High humidity air-impingement blanching (HHAIB) improves drying characteristics and quality of ground-cover chrysanthemum heads

Abstract

Abstract Effects of high humidity air-impingement blanching (HHAIB) temperature, relative humidity over a range of application time and drying temperature on air-impingement drying kinetics, colour attributes, browning index, blanching weight loss and total flavonoids content of chrysanthemum heads were studied. HHAIB could shorten the drying time of chrysanthemum heads significantly (p < 0.05) by up to 52% compared to the control group without blanching. Meanwhile blanching humidity has a greater influence on drying kinetic than other blanching parameters. D eff values of samples declined first and rose later with the growth of blanching humidity, while increased continuously with the growth of blanching temperature. The highest growth of total flavonoids content can be up to 21.6% under the HHAIB blanching conditions (110 °C of blanching temperature, 45% of relative humidity, 150 s of blanching time) in comparison with the control group. Lightness of all blanched samples was lower than the control group, and redness and total colour difference under different blanching conditions showed significant differences compared to the control group, while no obvious variation was observed in terms of yellowness values.