| Oyster mushrooms(Pleurotus Ostreatus)is a genus of basidiomycete subphylum,lateralis,and lateralis.Due to the rich nutrients and the characteristics of both medicine and food,pellagra is widely loved by consumers.Due to the strong respiration and transpiration,the fruiting body loses water seriously,and the enzyme activity in the fruiting body decreases,which is manifested as the softening of the mushroom body and the deterioration of the fruiting body.Storage temperature is one of the key factors affecting postharvest quality.Low temperature inhibits the metabolism of postharvest pellicle,reduces respiration,slows down the decline of enzyme activity,maintains the stable structure of cell wall,makes the mushroom body maintain a better texture and freshness,and effectively improves the storage quality.However,although low temperature can better maintain the physiological and biochemical activities of pellucid lateral ear,at low temperature,pellucid lateral ear will occur lignification,accompanied by the increase of lignin,cellulose and other content,performance for texture hardening,shelf life shortened.In recent years,the postharning preservation of oyster mushrooms is mainly focused on the research of the physiological characteristics and quality changes of oyster mushrooms at a single storage temperature,and less attention is paid to the lignification under low temperature and low temperature combined with air-conditioned packaging,the causes of lignification and the appearance of lignification.Therefore,it is of great significance to study the storage temperature for the quality of oyster mushrooms lateralis and the key enzymes of lignin synthesis.This experiment adopts the rough skin give ear "early autumn" 615 varieties as experimental material,respectively,set up two different storage temperature,rough skin and ear,during the course of a storage of nutrients,antioxidant enzyme activity,lignin content and lignin related enzyme activity index were determined,and combined with low temperature and a plastic bag storage way of rough skin and ear,during the period of storage cell structure,cell wall hydrolases activity measurement analysis,through the microcosmic structure of the cell walls of paraffin section observation,to compare the quality of the rough skin give ear under two kinds of storage temperature change and lignification degree.Finally,through the measurement of relevant physiological indicators during the shelf period,the external manifestations of the lignification of the pellagra lateral ear were investigated.The main research results are as follows:(1)Cryopreservation can significantly reduce the weight loss rate and increase MDA in the oyster mushrooms.The decrease of protein and total phenol content was slowed down.Maintain high fiemness,cellulose and lignin,inhibit postharvest nutrient loss.The weight loss and MDA content were lower at 1? than at 5?,and the activities of POD,PAL and CAD were higher than at 5?.CAT activity was maintained at 1? in the early stage of storage,and CAT activity was increased at 5? in the later stage and was higher than 1?.Storage at 1? slowed down the decrease of firmness,soluble sugar,soluble protein and other nutrients in oyster mushrooms,and promoted the accumulation of cellulose and lignin contents.To sum up,1? storage quality is better than 5? storage,and the degree of lignification is higher during storage.(2)After low temperature storage,the quality of oyster mushrooms decreased to a certain extent during the shelf life.The oyster mushroom stored at 5? could maintain stable hardness and CAT,and maintain higher POD and Cx.During the shelf life,the weight loss rate of oyster mushrooms increased continuously,and the storage at 5? was greater than 1?.The firmness decreases with the shelf life.In 0d-1d,the firmness of 1? decreases rapidly and is lower than 5?.After that,the firmness remains stable.MDA continued to increase,which increased at 5? and then decreased rapidly,and was lower than 1? at the end of shelf life.The POD of oyster mushrooms at 5? showed an upward-steady-upward trend,and was significantly higher than 1?.CAT activity decreased sharply in shelf life of 0d-2d after 1? storage,and was lower than 5? after 2d storage.Cx showed the opposite change trend in the two treatments at the early stage of the shelf.At 0d-2d and 1?,Cx activity increased first and then decreased and was higher than 5?,and the change was stable after 2d.It was found by paraffin section of oyster mushrooms fold that with the extension of shelf life,the structure of the somatic cells of the daughter of oyster mushrooms became disordered and fuzzy,and the structure of the cell of the shelf life of oyster mushrooms cell became more orderly and orderly after storage at 5?.It can be seen that the quality of pellucid lateral ear in shelf life after 5? storage is better than that of 1? storage,and the storage effect is better.(3)Low temperature storage combined with PE packaging bag can significantly improve the storage quality and life of oyster mushrooms.Compared with the nude control,PE packaging significantly inhibited the weight loss rate and the increase of MDA in the oyster mushrooms,slowed down the increase of firmness and whiteness,reduced the loss of protein content,and delayed the peak of POD,CAT and Cx activities.During storage,the whiteness,weight loss and MDA of oyster mushrooms increased continuously,and the sealing treatment was lower than the open treatment.The hardness decreases gradually,and the sealing firmness is lower than the opening;The protein content of the seal treatment was significantly lower than that of the open treatment.POD first rose and then fell.At 0d-4d,POD in sealing treatment was higher than the exposure,and POD in 4d-8d decreased rapidly and was lower than the exposure treatment.CAT activity showed a trend of decreasing and then increasing,and the CAT activity was higher at 0d-2d in early storage and 6d-8d in late storage.Paraffin sections showed that with the increase of storage days after postharvest,the sealing treatment was more orderly than the open treatment.Therefore,under low temperature storage,PE packaging storage effect is obviously better than all exposed placement,sealing packaging storage effect is better than exposure. |
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