Fungal bioprocessing to improve quality of pennycress meal as potential feeding ingredient for monogastric animal

Pennycress is an annual cover crop in temperate North America and its seeds contain around 30% of oil and 20% of crude protein. Pennycress oil can be used for biodiesel production, while the seed meal has limited use in animal feed due to its relative high content of phenolic compounds and crude fiber. The nutritional value of pennycress meal (PM) can be improved by processing with GRAS fungal strains. In this study, three fungal strains, Rhizopus oryzae (RO), Mucor indicus (MI), and Aspergillus oryzae (AO), were used to ferment PM that contains 21% of total amino acids and 17% of structure carbohydrates. The fermentation was performed by inoculating each strain to the sterilized PM with initial moisture of 60% and incubated statically at 28 °C for 6 days. Amino acids profile, structure carbohydrates, soluble sugar, phytate, and mycotoxins including total aflatoxins, zearalenone (ZEN), and deoxynivalenol (DON) were monitored on the samples after fermentation. As compared to control without fermentation, the total amino acids were improved by 4.0% with RO and 5.9% with AO. Threonine, arginine, alanine, and lysine were significantly enriched in RO and AO treated meal. RO and MI degraded the fiber component into cellobiose, which was increased by 3 and 5.8-fold, respectively. Phytate was reduced by 46.6% with RO, 37.3% with AO, and 33.3% with MI. Compared with the control, ZEN was reduced by 39.3%, 32%, and 50% in AO, MI and RO treated meal, respectively. Total aflatoxin content was low in PM, and MI and RO treatments further reduced its content after fermentation. No significant change of DON was observed in the PM fermented by each strain. This study demonstrated the potential of using fungi to improve the feeding value of PM, which could potentially promote the plantation of oilseed crops in the region.