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

Abstract

To evaluate the effects of the roasting process on the extraction yield and oil quality, peanut seeds were roasted at different temperatures (130-220°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°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°C had a relatively low peroxide value, a strong oxidative stability, and the best flavor score. Using the same seedroasting temperature (190°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°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%.

Characterizing the structural and surface properties of proteins isolated before and after enzymatic demulsification of the aqueous extract emulsion of peanut seeds

“…However, the organic solvent is highly flammable and toxic, forming fugitive emissions of volatile organic compounds (VOCs) (Johnson, 2000). Due to the environmental safety and health concerns, and the desire for simultaneous extraction of oil and protein, aqueous extraction processing (AEP) of peanuts (Li, 1984;Rhee, Cater, & Mattil, 1972;Sharma, Khare, & Gupta, 2002;Zhang, Lu, Yang, Li, & Wang, 2011) and other oilseeds (Dominguez, Nunez, & Lema, 1995;Fullbrook, 1983;Liang, Zhang, & Cong, 2012; de Moura, Maurer, Jung, & Johnson, 2011;Zhang, Wang, & Xu, 2007) has attracted increased interest. The process usually consists of an aqueous (enzymatic) extraction of the comminuted materials, followed by a centrifugal separation of the slurry into oil, emulsion, aqueous, and solid phases.…”

“…Some physical and physicochemical treatments were previously utilized to demulsify the emulsions formed during the AEP of peanuts (Li, 1984;Rhee et al, 1972;Zhang et al, 2011). These methods are effective, though they are energy-intensive.…”

Color and texture of low-calorie peanuts as affected by a new oil extraction process named “Mechanical Expression Preserving Shape Integrity” (MEPSI)

“…After several preliminary trials at the laboratory, a light initial air roasting (140°C, 15 min) was performed in an oven (Memmert, Universalschrank, UFE700, Germany) in order to develop the flavor and color characterizing peanuts and to partially denature proteins in order to facilitate subsequent oil extraction (Zhang et al 2011). Then, peanuts were manually peeled by hand rubbing.…”

Biotransformation of aflatoxin B1 and aflatoxin G1 in peanut meal by anaerobic solid fermentation of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus

“…Peanuts are one of the most widely grown oil seeds in the world with 29 million metric tons produced every year (Zhang et al, 2011). A majority of peanuts are crushed to produce oil and this process generates a large amount of peanut meal as the coproduct (Reddy et al, 2013).…”