Factors Affecting the Discoloration of Hard-Cooked Egg Yolks

Peelability of Hard-cooked Eggs

“…After the eggs had been stored 48 hours, the average pH decrease was 0.27 The peel score and yolk colour grade were inversely related-a high peel score indicated a low or zero colour grade (Table 9). Baker et al (1967) claimed the longer the eggs were stored at 10°C. the darker the yolks became after cooking and this they related to changes in yolk pH.…”

A review on the development of pickled eggs: rapid pickling and quality optimization

“…It is a circle of gray-black or gray-green material that tends to form at the junction of salted egg whites and yolks after the salted eggs are cooked at a high temperature, which is considered to be the result of the combined action of protein, iron, S 2− and pigment ( Li et al., 2021 ). Although the outer black layer has been shown to be more easily formed under alkaline conditions ( Baker et al., 1967 ; Tinkler and Soar, 1920 ), its specific formation mechanism has not been clarified. However, three hypotheses have been proposed.…”

Egg and egg product flavor

“…Dimethylthiazole levels were approximately the same in both products, but trimethylthiazole in the ovalbumin was twice as high as that in egg white. Baker et al (1967) reported that albumin served as the source of hydrogen sulfide formation in eggs.…”