Content area
Full text
Article history
Received: 27April 2016
Received in revised form: 22 June 2016
Accepted: 24 June 2016
Keywords
Cleavage of proteins
Kinetic, screening design
Optimization
Ultrasound
Abstract
The production of soymilk and tofu results in an insoluble residue called okara that present 23% of soybean protein. The objective of this study was to optimize the protein hydrolysis conditions of okara with Alcalase® endopeptidase. A central composite rotational design was carried out to evaluate the influence of enzymatic reaction temperature (40 - 70°C), enzyme:substrate ratio (1.0 - 10.0%, g enzyme/100 g protein) and pH (7.0 - 9.0) on the degree of hydrolysis (DH). Kinetic of reaction curves (DH versus time) were characterized by high initial reaction rates followed by decreases in the reaction rate up to the stationary phase. By the response surface methodology, the process of hydrolysis was optimized in order to get higher values of DH. The results showed a quadratic dependence of DH in respect to all independent variables. The optimum condition of enzymatic hydrolysis was 55°C, enzyme:substrate ratio of 8.8% and pH 9.0. Under this condition, a experimental DH of 37.3% was obtained and the predicted model was validated. In addition, the pretreatment of okara using ultrasound was evaluated, aiming to increase the DH. There was significant difference (p < 0.1) on DH value (38.8%) obtained at °ptimum condition, increasing 4%.
© All Rights Reserved
(ProQuest: ... denotes formulae omitted.)
Introduction
Soybean (Glycine max) is an oilseed, whose Brazilian production has been growing continuously in recent decades, reaching 86.7 million ton in 2014 (FAO, 2016), due to the demand for human consumption, production of oil and biodiesel, and animal feed. Cultivated especially in the Midwest and South regions of Brazil, soybean is an important crop of national agriculture because its sales have important participation on Brazilian trade balance, with annual negotiations above US$ 20 billion (IBGE, 2011; MAPA, 2013). In addition to economic importance, soybean has great nutritional value, because it is an important source of vegetable protein and contains functional components, such as phospholipids, antioxidants, oligosaccharides, phytosterols and isoflavones (Liu, 1997).
From the soybean, various derivative products have been developed such as misso, shoyu, tempeh, natto, soymilk, tofu, soy flour, toasted flour soybean and soybean sprouts. The production of soymilk and...