2019 ASHS Annual Conference

Anthocyanins and hydroxycinnamic acids (HCAs) were identified and quantified by HPLC–DAD/MS in 4 to 7 cultivars over three years and at 2 stages of maturity in 2 years. Total phenolic (TP) concentration was measured by the Folin−Ciocalteu method and antioxidant activity (AOA) by DPPH assay. Anthocyanin concentration was highly variable among cultivars, and less variable with stage of maturity and among the three years of testing. Increase in anthocyanin concentration with advance in maturity was generally small in most cultivars, but substantial in ‘Methley’ and ‘Obilnya’ which had higher concentration than most other cultivars. ‘Abundance’, ‘Toka’ and ‘Castleton’ had two types of anthocyanins, predominantly cyanidin-glucoside and lower concentrations cyanidin-rutinoside, whereas, in ‘Obilnya’ and ‘Vanier’, cyanidin-rutinoside was the predominant anthocyanin. The two cultivars derived from P. ceracifera, ‘Methley’ and ‘Obilnya’, had cyanidin-galactoside in addition to the other two anthocyanins. The P. americana-hybrid plum, ‘Kahinta’ had only cyanidin-glucoside as did ‘Superior’. Concentration of HCA’s was greater in European than in Asian and American-hybrid plums, except for ‘Toka’ which also had a high concentration. Large year-to-year variation in HCA occurred in some cultivars, whereas, variation due to advanced maturity was small. American hybrids displayed greater TP and AOA than European plums, and similar AOA as Asian plums. Although TP was greater in 2015 than in 2016, the curvilinear relationship between TP and AOA was similar in both years.