Electromagnetic fields assisted blanching—Effect on the dielectric and physicochemical properties of cabbage

Abstract

AbstractBlanching is an important step in commercial processing of vegetables. The application of innovative thermal technologies (such as electromagnetic fields) in the blanching process is gradually becoming the mainstream. The dielectric materials (e.g., high‐moisture foods) can be heated by the electromagnetic fields and its heating mechanism are closely related to dielectric properties. In this study, the mechanism on dielectric properties of cabbage by electromagnetic fields assisted blanching, including radio frequency (27.12 MHz) blanching (RFB), low frequency (915 MHz) microwave (LFMB), and high frequency (2,450 MHz) microwave (HFMB) was studied and their effects on physicochemical characteristics were also investigated. Compared to hot water blanching, electromagnetic fields assisted blanching significantly improved the dielectric properties and increased nutrient retention of blanched cabbage. Higher ε′ (174.38, 74.69) and ε″ (434.82, 16.50) values of blanched cabbage were obtained through RFB at 27.12 MHz and 915 MHz. The ε′ and ε″ values of blanched cabbage at 2,450 MHz were similar by using electromagnetic fields assisted blanching. Richer volatile compounds, better flavor, higher chlorophyll content (422.77 mg/100 g dry solid) and ascorbic acid content (19.32 mg/g dry solid) were also observed in the RFB blanched cabbage. RFB could be a promising and efficient method for cabbage blanching.Practical ApplicationsElectromagnetic field‐assisted blanching is superior to conventional hot water blanching in dielectric properties and products physicochemical characteristic, which can be developed into a new and highly efficient alternative pretreatment method. This study provides a theoretical basis for the electromagnetic field‐assisted blanching and quality control of cabbage.