Emulsifying Property and Emulsifying Stability of Alkali Extracted Tea Residue Protein

The alkali-extracted tea residue protein (ATRP) is a novel protein resource with the potential to become a food-grade emulsifier. This study assessed ATRP's emulsion type and hydrophilic-lipophilic balance value, analyzed the effects of various emulsification factors (oil-water ratio, emulsifier concentration, pH, storage temperature) at room temperature (20 ℃) on emulsifying performance (10-minute settling) and stability (15-day settling), followed by a comparison of emulsifying performance and stability of soybean isolate protein and whey protein emulsions. The results showed that the ATRP emulsion was of the water-in-oil (O/W) type, with a hydrophilic-lipophilic balance of 13. Under conditions of a 7:3 oil-water ratio, 4 mg/mL concentration, pH of 7, and storage temperature of 20 ℃, ATRP exhibited good emulsification properties. Under these conditions, the ATRP emulsion showed an EAI of 43.3 m²/g and a CI of 97% after 10 minutes of settling. After 15 days, the EAI and CI values remained strong at 82.9% and 88.5% respectively, indicating excellent stability. Compared with the emulsion of soy protein isolate or whey protein, the ATRP emulsion had little change in particle size during storage and the ζ-potential was double and 2.5 times, showing better emulsifying properties.