Research And Development Of Soft Canned Daylily Products And Sterilization Technology

In recent years,as a special agricultural product of Ningxia Hui Autonomous Region,the planting area and output of daylily have been greatly increased,and it has become the hope of local rural revitalization.Daylily is rich in nutrition,but it is extremely perishable after picking.In the industry chain of daylily,except a small part of daylily are directly sold in the form of fresh vegetables,most of them are dried and stored by drying technology to meet the needs of consumers.However,the potential application value of daylily has not been studied in depth,and its processing technology and method are lack of innovation,and its economic value remains to be developed.Therefore,the research and development of daylily processing technology is particularly important.This paper takes Ningxia daylily as the research object,explores the formula and sterilization process of yellow kimchi,and predicts the shelf life model of yellow kimchi.Its main contents and research results are as follows:By analyzing the physical and chemical characteristics,flavor characteristics and microbial diversity in the fermentation process of soft canned daylily with 4%,5%,6%,7%,8%and 9%salt concentration,the quality characteristics of naturally fermented soft canned daylily were evaluated.The main research results are as follows:The content of nitrite in each group was within the national standard range during storage,and the fermentation cycle of 7%salt content was 4 days,which was lower than that of 8%and 9%salt content of daylily soft canned,and the hardness and chroma values were significantly higher than(P<0.05)4%and 5%salt concentration of daylily soft canned.The contents of volatile flavor compounds and amino acids at 7%salt concentration were significantly higher than those in other control groups(P<0.05),and the contents of esters,alcohols and aldehydes were higher.According to the analysis of various indexes,when the salt concentration is 7%,the soft canned daylily has better taste.Different amounts of excipients had different effects on physicochemical properties and sensory evaluation of yellow flower pickles.By changing the concentration of sugar,calcium chloride and citric acid,the best formula of yellow flower pickle was studied.Based on the results of single factor test,Box-Behnken response surface method was used to predict the optimal formula of yellow kimchi,which was 5.60%sugar concentration,0.78%calcium chloride concentration and 0.38%citric acid concentration,and the sensory evaluation value of yellow Kimchi was 84.71,taking the sensory evaluation and hardness of yellow Kimchi as response values.The hardness value is 501.69.According to the actual situation,the above process was adjusted and optimized to the concentration of sugar of 5.6%,calcium chloride of 0.8%,citric acid of 0.4%.The experiment was repeated three times to verify the process conditions.The samples of vacuum packed soft canned daylily were stored at 25℃ for 30 days by low temperature plasma sterilization and pasteurization treatment.The total number of colonies,pH,hardness,color and color were measured every 6 days and combined with sensory evaluation to select the most suitable sterilization method for soft canned daylily.The results show that pasteurization is better than low temperature plasma sterilization.In terms of texture,pasteurization is higher than low temperature plasma sterilization.From the point of view of chroma value,low temperature plasma sterilization has the least damage to the color of canned daylily,and can significantly improve the yellowness of kimchi and reduce the sensory properties.In terms of sensory evaluation value,pasteurization>low temperature plasma.To sum up,pasteurization is the best sterilization method for soft canned daylily.The changes of physicochemical index and sensory evaluation value of vacuum packaged daylily soft canned product were studied at different storage temperatures after pasteurization,and the shelf life prediction model was established.The results show that the average value of the first-order kinetic model established by hardness,total acid and L*value and the Arrhenius equation fitting coefficient R2 are all above 0.90,indicating that the established model can accurately predict the quality deterioration and remaining shelf life of daydaylower after sterilization in the temperature range of 15-35℃.