Effects Of Hot Air Drying On Sensory Quality Of Shiitake Mushrooms

This subject belongs to the National Natural Science Foundation of China Youth Science Fund Project "Relationship between the formation of sulfur-containing amino acids and sulfur-containing aroma components during the drying process of shiitake mushrooms and its molecular mechanism"(31801508).The shiitake mushrooms meat is fat and tender,the taste is delicious,and the aroma is rich.It not only has high nutritional value,but also has the functions of lowering blood pressure,anti-virus,anti-cancer,etc.,and can be eaten as a medicinal fungus.Shiitake mushrooms are the first of the edible fungi in many edible fungi,and they have received great attention because of their nutritional value,medicinal value and scent.Fresh shiitake mushrooms have a high water content and are accompanied by strong respiration which prevents them from staying fresh for a long time.Drying is currently the most common way to preserve shiitake mushrooms.The drying method not only effectively prolongs the shelf life of the shiitake mushrooms,but also enhances the flavor of the shiitake mushrooms,giving them a strong umami taste and a unique flavor similar to meat and cheese.At present,the research on the quality of shiitake mushrooms focuses on the effects of different drying methods on the components of dried shiitake mushrooms and the changes in flavor components during storage.In this study,the dried shiitake mushrooms were dried by hot air drying method.The effects of hot air drying on the rehydration rate,color and texture of shiitake mushrooms were studied.The gas chromatography-mass spectrometry(GC-MS)technique was used to study the drying of shiitake mushrooms in hot air drying process.The volatile flavor changes,the electronic nose and sensory evaluation are used to comprehensively evaluate the aroma of the shiitake mushrooms,and the liquid chromatography coupled with tandem mass spectrometry(LC-MS/MS)technique is used to study the changes of the flavor component of the shiitake mushrooms during the hot air drying process.And using the electronic tongue to measure the taste of the mushroom in the hot air drying process,which provided a theoretical basis for the development and deep processing of shiitake mushrooms related flavor products.This topic mainly studies from the following aspects:(1)The effects of hot air drying on the rehydration rate,color and texture quality of shiitake mushrooms were studied.The results showed that the rehydration rate of the shiitake mushrooms pileus after drying was(305.84±17.66)(%),and the rehydration rate of the shiitake mushrooms stipe after drying was(259.56±8.27)(%).The rehydration rate of the shiitake mushrooms pileus is higher than the rehydration rate of the shiitake mushrooms stipe after drying.During the hot air drying process,the rehydration rate of shiitake mushrooms gradually increased.the external color and internal color of the shiitake mushrooms pileus and the shiitake mushrooms stipe decreased after the hot air drying,and the color change inside the shiitake mushrooms after drying was higher than that of the shiitake mushrooms outside.The color changes to a large extent.During the hot air drying process,the L,a,and b values of the shiitake mushrooms decreased,indicating that the heat treatment caused the maillard reaction to produce melanin,which caused the color of the shiitake mushrooms to become black.after drying,the hardness,springiness,adhesiveness,gumminess,chewiness and resilience of the shiitake mushrooms were reduced,and the shearing force was increased.During the hot air drying process,the hardness of shiitake mushrooms first decreased and then increased.The springiness and resilience showed a trend of increasing first and then decreasing,the adhesiveness gradually decreased,the degree of gumminess and chewiness degree gradually increased,and the shearing force increased gradually indicating that the drying time affected the texture characteristics such as the hardness,springiness,adhesiveness,gumminess,chewiness and resilience and shearing force.(2)Based on headspace solid phase microextraction and gas chromatography-mass spectrometry(GC-MS),the effects of hot air drying on volatile flavors of shiitake mushrooms were studied.Comprehensive evaluation of the aroma of mushroom by electronic nose and sensory evaluation.The results showed that the volatile flavor components in shiitake mushrooms mainly include alcohols and aldehydes.The flavor composition of ketones,ketones,sulfur-containing,alkanes and esters,fresh shiitake mushrooms and dried shiitake mushrooms is different,mainly in the difference between alcohol-based octacarbon compounds and sulfur compounds.The main flavor substances of fresh shiitake mushrooms are 8-octane compounds mainly composed of 1-octene-3-ol and 3-octanone.The volatile flavor components of dried shiitake mushrooms are higher in sulfur-containing compounds,indicating that the mushrooms are in the process of hot air drying.Carbon compounds are susceptible to thermal decomposition,and the interaction of mono-and di-carbonyl compounds,hydrogen sulfide,and ammonia results in a gradual increase in the content of sulfur-containing compounds.The results of electronic nose measurement showed that the ammonia and aromatic components,hydrides and alkane compounds changed little after drying,and the aromas of benzenes,nitrogen oxides,methyl compounds and alcohols and aldehydes and ketones were significantly reduced(p<0.05).The results of artificial sensory evaluation showed that the fresh shiitake mushrooms pileus was characterized by rich green cabbage,the caramel scent of dried shiitake mushrooms pileus was the most intense,the fresh shiitake mushrooms stalk was richer,the dried shiitake mushrooms stipe was characterized by caramel scent,and the shiitake mushrooms was dry.The grassy and green notes in the process gradually decreased,indicating that 1-octene-3-ol was thermally decomposed.(3)Based on liquid chromatography coupled with tandem mass spectrometry(LC-MS/MS),the effect of hot air drying on the taste of shiitake mushrooms was studied.The results showed that the 5’-inosinic acid content in fresh shiitake mushrooms was the highest,and the 5’-inosinic acid in the shiitake mushrooms pileus before drying.The concentration was 172.56μg/g,the concentration of 5’-inosinic acid in the shiitake mushrooms stipe was 177.16μg/g,and the content of 5’-guanylic acid in the dried shiitake mushrooms was the highest.The concentration of 5’-guanylic acid in the mushroom pileus and the mushroom stipe after drying was 212.2 μg/g and 122.96 μg/g,respectively.During hot air drying,the concentration of 5’-guanylic acid and 5’-adenylate decreased first and then increased,the concentration of 5’-inosinic acid,5’-xanthic acid,5’-uridine,and 5’-cytidine increased first and then decreased.The results of the electronic tongue test showed that the umami taste and bitterness were the main taste characteristics of the taste of the shiitake mushrooms,and the astringency was small,and the sourness and the salty taste were below the tasteless point.During the whole drying process,the bitterness and umami taste of the shiitake mushrooms are large and the astringency is small.The main nucleotide indicating the umami taste in the shiitake mushrooms is guanylic acid.The bitterness,umami and astringency of shiitake mushrooms all showed an increasing trend.