Study On The Effect Of Different Processing Methods On The Quality Of Pleurotus Geesteranus

Pleurotus geesteranus is popular among consumers because of its rich yield,delicious taste,high protein content,rich in a variety of amino acids,polysaccharides,vitamins,minerals and so on.The daily consumption of Pleurotus geesteranus requires cooking or processing.The nutritional properties and flavor quality of foods are affected to different degrees by different processing methods due to different conditions of heat transfer medium,heating temperature and time.In this paper,we use fresh Pleurotus geesteranus as raw materials to investigate the effects of different processing methods(boiling,microwave,vacuum cooking,air frying and deep frying)on the eating quality of Pleurotus geesteranus.Moreover,the changes of flavor quality were studied with emphasis.The volatile compounds of Pleurotus geesteranus in different cooking methods were detected by GC-MS,the aroma-active compounds were identified by GC-O-MS and OAV values,and the omission and recombination models were constructed to verify the contribution of each characteristic compound on the overall aroma of Pleurotus geesteranus in different processing methods.The nutritional indexes,antioxidant activity,flavor characteristics and taste changes of Pleurotus geesteranus in different processing methods were completely elaborated,which can provide theoretical basis and technical guidance for comprehensive utilization,rational processing and scientific cooking of Pleurotus geesteranus.The specific research results are as follows:(1)The differences of nutritional components and the antioxidant activity of Pleurotus geesteranus prepared in six processing methods(boiling,microwave,vacuum cooking,air frying without oil,air frying with oil and deep frying)were compared and analyzed.The polysaccharide and polyphenol contents of Pleurotus geesteranus were reduced after processing,and the samples in air frying without oil treatment had the highest content of polysaccharide,polyphenol and alcohol-soluble protein.The antioxidant capacities of fresh and different processed mushroom samples were compared by DPPH radical scavenging rate,ABTS scavenging rate and reducing capacity.The results showed that the antioxidant capacities of alcoholic extracts in processed mushroom samples were higher than that of water extracts.The antioxidant capacity of the six processing methods was directly proportional to the polyphenol content of the samples.The antioxidant capacity was ranked as follows:air frying without oil>vacuum cooking>microwave>air frying with oil>deep frying≈boiling.(2)The GC-MS method was used to compare and analyze the differences of volatile compounds in fresh samples and Pleurotus geesteranus treated by different processing methods detected by two columns with different polarities(DB-5MS and DB-WAX columns),and to investigate the differences of flavor quality in different mushroom samples.DB-WAX column was more suitable for the separation of volatile compounds in Pleurotus geesteranus treated by different processing methods,due to its more diversities and higher content of volatile compounds.After processing,the content of alcohols,ketones and esters had a decreasing trend The content of aldehydes decreased after boiling,microwave and vacuum cooking treatments,while increased after air frying without oil,air frying with oil and deep frying treatments.There was a significant difference in flavor quality between fresh Pleurotus geesteranus and processed samples.The flavor property of samples in hot air frying with oil was similar to those in deep frying treatment,while the samples in boiling,microwave and vacuum cooking had similar flavor properties.The samples in air frying without oil were significantly different with other processing samples,which had the highest types and contents of volatile compounds.(3)The characteristic aroma components of Pleurotus geesteranus in different processing methods were identified using GC-O-MS method and OAV values analysis.The omission and recombination models using aroma-active compounds with OAV>1 were conducted to verify the contribution of each compound to the overall aroma.GC-O-MS results showed that the mushroom aroma was reduced after processing of fresh Pleurotus geesteranus,and the roasted aroma was increased after high temperature treatment.Fourteen aroma-active compounds were detected in samples prepared by air frying without oil and vacumn cooking.The key characteristic compounds in vacumn cooking samples were consisted of hexanal,(E)-2-hexenal,(E)-2-heptenal,nonanal,hexanol,1-octen-3-ol,2-undecanone and 2-ethanedi-3,5-dimethylpyrazine.(4)The effects of different processing methods on physicochemical indexes,sensory quality and taste characteristics of Pleurotus geesteranus were studied.The EUC results showed that the umami intensity of microwave samples was much higher than those of the other five processing methods.The results detected by electronic tongue showed that the umami intensity of microwave samples was the highest in all the sampels.Sensory results indicated that mushrooms had umami note after microwave treatment,and mushrooms aroma after vacuum steaming treatment,and baking odor after air frying with oil treatment.The overall acceptability scores of the above-mentioned three treatments were relatively high.The results provides guidance for people to choose different processing methods.