Identification Of Characteristic Flavour Compounds In Mushroom(Agaricus Bisporus (Lange) Sing) Soup And Flavour Release During Cooking Process

Button mushroom (Agaricus bisporus (Lange) Sing) is the most popular cultivated mushroom in China. It is currently used to produce fresh mushrooms, dried mushrooms, canned mushrooms and other rough forms, but the deep processing of this edible mushroom is insufficient. This hinders the development of the mushroom industry. Nowadays, the nutrition and functional properties of button mushroom were studied, but there were few studies about its flavour compounds and products. Button mushroom was a good material for producing soup due to its rich nutrients and unique flavour. The research on the characteristic flavour active compounds of mushroom soup and flavour release during cooking process has important theoretical significance and practical value for deep processing of button mushroom industry.Button mushroom was used to produce mushroom soup in this study. The characteristic aroma-active compounds and taste-active compounds were identified by instrumental analysis and sensory analysis. Effect of different cooking methods on the flavour constituents of mushroom (Agaricus bisporus L.) soup was studied. Flavour releasing of mushroom soup during cooking was investigated. The mechanism of the flavour formation was explored by adding some precursors. Enzyme technology was used for releasing the nutrition and flavour of mushroom. The main content of this thesis was as follows:Instrumental analysis (HPLC) and sensory evaluation were used to analyze the characteristic taste compounds of mushroom soup. Taste activity value (TAV) was used to determine the characteristic taste compounds in the soup. The result showed that mannitol, Glu and Ca2+ were the characteristic taste compounds. Because of the synergistic interaction between umami amino acids and 5’- nucleotides, the 5’- nucleotides was regarded as the characteristic taste compounds.SDE and HS-SPME were used to extract the volatile compounds and GC/MS was used to identify constitute and content of volatile compounds. The identified aroma compounds included C8 derivatives of octane and octene, such as 1-octen-3-ol, trans-2-octen-1-ol, 1-octen-3-one, benzaldehyde derivatives and heterocyclic compounds. SPME was proved to detect more flavour compounds (50) than SDE (41), and the relative contents of C8 derivatives of octane and octene, benzaldehyde derivatives and heterocyclic compounds extracted by SPME were higher than those extracted by SDE. Therefore, SPME was chosen as the extraction method. The effect of extraction conditions ( fiber, extraction time and temperature) on the volatiles in mushroom soup was studied, and the result indicated that DVB/CAR/PDMS fiber was suitable for mushroom soup flavour extraction and the flavour was extracted at 55°C for 30 min. HP-5 and DB-WAX columns were used to separate the volatiles, and DB-WAX column was suitable for the separation of volatile compounds.GC/O was used to determine the aroma-active compounds by Aroma Extract Dilution Analysis (AEDA) and time-intensity method (OSME) analysis. Mushroom flavour (1-octen-3-one), cooked mushroom flavour (3-octen-2-one), roast nut flavor (2, 6-dimethylpyrazine), green flavor (1-hexanol) and fruity flavor (dihydro-5-pentyl-2(3H)-furanone), popcorn flavor (unknown), sauce flavour (unknown), floral (benzeneacetaldehyde) are the main flavour of the mushroom soup.Effect of cooking methods on the flavour constitutes and flavour profile was analysed by instrumental analysis (HPLC, GC/MS, GC/MS/O, Electronic nose) combined with sensory evaluation. Results showed that the flavour constitutes were significantly different depending on different heating treatment. The umami intensity was highest in traditional cooking mushroom soup, but the EUC was highest in microwaved mushroom soup. It indicated that umami amino acids and nucleotides were one of the factors affecting the umami taste.The flavour constitutes and sensory evaluation changes of mushroom soup during cooking process were determined by instrumental and sensory analysis. The nonvolatile compounds were increased before 30 min of cooking and up to a dynamic equilibrium between 30-60 min, then decreased after 60 min. It indicated that the nonvolatile compounds not only contributed to the taste of mushroom soup, but were the precursors of volatile compounds. Most of the aroma-active compounds increased during the first 30 min cooking time and decreased or disappeared after 60 min of cooking. Therefore, long time cooking was negative for the mushroom soup flavour. The rank-order test result showed that the umami intensity was positively correlated to EUC, but the total acceptability score was not related to the EUC. It indicated that mushroom soup flavour was due to the aroma-active compounds. The correlation between the aroma-active and umami-related compounds’concentration and the sensory attributes was analysed by partial least square regression (PLSR). Correlations between the flavour compounds and sensory attributes of mushroom soup indicated that specific flavour active compounds could be associated with specific sensory attributes.The mechanism of volatile flavour formation in mushroom soup during cooking process was preliminaryly explored by adding amino acids. The result indicated that the impact of amino acids addition on aldehydes, ketones and heterocyclic compounds formation was significant. 3-methyl butanal increased with Leu addition, and methional, 2-acetylthiazole increased with Met addition. Pyrazine compounds increased with Ala and Leu addition.The effect of enzymatic pre-treatment on the nutrition and flavour of mushroom soup was investigated. The results indicated that the levels of solid, protein and free amino acids increased significantly in the mushroom soup compared with the control, and the effect of edible fungus hydrolase was better than cellulase and other protease.