| In this paper,Flammulina velutipes were used as experimental material.The optimal concentration of 1-MCP was determined by pre-experiment.The Flammulina velutipes were treated with 1-MCP at a concentration of 5.625 μL/L for 10 h at 4℃.The Flammulina velutipes in control were treated with water.The treated Flammulina velutipes were divided into four groups: The samples in control group(Control)were placed directly into ordinary plastic trays using 0.1 mm ordinary PE plastic wrap;The1-MCP treated samples in treatment group 1(1-MCP)were packaged with 0.1 mm ordinary PE plastic wrap;The samples in treatment group 2(Crisper)were directly put into a 4 mm polypropylene(PP)crisper;The1-MCP treated samples in treatment group 3(1-MCP+Crisper)were put into a 4 mm polypropylene(PP)crisper.All the samples were sealed and stored at 4℃,with the environment in relative humidity of 55% to 60%.The effects of 1-MCP treatment,crisper packaging and the combination of 1-MCP treatment and crisper packaging on the quality of Flammulina velutipes were studied.The contents of lignin,cellulose and pectin and other cell wall composition were measured;the enzyme activity changes related to browning,lignification and softening such as polyphenol oxidase(PPO)Peroxidase(POD),phenylalanine ammonia lyase(PAL),cinnamyl alcohol dehydrogenase(CAD),cellulase(Cx),pectin methylesterase(PME)and polygalacturonic acid(PG)were determined.The transcription levels of browning,lignification and softening key enzyme gene were analyzed.The main findings are as follows:(1)The results of quality and sensory indexes of the samples in control group and the treatment groups during the storage period showed that the quality and the nutritive components of Flammulina velutipes during storage were all determined by 1-MCP treatment,polypropylene crisper packaging and the combination of 1-MCP treatment and crisper packaging.The effect of polypropylene(PP)crisper packing was better than that of 1-MCP.The results showed that the crisper packaging could effectively prolong the storage time of Flammulina velutipes to 30 d,and maintain the good organoleptic quality of Flammulina velutipes and inhibit the increase of respiratory intensity of the mushroom significantly(P<0.05);delay the degradation of nutrients,such as soluble solids,soluble proteins,reducing sugars and amino acids,inhibit the relative increase of conductivity,keep the malondialdehyde content at a relatively low level during storage to reduce the peroxidation of cell membrane lipids,reduce the cell membrane damage,and delay the maturation and aging of mushroom.The 1-MCP treatment and the crisper package have a synergistic effect,the samples in combination of the two treatments group were higher than them in other groups in sensory scores,soluble solids,reducing sugars and soluble protein contents significantly(P<0.05).The decline of vitamin C in 1-MCP+Crisper group was lower than them in other groups significantly(P<0.01).(2)The results of determination of substrate content and key enzyme activity related to browning,lignification and softening of samples in the control group and each treatment group during storage period showed that the 1-MCP treatment,polypropylene crisper packaging and the combination of the two treatments can significantly inhibit the increase of browning degree of Flammulina velutipes during the storage(P<0.05),inhibit the accumulation of lignin and the decrease of the content of cellulose and pectin,and has certain inhibitory effect on the activity of enzymes involved in browning,lignification and softening.Among them,the inhibition effect of the crisper packaging is higher than the 1-MCP treatment,the combination of the two treatments was the best.Crisper packaging and the combination of the 1-MCP treatment and crisper packing can effectively inhibit the increase of PPO and POD activity significantly(P<0.05)and delay the peak of PPO activity during the whole storage period.At the same time,the crisper packaging and the combination of the 1-MCP treatment and crisper packing can effectively delay the peak of PAL and CAD activities,inhibit the activity of Cx,PME and PG significantly(P<0.05),and maintain the weak Cx activity throughout the storage period.The 1-MCP treatment can significantly inhibit the activity of PAL and CAD(P<0.05),but it has no significant inhibitory effect on the softening-related enzyme activity of Flammulina velutipes.(3)The results of transmission electron microscopy and scanning electron microscopy showed that the crisper packaging and the combination of the 1-MCP treatment and crisper packing could effectively maintain the integrity and stability of Flammulina velutipes cellular structure.The crisper packaging and the combination of the 1-MCP treatment and crisper packing can maintain the stability and unity of Flammulina velutipes cell wall to the maximize to alleviate and inhibit the emergence of plasmolysis and to prevent cell membrane rupture.The 1-MCP treatment had a certain effect on the suppression of excessive membrane breakage and the outflow of contents.(4)The RNA-Seq technology was used to determine the transcriptional level of key enzyme genes in the control and treatment groups on day 0,6 and 12.The results showed that the 1-MCP treatment,the crisper packaging and the combination of the 1-MCP treatment and crisper packing could effectively affect the expression of enzyme genes related to the browning,lignification and soften of Flammulina velutipes.Among them,The crisper packaging and the combination of the 1-MCP treatment and crisper packing can significantly inhibit the transcription levels of most genes related to PPO,POD,PAL,Cx,PME and PG(P<0.05).The 1-MCP treatment had inhibition effects on the transcriptional level of some genes of PAL and PME significantly(P<0.05).But overall,the inhibitory effect of gene transcription levels from high to low was as follows: 1-MCP combined with crisper packaging process > crisper packaging > 1-MCP treatment. |
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