| Summary: | 碩士 === 國立臺灣大學 === 畜產學研究所 === 89 === Liquid egg exhibited no plasticity during heating process, because proteins immediately denatured and solidified after boiling or shallow frying. The purpose of this experiment was to make thick omelets using liquid egg mixed with texture stabilizers, and an attempt was made to improve gelation property of liquid egg after heating. In addition, thick omelets needed post-processing to reduce microorganism concentration and ensure safety, and improvement of greenish-black discoloration during post-processing.
As the results showed, the addition of textural stabilizers to liquid egg increased the material viscosity significantly and allowed the egg surface to be rolled up easily without cracking. Textural stabilizers can improve moisture content, water holding capacity and product yield, but have no significant effect on water activity. The addition of textural stabilizers can increased hardness, cohesiveness, chewiness and gumminess significantly, but 1.5% guar gum or xanthan decreased these texture properties. The optimum additives were 4-5% potato starch, 0.5%κ-carrageenan, 1.5% locust bean gum, and 1.0% guar gum; xanthan was not suitable for thick omelets.
Sodium ultraphosphate, disodium dihydrogen pyrophosphate and β-carotene can improve the greenish-black discoloration of thick omelets after post-processing, and sodium ultraphosphate and disodium dihydrogen pyrophosphate were more significant than β-carotene. The optimum additive range of sodium ultraphosphate and disodium dihydrogen pyrophosphate were 0.14-0.15%, and that of β-carotene was 300ppm.
The total plate counts of thick omelets after vacuum packaging and post-processing (88℃, 55min) were consistently under 1.0×104 CFU/g, and pathogens such as Salmonella spp., Staphylococcus aureus, coliform group and Escherichia coli were not detected during 5 days of storage at 18℃. Results showed that thick omelets, after vacuum packaging and post-processing, can be kept safety during storage and selling period at 18℃.
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