Phenolics and Volatiles in Arkansas Fresh-Market Blackberries (Rubus subgenus Rubus Watson)

Blackberries (Rubus subgenus Rubus Watson) are an excellent source of health-promoting polyphenols and possess unique flavors. The physicochemicals, polyphenols, and volatiles of 16 blackberry genotypes (seven cultivars and nine breeding selections) developed at the University of Arkansas System Division of Agriculture were evaluated in 2019. The blackberry genotypes differed in physicochemicals, polyphenols, and volatiles. The physicochemicals of the blackberries varied with soluble solids of 9.7-12.5%, pH 2.9-3.8, titratable acidity 0.5-1.7%, and soluble solids/titratable acidity ratio of 5.7-19.5. Only five genotypes (A-2528T, A-2610T, A-2620T, A-2658T, and Sweet-Ark Caddo (R)) were within a desired soluble solids/titratable acidity ratio of 10-13. The total anthocyanins ranged from 86.3 mg/100 g (A-2658T) to 235.3 mg/100 g (A-2547T), total flavonols ranged from 3.9 mg/100 g (Ouachita) to 16.3 mg/100 g (A-2528T), and total volatiles ranged from 2419 ng/g (A-2528T) to 5574 ng/g (A-2587T). Aldehydes (45%), esters (18%), monoterpenes (15%), alcohols (10%), and acids (10%) were the major classes of volatiles found in these Arkansas blackberry genotypes. The 10 major volatiles expressed as percentage of total volatiles across all genotypes were hexanal (26%), ethyl acetate (16%), 2-heptanol (6%), octanoic acid (6%), pentanal (4%), 2-hexenal (4%), linalool (3%), 2-butenal-3-methyl (3%), a-pinene (2%), and butanal-2-methyl (1%). Sweet-Ark Ponca (R), A-2547T, and A-2658T contained the highest concentrations of major odorants. A-2547T, which had the highest soluble solids/titratable acidy ratio and highest levels of total anthocyanins and major odorants, was a promising breeding selection. For this physicochemical, phenolic, and volatile data, A-2547T was a promising breeding selection for the UA System Blackberry Breeding Program. This research provided a base for future evaluations on using metabolomic data (especially volatiles) and consumer sensory data to determine drivers of flavor preferences for fresh-market blackberries.