Pouliou Nikoletta, Paraskevaidou Eirini Chrysovalantou, Goulas Athanasios, Exarhopoulos Stylianos, Dimitreli Georgia
Department of Food Science and Technology, International Hellenic University, 57400 Thessaloniki, Greece.
Department of Hygiene and Technology of Food of Animal Origin, School of Veterinary Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Molecules. 2025 Aug 1;30(15):3230. doi: 10.3390/molecules30153230.
Kefiran, the extracellular polysaccharide produced from the Generally Recognized as Safe (GRAS) bacteria in kefir grains, with its well-documented functional and health-promoting properties, constitutes a promising biopolymer with a variety of possible uses. Its compatibility with other biopolymers, such as milk proteins, and its ability to form standalone cryogels allow it to be utilized for the fabrication of films with improved properties for applications in the food and biomedical-pharmaceutical industries. In the present work, the properties of kefiran films were investigated in the presence of milk proteins (sodium caseinate, native and heat-treated whey proteins, and their mixtures), alongside glycerol (as a plasticizer) and cryo-treatment of the film-forming solution prior to drying. A total of 24 kefiran films were fabricated and studied for their physical (thickness, moisture content, water solubility, color parameters and vapor adsorption), mechanical (tensile strength and elongation at break), and optical properties. Milk proteins increased film thickness, solubility and tensile strength and reduced water vapor adsorption. The hygroscopic effect of glycerol was mitigated in the presence of milk proteins and/or the application of cryo-treatment. Glycerol was the most effective at reducing the films' opacity. Heat treatment of whey proteins proved to be the most effective in increasing film tensile strength, reducing, at the same time, the elongation at break, while sodium caseinates in combination with cryo-treatment resulted in films with high tensile strength and the highest elongation at break. Cryo-treatment, carried out in the present study through freezing followed by gradual thawing of the film-forming solution, proved to be the most effective factor in decreasing film roughness. Based on our results, proper selection of the film-forming solution composition and its treatment prior to drying can result in kefiran-glycerol films with favorable properties for particular applications.
开菲尔粒中由一般认为安全（GRAS）的细菌产生的胞外多糖——开菲尔多糖，具有充分记录的功能和促进健康的特性，是一种有多种潜在用途的、很有前景的生物聚合物。它与其他生物聚合物（如乳蛋白）的相容性以及形成独立冷冻凝胶的能力，使其可用于制造具有改进性能的薄膜，应用于食品和生物医学制药行业。在本研究中，研究了在乳蛋白（酪蛋白酸钠、天然和热处理乳清蛋白及其混合物）存在的情况下，以及甘油（作为增塑剂）和在干燥前对成膜溶液进行冷冻处理时，开菲尔多糖薄膜的性能。共制备了24种开菲尔多糖薄膜，并对其物理性能（厚度、水分含量、水溶性、颜色参数和蒸汽吸附）、机械性能（拉伸强度和断裂伸长率）和光学性能进行了研究。乳蛋白增加了薄膜的厚度、溶解度和拉伸强度，并降低了水蒸气吸附。在存在乳蛋白和/或进行冷冻处理的情况下，甘油的吸湿作用得到缓解。甘油在降低薄膜不透明度方面最有效。事实证明，乳清蛋白的热处理在提高薄膜拉伸强度方面最有效，同时降低了断裂伸长率，而酪蛋白酸钠与冷冻处理相结合则产生了具有高拉伸强度和最高断裂伸长率的薄膜。在本研究中，通过对成膜溶液进行冷冻然后逐渐解冻进行的冷冻处理，被证明是降低薄膜粗糙度的最有效因素。根据我们的结果，适当选择成膜溶液的组成及其在干燥前的处理，可以得到具有适合特定应用的良好性能的开菲尔多糖 - 甘油薄膜。
