| [Object] The post-harvest mushroom was prone to browning during storage,transportation and processing,which affected the nutritional value and commercial value of Lentinus edodes.This study was mainly to explore the browning mechanism of Lentinus edodes during processing and to find the effective way to suppress the browning of Lentinus edodes,which provided a theoretical basis for controlling browning of mushrooms and improving storage quality.[Methods]With fresh Lentinus edodes as raw material,the best composite color-protecting agent was determined by single factor test and response surface method,and the browning mechanism of Lentinus edodes was studied by using different color-protecting agents.The effects of different pretreatments such as blanching,color protection,blanching combined color protection on the browning-related enzymes,compositions and color value of lentinus edodes were studied.Lentinus edodes were treated with ozone at different concentrations(1.07,2.14,3.21,4.28,5.35,6.42,7.49,8.56,9.63mg/m3),and the best ozone treatment concentration was selected based on the color,polyphenol oxidase activity and antioxidant enzyme activity;then the effects of one-time and intermittent ozone treatment on the browning-related indicators of Lentinus edodes during storage at 4? were studied.The effects of different doses(2,4,6,8 k J/m2)of short-wave ultraviolet treatment on browning of Lentinus edodes during storage were studied.[Results](1)The best color-protection formula was citric acid 1.0%,L-cysteine 0.06%,ascorbic acid 0.55%,EDTA-2Na 0.4%.The color-protecting effect of composite color-protecting agent was better than that of single color-protecting agent,and the compound color protection was the most significant.All color protection treatments could inhibit the activity of PPO and PAL,and compound color protection is the most significant.Citric acid and compound color protection can significantly inhibit the activity of POD,while it improved the activity of SOD and CAT.The compound color protect can maintain the high content of reducing sugar and total phenol,while it reduced the content of free amino acid and soluble protein.Statistical analysis indicated that L* was significantly positively correlated with POD,CAT,PAL and SOD,While there was a negative correlation between L* and PPO,reducing sugar,free amino acid and soluble protein content.(2)Color protection combined with blanching treatment has the best color protection effect,its L* value is 62.6,while the L* value of control group is 42.6;each treatment can reduce PPO,POD and PAL activity,while color protection combined with blanching is most significant,the inhibition rate of enzyme activity reached 73.7%,53.9% and 87.4%,respectively.The blanching and color protection combined with blanching could significantly reduce SOD activity,and the inhibition rate of enzyme activity was 87.3% and 84.3%,respectively.Compared to the control,the CAT activity of color protection was increased by 80.1%.Color protection combined with blanching can reduce free amino acid,soluble protein content and reducing sugar content,while increased total phenol content.(3)The optimal concentration of ozone treatment was 3.21mg/m3.Intermittent ozone treatment can effectively delay the browning of Lentinus edodes,inhibit the increase of PPO activity,increase the activity of POD,SOD and CAT,and maintain high content of total phenol and soluble protein,while reduced the accumulation of free amino acids and had a good inhibitory effect on the total number of colonies,molds and yeasts.(4)Appropriate UV treatment dose was conducive to the preservation of color of Lentinus edodes,delaying the increase of free amino acid content and degradation of soluble protein,maintaining high content of reducing sugar and total phenol;The PAL,SOD,CAT and POD activities was maintained at high level,while the PPO activity was inhibited.The UV treatment effectively inhibited the growth of microorganisms and delayed the ripening and browning process of fruits.[Conclusion] Non-sulfur protection color can control the browning of lentinus edodes tissues by inhibiting the activity of PPO and improving the activity of antioxidant enzyme.Enzymatic browning is the main cause of browning of lentinus edodes paste;Color protection combined with blanching can better inhibit the browning of mushroom paste;3.21mg/m3 batch ozone treatment was beneficial to improve the storage quality of post-harvest mushrooms and prolong its shelf life;4k J/m2 UV treatment can better control the browning of mushrooms and maintain the quality of mushrooms. |
PDF Full Text Request