Studies On The Fresh-keeping Effect Of Cold Shock And Nano-packaging On Postharvest Vegetable Soybeans

Vegetable soybeans are usually harvested in late summer and early autumn.At this time,the temperature is high.After harvest,vegetable soybeans have high water content,strong respiration and metabolism,and are susceptible to microbial infection and browning and decay,resulting in the sensory and sensory effects of vegetable soybeans.The eating quality is severely reduced.Cold shock treatment is a commonly used method for the preservation of fruits and vegetables.Nano packaging bags are a new type of packaging material.Different nanomaterials have different fresh-keeping effects on the preservation of fruits and vegetables.In order to find a green and pollution-free vegetable soybean preservation method,this article uses"Tongdou No.6"as the material to study the use of cold shock treatment,nano packaging and cold shock combined with nanocomposite material treatment for postharvest vegetables under normal temperature conditions.The effect of soybean postharvest quality and active oxygen metabolism,the results show:1.Vegetable soybeans have vigorous respiration and metabolism after harvest,and are prone to yellowing when placed at room temperature,causing browning and senescence,leading to decay,and this change process is rapid.After cold shock treatment of vegetable soybeans with a mixture of ice and water at 0°C,the increase in browning index and weight loss rate was significantly inhibited,the occurrence of decay was reduced,and the better appearance quality was maintained.Compared with the control group,the cold shock treatment maintains higher CAT,APX and SOD activities,inhibits the accumulation of O2^·-and MDA content,and at the same time inhibits the activity of PPO and POD enzymes,and maintains a higher content Total phenols and total flavonoids.It plays an effective role in delaying the senescence and decay of vegetable soybeans.2.The nano materials used in this experiment are added with nano silver,nano titanium dioxide,nano silicon dioxide and attapulgite,which can inhibit the evaporation of water and reduce the browning and water loss of vegetable soybean pods.Vegetable soybeans after nano-packaging treatment maintain a high chlorophyll content,maintain a good appearance quality,while inhibiting the increase of MDA content,delaying the decline of CAT,APX and SOD activities,and OH^-free Radical scavenging rate and DPPH free radical scavenging rate.It eliminates the excessively high content of active oxygen in the body,inhibit the increase in H₂O₂ content and O2^·-production rate,protect the stability of cell membranes,delay the browning and decay of vegetable soybeans,and extend the storage period.3.After cold shock combined with nano-material packaging,it significantly inhibits the increase in weight loss rate and browning index of vegetable soybeans,maintains a higher content of VC,total phenols and total flavonoids,and significantly improves the activities of SOD and CAT enzymes,as well as OH^-free radical scavenging rate and DPPH free radical scavenging rate,it inhibits the activity of PPO and POD enzymes,and also inhibits the accumulation of H₂O₂ and O2^·-content.The above results show that cold shock combined with nano-material packaging can reduce the damage to vegetable soybeans by improving the activity of antioxidant enzymes and inhibiting the accumulation of reactive oxygen species.