| ’Yali’ pear,an famous local variety with a long planting history in Hebei Province,can be stored about one month at ambient temperature,but is vulnerable to mechanical damage with crispy flesh and high water content during post-harvest handling,which caused a decline in commodity value and food quality,and shorten the storage time.Therefore,it is of great significance for preventing mechanical damage and improving fruit quality to study the influence of mechanical damage on the physiological and biochemical mechanism of ’Yali’ pear.In this paper,with the ’Yali’ pear as material,the influences of impact injury on the storage effect of pear fruit were studied by adopting different angle drop treatments.The main research results were as follows:(1)Different dropped angle treatments(20°,40°,60°)research on ’Yali’ pear storage physiology and quality indicators had shown that:On the 10th day of storage,the firmness was 4.74 kg/cm2,decay rate was 5.56%,SSC was 11.02%and the respiration rate was 2.29 CO2 mg·kg-1·h-1 under CK,which were extremely significant difference with the 40°,60°treatment(P<0.01);TA content was 0.25%,which was extremely significantly higher than the other treatments(P<0.01);Weight loss rate was 3.98%and ethylene release rate was 126.54 μL·kg-1·h-1,which were extremely significantly lower than the 60° treatment(P<0.01),while there were no significant difference with the 20°,40° treatment.The electronic nose could distinguish the volatile gas from the same storage point in the CK and the 20° treatment,and the CK volatile gas distribution area could be completely separated.The volatile gas distribution areas of 40°,60° treatment and the CK were crossed for 4 d and 2 d of storaged,respectively,and the CK volatile gas distribution area was also partially crossed.The storage points were closely spaced,indicating that in the entire system,volatile gas of the 40°,60° treatment changed significantly,and when damaged more seriously,the change more obvious.Compared with the PCA method,electronic nose could even more distinguish damaged pears stored at different shelf life by the LDA method,which the distribution area of the volatile gas in the fruit was more concentrated.LA showed that damaged treatments significantly increased W1S(methane),W5S(nitrogen oxides),W1W(sulfides and terpenes),W2W(organosulfides and aromatic compounds)and W2S(alcohols and some aromatic compounds)generate.Correlation analysis shows that the sensor signal response values were negatively correlated with firmness and TA content,and positively correlated with weight loss rate and decay rate.The correlation was better when the damage was more severely.The signal response values of the 60° treatment were negatively correlated with the firmness and TA content significantly,and positively correlated with the weight loss rate and decay rate significantly.60° treatment storage effect was worst after the comprehensive comparison.(2)60° dropped treatment research on ’Yali’ pear physiology and biochemistry indicators of browning had shown that:On the 10th day of storage,the relative electrical conductivity of peel was 20.67%,MDA content was 1.73 μmol·g-1,total phenols content was 781.90 mg/g and the PPO activity was 4.02 ΔOD420·min-1·g-1 under CK,which were extremely significantly difference with the damaged area(P<0.01);POD activity was 3.91ΔOD470·min-1·g-1,significantly lower than damaged area(P<0.05).The relative electrical conductivity,POD activity,and total phenols content of the pulp were 52.72%,0.04ΔOD470·min-1·g-1,and 77.42 mg/g,respectively,which were extremely significantly difference with the damaged and adjacent areas(P<0.01);The PPO activity was 1.23ΔOD420·min-1·g-1,which was extremely significantly lower than the adjacent area(P<0.01),while there was no significant difference with the damaged area.According to HPLC analysis,the contents of arbutin and chlorogenic acid were the highest in the pear fruit,and were also the main substrates for enzymatic browning.(3)Different material packaging treatments(net,PE film,net+PE film)research on 60° dropped ’Yali’ pear storage physiology and quality indicators had shown that:On the 10th day of storage,the firmness was 6.23 kg/cm2,weight loss rate was 4.52%,the respiration rate was 1.39 CO2 mg·kg-1·h-1 and ethylene release rate was 150.42 μL·kg-1·h-1 under CK,which were extremely significant difference with the other treatments(P<0.01);SSC was 10.30%and TA content was 0.28%,which were extremely significant difference with the 60° injury,60° injury+net,60° injury+PE film treatments(P<0.01).The PPO activity was 4.63 ΔOD420·min-1·g-1,which was significant difference with the 60°injury+net+PE film(P<0.05),while there were extremely significant difference with the other treatments;POD activity was 3.91 ΔOD470·min-1·g-1,which was significant difference with the 60° injury,60° injury+net(P<0.05),while there were no significant difference with the other treatments.60° injury+net+PE film treatment reduced the expansion trend of browning area during the storage.net+PE film treatment storage effect was better after the comprehensive comparison. |
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