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.
Degradation of the peanut cell wall is a critical step in the aqueous enzymatic extraction process to extract proteins and oil bodies. Viscozyme® L, a compound cell wall degrading enzyme, has been applied as an alternative to protease in the process of aqueous enzymatic extraction, but the mechanism of cell wall enzymolysis remains unclear. The present study aims to investigate the changes in cellulose, hemicellulose, and pectin content of the peanut cell wall hydrolyzed by Viscozyme® L. The degree to which the main components of the peanut cell wall, such as trans-1, 2-cyclohexanediamine-N,N,N’,N’-acetic acid-soluble pectin (CDTA-soluble pectin), Na2CO3-soluble pectin, cellulose, and hemicellulose, are degraded is closely related to the extraction of oil bodies and peanut protein at different solid-liquid ratio of powered peanut seed in distilled water, enzyme concentration, enzyme hydrolysis temperature, and enzyme hydrolysis time. The key sites of Viscozyme® L activity on cell wall polysaccharides were explored by comparing the changes in chemical bonds under different extraction conditions using Fourier-transform infrared spectroscopy (FT-IR) absorption bands and principal component analysis (PCA). Viscozyme® L acted on the C-O stretching, C-C stretching, and CH2 symmetrical bending of cellulose, the C-O stretching and O-C-O asymmetrical bending of hemicellulose, and the C-O stretching and C-C stretching of pectin.