低温刺激对凝固型酸乳质构的影响

Effect of low-temperayure-stimulating on quality and structure of set yoghurt

将酸乳发酵剂STZ和LBZ在低温条件下进行刺激培养,确定了STZ的低温刺激温度为33℃,LBZ的为37℃,而后将鲜奶分别在这两个温度下发酵,同时以42℃发酵的作为对照,测定其相关参数,并对其机理进行了探讨。研究发现,经低温刺激后其后酸化能力显著降低,STS和WHC下降,黏度增大,硬度、黏聚度和弹性均有不同程度地降低,其主要原因可能是低温延长了酸乳的凝固时间,使蛋白质网络形成得更充分,同时产生了大量的EPS,EPS干扰了酪蛋白之间的相互作用。

We cultured STZ and LBZ at low temperature then confirmed the stimulating temperature of STZ was 33 ℃and LBZ was 37 ℃. Yoghurt were made at these two temperature, two others were made in 42 ℃ which used as CK. After fermented, some related indexes were measured and also the mechanism discussed. We discovered that by low-temperature-stimulating the yoghurt＇s ability of later-acidification was decreased significantly, WHC, STS, hardness, cohesiveness and springiness also reduced with different degrees, while viscidity increased. The possible reason was the clotting-time was extended by low-temperature-stimulating which impelled the protein net formed more sufficiendy, simultaneous the yoghurt produced more EPS, EPS disturbed the interaction between caseins