Effect Of High O₂ Dynamic Controlled Atmosphere ?DCA? On Postharvest Physiology And Quality Of Agaricus Bisporus

Agaricus bisporus is highly perishable due to its thin protective structure.Meantime,the high metabolism of white mushroom could accelerate the loss of nutrition value and commercial quality.In order to preserve it well,dynamic controlled atmosphere(DCA)was used to extend the shelf life of white mushroom.The single factor experiment was conducted and white mushroom storage conditions were optimized for orthogonality.The physic-chemical property changes including physic-chemical quality and cell wall metalbolism under optimal storage condition were obtained during storage of white mushroom.The preservation mechanism of high oxygen dynamic controlled atmosphere was indicated according to studying the principle of texture deterioration by correlational analyses between physic-chemical property and firmness.The research contents and results were as follows.1.In this study,Agaricus bisporus were stored at(2±1)?.The first-stage gas(100%O2,90% O2+10% CO2,80% O2+20% CO2,70% O2+30% CO2),transaired time(2nd,3rd,4th and 5th day)and second-stage gas(100% O2,90% O2+10% CO2,80% O2+20% CO2,70% O2+30% CO2)were determined as a single factor on the effect of white degree,firmness and open-caps ratio.Meantime,mushroom storage conditions were optimized for orthogonality.The results showed that the effect of frontal gas on white degree was significant(P < 0.05),the effect of subsequent gas on white degree and firmness was significant(P < 0.05)and the transaired time had no significant effect on the quality of mushrooms.The best condition of orthogonal optimization was 100% O2 first-stage gas,transaired time 3rd day and 80% O2+ 20% CO2 second-stage gas.The white degree,firmness and open-caps ratio in this condition was 83.28,6.84×105Pa and 4% respectively.2.The physic-chemical quality was determind under best condition.Compared with SCA(static controlled atmosphere),DCA(dynamic controlled atmosphere)could inhibit the decrease of soluble protein content of white mushroom significantly(P < 0.05),maintain its good nutrient quality.Meantime,it delayed the respiration rate(P < 0.05)and maintained certain cell membrane integrity,slowed down the senescence of white mushrooms.In addition,white mushroom stored in DCA had moderate POD,higher APX and CAT activity and lower PPO activity than those stored in SCA.In this study,DCA treatment maintained relatively good quality of Agaricus bisporus during storage andextended its storage time to 28 d.3.The effects of different controlled atmosphere treatments on cell wall metalbolism of Agaricus bisporus were studied.The study showed that DCA treatment maintained significantly(P < 0.05)higher chitin content of mushroom than SCA and control,lower chitinase activity(P < 0.05)than control,inhibited chitin degradation in the cell wall.Meantime,DCA treatment significantly inhibited the cellulose enzyme activity(P < 0.05)of mushroom and maintained high content of cellulose and the tissue compressive resistance.In the late storage stage of mushroom,the stipe lignin content rised sharply and the degree of lignification was deepened.The stipe lignification degree was higher than pileus.4CL and CAD activity was significantly positive correlated with lignin content,while there was no significant correlation between lignin content and PAL activity.DCA treated mushroom had significantly lower(P < 0.05)lignin content than the control,indicated that the DCA treatment inhibited the accumulation of lignin by inhibiting the 4CL and CAD activity of mushroom.DCA treatment delayed the process of lignification of mushroom and maintained its good eating quality.4.The correlation analysis and principal component analysis were carried on the physic-chemical property and texture of Agaricus bisporus.Correlation analysis showed that the indicators which largerly correlated with mushroom texture change mainly included WL,RR,MP,SS and SP,PPO,chitin and cellulose.The two principal components that influence mushroom texture were membrane factor and cell wall factor.The differences in the effects on texture of DCA treatment and SCA treatment were mainly reflected in the respiratory intensity and cell wall components.