Pulsed Electric Fields enhances calcium infusion for improving the hardness of blanched carrots

Abstract

Abstract This study investigated the feasibility of using Pulsed Electric Fields (PEF) to facilitate calcium infusion, with the aim to improve the hardness of blanched carrots. Moreover, this study explored the relationships between carrot hardness and in vitro β-carotene bioaccessibility, and between in vivo mastication effects and the in vitro β-carotene bioaccessibility of different individuals. Findings showed that calcium infusion facilitated by PEF treatment at an electric field strength of 1.9 kV/cm was effective in improving the hardness of blanched carrots by 57%, leading to similar level of hardness for carrots subjected to conventional overnight soaking in calcium chloride solution followed by moderate temperature precooking (60 °C, 30 min). PEF could shorten the calcium infusion to 12.12 ms and reduce the required calcium concentration to 300 ppm. Moreover, in vivo mastication of blanched carrots preserved by new and conventional approaches revealed that the hardness perception and in vitro β-carotene bioaccessibility of carrot samples were predominantly influenced by the differences in masticatory pattern between individuals. Overall, PEF would be a fast solution to enhance calcium infusion for preserving hardness of blanched carrots and the in vitro bioaccessibility of β-carotene was comparable between carrots with PEF-enhanced calcium infusion and conventional calcium infusion. Industrial relevance This study demonstrates the feasibility of using PEF to accelerate the infusion of calcium ions into carrot to preserve its hardness after blanching. It was found that overnight soaking of carrots with CaCl2 could be shortened tremendously in which the passive diffusion of calcium ions into the carrot cells can occur instantaneously during PEF at a lower concentration of CaCl2. Moreover, the application of a PEF-assisted calcium infusion pre-treatment can produce blanched carrots with similar hardness as those preserved with overnight calcium infusion followed by moderate temperature precooking at 60 °C for 30 min. This implies that PEF could replace the precooking step to achieve similar carrot hardness after blanching. More importantly, this study had gathered new information on how consumers perceived the hardness of blanched carrots preserved by PEF-assisted calcium infusion technique and on the bioaccessibility of carotenoids after an in vivo mastication to orally process the carrots.