| In this paper,umami peptides of Grifola frondosa mushroom were identified after a series separation and purition techniques guided by sensory evaluation and the key taste compounds of Grifola frondosa mushroom were characterized.These findings provided an important scientific basic to better develop the food value of edible fungi.The main research contents and results are as follows:(1)The flavor substance in Grifola frondosa mushroom was prepared by the cooking method and the enzymatic hydrolysis method.The conditions for three extract methods were optimized and were as follows: the best extraction conditions for high pressure cooking were:ratio of material to liquid 1:20,time 1.5 h,pressure 40 k Pa;The best extraction conditions for atmospheric cooking were: ratio of material to liquid 1:20,time 2h,temperature 100 °C;The best extraction conditions for enzymatic hydrolysis were: cellulase and flavor protease step by step,the ratio of material to liquid is 1:20,the hydrolysis time is 1.5h,and the temperature of cellulase was 45 °C,p H 3.5,the added amount was 0.5% of the substrate mass;the temperature of the flavor protease was 50°C,p H 6.0,and the added amount was 0.4% of the mass of the substrate.(2)The total amount of soluble sugar in all the treatment solution was significantly decreased,especially the high pressure cooking after the flash extraction.On the contrary,the total amount of organic acids increased by the three different extract methods and the organic acids increased significantly after flash extraction.The total amount of amino acids increased after two kinds of enzymatic hydrolysis while decreased after high pressure cooking.And the flavor amino acids increased significantly through complex enzymatic hydrolysis.The molecular weight which less than 3 000 Da distributes gave highest content by two enzymatic hydrolysis,but the content decreased after flash extraction,which indicate that flash extraction was unfavorable for free amino acids retain.PCA analysis showed that the taste and taste substances are significantly different from the original both by the enzymatic hydrolysis and the high pressure cooking.Also,they are changed significantly after the flash extraction.(3)The peptides were separated and purified from the Grifola frondosa mushroom by ultrafiltration,gel filtration chromatography and reversed-phase high performance liquid chromatography.The amino acid sequence of the taste peptide was determined by ultra performance liquid chromatography with quadrupole time-of-flight mass spectrometry.The amino acid sequences were RSGV and YHGPF.These identified peptides were subjected to solid phase synthesization and further sensory analysis to analyze their taste characteristics,umami enhancement effects,and dose-response relationships.(4)To investigate key taste-active components in Grifola frondosa mushroom,twenty-six putative taste compounds in Grifola frondosa mushroom were quantitatively analyzed and the pivotal components were identified by taste reconstitution,omission and addition tests.Moreover,the role of flavor peptides in overall taste profile of Grifola frondosa mushroom were evaluated.Sensory evaluation revealed that glutamic acid,serine,arginine,lysine,AMP,IMP,GMP,lactic acid,succinic acid,sodium,potassium,phosphates and chlorides,were the core taste-active contributors to Grifola frondosa mushroom.Besides glutamic acid,GMP and succinic acid,the characteristic Grifola frondosa mushroom-like umami and kokumi profiles were induced by adding flavor peptides,among which Arg-Ser-Gly-Val were identified as key substances on the basis of addition test and dose-response analysis.The present data may help to reveal the secret of delicious taste of Grifola frondosa mushroom and provide the basis for development of deeper flavor analysis. |
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