Study On Near Infrared Spectroscopy Rapid Detection And Quality Control Of Chilling Injury Of Peach Fruit

Peach fruit is fresh and juicy,sweet and delicious and nutritious,deeply loved by consumers.Peach is a typical respiratory jump fruit,which is prone to chilling injury(CI)during low temperature storage.The symptoms of CI are fruit flocculation,lignification,pulp browning and flavor loss.The CI is appeared in the interior of the fruit and could not be recognized by the naked eye.The traditional cold injury browning and quality monitoring methods of peach fruit are mostly artificial destructive and inefficient.There is an urgent need to establish a rapid and non-destructive method to monitor CI browning and quality of peach fruit.At the same time,the quality control is adopted to prevent the occurrence of CI,and the combination of control and inspection was realized to reduce the economic loss of peach fruit caused by chilling injury.In this paper,near infrared(NIR)spectroscopy technique was used to establish quantitative and qualitative models of CI.The performance of NIRS qualitative and quantitative models of nutritional quality and texture characteristics of CI of peach fruits stored at different low temperatures were compared,and the best qualitative model method of chilling browning index of peach fruits was determined.The effects of 1-methylcyclopropene(1-MCP)and ethylene adsorbent(EA)on chilling browning and quality of peach fruits were also studied,and the inhibitory effects of different treatments on chilling injury were analyzed.The main results were as follows:(1)the quantitative models of soluble solids SSC content(SSC),titratable acid(TA)content,sugar-acid ratio and hardness of peach fruit during storage were established by partial least square(PLS).The correlation coefficients of correction set were 0.93,0.69,0.74 and 0.97,respectively,and the correlation coefficients of verification set were 0.79,0.69,0.68 and 0.95,respectively.The qualitative model of cold injury browning indexs of peach fruit was established by partial least square recognition method(PLS-DA).The total accuracy of two-classification model and multi-classification model were 0.93 and 0.71,respectively.The results show that.The prediction performance of NIR spectroscopy on SSC and firmness of peach fruit was better,but the prediction result of TA and sugar-acid ratio was slightly worse.The established two-classification model could quickly identify the CI browning indexs,and the result of the multi-classification model was slightly poor,but it could still be used for preliminary screening of different CI stages of peach fruits during low temperature storage.(2)The CI quality of peach fruit was monitored by NIRS at 0℃ and 4℃.The occurrence of chilling browning and internal quality deterioration were delay at 0℃.In the quantitative prediction of peach fruit quality under different temperature combinations based on near infrared spectroscopy,and the best prediction set correlation coefficients was 0.87.The highest correlation coefficient of the verification set of the F-score comprehensive prediction model mixed with different temperatures was 0.77.In the two class classification models,the highest prediction accuracy was obtained by SVM method at 0℃,and PCA-DA model with the combination of 4℃ and 0℃ and 4℃ had the best classification results.In the multi-class classification models,the best prediction results can be obtained by PCA-DA method,with the highest prediction accuracy of 0.81.The prediction correlation coefficient of various quality parameters,F value and CI browning of peach fruit was high and the prediction results were good.NIR spectroscopy could be used for the detection of single quality index,comprehensive score and browning grade of peach fruit stored at different low temperatures.(3)The effects of 1-Methylcyclopropene(1-MCP)and ethylene adsorbent on the chilling injury of peach fruit were studied.The two treatments could delay the decline of fruit firmness and reduce the increase of chilling browning,and maintain relatively high SSC.There was no significant change in TA among the treatment groups.The treatment of 1-MCP combined with ethylene adsorbent had the most obvious control effect on peach fruit CI.In sucrose metabolism,The combination1-MCP and ethylene adsorbent could significantly inhibit the decrease of the content of sucrose,fructose and glucose,the activity of neutral invertase and acid invertase.The activities of SS and SPS treated with MCP and ethylene adsorbent treatment were kept at a high level.The combined treatment of 1-MCP and ethylene adsorbent could improve the cold tolerance of fruit and reduce the occurrence and the decrease of hardness and the loss of nutrients caused by CI.