| The loquat fruit,which is soft and juicy,sweet and sour,is widely loved by consumers.Loquat fruit has high water content,so it ages fast after harvest and is extremely easy to decay and deteriorate during transportation with high loss rate.In addition,the loquat fruit is prone to suffer from various physiological diseases after harvest,which seriously affects their storage quality.In this paper,"Dawuxing" loquat was used as the test material.By studying the effects of oxygen scavenger packing on the chilling injury and physiological metabolism of loquat under cold storage,this paper is meant to explore an economical and convenient way of loquat preservation.The main results obtained are as follows:(1)Using the response surface method,with the addition of iron powder,diatomite,NaCl as factors,the regression equation with oxygen reduction as the response value is:Y=7.48+0.6375 A+0.075 B-0.0875 C+0.975 AB+1.05 AC+0.725 BC-2.115 A2-1.34 B2-2.265 C2.According to the mathematical model established by response surface analysis,the optimal condition is:1.1 g of iron powder,0.3 g of diatomite,0.2 g of NaCl.Under this condition,the deoxidizer has a good deoxidizing effect.(2)Slow-release deoxidizer can achieve the goal of continuous deoxidization.The oxygen reduction of the 2.0%polyethylene glycol group increased more than that of the other treatment groups,and the deoxidization effect was better than other groups.The 2.6%sodium alginate treatment group had a stronger ability to sustain deoxidization.The higher the proportion of iron powder in the linked solution,the better the effect of early-stage rapid deoxidization.The different ratio of activated iron powder to slow-release iron powder led to different continuous deoxidization days.Considering various aspects,the formulation of the slow-release deoxidizer is:1.1 g of iron powder(the ratio of activated iron powder to slow-release iron powder is 3:1;the concentration of polyethylene glycol,sodium alginate and the ratio of iron powder addition in the process of making slow-release iron powder is 2.0%,2.6%and 10%),0.3 g of diatomite,and 0.2 g of NaCl.(3)Study the effects of oxygen scavenger packaging on the quality and volatile flavor compounds of loquat under cold storage,and analyze the effects of oxygen scavenger packaging on the occurrence of chilling injury.Both self-modified atmosphere packing and oxygen scavenger packing could effectively inhibit the color change of loquat,inhibit the increase of weight loss,relative conductivity,inhibit the decrease of soluble solids,soluble protein,and titratable acid content,and prolong the accumulation period of soluble sugar,so as to reduce the chilling injury symptoms of loquat.The oxygen scavenger packing is significantly different from the control group,and the preservation effect is much better.A total of 18 main volatile components were detected in loquat,including 5 esters,4 alcohols,4 aldehydes,2 ketones,2 olefins,and 1 phenol.The content of 2-hexenal,a representative volatile substance,is the highest in each period.(4)Long time of cold storage will destroy the physiological and metabolic balance of fruit,lead to a large accumulation of reactive oxygen species and the aggravation of oxidative stress of fruit tissue,which causes damage to cell membrane function.Oxygen scavenger packing significantly inhibits the increase of H2O2 content,O2-production rate,and MDA content,increases the activities of SOD,CAT,APX,and GR enzymes,and reduces the reduction of GSH and AsA content,so as to inhibit the damage of loquat fruit by reactive oxygen species,reduce the damage of chilling injury and maintain the quality.(5)Respiration,the most important life activity during the post-harvest process of fruits and vegetables,is closely related to the ripening and aging.The loquat fruit packed with deoxidizer maintained a certain aerobic respiration at the same time of anaerobic respiration.Oxygen scavenger packaging inhibits the increase of pyruvate content in loquat,enhances the activity of key enzymes for anaerobic respiration,like PDC and ADH,reduces the respiration rate of loquat fruit,and inhibits the decrease of MDH,SDH and CCO activities,so that the loquat fruit can preserve good commercial value after storage. |
