Electron beam irradiation on Fuzhuan brick-tea: Effects on sensory quality and chemical compositions

The aim of this study was to evaluate the electron beam irradiation effects on sensory quality and major chemical components in Fuzhuan brick-tea (FBT) at doses of 0, 1, 4, and 7 kGy. Furthermore, these samples were compared with those aged 3 years. The dose of 1 kGy showed no effect on appearance of the FBT infusion and amount of the major chemical components. However, when the dose rose to 4 or 7 kGy the color of tea infusion gradually deepened and red changed much like aged teas, moreover, the brightness is not lowered. Leather, musty-dry, straw-like, bitter, hay-like, brown, medicinal and woody are the typical flavor quality characteristics of FBTs. Most sensory attributes were not affected significantly by irradiation except a decrease in intensity of barnyard, woody, and tobacco in aroma and almond, green, and metallic in flavor. The comprehensive sensory quality of FBTs including appearance, aroma and flavor were improved following irradiation dose of 4 or 7 kGy. Like aged teas, the total tea polyphenols, soluble sugar, free amino acid and water extracts increased while the caffeine and total flavonoids decreased after irradiation. Irradiation at 4 kGy induced significant increase in the concentration of the catechins, especially EGCG (increased similar to 57%), contrary to aged tea which decreased about 10%. It is concluded that irradiation at 4 kGy had positive effects on FBT for getting not only better sensory quality but also high concentration of polyphenols.