Non-volatile taste components of Agaricus blazei, Agrocybe cylindracea and Boletus edulis

Abstract

Three species of dried mushrooms are commercially available in Taiwan, namely Agaricus blazei (Brazilian mushroom), Agrocybe cylindracea (black popular mushroom) and Boletus edulis (king bolete), and their non-volatile taste components were studied. All mushrooms were high in contents of carbohydrate, crude fiber and protein but low in contents of crude ash and fat. Arabitol, myo-inositol, mannitol and trehalose were detected in these three mushrooms, whereas glucose was not found in B. edulis. Contents of total soluble sugars and polyols ranged from 150.33 to 225.08 mg/g. Total free amino acid contents were low in these three mushrooms and ranged from 8.97 to 14.91 mg/g. The contents of MSG-like components ranged from 1.24 to 4.40 mg/g were in the descending order of the A. blazei, A. cylindracea and B. edulis. Total 5′-nucleotides contents of A. blazei and A. cylindracea were higher than that of B. edulis whereas flavor 5′-nucleotides content of A. blazei was higher than those of A. cylindracea and B. edulis. Equivalent umami concentrations values in three mushrooms ranged from 10.46 to 135.90 g per 100 g. Overall, these three mushrooms possessed highly umami taste.

Introduction

Mushrooms are health foods with relatively low in calories and fat but rich in vegetable proteins, chitin, vitamins, and minerals. Furthermore, it is suggested that they constitute an increasing share in the world diet (Manzi, Gambelli, Marconi, Vivanti, & Pizzoferrato, 1999). Mushrooms are also thought to be beneficial for such diseases as hypertension, hypercholesterolemia, and cancer (Bobek and Galbavy, 1999, Borchers et al., 1999). Mushrooms have been used as foods and food flavoring materials in soups and sauces for centuries, due to their unique and subtle flavor.

Agaricus blazei Murrill (Agariaceae), Brazilian mushroom, was reported to possess antitumour and immunomodulating activities (Kawagishi et al., 1989). Its isolated polysaccharides could stimulate lymphocyte T-cells in mice (Mizuno, Morimoto, Minate, & Tsuchida, 1998). Recently, A. blazei is used for the prevention of cancer and/or as an adjuvant with cancer chemotherapy drugs after the removal of a malignant tumor (Ishihara, 1999). Agrocybe cylindracea (DC: Fr.) Mre. [syn. Agrocybe aegerita (Briganti) Singer] (Bolbitiaceae) also called black poplar mushroom (Leu, 1992). Fruit bodies of this mushroom are found to be medically active in several therapeutic effects such as antitumor, antifungal, nerve tonic, hypercholesterolemia and hyperlipidemia (Wasser & Weis, 1999). Extracts from A. cylindracea possessed antimutagenic activities and might play a role in the prevention of cancer (Shon & Nam, 2001). Furthermore, two new indole derivatives isolated from its methanolic extract inhibited lipid peroxidation in rat liver microsomes (Kim et al., 1997).

Boletus edulis Bull.: Fr. (Boletaceae), king bolete, was a popular edible mushroom in Europe, North America, and Asia (Arora, 1986). Fresh and dried king bolete may be marketed in oriental restaurants and oriental, gourmet, and health food stores. The flavor of this dried king bolete including odor and taste is marvelous-nutty, earthy, and meaty all at once.

Currently, these three tasty mushrooms are available in Taiwan in dried forms. However, the chemical composition and the profile of taste components of these mushrooms were not known. Accordingly, our objective was to examine the non-volatile taste components in the three dried mushrooms, including their proximate compositions, soluble sugars, free amino acids and 5′-nucleotides. Equivalent umami concentrations (EUC) of these mushrooms were also evaluated.