Effects of different harvesting periods on the storage quality and senescence of apple at room temperature

Abstract: There are many factors affecting fruit storage and preservation, and harvesting, as the first technical measure for fruit post-harvest treatment, plays an important role in ensuring the quality of fruit harvesting and post-harvest storage. The changes of storage quality and softening senescence of 'Saiwaihong' apple fruits at room temperature (20±1℃) in three different harvesting date (August 29, September 7 and September 16) during 116～134 days in Tongliao area were studied, in order to determine the optimum harvesting maturity and the suitable harvesting time of 'Saiwaihong' apple, and to provide technical support for the large-scale popularization of superior new varieties in production. The results showed that with the delay of harvesting time (i.e. the increase of fruit maturity), fruit firmness gradually decreased, the content of soluble solids (SSC) and titratable acid content increased by degrees, seed color gradually turned brown to full brown, and vitamin C content was the highest at harvesting time II. The firmness, vitamin C and titratable acid content of fruits in three harvesting time decreased gradually with the prolongation of storage time. From the collection to the end of the storage, The firmness of fruits harvested on harvesting time I has maintained the highest. The higher vitamin C and titratable acid content of fruits were maintained in harvesting time II.The SSC of harvesting time III fruit remained the highest (19.60%～20.99%) all the time, but fruit softening and senescence are faster. The fruit harvested earlier (harvesting time I) had higher content of original pectin and cellulose during storage at room temperature, which inhibited the production of soluble pectin, delayed the peak time of PG activity and cellulase activity, reduced its peak value, delayed the peak time of respiration and ethylene, and delayed the softening and senescence of fruit, however, the appearance, color, taste and flavor of the fruit were relatively poor, so early harvesting is not recommended. Malondialdehyde (MDA) and ethanol content of fruit harvested at harvesting time III accumulated more, fruit senescence was faster, shelf life was shorter, and fruit was only suitable for short-term storage or fresh sale. The comprehensive analysis showed that 'Saiwaihong' apple at harvest stage II not only had good internal quality and appearance, but also had good storage and transportation performance. Therefore, it is suggested that the optimum harvest time of 'Saiwaihong' apple in Tongliao area should be from 5～10 September (1～2 days late). The reference criteria for harvesting maturity were as follows: the number of days of fruit growth and development were 123～128 d, Pulp firmness were 11.0～11.5 kg/cm2, soluble solids content (SSC)≥16.5%, seed color was about 3/4 browning, starch dyeing was about 4.5 grade.