Comparison of storability and flavor among peach fruits with different soluble solids contents based on clustering and principal component analysis

Abstract:【Objective】Texture, color, sugar and acid, soluble solids content (SSC) and volatile compounds are important factors for peach fruit. Fruit quality deterioration, such as loss of flavor, accumula-tion of harmful substances and chilling injury caused by long-term cold storage or cold-chain transporta-tion, is the main reason that lead to decrease of purchasing power of consumers and hinder the export of fresh fruit. Storage and fresh-keeping technology is an important link to solve the above problems. In addition, more and more enterprises have introduced the classification equipment, based mainly on SSC, which has become an increasingly concerned about internal quality index. However, the correla-on between SSC and fruit texture, flavor and storability, and the study on storage period and quality di-vided by quality, SSC, sugar acid and volatile compounds are seldom reported.【Methods】In this study, Hujingmilu peach was used as materials. On the premise of the same fruit firmness of pulp (fruit firmness without peel 12.5-21.2 N) based on SSC, the fruit was divided into high SSC group (SSC＞14.5%), middle SSC group (SSC was12.5%- 13.5% ) and low SSC group (SSC≤12% ). The fruits of different SSC group were placed in plastic baskets lined with grooves, and then precooled and stored in a cold storage at 2-4 ℃ with 85%-90% relative humidity. Fruit Texture, SSC, sucrose, fructose and glucose contents, sensor value of 10 electronic nose sensors were measured on 0 d, 7 d, 14 d, 21 d, 28 d and 28 d + 3 d, 28 d + 5 d after cold storage, and 10 people were assigned for marking sensory score. The texture and flavor of peach fruit in different storage periods were determined by computer R technology based on clustering and principal component analysis, and the storability and flavor of peach fruit with different SSC contents were evaluated.【Results】Based on the storage time, there was a strong correlation be-tween firmness with peel, firmness without peel, chewiness and flesh brittleness, and there was also a strong correlation between fructose and glucose content. The electronic nose sensors S6 (methane) and S7 (hydrogen sulfide) were located in three separate spaces with sensors S8 (ethanol) and S9 (aromatic components and organic sulfides). During cold storage, the fruit with high and medium SSC group main-tained higher tissue, firmness, SSC, fructose and glucose content, and S6 response value was significant-ly lower than that with low SSC group. During shelf life, the firmness with peel, firmness without peel, chewiness and flesh brittleness, SSC, fructose and glucose contents and S2, S7, S8, S9 sensor value with high and medium group were significantly higher than those with low group, and the S6 sensor value was significantly lower than that with the low group. On the basis of quality and sensor value, storage time can be divided into groups similar to sensory evaluation. There were some differences among fruit groups with different SSC contents. Cluster analysis can be used to classify fruit with high and medium SSC at 3 d and 5 d of shelf-life, which showed that increasing SSC contents can prolong shelf-life and maintain shelf-life quality. Among them, the partition of sensor value of high SSC group fruit was ad-vanced to 0-7 days compared with 10 quality parameters (cluster group Ⅰ 0-21 d) and 10 sense scores (cluster group Ⅰ 0-14 d), and the criterion of storage quality evaluation should be further optimized. 【Conclusion】Improving SSC contents in fruit can prolong the safe storage period of fruit and keep the inherent flavor of fruit. High SSC fruit stored 0-14 days with 3 and 5 d of shelf life, and medium SSC group fruit stored 0- 7 days were classified as high- quality commercial fruits, and the high SSC fruit stored at 14-28 d and the medium-sugar fruits stored at 7-21 d with 3d of shelf life were classified as commercial fruits. It is recommended that fruit with SSC below 12% should not be refrigerated for lon-ger than 7 days.