Effect Of Packaging Preservation Technology On Potato Quality And Preliminary Design Of Solid Enzyme TTI

Due to the problem of poor preservation and warehousing technology,the potato industry failed to obtain high yields and increased production though bumper crops were got.Therefore,effective fresh-keeping packaging research for potatoes was imminent.This project aims to effectively extend the storage period of potatoes,investigating how various antibacterial packaging materials,food preservatives and other fresh-keeping packaging technology impact on the quality of potatoes.The research Used enzyme entrapment techology to prepare tyrosinase and combined enzymatic reaction to design a new type of solid-state time temperature indicator(TTI).The TTI could indicate food freshness,which laid the foundation of designing a complete potato packaging system.This research could also provide references to agricultural products processing and the food industry.The results are concluded as follows:(1)The effect of antibacterial packaging materials on the quality of potato.Potato was used as the research object,Parameters such as physical quality and nutritional quality were investigated in packaging materials,which contained Polyethylene(PE),polybutylene succinate(PBS)and its antimicrobial film containing chitosan(CTS),Nano-ZnO(Nano-ZnO)and potassium sorbate(Pto).The results showed that antimicrobial films effectively reduced the germination and rot,and the loss of the nutrients when comparing with conventional storage during storage of preservation.Among them,when PE/CTS/Pto antibacterial film was used as its packaging material,its respiratory intensity was reduced to 4.6 mg/kg·h,the content of vitamin C was effectively maintained as well as the dry matter content was still remain at about 22%.In addition,the accumulation of malondialdehyde,which is harm to potatoes was also reduced.Forthemore,the potatoes packed by PE/CTS/Pto antibacterial film showed superior properties in color,appearance and texture aspects.PE/CTS/Pto antibacterial film could effectively extend the storage period of potatoes.(2)Effect of food-grade preservatives on the quality of potato.Malic acid(MA),Chitosan(CTS),Citric acid(CA)were sprayed on the surface of potato tubers and ultraviolet radiation process was used to keep potatoes fresh.Parameters such as physical quality and nutritional quality were investigated in packaging preservation process.The results showed that preservation and ultraviolet radiation process effectively reduce the germination and rot,the loss of the nutrients.Among them,malic acid(MA)could maintain the quality of fresh potatoes,which had reduced the respiration rate and mitigated the loss of dry matter.MA could effectively extend the storage period of potatoes.(3)Design and preliminary application of solid enzymatic time-temperature indicator(TTI).The tyrosinase was immobilized with sodium alginate as a fixed substrate,then sodium carboxymethylcellulose was used as the stabilizer,while calcium chloride acted as the fixed agent.The optimal fixed single factor concentration was explored immobilized tyrosinase which were further used to prepare TTI.The results showed that the 2% sodium alginate concentration,0.3% sodium carboxymethylcellulose and 2% the calcium chloride were immobilized enzyme has the best performance.Tyrosine and immobilized tyrosinase were immobilized on polyvinyl alcohol gel sustained-release films,hence a new solid-state enzymatic time-temperature indicator based on tyrosinase-enhancing reaction was fabricated.In this research,adjustment of single factor content and reference indication time were explored to optimize the preparation conditions.After activation energy analysis,the activation energy of the prepared TTI was 0.975 kJ/mol.In the detection of the nutritional quality of fresh-cut potatoes,the bacterial stored about 120 h at 4°C,whose extending time had exceeded the raw food standards.The fresh degree of fresh-cut potato was indicated by the total number of bacterial.The activation energy of freshness was 0.2119 kJ/mol,which was accordance with the calculated activation energy of TTI(Ea=0.925 kJ/mol).The result was consistent with the relevant standards of TTI for interior foods.In addition,the time temperature indicator prepared in this work is compact and easy to adhere,transparent and easy for the consumer to observe.