Mid-early maturing apples can enrich the fruit market and constitute an important part of the apple industry. It is of great significance to study the quality and storage characteristics of mid-early maturing apples. In this study, ‘Luli’ and ‘Luyan’ apples as well as their parental variety Gala (as a control) were investigated for differences in their storage quality and phenolic composition. The results showed that ‘Luli’ apples had higher soluble solid content (SSC) and skin a* value and better appearance quality compared with ‘Gala’ apples, being suitable for fresh consumption. However, ‘Luyan’ apples possessed high total acid content and low solid/acid ratio, produced a largest amount of ethylene during storage, and had poor storability. Compared with ‘Gala’ and ‘Luyan’ apples, ‘Luli’ apples had higher contents of total phenolics and flavonoids and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, indicating stronger antioxidant capacity. The main phenolics in apples varied depending on the variety, maturity and fruit part. Chlorogenic acid was the most abundant phenolic compound in ‘Luli’ and ‘Gala’ apples, while epicatechin was the most abundant phenolic compound in ‘Luyan’ apples. The content of phenols in the peel was higher than that in the pulp. Correlation analysis and principal component analysis showed that fruit firmness had a significant negative correlation with a* value (P < 0.001), and SSC had a significant positive correlation with the contents of total phenolics, total flavonoids, chlorogenic acid and DPPH radical scavenging capacity (P < 0.001). Principal component 1 (PC1) is mainly determined by the content of total phenolics, total flavonoids, chlorogenic acid, and epicatechin. Mature ‘Luli’ and ‘Gala’ apples are relatively similar in PC1. This study provides a reference for the preservation and processing of mid-early maturing apples.

The quality and physiological changes of ‘Luli’ and ‘Gala’ apples during low-temperature storage were explored to provide a theoretical basis for the storage and preservation of new mid-early ripening apple varieties. The results showed that the hardness, soluble solids content and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity of ‘Gala’ and ‘Luli’ apples showed a downward trend during cold storage and the shelf life period. After 90 days of storage, the hardness of ‘Gala’ apples decreased by 56.3%, while that of ‘Luli’ apples decreased only by 30.7%. Compared with ‘Gala’ apples, ‘Luli’ apples had lower polyphenol oxidase and lipoxygenase activities and higher contents of total phenols, flavonoids and chlorogenic acid during storage. During low temperature storage, the contents of individual phenolics in ‘Luli’ apples decreased, and the contents of chlorogenic acid, epicatechin, hypericin, and ferulic acid decreased most in the first 15 days, but did not significantly change during the shelf life period. The contents of catechins, p-coumaric acid, rutin, and caffeic acid in ‘Gala’ apples increased slightly after 15 days of low temperature storage and then decreased, but decreased gradually during the shelf life period. The contents of all phenolics decreased during the shelf life period. The major aroma components in ‘Gala’ and ‘Luli’ apples were aldehydes, alcohols and esters, among which 3-methyl-2-buten-1-ol, isoamyl benzoate, nonanal, 2-amino-6-methylbenzoic acid, 1-methyldibenzofuran and diisobutyl phthalate were only detected in ‘Luli’ apples. During low-temperature storage, the relative contents of aldehydes in both varieties decreased, while the relative contents of alcohols and esters showed an increasing trend. The relative content of alcohols in ‘Luli’ apples decreased during the shelf life period, while the opposite trend was observed for ‘Gala’ apples. In conclusion, ‘Luli’ apples exhibited higher fruit hardness, antioxidant capacity and phenol content during low-temperature storage and the shelf life period, and the overall storage quality was better than that of ‘Gala’ apples.