Characteristics and emulsifying properties of two protein fractions derived from the emulsion formed during aqueous extraction of Camellia oil

• Published in: Food hydrocolloids Vol. 87; pp. 644 - 652
• Main Authors: Yang, Jian-Yuan, Peng, Bin, Wang, Mei, Zou, Xian-Guo, Yin, Yu-Long, Deng, Ze-Yuan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2019
• Subjects: Camellia oleifera Abel. seeds; Emulsifiable proteins; Emulsifying properties; Purification; Structural characteristics; Camellia oleifera Abel. seeds; Purification; Structural characteristics; Emulsifiable proteins; Emulsifying properties
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2018.08.043

Emulsification is a key issue which makes oil hard to be separated during aqueous extraction from Camellia Oleifera Abel. seeds. Therefore, de-emulsification is required to recover and enhance oil yield. To investigate the major protein components resulting in a stable emulsion, the emulsifiable proteins of Camellia oleifera Abel. seeds (CSEP) were obtained from the emulsions formed during aqueous extraction of Camellia oil, and two major protein fractions (CSEP-A and CSEP-B) were isolated and purified from CSEP. CSEP-A consisted of a small amount of polysaccharides and seven major subunits/proteins with a molecular weight ranging from 13 to 35 kDa. CSEP-B was a protein mixture with a molecular weight range of 13–15 kDa. At neutral pH condition, CSEP-A had higher intrinsic fluorescence intensity and surface hydrophobicity compared to CSEP-B. There were more β-sheet, but lesser α-helix in protein secondary structure of CSEP-A. Both CSEP-A and CSEP-B were rich in Glu, Arg and Asp. However, hydrophobic amino acids contents in CSEP-A (33.47 ± 2.35%) was significantly higher (p < 0.05) than that in CSEP-B (18.70 ± 0.03%). CSEP-A had a significantly higher (p < 0.05) emulsifying activity index (EAI), significantly lower (p < 0.05) creaming index (CI) and similar emulsion stability index (ESI) compared to CSEP-B, and the emulsion droplets formed with CSEP-A showed better stability. Oleosins were found to be major emulsifiable proteins in CSEP-A, which may contribute to the excellent emulsifying properties of CSEP-A. [Display omitted] •Two protein fractions were isolated and purified from the emulsions formed during aqueous extraction of Camellia oil.•The intrinsic fluorescence intensity and surface hydrophobicity of CSEP-A were higher than those of CSEP-B.•The emulsifying properties of CSEP-A was higher than those of CSEP-B.•Oleosins were found to be major emulsifiable proteins in CSEP-A.