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Development of enzyme processes for production of egg white protein hydrolysates

Egg white hydrolysates possess properties that make them attractive as protein sources in human nutrition. The aim is to develop a novel technology based on selected enzymes and non-thermal process to produce customized high value egg white protein hydrolysates in an optimised process.

The use of egg white hydrolysed proteins has attracted particular interests as a protein source in human nutrition providing a number of benefits when compared to unhydrolysed protein ingredients. In addition to improved functional properties like good solubility, high foaming and emulsification capacities, the protein hydrolysates could also have good properties relating to nutrition physiology. Of high importance is the production of hydrolysates which contains bioactive peptides and does not have allergen potential to be used as the primary or only source of protein in “infant formula”, diets, or “medical food”. However, the production of these functional ingredients requires new and innovative technologies because they are sensitive to a variety of environmental processing factors that may cause the loss of nutritional quality and chemical degradation. The ENZEGG project gathers the complementary skills of three partners in order to develop an efficient and low-cost enzyme process for producing egg white protein hydrolysates with added functional and health benefits to be used in products for special nutrition as well as in consumer products for general use. The overall aims of this project are to: 1) design of an optimized integrated enzyme-catalyzed process consisting of non-thermal egg white pretreatment and enzyme hydrolysis step to convert egg white proteins into high value hydrolysates; 2) explore the effect of HP treatment on the egg white proteins` digestibility and its potential to reduce their allergenicity; 3) apply process engineering principles to optimize the enzymatic hydrolytic step based on both economic effect and protein hydrolysates` quality; 4) evaluation of the benefits of this optimized process in comparison with commercial processes; 5) generate good quality products competitive on domestic markets as well as abroad; 6) transfer know-how from the scientific research to biotech companies and food industry; and 7) achieve positive economic effects in the participating countries. First, research work will be perform to investigate the effectiveness of replacing conventional thermal treatment with high pressure processing (HPP) for improvement the overall process performances including the ability to process egg white protein at lower temperature, to reduce the microbial load, extend shelf-life and produce protein solutions with new functional properties. HPP appears to induce a range of structural changes in several food proteins dependent on the conditions of treatment. HPP may lower proteins` allergenicity by reducing their structural integrity and promoting unfolding in ways that increase susceptibility to hydrolysis by a commercial protease. The level of effects is dependent on a number of factors including the pressure, length of exposure, composition of the food system, concentration, temperature, pH, and ionic strength. For this purpose, thorough optimization of process parameters will be carried out using both protein model systems (ovalbumin and ovomucoid) and egg white substrate to understand the relationship of protein structure modification to functional property changes. Specifically, the objectives are to investigate: 1) HP-induced changes in egg white protein structure using CD and Raman Spectroscopy 2) the effects of HP treatment on egg white protein digestibility 3) the possibility of using HPP to change the proteolytic pattern of ovalbumin as a major egg white allergen 4) effects of HP treatment on gelation, texture, foaming, and colour of egg white, and 5) engineering aspects. The potential of alternative pressure treatments (i.e. lower pressures x longer times) or a combination of heat and pressures will further investigated, with the aim of simplifying process and reducing cost. Modeling and design of enzymatic hydrolytic process are also critical tools used in the project and development program. The enzymatic hydrolytic step could result in peptide mixtures poorly characterized and with unpleasant bitter taste making them unsuitable for human consumption. The intensity of bitterness, the profile and concentrations of peptides in hydrolysates are characteristic of the individual protein-enzyme system and could be efficiently modulated by chosen values of the process parameters. The full exploitation of proteases in processing requires thorough understanding of their reaction mechanisms involved in both micro- and macroscale. Accordingly, the research of the projects will also focus on: 1) selection the best combination of the mixture and/or pure exo- and endo-peptidases preparations for obtaining hydrolysates which are high value in terms of nutrition physiology but does not have a bitter flavour 2) optimization the degree of hydrolysis and mode of its control 3) optimization of bioprocess parameters and operating regime of bioreactors and 4) modelling the reaction kinetic for the quantitative explanation of process parameters effects.
Acronym: 
ENZEGG
Project ID: 
6 750
Start date: 
01-09-2011
Project Duration: 
40months
Project costs: 
1 250 000.00€
Technological Area: 
Food Processing
Market Area: 
Health food

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