Uncovering the nutraceutical potentials of fermented sago starch “Lemantak” by endophytic fungi

Abstract

Fermentation food has been widely consumed since ancient times due to its many beneficial properties as well as improved texture and taste. Raw sago starch “lemantak” (RSS “lemantak”) is one of the staple foods in the state of Sarawak. Derived from the bark of Metroxylon sagu, this starch has yet to be investigated in terms of its phytochemical and nutraceutical properties after being subjected to fermentation. This study investigated the nutraceutical of fermented RSS “lemantak” in its phenolic content and antioxidant activity in different fermentation conditions by selected endophytic fungi, Aspergillus niger, Penicillium chermesinum and Fusarium equiseti. This study compared two different fermentation modes and also investigated phenolic production by manipulating the fungal consortia, incubation period as well as the solvent used. It was determined that the best endophyte culture was consortia of Aspergillus niger and Penicillium chermesinum under solid state fermentation (SSF) while monoculture Aspergillus niger was the best fungal culture under SMF. It was found that the dual cultures of Aspergillus niger and Penicillium chermesinum (AP) showed high total phenolic content of 174.95 mg GAE/g and high antioxidant activity at different concentrations ranging from 90.21-76.17% under solid-state fermentation at day 7. In contrast, under submerged fermentation, it was found that consortia of Aspergillus niger and Penicillium chermesinum produced low phenolic content of 11.54 mg GAE/g and had lower antioxidant capacity with the range values of 39.26-34.03%. On the other hand, monoculture Aspergillus niger strives best under SMF at 203.65 mg GAE/g and has good antioxidant activity of 90.72-14.15% of scavenging activity. Nevertheless, it was determined that the dual culture of AP showed high potential based on the phenolic content antioxidant activity under SSF while monoculture A. niger showed potential as a phenolic content producer and antioxidant activity. This study ascertained that the best conditions for fermented RSS “lemantak” with higher phenolic content and antioxidant properties are the methanol extract of fermented RSS inoculated with dual cultures Aspergillus niger and Penicillium chermesinum for a period of 7 days of incubation under SSF.