A Tea Saponin-Carbohydrate-Protein Complex Could Be One Key Emulsifiable Compound in the Emulsion Formed during Aqueous Extraction of Camellia Oil

The oil/water (O/W) emulsions are spontaneously formed during the process of aqueous extraction of camellia oil which indicates that there are natural emulsifiers with excellent emulsifying capacity exist in Camellia oleifera Abel. seeds. To explore the formation mechanism of these emulsions, a strongly emulsifiable component, a tea saponin-carbohydrate-protein complex (TCPC), is separated and purified by means of chromatography. Its physicochemical properties are characterized by the fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy. The emulsifying properties of O/W emulsions prepared with TCPC (pH 7.0) are investigated systematically. The results show that the emulsions are remarkably stable over a wide range of pH values (5–11), ionic strength (0–200 m m NaCl), thermal treatment (60–90 °C; 30 min), and even after 14 days storage at room temperature (10–25 °C). Moreover, the rheological properties reveal that all determined emulsions show typical pseudoplastic fluid characteristics and shear-thinning flow behavior. However, the emulsions are unstable during freeze-thaw cycle. These results imply that TCPC may be one key emulsifiable compound during aqueous extraction of camellia oil. Practical Applications : Aqueous extraction is a promising technique for edible oil extraction from Camellia oleifera Abel. seeds because of its nutrition, safety and economy. However, the oil/water emulsions formed during the process of aqueous extraction of camellia oil, which makes oil hard to be separated. TCPC with excellent emulsifying activity and emulsion stability was separated and characterized, which could be regarded as a potential target to obtain free oil by frozen/thawed method. Thus, it could be contributing to the industrial application of aqueous extraction of camellia oil.