High pressure-induced rheological transitions in egg protein dispersions

Abstract

Eggs have been one of the first multifunctional ingredients, well known for their whipping, gelling and emulsification properties, where the proteins are the dominant component. Egg yok is an ingredient of high nutritional value with unique sensory properties and excellent functionalitu used in the manufacture and stabilisation of egg-containing fodstuffs and provides an inexpensive source of high quality protein. Processing conditions such as temperature and ultra high pressure (UHP) involve complete or partial denaturation of most food systems, including egg yolk. However, pressure processing does not effect the sensory and nutrional characteristics of fresh products (i.c. natural colour, flavour, taste, texture and vitamins) and allows to be obtained gels with a unique texture since pressure is instantaneously uniformly felt trhrough the food. Moreover an increasing demand of high quality, minimally processed, aditive-free an microbiologically safe foodstuff have lately made UHP technology fairly attractive. On the other hand, variables properties of the system. The main objetive is to study the influence of UHP processing on the rheology and microstructure of egg yolk dispersions. First of all, this work focuses on pressure-induced transitions. The effect of protein concentration and pH is also evaluated