Dynamic Changes of Active Components and Volatile Organic Compounds in Rosa roxburghii Fruit during the Process of Maturity

Abstract

Rosa roxburghii (R. roxburghii), native to the southwest provinces of China, is a fruit crop of important economic value in Guizhou Province. However, the changes in fruit quality and flavor during R. roxburghii fruit ripening have remained unknown. Here, this study investigated the changes of seven active components and volatile organic compounds (VOCs) during the ripening of the R. roxburghii fruit at five different ripening stages including 45, 65, 75, 90, and 105 days after anthesis. The results indicated that during the ripening process, the levels of total acid, vitamin C, and soluble sugar significantly increased (p < 0.05), while the levels of total flavonoids, superoxide dismutase (SOD), and soluble tannin significantly decreased (p < 0.05). Additionally, the content of total phenol exhibited a trend of first decreasing significantly and then increasing significantly (p < 0.05). A total of 145 VOCs were detected by HS-SPME-GC-MS at five mature stages, primarily consisting of aldehydes, alcohols, esters, and alkenes. As R. roxburghii matured, both the diversity and total quantity of VOCs in the fruit increased, with a notable rise in the contents of acids, ketones, and alkenes. By calculating the ROAV values of these VOCs, 53 key substances were identified, which included aromas such as fruit, citrus, green, caramel, grass, flower, sweet, soap, wood, and fat notes. The aromas of citrus, caramel, sweet, and wood were predominantly concentrated in the later stages of R. roxburghii fruit ripening. Cluster heatmap analysis revealed distinct distribution patterns of VOCs across five different maturity stages, serving as characteristic chemical fingerprints for each stage. Notably, stages IV and V were primarily characterized by a dominance of alkenes. OPLS-DA analysis categorized the ripening process of R. roxburghii fruit into three segments: the first segment encompassed the initial three stages (I, II, and III), the second segment corresponded to the fourth stage (IV), and the third segment pertained to the fifth stage (V). Following the variable importance in projection (VIP) > 1 criterion, a total of 30 key differential VOCs were identified across the five stages, predominantly comprising ester compounds, which significantly influenced the aroma profiles of R. roxburghii fruit. By integrating the VIP > 1 and ROAV > 1 criteria, 21 differential VOCs were further identified as key contributors to the aroma changes in R. roxburghii fruit during the ripening process. This study provided data on the changes in quality and aroma of R. roxburghii fruit during ripening and laid the foundation for the investigation of the mechanism of compound accumulation during ripening.

Keywords: HS-SPME-GC-MS; Rosa roxburghii; active components; maturity stage; volatile organic compounds.

Figure 1

(A) Pictures of R. roxburghii fruit at different stages of maturity. The numerals I, II, III, IV, and V represent 45, 65, 75, 90 and 105 days after anthesis, respectively. (B) The content of active components of R. roxburghii fruit at different stages of maturity. TA, total acid; TF, total flavonoid; Vc, vitamin C; SOD, superoxide dismutase; TP, total phenolic; ST, soluble tannin; SS, soluble sugar. The different lowercase letters above the same color bars represent significant differences (p < 0.05).

Figure 2

The relative contents (A) and percentage contents (B) of different types of volatile organic compounds (VOCs) in R. roxburghii fruit at different ripening stages. The numerals I, II, III, IV, and V represent 45, 65, 75, 90 and 105 days after anthesis, respectively.

Figure 3

Aroma descriptions and the relative contents of VOCs with an ROAV of >1 in R. roxburghii fruit at different ripening stages. (A) Characteristic flavor wheels; (B) relative contents; and (C) percentage contents.

Figure 4

Clustering heat map and OPLS-DA analysis of VOCs in R. roxburghii fruit at different ripening stages. (A) Clustering heat map; (B) score plot (R²X = 0.995, R²Y = 0.921, Q² = 0.817); (C) 200 permutation test cross-validation plot (R² = 0.0722, Q² = −0.85); and (D) VIP diagram, red bars represent VOCs with VIP value over 1.