Effects of storage temperature and harvest period on storage quality of Citrus reticulata Blanco 'W.Murcott' fruit

LIU Ping; LIU Xiaofeng; LIN Zizhen; FU Huimin; WU Xiaoxiao; DENG Chongling

doi:10.13925/j.cnki.gsxb.20240187

Abstract：[Objective]In this study,the suitable harvest time and storage temperature of W.Murcott was clarified,so as to extend the market supply time and relieve the pressure of sales,and provide refer-ence for the harvest time and storage period of W.Murcott fruit in Guangxi.[Methods]W.Murcott fruit samples were collected at 4 harvest dates(November 29th,December 22nd,January 19th and Marchlst)and stored at 3 temperatures(2-4 ℃,6-8 ℃ and room temperature).The changes in weight,color,soluble solids,titratable acid,vitamin C,reducing sugars,citric acid,methanol,ethanol and acetal-dehyde in the fruit during storage were traced and shelf life were predicted.[Results]During storage,L*,a*,b*of W.Murcott fruit tended to level off after a rapid rise.They were highest in fruit stored at 6-8 ℃,followed by those in fruit stored at room temperature,and lowest in fruit stored at 2-4 ℃.On the 60th day of storage,the a*value of the fruit stored at 2-4 ℃,6-8 ℃ and room temperature were 12.94,26.51 and 21.46,respectively.Low temperature storage significantly reduced the rate of weight loss and delayed the decrease in titratable acid and vitamin C contents,and the longer the storage time and the lower the temperature,the more significant the effect was.On the 90th day of storage,the weight loss rate of fruits stored at 2-4 ℃,6-8 ℃ and room temperature were 1.73％,2.12％and 3.37％,respectively.The content of titratable acid was 0.95％,0.78％and 0.63％,respectively;and the contents of vitamin C were 16.00,15.13 and 12.64 mg·100 mL1,respectively.The contents of reducing sugars increased first and then decreased,and the contents of reducing sugar sin fruit stored at low tempera-tures were higher than those stored at room temperature.The contents of ethanol and acetaldehyde rose in a fluctuating manner,with the highest at 2-4 ℃,the second at 6-8 ℃,and the lowest at room temper-ature.The contents of ethanol and acetaldehyde were lower within the first 60 days of storage at 2-4 ℃ and 6-8 ℃ and significantly higher at 2-4 ℃ than at 6-8 ℃ after 75 days at storage.L*,a*and b*of W.Murcott fruit gradually increased and reached the peak in phase Ⅲ with the delay of harvest date.During storage at 6-8 ℃,L*and a*increased continuously and then tended to level off.These color values in different phases followed a pattern of Phase Ⅲ and Phase Ⅳ＞Phase Ⅱ＞Phase Ⅰ,and the difference between phases was significant.The value of b*increased first and then decreased,and the later the harvest,the earlier the peak value of b*appeared during storage.Fruit weight loss was the fast-est in phase Ⅳ and slowest in phase Ⅲ.The content of soluble solids increased with the delay of har-vest,and was significantly higher in phase Ⅲ and phase Ⅳ than that in phase Ⅰ.The contents of titrat-able acids and vitamin C decreased with the delay of harvest,and were highest in phase Ⅰ and the low-est in phase Ⅳ.The content of reducing sugars first increased and then decreased with the delay of har-vest,and was significantly higher in phase Ⅱ and phase Ⅲ than in phase Ⅰ and phase Ⅳ during stor-age.The content of citric acid decreased with the delay of harvest and fluctuated during storage,and the lowest content was found in fruit harvested in phase Ⅳ and stored at 6-8 ℃.The contents of ethanol and acetaldehyde increased with the delay of harvest time.During storage at 6-8 ℃,the rising rate of ethanol and acetaldehyde contents in the four phases followed a pattern of phase Ⅰ＜phase Ⅱ,phaseⅢ＜phase Ⅳ.At the 60th day of storage,the ethanol contents in fruit in phase Ⅰ,phase Ⅱ,phase Ⅲ,and phase Ⅳ were 285.61,894.79,654.68 and 1 311.58 mg·L-1,respectively.The contents of ethanol,acetaldehyde and methanol were significantly higher in the shelf-life than those in storage period.The ethanol content exceeded the threshold of 1500 mg·L-1 in fruit harvested in phase Ⅰ shifted to room temperature after stored for 120 days,and exceeded the threshold in fruit harvest in phase Ⅱ,phase Ⅲand phase Ⅳ after 60 to 75 days of storage.[Conclusion]Compared with room temperature storage,low temperature storage could reduce the weight loss rate significantly,delay the decreasing rate of ti-tratable acid and vitamin C contents,and increase the soluble sugar content in W.Murcott fruit.6-8 ℃ fruit occurs when the green color of the fruit basically fades,the soluble solids reach 11％,and the titrat-able acid is greater than 0.8％(about late December to late January of the following year in Guilin ar-ea).6-8 ℃ is suitable low temperature for storage the fruit of W.Murcott but storage time at this cold temperature range should not be longer than 90 d and should not be move out of storage at room temper-ature after 60 days of storage at low temperature.