贵州三穗特色黄皮蛋加工过程中凝胶形成及颜色变化分析

Analysis of Gel Formation and Color Change during the Processing of Yellow Preserved Eggs in Sansui,Guizhou

为研究三穗特色黄皮蛋加工过程中凝胶形成及颜色变化机理,以黄皮蛋无铅腌制工艺为基础,测定并分析黄皮蛋加工过程中蛋清游离碱度、微观结构、蛋白质二级结构及分子间作用力、质构特性、色差、还原糖含量、游离氨基酸的动态变化情况。结果表明,腌制过程中(0~18 d),蛋清游离碱度不断升高,离子键作用力先升高后降低,氢键作用力、疏水作用力、二硫键作用力则逐渐增加;蛋白从粗毛孔无序状态变为有序的三维网状纤维结构;在第12天时,凝胶质构特性各指标总体最高,β-折叠和β-转角为主要结构。腌制12~18 d,高碱度导致凝胶结构被破坏,网孔变大,离子键作用力及质构特性指标水平呈下降趋势。腌制结束(18 d)后,蛋清游离碱度逐渐下降后趋于稳定,质构特性指标水平整体先上升后趋于稳定,凝胶结构自我修复,网孔紧密,凝胶结构稳定。维持凝胶结构的主要作用力为离子键和二硫键,蛋白质二级结构主要为β-折叠和β-转角。在色泽形成过程中,羰氨反应与蛋白质分解同时进行,蛋清还原糖含量降低,总游离氨基酸含量先降低后升高,蛋清红绿度(a值)和黄蓝度(b值)逐渐升高,颜色逐渐变黄变暗。腌制结束后,蛋清各色泽均无明显变化,形成稳定的金黄色。综上可知,黄皮蛋腌制阶段的6~12 d是控制品质的关键阶段,腌制结束后常温放置6 d,蛋清凝胶性质略微提升,色泽稳定,产品品质更佳。

In order to study the mechanism of gel formation and color change during the processing of Sansui featured yellow preserved eggs,produced by leadless curing,the dynamic changes of free alkalinity,microstructure,protein secondary structure,intermolecular forces,texture,color difference,reducing sugar content and free amino acid contents in egg white were measured and analyzed.The results showed that during the curing process(from day 0 to 18),the free alkalinity increased continuously,and ionic bond interactions increased first and then decreased,while hydrogen bonding interactions,hydrophobic interactions and disulfide bonding interactions increased gradually.The protein structure was transformed from disordered macroporous to ordered three-dimensional reticular.On the 12th day,the texture properties of the gel were the highest,andβ-sheet andβ-turn were the major secondary structure components.From day 12 to day 18,the structure of the gel was destroyed due to the high alkalinity,showing larger holes,and ionic bonding interactions and texture properties exhibited a downward trend.After the completion of curing(18 days),the free alkalinity decreased gradually and then became stable,and the texture properties increased at first and then tended to be stable;the gel structure could be self repaired,becoming tight and stable.The main forces responsible for maintaining the gel structure were ionic bonding and disulfide bonding,and the major protein secondary structures wereβ-sheet andβ-turn.In the process of color formation,carbonyl ammonia reaction and protein decomposition occurred at the same time;the content of reducing sugar in egg white decreased,and the content of free amino acids decreased at first and then increased;the redness-greenness value(a)and yellowness-blueness value(b)of egg white gradually increased,and the color gradually became yellow and dark.After the completion of curing,there was no significant change in any of the color values of egg white,indicating the formation of a stable golden yellow color.Finally,it is concluded that the curing stage from day 6 to day 12 could be the key to controlling the quality of yellow preserved eggs.After curing,the gel property of egg white was slightly improved,the color was stable,and the product quality was better when stored at room temperature for 6 days.