School of Agriculture and Food Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
Progel Pty. Ltd., Level 7, GP South, Staff House Road, The University of Queensland, Brisbane, Queensland 4071, Australia.
Food Res Int. 2021 Dec;150(Pt A):110778. doi: 10.1016/j.foodres.2021.110778. Epub 2021 Oct 21.
This study investigated the effects of milk protein concentrate (MPC85) (untreated, cold-renneted, and pre-heated (80 °C, 30 min)) addition on the physical/mechanical properties of sodium alginate (2% w/w) composite gels in millimeter-size (bead) and centrimeter-size gel forms. The gels were characterized for the degree of syneresis, swelling behavior, hardness, stiffness, viscoelastic behavior, and surface morphology of freeze-dried gel. The results showed that the addition of untreated and treated MPCs reduced the hardness, the stiffness and the solid-like behavior of the alginate gels. Untreated MPC and pre-heated MPC caused no effect on syneresis of alginate gels. The addition of cold-renneted MPC reduced the degree of syneresis in composite gels by 13.7%. Similarly, the addition of cold-renneted MPC reduced (by 16.4%) the degree of syneresis of the alginate composite gels after incubation in simulated gastric fluid (SGF). After incubation in simulated intestinal fluid (SIF), the gel containing alginate only swelled while gels containing untreated MPC and pre-heated MPC experienced degradation and a severe mass loss. Meanwhile, the gels containing cold-renneted MPC swelled and at the same time eroded. Moreover, only cold-renneted MPC composite gels showed lower shrinkage and wrinkles on the surface of the beads during lyophilization. Therefore, based on these results, it is indicated that cold-rennet induced gelation method could increase the effectiveness of MPC as a composite material for alginate gels.
本研究探讨了乳蛋白浓缩物（MPC85）（未经处理、冷凝和预加热（80°C，30 分钟））的添加对毫米尺寸（珠）和厘米尺寸凝胶形式的 2%w/w 海藻酸钠复合凝胶的物理/力学性能的影响。对凝胶的离浆程度、溶胀行为、硬度、刚性、粘弹性行为和冷冻干燥凝胶的表面形态进行了表征。结果表明，未经处理和处理的 MPC 的添加降低了海藻酸钠凝胶的硬度、刚性和固态行为。未经处理的 MPC 和预加热的 MPC 对海藻酸钠凝胶的离浆没有影响。冷凝 MPC 的添加降低了复合凝胶的离浆程度 13.7%。类似地，冷凝 MPC 的添加降低了（16.4%）模拟胃液（SGF）孵育后海藻酸钠复合凝胶的离浆程度。在模拟肠液（SIF）孵育后，仅含有海藻酸钠的凝胶发生溶胀，而含有未经处理的 MPC 和预加热的 MPC 的凝胶发生降解和严重的质量损失。同时，含有冷凝 MPC 的凝胶发生溶胀和同时侵蚀。此外，只有冷凝 MPC 复合凝胶在冷冻干燥过程中珠粒表面的收缩和皱纹较小。因此，根据这些结果，表明冷凝诱导的凝胶化方法可以提高 MPC 作为海藻酸钠凝胶复合材料的有效性。
