Effects of simultaneous water-enzyme separation on the physical and chemical properties of peanut oil and protein

Abstract

Peanut (Arachis hypogaea L.) is widely cultivated as a valuable industrial oilseed. This study aimed to investigate the oil and protein that was extracted from peanuts by aqueous enzymatic method (AEM). Compared with freeze-thaw demulsification (FTD), n-hexane extraction (NHE) and protease demulsification (PD), the fatty acid composition of oil by combination of oleic and citric acids demulsification (COCAD) was similar. The acid value of the oil extracted by new AEM and various demulsification methods was between 0.12 and 0.59 mg KOH/g, the peroxide value was between 0.06 and 0.19 g/100 g, the free fatty acid content was between 0.32% and 0.71%, and the oxidation induction time was between 0.13 and 3.21 h. The content of tocopherol in oil: NHE>FTD>PD>COCAD. The amino acid and protein subunit compositions of peanut protein extracted by AEM (AEMPP), peanut protein isolate (PPI) and commercially available peanut protein (CAPP) were similar. Scanning electron microscope revealed that protein powders morphology of various extraction methods. Compared to CAPP and PPI, β-turns and random coil structure of AEMPP was increased. The solubility, water and oil holding capacity, emulsifying activity index, emulsification stability, foaming property and foam stability of protein: AEMPP > PPI > CAPP. This study provides a theoretical basis for the large-scale industrial application of AEM.