The effects of innovative infrared-steam blanching (ISB) on the peroxidase (POD) inactivation, POD inactivation kinetics, characteristic component (phenolics, carotenoids and flavonoids) content, colour and regeneration of POD activity during storage of Chrysanthemum indicum L. flowers were comparatively studied following steam blanching (SB) and infrared blanching (IB). ISB and SB allowed a stable surface temperature of the flowers at approximately 100 °C, and IB caused the temperature rose up to a high value of 129.2 °C. POD was inactivated to 5.7% of its residual activity after ISB for 90 s, 5.8% after SB for 180 s and 5.3% after IB for 270 s. In all processes, the POD inactivation kinetics followed a first-order model (R 2 varied from 0.932 to 0.957) and ISB achieved lower T 1/2, E a and D values and a higher k value than SB and IB. The sample blanched with ISB maintained more characteristic components and colour retention than those blanched with SB and IB. Moreover, ISB allowed the brightest colour and prevented the regeneration of POD activity in dried C. indicum flowers during storage. Therefore, ISB for 90 s at 100 °C is recommended as a more suitable method for blanching C. indicum flowers. The findings in the current work provide a new blanching method for natural plant products.
Keywords: Characteristic component content; Chrysanthemum indicum L. flower; Colour; Enzymatic inactivation; Infrared-assisted steam blanching; Storage.