ARC Dairy Innovation Hub, School of Agriculture and Food Sciences, The University of Queensland, St Lucia, QLD 4072, Australia.
ARC Dairy Innovation Hub, School of Agriculture and Food Sciences, The University of Queensland, St Lucia, QLD 4072, Australia; School of Science, RMIT University, VIC 3001, Australia.
Food Res Int. 2019 Sep;123:153-165. doi: 10.1016/j.foodres.2019.04.054. Epub 2019 Apr 26.
Milk fat globule size plays a significant role in stability, microstructure and nutritional functionalities of dairy-based products. Understanding of thermal stability of differentiated-size fat globules in dairy creams can provide intervention opportunities for improving functionalities and shelf-life of dairy-based products. This study focused on apparent thermal and UHT stability of native, homogenized (from native cream) and recombined creams (sodium caseinate-stabilized anhydrous milk fat) as a function of their fat globule sizes at 18 and 36% fat contents. Native creams were fractionated by the two-stage centrifugal method into five sizes (1.45, ~2.45-3.65, ~3.85 and ~4.5 μm) whereas homogenized and recombined creams (1.45, 2.45, ~3.85 and ~4.5 μm) were obtained by microfluidisation. All cream samples were tested for thermal stability at 140 °C following a test similar to Heat Coagulation Time. Some selected creams were also studied for UHT stability at 140 °C for 4 s. Native creams exhibited diverse thermal stability depending upon fat content and size; however, native creams (2.45-3.65 and ~4.5 μm) were UHT stable. Native creams of all sizes were also significantly more thermal stable than homogenized creams. Homogenized creams of all sizes at both fat contents showed poor apparent thermal and UHT stability. It appeared that small fat globules of native creams were more heat stable than larger fat globules at 18% fat content. Recombined creams made with sodium caseinate as emulsifier (without the presence of other milk components) were the most stable among all. However, dilution of recombined cream with skim milk or lactose significantly reduced their apparent thermal stability, but they were UHT stable.
牛奶脂肪球大小在乳制品的稳定性、微观结构和营养功能方面起着重要作用。了解乳制品奶油中差异化大小脂肪球的热稳定性，可以为改善乳制品的功能和保质期提供干预机会。本研究以 18%和 36%脂肪含量的天然奶油、均质化（来自天然奶油）和重组奶油（酪蛋白酸钠稳定的无水乳脂）为研究对象，重点研究了其脂肪球大小对其表观热稳定性和 UHT 稳定性的影响。天然奶油通过两步离心法分为五个大小（约 1.45μm、2.45-3.65μm、3.85μm 和 4.5μm），而均质化和重组奶油（约 1.45μm、2.45μm、3.85μm 和 4.5μm）则通过微流体制备。所有奶油样品均在 140°C 下进行热稳定性测试，测试方法类似于热凝固时间测试。一些选定的奶油还在 140°C 下进行了 4s 的 UHT 稳定性测试。天然奶油的热稳定性因脂肪含量和大小而异；然而，2.45-3.65μm 和 4.5μm 的天然奶油是 UHT 稳定的。所有大小的天然奶油的热稳定性也明显高于均质化奶油。所有大小的均质化奶油在两种脂肪含量下均表现出较差的表观热稳定性和 UHT 稳定性。似乎在 18%脂肪含量下，天然奶油的小脂肪球比大脂肪球更耐热。作为乳化剂的酪蛋白酸钠（没有其他牛奶成分）制成的重组奶油是所有奶油中最稳定的。然而，将重组奶油与脱脂乳或乳糖稀释会显著降低其表观热稳定性，但它们是 UHT 稳定的。
