Assessment of physicochemical quality, antioxidant content and activity, and inhibition of cholinesterase between unripe and ripe blueberry fruit

Five Korean blueberries ("Nelson", "Duke ", "Bluejay ", "Toro", and "Elliot ") were harvested at two maturity stages (unripe and ripe) to evaluate fruit quality and antioxidant activities. The Hunter L, a, and b color of ripe blueberries was lower than that of unripe fruit. Soluble solid concentration (SSC) and pH increased, and titratable acidity (TA) and firmness decreased as the blueberries matured. The ripe blueberry fruits showed a higher SSC/TA ratio than the unripe fruits. Although total anthocyanin, flavonoids, phenolics content, and antioxidant activity were higher in ripe blueberries than in unripe fruit, the unripe fruit had higher acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition activities than ripe fruit in all cultivars. Total antioxidant activity was highly correlated with total flavonoids and phenolics. The relationships between the total antioxidant activity and the AChE or BChE inhibitory activity are negative. There were several physicochemical quality and antioxidant activity differences in blueberries, depending on the cultivar and the maturity at harvest. Unripe fruits also contain potential health-promoting bioactive compounds as functional food ingredients.