Increasing the water stability of sinking feed grits using edible fungal hyphae for reducing aquatic waste: a laboratory study

Binding agents and extruder machines are commonly used to produce aquafeeds with high water stability, preventing feed disintegration and wastage. This technique is complicated and costly. The alternative use of living microorganisms as the binding agent without a high temperature extrusion has been studied. This research aimed at increasing the water stability of sinking-aquafeed grits using edible fungal hyphae as a binding agent through fungal fermentation, with and without subsequent oven-drying. Commercial sinking pellets were pulverized and subjected to 3 different treatments: fermentation and oven-drying, fermentation without oven-drying, and oven-drying without fermentation. Results showed that the oven-dried unfermented aquafeed disintegrated and sank in water. In contrast, the fermented feeds, with or without oven-drying, showed better stability and floatability in water. The combination of fermentation and oven-drying produced the highest water stability of 73.59 ± 12.13% as well as the highest floatability of 86.67 ± 5.77% at the 120th minute. These values were higher than the undried fermented feed (36.90 ± 0.83 water stability and 74.0 ± 8.94% floatability). Thus, the fungal hyphae possessed the ability to bind the aquafeed constituents, enhancing the water stability and floatability, which was further improved by oven-drying.