Effect of zinc fortification on the vitamin, mineral, and amino acid composition of Pleurotus ostreatus cultivated on different wood substrate

Zinc is an essential nutrient and appears to be deficient in the diet of most individuals, in both industrialized and non-industrialized countries. Hence, strategies to increase the zinc content of food are germane. This study examines the impact of zinc fortification on the vitamin, mineral, and amino acid composition of Pleurotus ostreatus cultivated on different tropical wood substrates, namely Canarium sp., Pycnanthus angolensis, and Ceiba pentandra. Results showed significant variations in the nutritional composition of both zinc-fortified and non-fortified P. ostreatus. Non-zinc fortified P. ostreatus cultivated on Pycnanthus angolensis has the highest vitamin A content (8.08 mg/100 g), whereas zinc-fortified samples grown on the same substrate recorded the highest vitamin C concentration (282.72 mg/100 g). Mineral analysis revealed a general increase in zinc content in P. ostreatus across all fortified substrates, with values ranging from 0.51 to 1.95 mg/100 g. The highest zinc accumulation was observed in P. ostreatus grown on zinc-fortified Pycnanthus angolensis. Potassium levels were naturally higher in non-fortified samples but increased slightly in fortified mushrooms cultivated on Canarium and Pycnanthus substrates, from 714.03 to 717.50 mg/100 g and from 539.96 to 580.33 mg/100 g, respectively. Amino acid profiling showed glutamic acid as the most abundant amino acid, with values between 9.07 and 11.17 g/100 g. The highest level was found in zinc-fortified P. ostreatus cultivated on Pycnanthus angolensis. The study shows that zinc fortification, in synergy with specific wood substrates, enhances the nutritional value of P. ostreatus, making it a promising functional food in addressing micronutrient deficiencies.