Study on storage characteristics of a new apple variety Ruixue

Abstract: 【Objective】As a new yellow and late-ripening apple variety, Ruixue apple was selected by the team of Northwest A & F University by crossing Qinfu No. 1 with Pink Lady. It has strong flavor and unique clear fragrance smell and is well accepted by consumers. In order to clarify the storage char-acteristics of Ruixue apples, the experiment was undertaken to understand the physiological characteris-tics, quality changes and disease occurrence during fruit storage, and to provide references for its fur-ther promotion.【Methods】The vigorous 5-year-old Ruixue apples grown at the Baishui Apple Experi-mental Demonstration Station of Northwest Agriculture and Forestry University of Shanxi Province were used as materials. They were picked at normal maturity. The single fruit was covered with foamed nets and shipped back to the laboratory in a box and placed at room temperature for 24 hours. The field heat in fruits was eliminated. The fruits were selected with same size and uniform coloring, and without pests, diseases, and mechanical damage, randomly divided into two groups, put in fruit baskets lined with polyethylene plastic film, and stored at low temperature (0±0.5 ℃) and normal temperature (20±2 ℃) , respectively. The regular samples were taken to determine the surface color, hardness, soluble solids, and titratable acid of the fruit. At the same time, the samples were frozen and ground with liquid nitrogen and stored in an ultra-low temperature refrigerator at -80 ℃ for the determination of vitamin C content and enzyme activity related to maturation and senescence. In addition, a part of the fruits were fixed to determine the respiratory intensity, ethylene release rate, weight loss rate, and external fruit ap-  pearance and skin brown disease and decay rates were examined. According to the physiological and biochemical quality and appearance changes of fruits under normal temperature and low-temperature,the storage characteristics of Ruixue apples were clarified.【Results】Under the condition of 0 ℃ cold storage, Ruixue apples can better maintain fruit hardness, soluble solids, titratable acid, and vitamin C contents, significantly reduce weight loss and alleviate fruit dehydration. The soluble solid content reached the maximum 17.48% when fruits were stored for 60 days, and only decreased by 2.18% when stored for 120 days; CAT, PPO and CAT activities changed greatly and reached the peak during storage for 70 days to 90 days; after 90 days of storage, the fruit surface color began to darken. The fruit color gradually began to turn yellow; when stored for 120 days, mild skin brown disease began to appear, and the water loss rate was only 1.22%. 30 days before storage at room temperature, the fruit hardness decreased rapidly. After 15 to 30 days of storage, the soluble solid content was higher, reaching 16.71%. After 30 days, the activity of CAT, PPO and CAT changed greatly, indicating that the fruit began to dam-age; 45 days later, the fruit surface color turned yellow, the water loss rate reached 5.1% at 60 days, and the fruit became very greasy. Diseases such as skin brown disease, bitter pit and gray mold appeared, and the surface of the fruit stems was browned, and the storage value was lost. Under 0 ℃ low-tempera-ture condition, the peaks of respiration and ethylene release appeared at 45 days and 60 days, and the peaks were 3.85 mg·kg^-1·h^-1 and 80.51 μL·kg^-1·h^-1, respectively. Under normal temperature storage conditions, the respiration peak was 25 d earlier, and the ethylene release peak was 10 d earlier, with peaks as high as 20.47 mg·kg^-1·h^-1 and 285.76 μL·kg^-1·h^-1, significantly accelerating fruit senescence.【Conclusion】Ruixue apples can better maintain the hardness, soluble solids, titratable acid and vitamin C content of the fruit under the low temperature of 0 ℃, prevent water loss, and inhibit the darkening and yellowing of the peel. When fruits were stored for 120 days, the various indexes remained relatively well and only slight skin brown disease appeared. However, the fruit senescence performed rapidly un-der normal temperature conditions. After 4 weeks of storage, the quality and nutrition of the fruit would change greatly, and various diseases appeared. It is recommended to sell and eat within 20-30 d. The re-sults could provide a basis for the production and references for the storage of Ruixue apples.