Dan Gao1, Ning Qiu1, Yaping Liu1, Meihu Ma1. 1. Key Laboratory of Environment Correlative Dietology, Ministry of Education, National Research and Development Center for Egg Processing, College of Food Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, P.R. China.
Abstract
BACKGROUND: Physical changes such as chicken egg white thinning and egg yolk flattening occur during storage, implying a decline in egg quality. To reveal the deteriorative process related to chicken egg internal quality, a comparative proteomic method was used in this study to analyze the alterations in egg yolk plasma proteins at different storage times (0, 20 and 40 days) under an ambient temperature of 22 ± 2 °C. RESULTS: Using two-dimensional electrophoresis followed by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry, 33 protein spots representing 12 proteins were identified with significant (P < 0.05) alterations in abundance at different storage times. The proteins that showed significant changes in abundance included serum albumin, vitellogenin fragments, IgY chains, ovalbumin, ovoinhibitor, α2 -macroglobulin-like protein 1-like, hemopexin, transthyretin, apolipoprotein A-I and β2 -glycoprotein I precursor. Accelerating degradation for most egg yolk plasma proteins was observed after prolonged storage (from day 20 to day 40). CONCLUSION: It is likely that the increased degradation of protease inhibitors such as ovoinhibitor and α2 -macroglobulin-like protein 1-like during prolonged storage lead to an imbalance of protease and antiprotease in egg yolk, which may play a key role in the degradation of egg yolk proteins. These findings will provide an insight into the effects of storage on egg yolk protein changes and give a deeper understanding of the deteriorative process of chicken egg yolk.
BACKGROUND: Physical changes such as chicken egg white thinning and egg yolk flattening occur during storage, implying a decline in egg quality. To reveal the deteriorative process related to chicken egg internal quality, a comparative proteomic method was used in this study to analyze the alterations in egg yolk plasma proteins at different storage times (0, 20 and 40 days) under an ambient temperature of 22 ± 2 °C. RESULTS: Using two-dimensional electrophoresis followed by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry, 33 protein spots representing 12 proteins were identified with significant (P < 0.05) alterations in abundance at different storage times. The proteins that showed significant changes in abundance included serum albumin, vitellogenin fragments, IgY chains, ovalbumin, ovoinhibitor, α2 -macroglobulin-like protein 1-like, hemopexin, transthyretin, apolipoprotein A-I and β2 -glycoprotein I precursor. Accelerating degradation for most egg yolk plasma proteins was observed after prolonged storage (from day 20 to day 40). CONCLUSION: It is likely that the increased degradation of protease inhibitors such as ovoinhibitor and α2 -macroglobulin-like protein 1-like during prolonged storage lead to an imbalance of protease and antiprotease in egg yolk, which may play a key role in the degradation of egg yolk proteins. These findings will provide an insight into the effects of storage on egg yolk protein changes and give a deeper understanding of the deteriorative process of chicken egg yolk.