Investigation of enzymatic hydrolysis kinetics of soy protein isolate: laboratory and semi-industrial scale.

Using parameters of optimal conditions from laboratory experiments often results in the loss of significant time and resources when trying to scale up the process. In this study, the comparison of results of laboratory and semi-industrial experiments of enzymatic hydrolysis of soy protein isolate is considered. The kinetics of peptides accumulation was investigated by colorimetric method in both microtube (volume reaction is 0.7 ml, 7.14 mg/ml of substrate, incubation in solid state thermostat) and industrial homogenizer (volume reaction is 4,000 ml, 100 mg/ml of substrate, rotor-stator type mixer). The enzyme preparation Protosubtilin G3x (main component is subtilisin) was used as an analogue of the Alcalase preparation, which is already widely used in the food industry. It was found that the pH and the number of proteolytic units in the reaction mixture of both scales had slightly different results of the kinetics, while the temperature showed significantly one. The laboratory scale of the reaction had a wide range of optimal temperature (40-60  C, 30  C showed slowest rate of kinetics reaction), whereas the semi-industrial scale had 50  C of optimal temperature (30, 40, 60  C had the same kinetics). It also was found that maintaining the pH value of the reaction mixture was not mandatory. The obtained results indicate the need to refine the process conditions using semi-industrial experiments before attracting industrial-scale resources. In the case of selection of conditions for the hydrolysis of soy protein isolate in production, it is necessary first of all to take into account the reaction temperature as the most irreproducible parameter when scaling.