Miladinovic, D. D.; Salas-Bringas, C.; Lekang, O. I.; Mbuto, E. J.; Suwal, P.

Yeast, particularly Cyberlindnera jadinii, is emerging as a significant alternative to fishmeal in aquaculture feed. Fishmeal is known for its superior feed conversion ratios (FCR), but yeast offers promising benefits. This study explores the effects of replacing fishmeal with torula yeast, both untreated and treated with protease and endo-exo 1.3-{beta}-glucanase, on feed pellet properties. Experiment 1 focused on how replacing fishmeal with yeast affects flow resistance and pellet quality. Experiment 2 examined the impact of enzyme-treated yeast on these parameters. The results showed that diets with 20% yeast, whether untreated or enzyme-treated, significantly increased flow resistance during pellet discharge. Additionally, the tensile strength of pellets with 20% yeast improved in both experiments. Pellets containing 10%, 20%, and 100% yeast exhibited aquaphobic behavior, which enhances feed consumption, reduces wastage, and supports sustainable feed manufacturing. However, pellets with 10% and 20% enzyme-treated yeast displayed lipophobic behavior, which is less desirable during post-production processes. Enzymatic treatment also reduced underwater swelling of pellets with 10% and 20% yeast, suggesting minimal enzymatic hydrolysis to lower underwater disintegration. Furthermore, the longitudinal surface roughness of pellets decreased with enzyme-treated yeast, with pellets containing 20% treated yeast showing the smoothest surface. This study highlights the potential of torula yeast as a viable fishmeal alternative, with specific benefits and considerations for its use in aquaculture feed.