Naderi Nassim, Pouliot Yves, House James D, Doyen Alain
Institute of Nutrition and Functional Foods (INAF), Department of Food Science, Université Laval , Québec, Québec G1V 0A6, Canada.
Department of Human Nutritional Sciences, University of Manitoba , Winnipeg, Manitoba R3T 2N2, Canada.
J Agric Food Chem. 2017 Sep 6;65(35):7774-7780. doi: 10.1021/acs.jafc.7b02892. Epub 2017 Aug 22.
In this study, the impact of pasteurization and freezing of raw material, as performed at a commercial scale, on egg yolk fractionation and folate recovery was assessed. Freezing induced denaturation of the lipoproteins in egg yolk, which prevented further fractionation of the yolk. Thermal pasteurization of egg yolk at 61.1 °C for 3.5 min as well as high hydrostatic pressure (HHP) treatment (400 MPa for 5 min) did not change (p < 0.05) the composition of egg yolk or yolk fractions after their recovery by centrifugation. Expressed as dry matter, folate in pasteurized yolk was measured to be 599 μg/100 g, while its concentration reached 1969.7 μg/100 g for pasteurized granule and 1902.5 μg/100 g for HHP-treated granule. Folate was not detected in plasma, emphasizing the complete separation of yolk folate into granule. Further, we studied the effect of HHP on different dilutions of egg yolk, which were then fractionated. Egg yolk was diluted with water at different concentrations (0.1, 1.0, 10, 25, and 50%), HHP-treated at 400 MPa for 5 min, and centrifuged. Characterization of the compositions of the separated granule and plasma followed. Folate was stable under the HHP conditions used. However, HHP caused separation of folate from the yolk structure into water-soluble plasma. After HHP processing, the amount of folate detected in the plasma fraction was significantly (p < 0.05) higher (1434.9 μg/100 g) in the 25% diluted samples but was significantly (p < 0.05) lower in HHP-treated granule samples. Native sodium dodecyl sulfate-polyacrylamide gel electrophoresis results showed that phosvitin, α-livetin, and apovitellenin VIa were the proteins most resistant to HHP. This study confirms that dilution of egg yolk before HHP treatment can significantly (p < 0.05) change the composition of granule and plasma fractions after centrifugal fractionation of egg yolk.
在本研究中，评估了商业规模下原料的巴氏杀菌和冷冻对蛋黄分级分离及叶酸回收率的影响。冷冻导致蛋黄中的脂蛋白变性，从而阻止了蛋黄的进一步分级分离。蛋黄在61.1℃下进行3.5分钟的热巴氏杀菌以及高压处理（400兆帕，5分钟），在通过离心回收后，蛋黄或蛋黄组分的组成没有变化（p<0.05）。以干物质计，巴氏杀菌蛋黄中的叶酸含量为599微克/100克，而巴氏杀菌颗粒中的叶酸浓度达到1969.7微克/100克，高压处理颗粒中的叶酸浓度为1902.5微克/100克。血浆中未检测到叶酸，这表明蛋黄叶酸完全分离到颗粒中。此外，我们研究了高压处理对不同稀释度蛋黄的影响，然后对其进行分级分离。蛋黄用水以不同浓度（0.1%、1.0%、10%、25%和50%）稀释，在400兆帕下进行5分钟的高压处理，然后离心。随后对分离出的颗粒和血浆的组成进行表征。在所使用的高压处理条件下，叶酸是稳定的。然而，高压处理导致叶酸从蛋黄结构中分离到水溶性血浆中。高压处理后，25%稀释样品中血浆组分中检测到的叶酸量显著（p<0.05）更高（1434.9微克/100克），但在高压处理颗粒样品中显著（p<0.05）更低。天然十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果表明，卵黄高磷蛋白、α-卵黄球蛋白和卵黄磷蛋白VIa是对高压处理最具抗性的蛋白质。本研究证实，在高压处理前稀释蛋黄可显著（p<0.05）改变蛋黄离心分级分离后颗粒和血浆组分的组成。
