There is an opportunity to harness the power of fermentation to solve multiple problems faced by the food production industry. Food waste has become a modern-day crisis in which valuable nutrients are being lost to landfill. On the other hand, the cost to produce crops for the purposes of feeding humans and animals continues to increase. Using food and agriculture waste in animal feeds is a strategy of upcycling wastes so that these nutrients can be looped back into food production. In this context, fermentation technology is attractive for aquaculture as various less suitable substrates can be converted into high protein microbial cells which contain a more desirable nutrient profile for aquafeeds.
In a preliminary assessment, hydrolysed chickpea was used as a fermentable feedstock to grow various yeast species. Pichia species were among the best performing yeasts achieving the highest microbial growth while consuming less glucose compared to the more common Saccharomyces cerevisiae
Pichia pastoris and S. cerevisiae biomass were assessed in a prawn (Penaeus monodon) growth and digestibility study to determine their suitability as feed ingredients. P. pastoris was cultured in-house while S. cerevisiae was purchased and assessed as two sources: human-grade Bakers yeast and animal-grade Brewers yeast. The three yeast ingredients were supplemented at 15% in a control diet (TC) containing traditional protein ingredients: fishmeal, canola meal and poultry meal. Diets were adjusted to be iso-nitrogenous and iso-energetic. A commercial diet was also assessed. Diets containing P. pastoris outperformed diets containing S. cerevisiae and performed similarly to the commercial diet for juvenile weight gain over 6 weeks (Table 1). All diets assessed were highly digestible for protein, lipid and carbohydrate (CHO).
Yeast can be a valuable protein ingredient for aquaculture diets. However, their value in producing sustainable ingredients has not been fully explored. Ongoing research will assess the economic and environmental benefits of fermenting food and agriculture waste for aquafeeds.