Functional properties of four kinds of oilseed protein isolates

Abstract

Plant proteins can be applied in food processing as alternatives to animal protein. Recently, popular additives of plant proteins such as soybean protein and peanut protein are widely applied in food products, like meat products, beverages, and breads. Besides, new plant proteins such as pumpkin seed protein and sunflower seed protein also get more and more attention in food industry. These plant proteins need to satisfy some special functional properties such as oil-absorbing ability and emulsifying property for developing new food products by industry. It is necessary to analyze these functional properties and make a comparison for better utilization. Since the alkaline solution and acid precipitation is still an effective method to satisfy the demand of industrial large-scale production to protein isolates. In the present study, using alkali solution and acid precipitation, four kinds of oilseed protein isolates such as peanut protein isolate (PEPI), pumpkin seed protein isolate (PUPI), sunflower seed protein isolate (SUPI), and soybean protein isolate (SOPI) were prepared from defatted peanut meal, defatted pumpkin seed meal, defatted sunflower seed meal and defatted soybean meal. The functional properties including water-absorbing ability (WA), oil-absorbing ability (OA), wetting time (WT), emulsifying ability (EA), emulsifying stability (ES), foaming ability (FA), and foaming stability (FS) of these four kinds of protein isolates were investigated. The results showed that different protein isolates exhibited different functional properties. Compared to the FA of PUPI (3.88 ± 1.69 %), SOPI (7.76 ± 2.04 %), and SUPI (9.33 ± 1.39 %), the FA of PEPI showed the highest value of 18.18 ± 0.97 %. The PUPI exhibited the shortest WT of 11.02 ± 3.13 s and the highest OA of 1.34 ± 0.004 mL/g. Besides, SOPI showed the highest EA value of 100.84 ± 9.69 m2/g. Notably, although not all functional properties of PUPI showed the best value, PUPI exhibited the shortest WT and the highest OA value, which makes it a candidate additive in meat products and might improve the OA and palatability of meat products. Moreover, PUPI does not contain chlorogenic acid, which is contained in SUPI, and therefore does not influence the organoleptic and nutritional quality of food products.