Improving Annatto Residue Bioconversion for Pleurotus ostreatus var. Florida Cultivation via Supplementation Strategies

The valorization of agro-industrial residues is essential for advancing circular bioeconomy systems. This study integrated the natural colorant and edible mushroom industries by evaluating annatto (Bixa orellana) residues as substrates for Pleurotus ostreatus cultivation. Two experiments were conducted, testing field and industrial residues at three incorporation levels (32.5%, 42.5%, and 52.5%, w/w on a dry weight basis) combined with different supplementation strategies (corn bran, wheat bran, and their mixture) in a completely randomized design. Field residues showed greater yield and biological efficiency, while industrial residues exhibited higher variability. Total yield reached 38.92%, while the lowest value was 24.28%, representing an increase of up to 65% depending on residue origin and supplementation strategy. Biological efficiency exceeded 140% under optimal conditions, with gains above 70% compared to the lowest-performing treatments. Field residues also promoted a higher number of bunches and greater average bunch mass. Overall, substrate origin, supplementation, and residue proportion were decisive for fungal performance, demonstrating that annatto residues are promising low-cost substrates for scalable mushroom production within circular economy systems.