Comparison of sterol composition between Tuber fermentation mycelia and natural fruiting bodies

Truffle, belonging to Tuber genera, is a nutritious and sterol-rich edible fungus, and sterol is a potential health beneficial compound. A comparison of Tuber sterol composition indicates that the total sterol contents in the fermentation mycelia (i.e., 10.5 mg g⁻¹) (n = 3) were approximately 3.2-5.6 times higher than that of the fruiting bodies (p < 0.05) with the addition of soybean flour into the basal fermentation media. Moreover, the phytosterol profile of fermentation mycelia could be significantly improved by adding soybean flour into the fermentation media. After the addition of soybean flour, stigmasterol and β-sitosterol appeared in the fermentation mycelia and the contents of total phytosterols (2279 μg g⁻¹) (n = 3), brassicasterol (943 μg g⁻¹) (n = 3), and campesterol (418 μg g⁻¹) (n = 3) were all increased significantly (p < 0.05). Moreover, the total contents of sterols and phytosterols in the fermentation mycelia cultured in the soybean media were much higher than those in the fruiting bodies (i.e., 1883-3240 and 479-1832 μg g⁻¹, respectively) (n = 3, p < 0.05). This work confirms the potentiality of Tuber fermentation mycelia as the alternative resource for its fruiting bodies from the viewpoint of sterols production.     

Nonvolatile taste components of fruit bodies and mycelia of Cordyceps militaris

Cordyceps militaris (L.) Link (Clavicipitaceae), northern Cordyceps, is currently available in Taiwan for use in the formulation of nutraceuticals and functional foods. The nonvolatile components in the form of fruit bodies and mycelia were studied. Both fruit bodies and mycelia were high in contents of carbohydrate, crude fiber and crude protein. Content of total sugars and polyols were 260.64 and 189.82 mg/g for fruit bodies and mycelia, respectively. Mannitol content was the highest in both fruit bodies and mycelia (117.66 and 112.55 mg/g, respectively). Contents of total free amino acids in fruit bodies and mycelia were 48.15 and 67.63 mg/g, respectively. The content of monosodium glutamate (MSG)-like components in fruit bodies (10.60 mg/g) was higher than that in mycelia (2.70 mg/g). The contents of total and flavor 5′-nucleotides were high in mycelia (26.27 and 9.34 mg/g, respectively). Equivalent umami concentrations of fruit bodies and mycelia were similar, and equivalent to the umami intensity given by 6.08 and 6.22 g of MSG, respectively. Overall, both fruit bodies and mycelia of northern Cordyceps possessed highly intense umami taste.     

Nonvolatile taste components of Grifola frondosa, Morchella esculenta and Termitomyces albuminosus mycelia

Three species of mushroom mycelia are commercially available in Taiwan, namely Grifola frondosa (maitake), Morchella esculenta (morel), and Termitomyces albuminosus (termite mushroom), and their nonvolatile taste components were studied. All mycelia were high in contents of carbohydrate, crude fat and protein but low in contents of crude ash and fiber. Arabitol, glucose, mannitol and trehalose were detected in these three mycelia and total amounts of sugars and polyols were 63.69-83.89 mg/g. Total free amino acid contents in three mycelia ranged from 35.67 to 50.37 mg/g. The monosodium glutamate-like components of G. frondosa mycelia (6.51 mg/g) was approximately twofold higher than M. esculenta and T. albuminosus mycelia (3.58 and 3.11 mg/g, respectively). As compared with other components, sweet and bitter components were much higher in these three mycelia. Contents of total 5′-nucleotides in these three mycelia ranged from 13.32 to 26.19 mg/g and were in the descending order of T. albuminosus>M. esculenta>G. frondosa. Equivalent umami concentration of T. albuminosus mycelia was higher than those of G. frondosa and M. esculenta mycelia. Overall, three mycelia possessed highly intense umami taste.     

Contents of sugars,free amino acids and free 5′-nucleotides in mushrooms,Agaricus bisporus,during post-harvest storage

Common mushrooms, Agaricus bisporus (Lange) Imbach, were stored at 12 °C for 12 days and composition changes were examined during post-harvest storage. The contents of total sugars, mannitol and fructose decreased steadily during storage, whereas the content of other reducing sugars, excluding fructose, remained constant. The content of total free amino acids increased from 77.92 at day 0 to 140.57 g kg⁻¹ at day 6, and then slightly increased to 151.65 g kg⁻¹ at day 12. The contents of nine amino acids increased over time, of these glutamic acid was the most significant. The content of monosodium glutamate-like components increased from 22.67 at day 0 to 47.12 g kg⁻¹ at day 12. However, the contents of sweet and bitter components increased comparably from 24.08 and 24.17 at day 0 to 47.15 and 50.75 g kg⁻¹ at day 12, respectively. Total 5′-nucleotide content peaked at day 3. The contents of three flavour 5-nucleotides were high at days 3 and 6. © 1999 Society of Chemical Industry     

Effect of gamma-irradiation on flavour 5′-nucleotides,tyrosine, and phenylalanine in mushrooms (Agaricus bisporus)

The impact of gamma-irradiation on 5′-nucleotides and on the free amino acids tyrosine and phenylalanine in fresh mushrooms was studied. After irradiation the samples were freeze-dried to avoid enzyme induced chemical changes. Three 5′-nucleotides could be detected using HPLC–UV and LC–ESI-MS: adenosine 5′-monophosphate (AMP), guanosine 5′-monophosphate (GMP) and guanosine 5′-diphosphate (GDP). Irradiation significantly reduced (p = 0.05) the GDP concentration (22%). AMP showed a marked reduction (46%) only at 5 kGy. GMP, tyrosine, and phenylalanine were not affected by gamma-irradiation.     

Comparison of umami-taste active components in the pileus and stipe of pine-mushrooms (Tricholoma matsutake Sing.) of different grades

Umami-taste active components in pine-mushrooms (Tricholoma matsutake Sing.) were compared according to different grades (first, second, third, and fourth) and parts (pileus and stipe). The contents of umami-taste active free amino acids, such as aspartic acid and glutamic acid, decreased in the order of second grade > third grade > fourth grade > first grade. Also, the contents of umami-taste active 5′-nucleotides were highest and lowest in pine-mushrooms of second and first grades, respectively. All the contents of umami-taste active amino acids and 5′-nucleotides were higher in the pileus than in the stipe, irrespective of pine-mushroom grades. Equivalent umami concentration values of pine-mushrooms ranged from 13.26 (in the stipe of first grade) to 204.26 g (in the pileus of second grade) per 100 g. All the quantitative data obtained in this study are highly consistent with our previously data on umami sensory intensities of pine-mushrooms.     

Influence of an adjunct culture of Lactobacillus on the free amino acids and volatile compounds in a Roncal-type ewe’s-milk cheese

Free amino acids and volatile compounds were analysed in a Roncal-type cheese made from pasteurized ovine milk with and without an added adjunct culture (Lactobacillus paracasei + Lactobacillus plantarum). In both batches, the total free amino acid concentration increased 11–12-fold with ripening time, the main amino acids being Leu, Glu, Lys, Phe, Val, and Ile. At the end of ripening, significant differences were recorded for Leu, Ile, Gaba, Phe, Pser, Ser, Gin, Ala, and Orn.