Fruit Quality and Chemical Contents of Hybrid Boysenberry (Rubus ursinus) Lines Developed by Hybridization and Gamma Irradiation

The Rubus fruit is an economically important berry crop that contains various functional compounds. The objective of this study was to analyze fruit qualities (i.e., pH, soluble solids content, titratable acidity, and mineral content) as well as fatty acid and phenolic compounds (i.e., ellagic acid and anthocyanins) among hybrid boysenberry lines developed by hybridization and gamma irradiation. There were no significant differences in the hybrid boysenberry fruit pH and titratable acidity (%) among the tested genotypes. However, the soluble solids content was higher in the BSA119 and BSA144 mutants than in the original genotype (BS_Hybrid). Meanwhile, linoleic acid was the most abundant fatty acid in the analyzed hybrid boysenberry fruits. The fatty acid composition did not differ significantly among the genotypes. The ellagic acid content of all genotypes ranged from 8.72 mg/100 g to 46.10 mg/100 g, with the highest concentration observed for the BSB127 genotype. Additionally, cyanidin-3-O-sophoroside (M-H+, 611 m/z) and cyanidin-3-O-glucoside (M-H+, 449 m/z) were the two major anthocyanins detected in the boysenberry and mutant genotypes, while cyanidin-3-O-glucoside was the predominant blackberry anthocyanin. The total anthocyanin concentrations of four mutant genotypes (i.e., BSA036, BSA078, BSA101, and BSB127) were significantly higher than that of the original genotype (382.0 mg/100 g). The highest total anthocyanin concentration was observed for the BSA078 genotype (467.9 mg/100 g). These results may be useful for identifying the optimal genotypes for breeding new cultivars with enhanced qualities and potential health benefits.