Change in nutrients of Citri Reticulatae ‘Chachi’ in relation to browning during aging

Citri Reticulatae ‘Chachi,’ also called “Guang Chen pi” (GCP), is a geoherb of Citri reticulatae pericarpium(CRP), mainly produced in Xinhui, Guangdong, China. It has been a food and traditional medicine for thousands of years. GCPs are popular green food, and can be divided into three picking times and different aging periods according to edible quality. Despite many pharmaceutical studies, there is little information on edible differences among GCP types. The dynamic changes in dietary value for different aging and picking times were investigated through quantifying polyphenols, soluble proteins, ascorbic acid, reducing sugars, polysaccharides, and β-carotene. The browning index (BI) and pH were also measured. Comprehensive analysis results showed that nutrient contents in brownish and reddish peels were close, and higher than in green peel. With aging time, ascorbic acid and β-carotene decreased, while dissolution of polysaccharides, polyphenols, and proteins increased, likely contributing to the aroma change. At the same time, pH of the system gradually decreased, but BI increased. Mathematical path analysis of related substrates and BI showed the greatest correlation of polyphenols with BI. The browning mechanism likely started with ascorbic acid degradation that caused reduced antioxidation, contributing to further reaction of polyphenols with other compounds to produce browning.