Fungal bioconversion of brewery by-products: assessment of fatty acids and sterols profiles

Waste management of brewery by-products is economically and environmentally problematic. In the frame of bio-recycling, this study aims to investigate the bioconversion of brewery by-products by filamentous fungi. Pleurotus ostreatus and Lentinula edodes were grown on different substrates based on brewer's spent grains (fresh and dry). Afterwards, fatty acids and sterols were determined. Following the selection of the suitable substrate composition for fungal growth, results showed that fatty acids composition of fungal biomasses varied significantly as a function of substrate and fungal strain. Interestingly, fungal fat might be used for human nutrition due to low SFA/UFA ratios (similar to 0.2-0.4) within the same range of vegetal oils. Sterols profile of fungi biomass revealed the predominance of ergosterol. Also, it was found that the fungi growing on by-products slightly reduced the cholesterol contents. As such, this approach focusing on the bioconversion of by-products using fungi can provide biomasses with a fat composition suitable for feed and human consumption.