利用分離雞蛋蛋黃製作鹹蛋黃之研究

Abstract

鹹蛋在臺灣為一種傳統且普及的加工蛋製品。一般鹹蛋的製作可以利用浸漬法與塗佈法鹽漬20-35天。品質良好的鹹蛋黃具有砂質感、出油及橘色外觀的特性。由於傳統鹹蛋的製作所產生的鹹蛋白鹽含量較高，而較少應用在食品工業。因此本試驗探討利用快速的浸漬方法以尋找最佳的浸漬條件供製作鹹蛋黃。 試驗的第一部份利用複因子設計以檸檬酸與檸檬酸鐵分別與鹽搭配並尋找最佳的鹽漬條件。第二部份則比較分離鹹蛋黃與傳統鹹蛋黃間理化特性、微細結構與官能品評之間的差異。 從砂質感分析我們發現，將蛋黃浸漬在鹽漬液分別含有1.0%檸檬酸鐵+25%食鹽與0.5%檸檬酸+25%食鹽具有最佳的砂質感。在理化特性評估中指出檸檬酸鐵組與檸檬酸組在鹽漬40小時後具有最佳鹹蛋黃的特性。化學成分分析中檸檬鐵酸組與檸檬酸組的水分含量明顯較傳統鹹蛋黃高，而蛋白質與脂質則明顯低於傳統鹹蛋黃（P < 0.05）。在出油量比較中則沒有顯著差異（P > 0.05）。在質地分析中顯示，檸檬酸鐵組與檸檬酸組的分離鹹蛋黃硬度顯低於傳統鹹蛋黃，而彈性、內聚性、膠著性與咀嚼性也明顯較傳統鹹蛋黃低（P < 0.05）。利用掃描式電子顯微鏡、穿透式電子顯微鏡及雷射掃描共軛焦顯微鏡觀察蛋黃顆粒體與油滴分佈情形與傳統鹹蛋黃相比均有相似的微細結構。利用SDS-PAGE蛋白質分析指出生鮮的蛋黃與鹹蛋黃間的蛋白質片段沒有明顯的差別。在官能品評中指出以檸檬酸鐵組的蛋黃的外觀有較佳的接受度，但是質地、風味及整體接受度與傳統鹹蛋黃相比均沒有顯著差異（P > 0.05）。 綜上所述，將分離的雞蛋黃鹽漬在1.0%檸檬酸鐵+25%鹽與0.5%檸檬酸+25%鹽的鹽漬液中40小時具有較佳的鹹蛋黃品質，且與傳統鹹蛋黃相比具有相似的理化特性。根據結果，此鹽漬條件或許在未來可以成為鹹蛋黃製程的一個新選擇。

Salted egg is a traditional and popular egg product in Taiwan. Generally, salted eggs are produced by immersing method and coating method for about 20-35 days. The desirable characteristics of salted yolk are encompassed in the gritty texture, oil exudation and orange color. However, the process of producing salted yolk yields egg whites with high salt content, which does not have many uses in the food industry. Thus, the objective of this study was to use rapid immersion method to find the optimal salting conditions for producing separated salted egg yolks. The first part of this study used ferric citrate (FC) and citric acid (CA) with salt as factorial design elements to research the optimal salting conditions. In the second part of this study, we investigated physicochemical properties, microstructures and conducted a sensory evaluation of separated salted yolk compared with salted yolk produced using the traditional immersion method (TM). From the gritty texture analysis, our findings demonstrated that the salting solution containing 1.0% FC + 25% salt (FC group) and 0.5% CA + 25% salt (CA group) had the most desirable gritty texture. The conclusion from the physicochemical properties evaluation showed that for the FC group and the CA group, salting for 40 hours yielded the most desirable characteristics of salted yolk. The chemical composition analysis indicated that the moisture content of FC group and CA group were significantly higher than the TM group, whereas protein and lipid contents were significantly lower than the TM group (P < 0.05). No significant differences among the groups were found when comparing oil exudation (P > 0.05). From the texture profile analysis, the FC and CA group had significantly lower yolk hardness, springiness, cohesiveness, gumminess and chewiness when compared to the TM group (P < 0.05). The yolk granules and distribution of oil droplet were observed using the scanning electron microscope, the transmission electron microscope and the laser scanning confocal microscope. The micrographs indicated that the microstructures of the separated salted yolk groups were similar to the TM group. SDS-PAGE analysis indicated that there were no differences in the protein patterns among fresh yolk and salted yolks. Sensory evaluation showed that the appearance of the FC group was significantly better received than the CA group and the TM group (P < 0.05); however, the texture, flavor and overall acceptability of the FC and CA groups was not significantly different compared to traditional salted yolk. In conclusion, the separated hen yolk salting in 1.0% FC + 25% salt and 0.5% CA + 25% salt of salting solution for 40 hours had desirable characteristics and similar physicochemical properties to traditional salted yolk. According to the results, these new experimentally determined salting conditions may apply on the new processes of producing salted yolk in the future.