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

Abstract

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 <italic>Pleurotus ostreatus</italic> cultivated on different tropical wood substrates, namely <italic>Canarium</italic> sp., <italic>Pycnanthus angolensis</italic>, and <italic>Ceiba pentandra</italic>. Results showed significant variations in the nutritional composition of both zinc-fortified and non-fortified <italic>P. ostreatus</italic>. Non-zinc fortified <italic>P. ostreatus</italic> cultivated on <italic>Pycnanthus angolensis</italic> 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 <italic>P. ostreatus</italic> across all fortified substrates, with values ranging from 0.51 to 1.95 mg/100 g. The highest zinc accumulation was observed in <italic>P. ostreatus</italic> grown on zinc-fortified <italic>Pycnanthus angolensis</italic>. Potassium levels were naturally higher in non-fortified samples but increased slightly in fortified mushrooms cultivated on <italic>Canarium</italic> and <italic>Pycnanthus</italic> 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 <italic>P. ostreatus</italic> cultivated on <italic>Pycnanthus angolensis</italic>. The study shows that zinc fortification, in synergy with specific wood substrates, enhances the nutritional value of <italic>P. ostreatus</italic>, making it a promising functional food in addressing micronutrient deficiencies.