Eggs that have been hard-boiled are frequently used as ready-to-eat food.
Refrigerated and frozen storage of hard-boiled eggs causes issues, such as
customer rejection owing to textural changes. The objective of this research is
to ascertain how storage temperature affects hard-boiled eggs’ alteration
in texture over time. Medium-sized brown shell eggs were acquired from a local
market, boiled at 100°C for 15 min, and then stored at room temperature
(25°C), refrigeration (4°C), and freezing (–18°C)
conditions for 0, 12, 24, and 48 h. Fourier transform infrared spectroscopy
(FTIR), texture profile, visual observation using a gemological microscope, free
amino acid content, and color were measured. Freezing had a substantial impact
on the eggs’ hardness, gumminess, chewiness, and cohesiveness
(p<0.05). The FTIR spectrums confirmed the textural changes in bonds of
amide A (3,271 cm
–1
), amide I (1,626.2
cm
–1
), amide II (1,539.0 cm
–1
), C=O
stretch of COO
-
(1,397 cm
–1
), asymmetric
PO
2
-
stretch (1,240 cm
–1
).
Microscopic images confirmed structural changes in eggs stored at
–18°C. The free amino acid content was lower in fresh and frozen
eggs than in the rest (p<0.05). However, there was no discernible
variation in the egg white’s color when eggs were kept at 4°C
(p>0.05).
Salmonella
spp. was found exclusively in eggs
kept at room temperature. In conclusion, hard-boiled eggs did not exhibit
structural or chemical changes when stored at 4°C for up to 48 h compared
to freezing and room temperature conditions.