Impact of Modified Atmosphere Storage on Eastern Thornless Blackberry Quality and Antioxidant Levels

Abstract

Modified atmosphere (MA) storage of blackberries may maintain quality and increase storage life, but there is limited information about how eastern thornless cultivars respond to MA's. Because there is also a growing interest in the health benefits of antioxidants in blackberries, it would be useful to know how those levels might change during MA storage. In 2002, the eastern thornless blackberry variety Chester was stored in MA; treatments included a control, or initial levels of 20% CO2 or 5% O2. Color, pH, firmness, fresh weight, soluble sugars, titratable acidity, total antioxidant capacity, and the levels of major classes of compounds with antioxidant activity of the fruit were measured at harvest, after 1 week of MA storage at 4 °C, and after 3 additional days at room temperature to simulate common industry practices and grocery display. Total antioxidant capacity was measured using the FRAP (ferric reducing/antioxidant power) assay, and total phenolics and anthocyanins were measured spectrophotometrically. In 2002, soluble sugar levels, fresh weight, titratable acidity, and all classes of antioxidants decreased from day 0 to day 7 to day 10 while the pH increased. Color values did not change. The only trait that differed among treatments was berry firmness; from day 0 to day 7 control fruit was the most firm, and those from the high CO2 treatment were the least firm. Studies were continued in 2003 with the addition of two more eastern thornless blackberry cultivars, Hull Thornless and Triple Crown, and these results will also be presented.