Effect of modified atmosphere packaging and ethylene absorbents on postharvest fruit quality and storage performance of 'Yuluxiang' pear

Abstract: 【Objective】The objective of this study is to optimize packaging bags and provide a scientific foundation for exploring a simple and efficient preservation technology for'Yuluxiang'pear during storage by studying the effect of modified atmosphere packaging and ethylene absorbents on postharvest physiology and quality.【Methods】The commercially matured'Yuluxiangli'fruits were respectively used in sealed 0.02 mm thickness PE film bags, sealed 0.02 mm thickness PE film bags + ethylene absorbent, sealed 0.03 mm thickness PE film bags, sealed 0.03 mm thickness PE film bags + ethylene absorbent, sealed 0.04 mm thickness PE film bags and 0.04 mm thickness PE film bags + ethylene absorbent. These bags were spontaneously formed into an atmosphere-controlled environment and stored at a temperature of (0 ± 0.5) ℃ and with a relative humidity of 90%-95%, and the unsealed 0.02 mm PE packaging bag served as a control. The O2, CO2 and ethylene concentrations in different bags were regularly monitored. After 150 and 210 days of cold storage, the fruits were taken out and placed under20 ℃, and fruit firmness, total soluble solids (TSS) , titratable acidity (TA) , vitamin C, chlorophyll fluorescence parameters, chlorophyll content and core browning index in the stored fruits were investigated at 0 and 7 days after cold storage. The ethylene production and respiration rate were measured during different shelf times. Variance analysis of related data was carried out by SPSS 22.0 software.【Results】The concentrations of O2 and CO2 in sealed bags reached the equilibrium on the 35 th day. The O2 volume fractions in the 0.02 mm thickness PE bags, 0.02 mm thickness PE bags+ethylene absorbent, 0.03 mm thickness PE bags, 0.03 mm thickness PE bags + ethylene absorbent, 0.04 mm thickness PE bags and 0.04 mm thickness PE bags + ethylene absorbent were 19.5%, 17.2%, 19.3%, 15.2%, 11.2% and14.0%, respectively. The CO2 volume fraction of 0.02 mm thickness PE bags, 0.02 mm thickness PE bags+ethylene absorbent, 0.03 mm thickness PE bags, 0.03 mm thickness PE bags+ethylene absorbent, 0.04 mm thickness PE bags and 0.04 mm thickness PE bags+ethylene absorbent bag were 0.9%, 1.3%, 1.1%, 2.1%, 3.2%, and 2.8%, respectively. The ability level of gas adjustment was 0.04 mm thickness PE bags, 0.04 mm thickness PE bags+ethylene absorbent, 0.03 mm thickness PE bags+ethylene absorbent, 0.02 mm thickness PE bags+ethylene absorbent, 0.03 mm thickness PE bags, 0.02 mm thickness PE bags from high to low in turn. Modified atmosphere package can reduce the yellowing rate of the peel and play a better green-keeping effect. On the 150 d, the 0.02 mm thickness PE bags' s total chlorophyll content was no significantly different among the treatments, but the total chlorophyll content of other treatments was significantly higher than the control. On the 210 d and (210+7) d, the total chlorophyll content of the 0.04 mm thickness PE film bags was significantly higher than that of the control and other treatments. Modified atmosphere package can cause an increase in core browning index. On the 210 d, the core browning index of the 0.02 mm thickness PE bags+ethylene absorbent was significantly lower than the control. The other treatments were significantly higher than the control, and the same thickness of the film bag, ethylene absorbent can significantly inhibit the increase in the core browning index. On the (210+7) d, the core browning index of 0.03 mm thickness PE bags+ethylene absorbent was not significantly different from the control. The core browning index of other treatments was significantly higher than that of the control, and the core browning index of 0.04 mm thickness PE bags + ethylene absorbent was the largest. Modified atmosphere package can reduce the content of total soluble solids in fruits. The thickness of the film bag was related to the extent of the total soluble solids (TSS) . Ethylene absorbent can improve the ethylene production rate during shelf life. The ethylene production rate of each treatment during shelf life was also higher than the control. The 0.03 mm thickness PE film bags were optimum modified atmosphere packaging bags for'Yuluxiang'pears. The results showed that the packaging bags reduced the chlorophyll content, Fm, Fvand Fv/Fmof the peel. Fruit firmness was not significantly different between the treatment and control groups, but the fruit core browning index was significantly higher than the control, and the total soluble solids (TSS) was significantly lower than the control.【Conclusion】'Yuluxiang'pear was more embodied in the storage period by using 0.03 mm thickness PE film bags for modified atmosphere packaging, and the O2 and CO2 concentrations in bags played a main role, and when O2 was maintained at 18.7% to 19.5% and CO2 at 1.2% to1.5%, there was a good preservation effect on keeping fruit peel green, but reduced the quality of the fruit such as titratable acidity (TA) , vitamin C; and increased the core browning index. Ethylene concentration showed less effect on the preservation of'Yuluxiangli'pears. Therefore, it was necessary to combine modified atmosphere package with 1-MCP treatments, thereby achieving the goal of preservation effect.