Bio-utilization of brewery waste (Brewer's spent yeast) in global aquafeed production and its efficiency in replacing fishmeal: From a sustainability viewpoint

Aquaculture contributes significantly to the world's food security. Future aquaculture developments depend mainly on sustainable aquafeed production. Fish meal (FM) is considered unsustainable and not eco-friendly but remains a major protein ingredient in aquafeeds production. The aquaculture sector seeks sustainable protein sources that can reduce the dependency on fishmeal in aquafeeds production. Brewer's spent yeast (BSY) is waste biomass obtained from beer breweries worldwide, and its disposal hazards the natural environment. BSY can be deactivated and used as a single cell protein source in aquafeeds as it has good nutritional value with high protein content (49%) and is cheaper than fishmeal. It also possesses antioxidant and immunostimulant properties. This review focuses on the utility of BSY biomass in aquafeed production. Broken line regression analysis from current literature suggests that the optimal range of BSY inclusion in feed is 10–31.5% for carnivores and 19–31.6% for omnivore fish; FM replacement using BSY is 30–50% for carnivores and 35–80.8% for omnivore fish. Also, the utilization of BSY in the global aquafeed industry could reduce fishmeal usage by up to 13.94% (0.369 MMT) globally and reduce the carbon footprint by about 1.79 megatonnes of CO2e and fish-in-fish-out ratio (FIFO) from 0.82:1 to 0.71:1. Thus, utilization of BSY in the aquaculture sector improves circular bio-economy and environmental sustainability in fish production.