Soy protein hydrolysates in bakery products

Abstract

Soy protein is an important food protein source owing to its nutritional benefits and functional properties. The nutritional composition of soy proteins includes essential amino acids, calcium, iron, magnesium, fiber, polyunsaturated fats etc. The aim of the study is to develop soy protein based products (pasta and cookie) using as ingredient soy protein hydrolysates (SPHs). Different SPHs were obtained from soy protein concentrate by enzymatic hydrolysis using the following proteolytic enzymes: Neutrase+Flavorzyme (NeuFla), Papain (Pap) and Umamizyme (Uma). The enzymatic hydrolysis determined an increase in the antioxidant capacity of the hydrolysates and improved content of amino acids (especially, lysine which is deficient in most cereal grains) and also improved the oil binding capacities of the SPHs. Pasta and cookies were manufactured using wheat flour as base ingredient. Wheat flour was substituted with 5% SPH. The sample made with 100% wheat flour was the control. Cookie and pasta samples with SPH addition had almost 1.2-and 1.3-fold higher protein content than control pasta, respectively. By SPH addition, the color of pasta was changed. The color variation of the pasta from the darkness to whiteness was: Uma > NeuFla > Pap > Control. There were positive correlations between L* (lightness parameter) of pasta and the corresponding SPHs (r = 0.91). In order to investigate the volatile composition of the samples, an electronic nose system was used. A discrimination index of 93 was achieved between control and cookies with SPHs, which explains a very distinct odor of samples. All the samples had different aroma compounds, but NeuFla and Uma cookies were more alike in volatile composition being situated in the opposite side of the PCA plot (Principal Component Analysis) compared to Pap cookie. The same conclusion was also observed for pasta samples. Regarding the taste, the products containing NeuFla and Pap had lower bitterness intensity than Uma. Soy protein hydrolysates obtained from SPC using the enzymes Papain or the combination between Neutrase and Flavorzyme can be used as supplements in wheat flour to enhance the nutritional value of pasta and cookie products.