Broadly Sourced Alternative Proteins Alter Muscle Metabolome While Maintaining Sensory Quality in Rainbow Trout ( <i>Oncorhynchus mykiss</i> )

Aquaculture is recognized as a key future food source, and to sustain increasing production and reduce the ecological footprint, new protein sources are needed. However, replacing the conventional fish and soybean meals may affect fillet quality. This study examined a phylogenetically broad set of protein sources and their effects on sensory attributes and metabolism of rainbow trout (<i>Oncorhynchus mykiss</i>). Five feeds derived from microfungi, black soldier fly, mealworm, blue mussel, and tunicate were evaluated against a soy-based control. Sensory attributes were assessed using Rate-All-That-Apply, and ¹H NMR metabolomics to analyze feed and muscle metabolomes. Phylogenetically closer protein sources showed more similar feed and muscle metabolite profiles, and only minor differences in color, root vegetable taste, and aroma were found. Metabolic effects involved osmoregulation, energy, and amino acid metabolism. Overall, insect-based feeds appeared most favorable based on sensory results and product quality biomarkers; however, all tested feeds remained viable.