Master of Science (MS)
School of Nutrition and Food Sciences
Surface coating is an effective/inexpensive method to preserve internal quality and minimize weight loss of shell eggs during storage without refrigeration. No research has been done to evaluate effects of coating on oxidative stability of cooked eggs. In the first study, soybean oil (SO) as a coating material was evaluated for its effects on internal quality and flavor volatile compounds of eggs throughout 5-weeks of storage at 25¢XC. Haugh unit (HU) and yolk index (YI) values decreased whereas weight loss increased during storage. After 5-weeks, SO-coated eggs had consistently higher HU (67.72 vs. 48.45) and YI (0.29 vs. 0.40) than the control. SO-coating significantly minimized weigh loss (0.95%) of eggs after 5-weeks storage (vs. 6.47% for the control). The major flavor volatiles in cooked eggs were aldehydes, ketones, alcohols, and sulfides. Soybean oil coted boiled eggs yielded the highest hexanal contents. In the second study, effectiveness of surface coatings using proteins, polysaccharides, or lipids in preserving quality and lipid oxidation of shell eggs was evaluated. After 5-weeks, lipid-based coatings had consistently higher HU (69.25 vs. 41.01-57.75) and YI (0.37 vs. 0.22-0.32) than control and other treatments. Lipid-based coating significantly minimized weigh loss (0.35%) of eggs after 5-weeks storage (vs. 4.84-6.84% for control and other treatments). After 5-weeks storage, compared with the control (8.37ƒÝg/100 g), hexanal of yolk of eggs coated with SO was higher (14.09ƒÝg), but that of eggs coated with alpha and beta chitosans, WPC, and MO was lower (3.24, 3.89, 4.34, and 6.13 ƒÝg). SO-coated eggs had highest TBARs values after 5-weeks storage. Palmitic, oleic, and linoleic acids were most abundant fatty acids in the yolk. The proportion of MUFAs and saturated fatty acids increased while the proportion of PUFAs decreased after 5 weeks of storage. This study demonstrated that surface coating can extend shelf-life of eggs, but potentially affect chemical compounds related to lipid oxidation in egg yolk during 5-weeks storage at 25¢XC.
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Jirawatjunya, Jinjuta, "Effects of Assorted Coating Materials and Room Temperature Storage on Internal Quality and Oxidative Stability of Shell Eggs" (2013). LSU Master's Theses. 2531.