# Analysis of the Quality and Chemical Composition of Double-Yolked Eggs Compared to Those of a Normal Structure

## TL;DR

Double-yolked eggs differ in structure and chemical composition from normal eggs, but may still be suitable for consumption due to higher unsaturated fatty acid content.

## Contribution

This study provides new insights into the quality and chemical differences of double-yolked eggs compared to single-yolked eggs.

## Key findings

- Double-yolked eggs have different proportions of morphological elements and higher total protein content in yolks.
- They show a higher content of unsaturated fatty acids, suggesting potential benefits for use as table eggs.
- No negative effects on egg quality were observed in double-yolked eggs.

## Abstract

Simple Summary: Double-yolked eggs occur in reproductive flocks, especially at the beginning of the laying period. Although the reasons for their occurrence are fairly well understood and work is underway to reduce them, the problem still affects about 1–2% of chicken eggs. Due to reduced hatchability, such eggs are hatchery waste, but may be of interest in the context of consumer eggs. The present study aimed to analyse the quality and technological suitability of eggs with a double yolk compared to eggs with a normal structure. Differences were shown in the proportion of individual egg morphological elements in the weight of the whole egg, as well as in the chemical composition. Small but positive differences in the content of unsaturated fatty acids suggest the possible use of double-yolked eggs as table eggs.

The study material consisted of 360 eggs from a reproductive flock of meat-type hens; 240 were double-yolked eggs and 120 were single-yolked as a control group. The eggs were numbered individually and then analysed for their quality in terms of characteristics of the whole egg (weight, shape index, specific gravity), shell (colour, strength, weight, density), albumen (pH, height, weight, Haugh units) and yolk (colour, weight, shape index, pH). During the analyses, yolks were sampled for analyses including basic composition, fatty acid profile (by gas chromatography) and fatty acid indices. It was found that double-yolked eggs differed significantly from single-yolked ones in terms of weight, proportion of individual elements in the egg weight, total protein content in the yolks as well as in terms of the fatty acid profile and their indices both due to the presence or absence of two yolks and in the context of the individual yolks analysed. The results indicate the possibility of using double-yolked eggs as table eggs due to the absence of negative effects stemming from being double-yolked and the increased content of biologically important components such as fatty acids.