course of fermentation, the level of phytate in the material decreased (the highest reduction rate was observed in the oil cake fermented with <i>R. oryzae</i> CBS 372.63), while peptides and fungal glucosamine were accumulated. Tempe-type fermentation can be considered as an alternative way of improving the bioactive parameters of pumpkin oil cake and, thanks to the various activities of different <i>Rhizopus</i> strains, it is possible to obtain products of desired parameters.