Enzymatic Properties Of Zucchini And The Technology Of Fresh-cut Coating Preservation

The “Zhen Yu” Zucchini were used as the material during the experience. Thecharacteristics of Zucchini polyphone oxidase and peroxides, the chose of the film of coatingand the effect of different concentrations of CMC coating for the quality of fresh-cut Zucchiniwere also studied. The chosen CMC were used as the vector. And then, through the singlefactor and orthogonal experiments, the effects of different preservatives AA, CaCl2, L-Cys onthe fresh-cut Zucchini quality were studied. The preservative effect of fresh-cut Zucchiniquality with Nisin, sodium lactates and potassium sorbet were further studied, on this basis.CMC was determined as the best composite preservative during the study. The main contentsand results were as followed:1. During the separation and purification of Zucchini polyphone oxidase and peroxides,Zucchini PPO and POD were purified by1.39times and8.44times separately. Both PPO andPOD showed the highest enzyme activity at35℃and pH6.6. PPO showed the highestenzyme activity while the substrate concentration was0.06mol/L.POD reached to themaximum while the optimal substrate concentration of H2O2were4.0mmol/L and guaiacol15mmol/L. The activity of PPO was inhibited at90℃for4min, while the activity of PODwas inhibited at90℃for only3min or at80℃for4min.1mmol/L or10mmol/L AA andL-Cys could obviously inhibit the activities of PPO and POD simultaneously, which couldreplace nitrite. Ca²⁺10mmol/L or Mg²⁺10mmol/L could obviously inhibit the activities ofPPO and POD simultaneously.2. The coating film of CMC gained a good fresh preservation effect for fresh-cut Zucchini.Different concentrations of CMC could delay the reduction of fresh-cut Zucchini in a certainextent.6g/L CMC coating film fresh-cut could better reduce the water loss of Zucchini, thedecline of its hardness and discoloration.Thus,the quality of fresh-cut Zucchini were better.And the shelf life was also extended.3. Ascorbic acid, calcium chloride and L-Cysteine played an important role in browningdegree of fresh-cut Zucchini during the storage time. The optimal formulation of thepreservative with6g/LCMC plaster were Ascorbic acid8g/L, Calcium chloride1g/L,L-cysteine0.8g/L,which could effectively inhibit browning of fresh-cut Zucchini.4. Nisin, sodium lactate and potassium sorbet played an important role in bacteriostasisfor fresh-cut Zucchini. The best optimal formulation were CMC6g/L CMC, ascorbic acid8g/L, calcium chloride1g/L, L-cysteine0.8g/L, potassium sorbet1.5g/L.