Biochemical and funcional properties of egg white hydrolysates produced by different proteases

Abstract

Enzymatic hydrolysis of egg white proteins (EWPs) has shown a great potential to improve their functional properties such as increased solubility, stability, and digestibility while still retaining their nutrition value. The high selectivity and mild reaction conditions associated with the enzymatic process have made this approach an attractive alternative in the production of EWPs with improved functional properties, which are often difficult to obtain by conventional chemical route. Moreover, the inherent specificity of various proteolytic enzymes should control the nature and extent of hydrolysis and thus the functional properties of the product. The focus of this work is to find the best combination of enzymes and the mode of both substrate pretreatment and process implementation for improvement of the overall hydrolysates` quality. For this purpose EWP solution was hydrolysed with several enzymes using both, one-step and two-step hydrolysis in a stirred stirred-tank reactor employing an enzyme to protein substrate weight ratio previously selected to obtain the desired level of conversion in the first step within a time period from about 20 to about 75 minutes depending of protease used. The obtained hydrolysates were then tested on antioxidant activity, flavour, solubility, digestibility emulsifying activity, foaming capacity and stability. Selected results have been presented in Figure 1. The application of two-step enzymatic process, based on the use of the bacterial alkaline protease in the first step, and then the introduction a more specific protease in the second step to selectively reduce the bitter peptides, seemed to be advantageous.