Properties of Green Tea Waste as Cosmetics Ingredients and Rheology Enhancers

Green tea waste (GTW) is a naturally abundant material, and it has not been widely reused into more valuable materials. The composition of GTW was identified using NMR for carbohydrate composition, an element analyzer for protein content, acetone and hot water extraction for evaluating extractives, and Klason lignin for lignin content. GTW can be converted into nanoparticles by carboxymethylation as pretreatment of the degree of substitutions (DS) and high-pressure homogenizer for nanoparticle making. GTW was prepared using various DS 0 until DS 0.4. The results showed that GTW DS has a more than −30 mV zeta potential, suitable for stable nanoemulsion formulations. The particle size of GTW DS decreases with increasing carboxyl content in the hydrogel, which has a width and length from GTW DS 0.3 to DS 0.4. As a humectant, the water retention value (WRV) of GTW with various DS was increased; DS 0.3 is the best. DS 0.4 has the highest viscosity, storage, and loss modulus as rheology modifiers.