Nutritional and amino acid content of stem and cap of Agaricus bisporus, Bulgaria

The purpose of this research was to evaluate nutritional value and the differences in the free amino acid content between the cap and stem of main cultivated species Agaricus bisporus - marketed in Bulgaria. The amino acid composition was determined by AccQ-Fluor amino acid derivates were separated on ELITE LaChrom HPLC system (VWRT Hitachi, Tokyo, Japan). The amino acid peaks were acquired using EZChrom EliteT software and were calculated based on amino acid calibration standard (amino acid standard H, Thermo Fisher Scientific). Agaricus bisporus is rich in carbohydrates (6.76 g/100 g fw), followed by proteins (1.28 g/100 g fw), ash (0.88 g/100 g fw) and fat (0.20 g/100 g fw). Also moisture (90.88% fw), and total energy (123.6 kJ/100 g fw) were calculated. The total phenolic and total flavonoid contents of Agaricus bisporus species were 28.74 mg/g and 9.56 mg/g respectively. The content of saturated fatty acids ( SFA) was (45.64%). The content of unsaturated fatty acids (UFA) in the oil from mushroom was (54.36%) and that of monounsaturated fatty acids (MUFA) consisted of (21.75%). On the other hand, the amount of monounsaturated fatty acids (PUFA) was higher (32.61%). On the grounds of the obtained data, it can be seen that in the phospholipid fraction from mushrooms, there predominated phosphatidic acids (29.60%) as a major component, followed by lysophosphatidylcholine (13.70%). The quantities of diphosphatidylglycerol and phosphatidylinositol in the phospholipid fraction were from (6.30% to 8.10%). Seventeen free amino acids, aspartic acid, serine, glutamic acid, glycine, histidine, arginine, threonine, alanine, proline, glycine, tyrosine, valine, methionine, lysine, isoleucine, leucine and phenylalanine acid were determined in mushroom's cap and stem. The total amino acid (TAA) content of cap was (139.22 mg/kg dw) and that of the stem (47.80 mg/kg dw). The essential amino acids (EAA) content of cap was (54.59 mg/kg dw) and that of the stem (39.49 mg/ kg dw). The essential to total amino acids ratios of the cap and the stem were (0.39 and 0.83) respectively. The principal component analysis (PCA) carried out on the 17 free amino acids produced a two dimensional pattern for which the first principal compound explained (90.71%) of the variance, while the second principal component contributed (9.29%) of the total variance. The results showed the free amino acid content of the analyzed wild edible mushroom was considerable, and that they may be important compounds contributing to the typical mushroom taste, nutritional value, and potent antioxidant properties.