Aqueous Enzymatic Extraction of Oil and Protein Hydrolysates from Roasted Peanut Seeds

To evaluate the effects of the roasting process on the extraction yield and oil quality, peanut seeds were roasted at different temperatures (130-220 A degrees C) for 20 min prior to the aqueous extraction of both oil and protein hydrolysates with Alcalase 2.4 L. Roasting temperatures did not significantly affect the yields of free oil, whereas the temperature of 220 A degrees C led to a reduced recovery of protein hydrolysates. The color and acid values of peanut oils did not change significantly with roasting temperatures. The enzyme-extracted oil with roasting at 190 A degrees C had a relatively low peroxide value, a strong oxidative stability, and the best flavor score. Using the same seed-roasting temperature (190 A degrees C), quality attributes such as color, acid and peroxide values, phosphorus content and oxidative stability of the enzyme-extracted oil were better than those of the oil obtained by an expeller. After the peanut seeds were roasted at 190 A degrees C for 20 min, with a seeds-to-water ratio of 1:5, an enzyme concentration of 2%, and an incubation time of 3 h, the yields of free oil and protein hydrolysates were 78.6 and 80.1%, respectively. After demulsification of the residual emulsion by a freezing and thawing method, the total free oil yield increased to 86-90%.