Effects Of Short-term Anaerobic Treatment Combined With Modified Atmosphere Packaging On The Postharvest Physiology And The Quality Of Agaricus Bisporus

Agaricus bisporus has high nutritional value,rich in protein,carbohydrates,dietary fiber,vitamins and essential amino acids,etc.,and has low fat and cholesterol content.However,in the process of post-harvest storage,due to its own respiratory characteristics and mechanical damage during picking,it will quickly usher in the respiratory peak,accelerate the decline in quality,and greatly shorten the shelf life.In this experiment,Agaricus bisporus was used as the experimental material.Agaricus bisporus was treated with N₂ for 6,12 and 24 hours anaerobic treatment at a temperature of 5?,and the combination of short-term anaerobic treatment and microporous modified atmosphere packaging(MAP)was studied.The effects of postharvest mushroom quality(including weight loss,texture,appearance,sensory,electronic tongue and amino acids,etc.),cell membrane and cell oxidation state(including anaerobic metabolites,active oxygen production rate,antioxidant enzyme activity,and ultramicro Structure,etc.),and the effects of the activities of key rate-limiting enzymes in the respiratory pathways such as the tricarboxylic acid cycle(TCA),pentose phosphate pathway(PPP)and glycolysis(EMP)(including citrate synthase,isocitrate dehydrogenation)Enzymes,?-ketoglutarate dehydrogenase(TCA cycle),6-P-gluconate dehydrogenase(PPP),phosphofructokinase(EMP)).The results show that moderate anaerobic treatment combined with microporous modified atmosphere packaging can change the respiratory pathway of Agaricus bisporus,reduce the degree of browning,reduce weight loss,maintain better texture and sensory quality,and achieve the purpose of extending shelf life.The main conclusions of this experiment are as follows:1.The effect of short-term anaerobic treatment combined with microporous air conditioning on storage quality6h and 12h anaerobic treatment can better maintain the appearance of Agaricus bisporus,the brightness value(L)of the mushroom is always maintained above 80 throughout the storage period,and the degree of internal and external browning is low.The 24h treatment group accelerated the color change,the L value dropped to 79 on the 3rd day,and the browning degree was always at the highest level.At the same time,the maintenance of texture(hardness,elasticity,cohesion,chewiness)in the 6h and 12h treatment groups was better than that of the control group.Similarly,the 24h treatment group accelerated the decline of texture quality.In addition,the 6h anaerobic treatment can better maintain its umami taste during the shelf life,and control the weight loss rate below 1.8%,effectively reducing the loss of mushrooms during storage.The 6h and 12h treatments helped to improve the sensory quality,texture,sensory score and umami taste;however,the 24h treatment accelerated the decay of the mushrooms,and the browning and weight loss rate increased more significantly.Although the amino acid content of the control group and the 24h experimental group were higher,the ratio of umami amino acids and the umami taste were lower than those treated at 6h and 12h.The results showed that the 6h short-term anaerobic treatment combined with microporous MAP can better maintain the appearance,texture,sensory score and umami taste of the mushrooms,and significantly slow down the decay rate of the mushrooms.2.The effect of short-term anaerobic pretreatment combined with micropore air conditioning on respiratory characteristicsAgaricus bisporus enters the peak of respiration on the third day.Anaerobic treatment has a significant inhibitory effect on the peak respiration.As the anaerobic treatment time increases,the inhibitory effect on the respiration rate shows a trend of first decline and then rise.The respiration rate on the third day was 305 mg CO₂/kg/h,while the respiration rate of the control group was 581 mg CO₂/kg/h),the respiratory rate was reduced by 47.5%,and the inhibitory effect on the respiratory rate continued throughout the storage period.By testing the activity of the main rate-limiting enzymes in the respiratory pathway,it was found that the6h and 12h treatment groups reduced the activity of the key rate-limiting enzymes in the main pathways of the respiratory chain(EMP,TCA and HMP),and there was no anaerobic fermentation due to anaerobic treatment.As a result of oxidative damage,the above combined effect reduces the excessive consumption of the fruit body due to respiration.However,the effects of the 24h treatment group on the various respiratory pathways showed opposite experimental results.The key rate-limiting enzymes of the main pathways of the respiratory chain(EMP,TCA,and HMP)increased,and the degree of anaerobic respiration was high,resulting in more obvious oxidation.Damage,thereby destroying the quality of mushroom fruiting bodies.3.The effect of short-term anaerobic pretreatment combined with micropore air conditioning on reactive oxygen species(ROS)metabolism and cell microstructureThere is a positive correlation between ROS content and aerobic respiration activity.Anaerobic treatment combined with microporous air conditioning can reduce ROS generation by reducing the respiration rate.ROS levels in all experimental groups are lower than those in the control group.The 24 h experimental group has more symptoms.Oxygen respiration keeps the ROS level more at the lowest level.6 h anaerobic treatment can increase the activity of SOD and CAT and reduce the rate of ROS(O₂^-,H₂O₂)production,thereby reducing the level of lipid peroxidation,and playing a positive role in maintaining the integrity of cell membranes.The acetaldehyde content of the 24 h experimental group reached the highest value(0.742821 ug/g FW)on the third day,which was significantly higher than that of the other experimental groups.The oxidative damage of cells was strengthened due to the toxic effect of acetaldehyde,and the storage tolerance of mushrooms decreased.Anaerobic treatment reduced the increase in conductivity and MDA content by inhibiting ROS metabolism.The 6 h treatment group had the best inhibitory effect,and the 12 h experimental group followed.The results showed that moderate anaerobic treatment and accumulation of fermentation metabolites are very important for maintaining the integrity of mushroom membranes and cells and delaying mushroom browning.This study found that appropriate short-term anaerobic treatment can not only inhibit the increase in the intensity of aerobic respiration,but also reduce the greater damage caused by excessive anaerobic respiration.This test also preliminarily proved that Agaricus bisporus passed.How does the adjustment of the breathing pathway affect the appearance quality and so on.It fills the gap of information on the respiratory metabolism and active oxygen metabolism of Agaricus bisporus by short-term anaerobic pretreatment.The solution of these problems will help us understand the tolerance of Agaricus bisporus to hypoxic or even anaerobic environment,and clarify the relationship between the respiratory metabolism regulation mechanism of Agaricus bisporus and the sensory quality of Agaricus bisporus.The storage and preservation of Agaricus bisporus provides theoretical basis and practical guidance.