低场核磁共振技术测定石花菜对酸奶水分迁移及超微结构的影响

Effects of Gelidium amansii on the water mobility and ultrastructure of yogurt by nuclear magnetic resonance

利用低场核磁共振及其成像技术对比了石花菜酸奶和酸奶水分迁移特性;并采用环境扫描电镜对石花菜酸奶超微形貌特征进行观察分析。结果表明,石花菜酸奶在发酵及储藏过程中的水分含量变化幅度小于不添加石花菜的酸奶,持水性增强;确定了前期发酵最优时间为6 h,冷藏后熟最优时间为24 h;通过环境扫描电镜观察发现石花菜酸奶中酪蛋白胶束与石花菜琼胶分子间相互缠结,蛋白链球颗粒粘结在致密的琼胶网络结构之中。

The changes of water mobility of Gelidium amansii yogurt and pure yogurt were analyzed by low-field nuclear magnetic resonance(NMR)and magnetic resonance imaging(MRI).The ultrastructural characteristics of G.amansii yogurt were analyzed by environment scanning electron microscope(ESEM).The results showed that the variation of water content in G.amansii yogurt was less than yogurt without G.amansii,and water holding capacity of G.amansii was increased.The optimal pre-fermentation time was 6 h,and the optimal time for cold-ripening was 24 h.ESEM showed that the casein micelle interlaced with G.amansii agar molecular,and the protein chain pellets were cohered in the dense structure of the agar network.