Bioactive compounds in fresh, fresh-cut, frozen pineapple and bioactive compounds changes in frozen pineapple during storage

Processing steps of frozen fruit include preparation of the raw material such as trimming, cutting and peeling followed by freezing step. These processes may effect on nutrition and bioactive compound in fruit. Moreover, long-term storage also may effect on nutrition and bioactive compounds as well. The purpose of this research is to gain the scientific data of effect of preparation step and freezing step on bioactive compounds changes in pineapple. Bioactive compounds of fresh, fresh-cut and frozen pineapple was investigated. The advantage of this information is useful to market expansion and promote healthy fruit. Pineapple fresh, fresh-cut, blanching and frozen pineapple were sampled to measure bioactive compounds. Fresh-cut, blanching and frozen processing of pineapple had no effect on flavonoids and β-carotene but decreased in phenolics, ascorbic acid and antioxidant activity of DPPH radical and FRAP radical. These bioactive compounds were gradually reduced after blanching and freezing process except β-carotene. Fresh-cut, blanching and freezing process had no effect on flavonoid content. Vitamin E of pineapple in all samples showed less than 0.05 mg 100 g^-1 FW and less than 7 µg 100 g^-1 FW of vitamin A. Bioactive compounds of pineapple contained 3.91-6.38 mg g^-1 FW of ascorbic acid, 0.50-0.67 mg 100 g^-1 FW of flavonoid, 38.27-45.01 µg 100 g^-1 FW of β-carotene, 33.89-39.93 mg GAE g^-1 FW of phenolic, antioxidant activity of DPPH radical as 462.96-637.91 µmol TE g^-1 and antioxidant activity of FRAP radical as 12.63-13.94 µmol TE g^-1. Effect of packaging and storage time on bioactive compounds changes in frozen pineapple was also studied. Frozen pineapple kept in VAC bag had higher flavonoids and β-carotene than PE bag during storage. No significant different of phenolics, ascorbic acid, antioxidant activity of DPPH radical in both PE and VAC bag was observed. Those bioactive compounds were gradually decreased in both packaging during storage.