Introduction
The development of sustainable aquafeeds requires not only maintaining fish growth and health but also ensuring high product quality for consumers. Fermented agricultural side-streams using fungal mycelium represent a promising alternative to soybean meal (Wan-Mohtar et al., 2021; Kalaiselvan et al., 2025; Yegin, 2025). However, their potential impact on quality and sensory attributes of fish fillets remains largely unexplored. This study investigated whether dietary inclusion of mycelium biomass produced via solid-state fermentation, affects the sensory quality of European perch (Perca fluviatilis) fillets.
Materials and Methods
European perch were fed diets in which composite mycelium meal (CMM) at 0% (CMM0), 5% (CMM5), 7.5% (CMM7.5), and 10% (CMM10) over 84 days. This corresponded to a replacement of soybean meal by CMM at 0%, 25%, 37.5%, and 50%, respectively. All diets were formulated to be isonitrogenous, isolipidic, and isoenergetic. After the feeding trial, fish were slaughtered under standardized conditions, and fillets were collected for quality assessment. Instrumental analyses included colour measurements (L*, a*, b*), muscle pH determination at multiple time points (at slaughter, after 7 days, and after frozen storage at 3 and 6 months), and texture profile analysis. Sensory evaluation was performed using an A-not A discrimination test (ISO 8588) to assess potential differences between control and experimental groups. Statistical analyses included McNemar tests for sensory data and generalized linear mixed models to account for repeated measures and panelist variability.
Results and Discussion
Fillet colour measurements showed occasional significant differences between groups. However, these were inconsistent across time points and colour channels, and no clear or systematic effects of dietary treatment were observed.
Muscle pH showed minor but significant differences between groups. At slaughter and after 7 days, pH was higher in CMM5 compared to the control. However, after 3 and 6 months of storage, all groups exhibited significantly lower pH values compared to CMM0.
Texture analysis revealed no significant differences among groups except for elasticity, which was lower in CMM7.5 compared to the other treatments.
Sensory analysis revealed no significant differences between fillets from control and experimental groups across all inclusion levels. McNemar tests showed no detectable discrimination between samples (p > 0.05), indicating that panelists could not distinguish fish fed mycelium-based diets from conventionally fed fish. These findings were supported by generalized linear mixed models, which confirmed the absence of significant product effects.
Although minor variations in texture, odour, and flavour were occasionally noted by panelists, these differences were inconsistent and likely attributable to natural variability among individual fish rather than dietary treatment. Variability within the control group itself further reduced the sensitivity of discrimination testing, highlighting a common limitation in sensory studies with biological products.
Conclusion
The inclusion of CMM in European perch diets did not negatively affect sensory quality or key physicochemical fillet properties. Minor differences in colour, pH, and texture were inconsistent and not indicative of systematic effects. These results support CMM use as a sustainable aquafeed ingredient without compromising product quality.
Acknowledgment
The project was financially supported by Innosuisse – Swiss Innovation Agency (Grant No. 111.280 IP-LS) and the collaboration with Kidemis AG.
References
Kalaiselvan, P., Devi, N.C., Deepti, M., Devi, A.A., Akamad, K., Dheeran, P., Debbarma, S., Vadivel, D., Rajesh, D., 2025. Solid-state fermentation - a sustainable future technology in aquafeeds? Front. Mar. Sci.12. https://doi.org/10.3389/fmars.2025.1669719
Wan-Mohtar, W.A.A.Q.I., Taufek, N.M., Yerima, G., Rahman, J., Thiran, J.P., Subramaniam, K., Sabaratnam, V., 2021. Effect of bioreactor-grown biomass from Ganoderma lucidum mycelium on growth performance and physiological response of red hybrid tilapia (Oreochromis sp.) for sustainable aquaculture. Org. Agr. 11, 327–335. https://doi.org/10.1007/s13165-020-00303-5
Yegin, S., 2025. Solid-state fermentation as a strategy for improvement of bioactive properties of the plant-based food resources. Bioresour. Bioprocess.12, 140. https://doi.org/10.1186/s40643-025-00981-7