Digestibility of proteins from different sources

In vitro protein digestibility can be useful for estimating protein nutritional quality. Eight protein sources were chosen to study in vitro protein digestibility, namely: sodium caseinate, whey, mushrooms, pea, soy, oat, hemp and sea buckthorn. Trypsin was used to achieve the enzymatic hydrolysis and the pH-drop technique was employed to determine in vitro protein digestibility. Substrate hydrolysis was rapidly initiated after enzyme addition in the case of pea protein, sodium caseinate, soy and whey proteins, whereas a slower pH decrease was registered in the case of mushroom proteins. The in vitro protein digestibility decreased in the following order: pea (87.2%) > soy (85.9%) > whey (85.6%) > caseinate (85%) > hemp (78.5%) > oat (77.5%) > sea buckthorn (76.2%) > mushrooms (68.2%). The sea buckthorn and mushrooms samples with the lowest protein contents (15.6% and 18.3%, respectively) had the lowest protein digestibility. However, no correlation between protein content and protein digestibility was found.