Correlation distance of browning characteristic and polyphenol distribution in apple slices from 20 Chinese cultivars

Abstract

Aim: The aim of this study is to investigate the polyphenol composition and distribution in the core, flesh, and peel of 20 apple varieties from China and its relation with browning characteristics of apple slices in the drying process. Methods: In this paper, the prominent phenolic compounds, which was determined by photo diode array-high-performance liquid chromatography (PDA-HPLC), and the chromatic value [coherent infrared energy (CIE) L*, a*, b*] were correlation analysised. Results: The results showed that apple core, flesh, and peel were characterized by phloridzin, chlorogenic acid, quercetin, and related derivatives respectively. The 20 apple varieties showed a significant difference (* P < 0.05) in browning variation in the drying process. The browning at the initial stage was mainly L* declined, which was induced by polyphenols enzymatic oxidation. While the browning was characterized by b* and a* value increment at the end of the drying process, where the Maillard reaction was the dominant factor. Conclusions: The correlation distance between the main phenolic compounds in apple core, flesh, and peel with the average chromatic L*, a*, and b* values varied at different stages of the drying process.