Effect of Combination of Salt and pH on Functional Properties of Frozen-Thawed Egg Yolk

Karina Ilona Hidas,Anna Visy,Attila Nagy,Csaba Németh,Adrienn Tóth,Lien Phuong Le Nguyen,László Baranyai,László Friedrich,Ildikó Csilla Nyulas-Zeke

doi:10.3390/agriculture11030257

Karina Ilona Hidas, Anna Visy + Show 7 more

Open Access

https://doi.org/10.3390/agriculture11030257

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Abstract

Egg yolk undergoes an irreversible gelation process at temperatures below −6 °C, which greatly impairs its application and increases its apparent viscosity. This work was aimed to investigate the effect of salt and pH in preventing the gelation of frozen-thawed egg yolk. Before freezing, 5% of salt was added into the pasteurized liquid egg yolk, then pH was adjusted to different levels (5.7, 6.0 and 6.3) with citric acid. After that, the yolk was stored at −18 °C for four weeks. Rheological and thermal properties of the fresh and frozen-thawed egg yolk were measured. In addition, the colour, turbidity and emulsifying properties were also determined. The results showed that pH of all samples increased during frozen storage, but at different rates. The combination of 5% of salt and pH at 6.0 and 6.3 could prevent the gelation, resulting in rheological properties more like the fresh liquid egg yolk. In addition, emulsifying properties also obtained better results for treated yolk. Moreover, L* value of treated egg yolk was higher before freezing and became lower after storage compared to control. The results of this work found that the combination of 5% of salt and adjusted pH could prevent the gelation of frozen-thawed liquid yolk.

Highlights

Eggs play a prominent role in the human diet due to their nutritional values including high-quality proteins, essential long-chain fatty acids, iron, phosphorus, trace minerals and vitamins A, D, E, K and B [1]
Liquid egg yolk was produced from caged hen eggs that have been laid for up to 3 days prior
The amount of citric acid added into liquid egg yolk was less than 1%

Summary

Introduction

Eggs play a prominent role in the human diet due to their nutritional values including high-quality proteins, essential long-chain fatty acids, iron, phosphorus, trace minerals and vitamins A, D, E, K and B [1]. The amount of shelled eggs consumed per capita varies greatly around the world, but the market for processed egg products is clearly on the rise [6]. Two groups of processed egg products are distinguished. Products from “first processing” are mainly for the food industry (such as liquid, frozen and powdered egg products), while speciality egg products (such as formulated and cooked eggs) are for consumers [7]. Processed egg products are used in the food industry for a wide variety of purposes, including: ingredients for pasta, bakery products, sea-food products, meat products, dairy products, mayonnaise, sauces and salad dressings [8,9]

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