Biochemical degradation and physical migration of nutritive compounds in blueberries after PEF and thermal pretreatments and osmotic dehydration

Authors: YU, YUANSHAN - Guangdong Academy Of Agricultural Sciences; Jin, Zhonglin; Fan, Xuetong; WU, JIJUN - Guangdong Academy Of Agricultural Sciences

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2017
Publication Date: 7/21/2017
Citation: Yu, Y., Jin, Z.T., Fan, X., Wu, J. 2017. Biochemical degradation and physical migration of nutritive compounds in blueberries after PEF and thermal pretreatments and osmotic dehydration. Food Chemistry. 239:1219-1215.10.1016/j.foodchem.2017.07.071.

Interpretive Summary: Blueberry fruits have the richest sources of bioactive compounds that benefit human health. However, these nutritive compounds could be lost during food processing. In this study, pulsed electric field (PEF) pretreatment was used to compare with thermal pretreatment before osmotic dehydration of blueberries. The results demonstrated that PEF pretreated samples had the less degradation loss of these compound, faster dehydration rate and superior appearance compared to thermally pretreated and non-treated samples. Therefore, PEF pretreatment could be a potential technology that balances nutritive quality, appearance, and dehydration rate of nutritional fruits.

Technical Abstract: Fresh blueberries were pretreated by pulsed electric fields (PEF) at 3 kV/cm or thermal pretreatment at 90 degrees C for 5 min after which they were subject to osmotic dehydration. The changes in contents of anthocyanins, predominantly phenolic acids and flavonols, total phenolics, polyphenol oxidase (PPO) activity and antioxidant activity in the blueberry samples during pretreatment and osmotic dehydration were investigated. Biochemical degradation and physical migration of these nutritive compounds from fruits to osmotic solutions were observed during the pretreatments and osmotic dehydration. PEF pretreated samples had the least degradation loss and the most migration loss of these compounds compared to thermally pretreated and control samples. Higher rates of water loss and solid gain during osmotic dehydration were also obtained by PEF pretreatment, reducing the dehydration time of blueberry samples from 130 h to 48 h. PEF pretreated and dehydrated fruits showed superior appearance to thermally pretreated and control samples. Therefore, PEF pretreatment is a preferred technology that balances nutritive quality, appearance, and dehydration rate.