Composition and nutritive value of protein in some Macedonian edible wild Russulaceae mushrooms

Increased protein requirements stimulated the interest in the introduction and use of new protein sources, which could compete as a substitute and addition to the ordinary protein food items of animal origin. Most literature data consider edible mushrooms as protein food products of the future, because the protein content of most of the species is higher than in many other natural products, the cultivation takes a short time and is inexpensive [1]. Nutritional quality of the mushroom protein varies and is strongly affected from the relative proportion of each amino acid. Thus, the purpose of this study was to estimate the concentration of the amino acid level present in the mushroom proteins, in order to evaluate the protein nutritional value of four mushroom samples of Russulaceae family collected in Macedonia. After acid hydrolysis and pre-column derivatization with phenyl isothiocyanate (PITC) determination of seventeen amino acids was carried out by HPLC method [2]. In the alkaline hydrolisates tryptophan was determined spectrophotometrically [3]. Evaluation of the protein quality was achivied by comparison of the essential amino acid content with the reference FAO/WHO pattern [4]. Essential amino acids made up 49–73% of all determined amino acids depending on the origin and the species of the fruit body. Lysine was the most often found limiting amino acid. The nutritional value of proteins calculated by biological value, protein ratio, chemical score and essential amino acid index was very high. The biological value of the mushroom proteins varied from 55.31 to 82.87%. Russula xerampelina could serve as a source of high quality proteins (PER=2.8) with high biological value (BV=82.87%) similar to beefmeat (BV=85%; PER=2.9). Lactarius deliciosus samples contains medium-quality proteins (PER=1.54) with lower biological value (BV=57.94%) similar to soybean (BV=59.9%; PER=1.6).

References: 1. Friedman, M. (1996), J. Agric. Food Chem. 44, 6–29. 2. Bidlingmeyer, B. (1984), J. Chrom. A 336: 93–104. 3. Shamanthaka, M.C. Sastry, D.R. (1986), J. Sci. Food Agric. 37: 535–538. 4. FAO/WHO Protein quality evaluation, Rome (1991).