Miloradovic Zorana, Kljajevic Nemanja, Miocinovic Jelena, Levic Steva, Pavlovic Vladimir B, Blažić Marijana, Pudja Predrag
Department for Animal Source Food Technology, Faculty of Agriculture, University of Belgrade, Nemanjina 6, 11081 Belgrade, Serbia.
Department for Food Technology and Biochemistry, Faculty of Agriculture, University of Belgrade, Nemanjina 6, 11081 Belgrade, Serbia.
Foods. 2020 Mar 4;9(3):283. doi: 10.3390/foods9030283.
Rennet coagulation of goat milk heated to 65 °C/30 min (Gc), 80 °C/5 min (G8) and 90 °C/5 min (G9) was studied. A rheometer equipped with a vane geometry tool was used to measure milk coagulation parameters and viscoelastic properties of rennet gels. Yield parameters: curd yield, laboratory curd yield and curd yield efficiency were measured and calculated. Scanning electron microscopy of rennet gels was conducted. Storage moduli (G') of gels at the moment of cutting were 19.9 ± 1.71 Pa (Gc), 11.9 ± 1.96 Pa (G8) and 7.3 ± 1.46 Pa (G9). Aggregation rate and curd firmness decreased with the increase of milk heating temperature, while coagulation time did not change significantly. High heat treatment of goat milk had a significant effect on both laboratory curd yield and curd yield. However, laboratory curd yield (27.7 ± 1.84%) of the G9 treatment was unreasonably high compared to curd yield (15.4 ± 0.60%). The microstructure of G9 was notably different compared to Gc and G8, with a denser and more compact microstructure, smaller paracasein micelles and void spaces in a form of cracks indicating weaker cross links. The findings of this study might serve as the bases for the development of different cheese types produced from high-heat-treated goat milk.
研究了加热至65℃/30分钟（Gc）、80℃/5分钟（G8）和90℃/5分钟（G9）的山羊奶的凝乳酶凝固情况。使用配备叶片几何工具的流变仪测量牛奶凝固参数和凝乳酶凝胶的粘弹性特性。测量并计算了产率参数：凝乳产率、实验室凝乳产率和凝乳产率效率。对凝乳酶凝胶进行了扫描电子显微镜观察。切割时凝胶的储能模量（G'）分别为19.9±1.71帕斯卡（Gc）、11.9±1.96帕斯卡（G8）和7.3±1.46帕斯卡（G9）。聚集速率和凝乳硬度随牛奶加热温度的升高而降低，而凝固时间没有显著变化。山羊奶的高温处理对实验室凝乳产率和凝乳产率均有显著影响。然而，G9处理的实验室凝乳产率（27.7±1.84%）与凝乳产率（15.4±0.60%）相比过高。与Gc和G8相比，G9的微观结构明显不同，其微观结构更致密、更紧凑，副酪蛋白胶粒更小，且存在呈裂缝形式的空隙，表明交联较弱。本研究结果可为开发由高温处理山羊奶制成的不同类型奶酪提供依据。
