Effect of different drying methods on the quality characteristic of dried pepper leaves

Dahongpao pepper leaves were chosen to study the effects of three kinds of drying methods ( hot air drying, vacuum drying and middle-short wavelength infrared drying) on the content of flavonoid and total phenols of dried pepper leaves.Results showed that the contents of flavonoid and total phenols in dried pepper leaves were significantly different with different drying methods ( p < 0.05) .The contents of flavonoid and total phenols in pepper leaves dried by hot air drying ( 55 ℃, 2 h) were13.39, 8.82 mg/g, respectively, while those in pepper leaves dried by vacuum drying ( 65 ℃, 0.07 MPa, 12 h) were 15.49 mg/g and 14.12 mg/g, respectively, those in pepper leaves dried by medium-short wave infrared drying ( 4.5 m/s of wind speed, 60 ℃, 450 W, and 2 h) were 14.40, 13.81 mg/g, respectively.Therefore, compared to hot air drying and vacuum drying, medium-short wave infrared drying was more appropriate for pepper leaves drying due to the shorter drying time and higher contents of flavonoids and total phenols.