Changes in the bioaccessibility of citrus polyphenols during industrial freezing process

Abstract

Citrus fruits can be consumed fresh or they can be subjected to various processes including freezing to extend their shelf life. The aim of the current study was to evaluate the bioaccessibility of polyphenols in samples collected at different stages of the industrial freezing process of oranges and grapefruits. The major polyphenols were identified and quantified using UPLC-ESI-MS/MS and HPLC-PDA, respectively. In addition, spectrophotometric methods were employed to determine the total phenolic and flavonoid contents along with total antioxidant capacity. The results showed that the bioaccessibility of flavonoids from frozen citrus fruits (26%-64%) was found to be lower than that of fresh fruits (27%-127%). Similarly, bioaccessibility of phenolic acids from frozen oranges (64%-76%) was significantly lower than that of fresh fruits (126%-152%). On the contrary, phenolic acids of frozen grapefruits were found to be more bioaccessible compared to fresh fruits (64%-217% and 50%-95%, respectively).