Changes of flesh texture and nutritional components of four apple cultivars during storage

Abstract:【Objective】The apple cultivar‘Huaguan’with long-term storage capacity and the apple cul- tivar‘Meiba’with short-term storage capacity were grown as the parental lines in the orchard of the Zhengzhou Fruit Research Institute, and‘Huashuo’was an early-season apple cultivar derived from the cross, whose fruits were nearly roundness, having a vermeil skin, pleasant flavor, long storage time, and weighing 232 g on average. The objective of this study was to compare fruit texture properties and nutritional components of different apple cultivars in order to provide a basis for predicting the quality and shelf life of apple fruits.【Methods】The texture profile analysis (TPA) was carried out with the texture analyzer. The fruits of‘Meiba’‘Huaguan’‘Huashuo’and‘Huarui’were used as the experimental materials. One hundred fruits of each cultivar were collected at harvest time, and they were selected with uniform size and shape, free from disease and mechanical damage. In this experiment, the time for collecting samples was based on the fruit softening speed.‘Meiba’and‘Huarui’were stored at room temperature for firmness measurement every 6 days, and‘Huashuo’and‘Huaguan’were measured every 10 days. Flesh texture properties including firmness, frangibility, gumminess, springiness, cohesive- ness and chewiness were measured by TA.XT plus texture analyzer, using P50 probe. The parameters were set as follows: the pre-test and post-test speeds were 60 mm·min-1, the mid-test speed was 30 mm·min-1, within 5 seconds interval between two compressions. The specimen deformation under compression was 60% and the trigger force was 0.1 N. For nutritional components in fruits, the soluble solids were determined by a digital Brix fractometer, titratable acid was determined by sodium hydroxide titration method, soluble sugar was determined by anthrone colorimetry method, and vitamin C was determined by 2,6-dichloroindophenol method. The acquired data were conducted by mathematical and statistical analysis using the Excel and the SPSS (version 22.0) was used for correlation analysis【. Results】The flesh texture of‘Huarui’and‘Meiba’decreased significantly within 6 days, as the firmness of‘Hua- rui’decreased from 30.1 N to 15.2 N, and frangibility decreased from 30.0 N to 14.7 N, which de- creased by 48.6% and 45.8%, respectively. Firmness and frangibility of‘Huashuo’decreased slowly within 30 days, and those of‘Huaguan’decreased slowly within 50 days. The tendency of gumminess, springiness, cohesiveness and chewiness changes was basically consistent with that of firmness and frangibility. At the end of storage, the flesh texture properties were slightly different, especially for the springiness and cohesiveness. During the whole storage period, the flesh cohesiveness, gumminess and chewiness of the long-keeping cultivars were significantly higher than those of the short-keeping culti- vars. Texture change was the most significant during fruit development and storage, and it was an im- portant index to evaluate fruit quality. For nutritional components, fruit maturity may play an important role. The soluble solids, soluble sugar and vitamin C contents of late-maturing cultivar‘Huaguan’were higher than those of the early-maturing cultivar at harvest, and the contents of soluble sugar of‘Huaguan’were significantly higher than those of other cultivars during the whole storage. The results of the determination of nutritional compositions showed that the nutritional value of fruits was not close in dif- ferent storage stages. In addition to the rapid decline of vitamin C content, other nutritional components lost slowly during storage. Correlation analysis showed that there were no significantly different chang- es in nutritional components among the four varieties, and there was no significant correlation between fruit texture properties and nutritional components, while there was a significantly positive correlation among flesh firmness, frangibility, gumminess, and chewiness.【Conclusion】Texture properties and nutritional compositions were different in four cultivars during storage. The correlations of firmness, frangibility, adhesiveness and chewiness among the four cultivars were significant, which may reflect the flesh texture changes of different apple cultivarsduring the whole storage stages. There was significant correlation between titratable acid and vitamin C content in four cultivars at different storage stages, which may result in nutrient transformation. The shelf life at room temperature indicated that the hard- ness and frangibility of‘Huarui’and‘Meiba’decreased significantly after 6 days of storage, and‘Huashuo’and‘Huaguan’could be stored for 30 and 50 days, respectively.