Effects of Pretreatment on the Yield of Peanut Oil and Protein Extracted by Aqueous Enzymatic Extraction and the Characteristics of Emulsion

Abstract

Peanut was crushed by dry comminution and wet comminution, and effects of comminution on peanut particle size and yield of peanut oil and protein were analyzed. The properties (surface protein concentration, particle size, and ξ-potential) of emulsion were compared. Moreover, different demulsification methods were used to investigate the stability of the emulsion. Results showed that yield of peanut oil and protein reached highest (87.23% and 82.05%, respectively) at dry comminution 72 s. At wet comminution 120 s, yield of peanut oil and protein was 89.91% and 84.70%, respectively, which were both higher than that of dry comminution significantly (P < 0.05). The surface protein concentration and ξ-potential of emulsion made by dry comminution (DCE) was 7.02 mg/m2 and 12.08 mV, respectively, and that was 10.71 mg/m2 and 15.25 mV of emulsion made by wet comminution (WCE), which were significantly higher than that of DCE (P < 0.05). The volume average particle size (D(4,3)) of DCE was 3.41 µm, which was significantly higher than D(4,3) of WCE (3.18µm, P < 0.05). Collectively, results of emulsion properties indicated stability of WCE was higher than DCE. Further, demulsification rate of DCE was significantly higher than that of WCE treated by freeze-thawing, pH, Papain, and Phospholipase A2 (P < 0.05). Demulsification effect of Alcalase 2.4L was best in these five demulsification methods, and demulsification rate of DCE reached 92.77%, slightly higher than WCE (92.67%), further illustrated stability of WCE was higher than DCE.