Frabetti Ana Caroline, de Moraes Jaqueline Oliveira, Jury Vanessa, Boillereaux Lionel, Borges Laurindo João
Department of Chemical and Food Engineering, Federal University of Santa Catarina, Engenharia Quimica et de Alimentos (EQA)/Centro Tecnologico (CTC), Florianópolis 88040-900, SC, Brazil.
Oniris, Nantes Université, CNRS, GEPEA, UMR 6144, F-44000 Nantes, France.
Foods. 2025 Jun 9;14(12):2033. doi: 10.3390/foods14122033.
In food drying processes such as cast-tape drying, refractance window, and drum drying, spreading food suspensions on hydrophobic surfaces is critical. This study investigated the effects of low-molar-mass sugars (glucose, sucrose, and fructose) on the rheology and surface tension of cassava starch suspensions, which served as model systems. Wettability was assessed on hydrophobic surfaces, including new polytetrafluoroethylene (PTFE) and polyethylene terephthalate (PET) films, with additional testing on sandpaper-abraded PTFE (named PTFE R+) to evaluate the influence of surface roughness. PET film exhibited lower roughness (Ra = X µm) and higher surface tension (71 mN/m) compared to PTFE (surface tension 65 mN/m). Contact angles on PET (93-124°) were significantly higher than on PTFE (89-113°), indicating greater product adhesion on PET. All suspensions showed pseudoplastic behavior, and the addition of the surfactant Tween 20 slightly reduced surface tension (by ≈1-5 mN/m) but did not significantly enhance wettability. Sucrose and fructose increased wettability on PTFE R+, but the effects of the sugar varied depending on the surface. These findings suggest that PTFE surfaces reduce product sticking during drying compared to PET. Interactions between sugars, Tween 20, and hydrophobic surfaces must be considered to optimize spreading and reduce product sticking during drying. This knowledge can guide improvements in drying processes for food products.
在诸如流延带式干燥、折射窗干燥和滚筒干燥等食品干燥过程中，将食品悬浮液铺展在疏水表面至关重要。本研究调查了低摩尔质量糖类（葡萄糖、蔗糖和果糖）对木薯淀粉悬浮液流变学和表面张力的影响，木薯淀粉悬浮液用作模型体系。在包括新型聚四氟乙烯（PTFE）和聚对苯二甲酸乙二酯（PET）薄膜在内的疏水表面上评估润湿性，并对砂纸打磨过的PTFE（命名为PTFE R+）进行额外测试，以评估表面粗糙度的影响。与PTFE（表面张力65 mN/m）相比，PET薄膜表现出更低的粗糙度（Ra = X µm）和更高的表面张力（71 mN/m）。PET上的接触角（93 - 124°）显著高于PTFE上的接触角（89 - 113°），表明产品在PET上的附着力更强。所有悬浮液均表现出假塑性行为，添加表面活性剂吐温20会略微降低表面张力（约1 - 5 mN/m），但并未显著提高润湿性。蔗糖和果糖提高了在PTFE R+上的润湿性，但糖类的效果因表面而异。这些发现表明，与PET相比，PTFE表面在干燥过程中减少了产品粘连。必须考虑糖类、吐温20和疏水表面之间的相互作用，以优化铺展并减少干燥过程中的产品粘连。这些知识可为食品干燥工艺的改进提供指导。
