离子强度和pH值对胶原纤维膜性能的影响

胶原纤维膜是一种重要的可食性蛋白膜,但其性能受到多种外界因素的影响。为了提高胶原蛋白膜的性能,使其能更好的应用于食品包装等,本实验研究了不同p H值(2、3、5、7、11)和不同离子强度(0.1、0.2、0.3 mol/L)对胶原纤维膜机械强度和微结构的影响。实验表明,p H值对胶原纤维膜的厚度无显著性影响,但膜的拉伸强度和断裂延伸率随p H值增大而明显表现为V型变化,且在p H=2时膜的拉伸强度达到最大值67.67±2.57 MPa,此时膜表面较光滑,质地均匀;随着离子强度的增加,膜的厚度逐渐增加,机械性能显著降低,膜表面粗糙度程度增加,并扰乱了纤维之间排列;与干膜相比,湿膜的拉伸强度发生较大下降,而断裂延伸率却大幅度增加。此外,随离子强度增加以及成膜液的p H偏离胶原纤维的等电点,膜的膨胀性能增加。

Effects of Ionic Strength and pH on the Properties of Collagen Fiber Film

Collagen fiber film is one of the important edible protein films, but its performance is affected by a variety of external factors. In order to improve the performance of collagen film and make it more suitable for food packaging, this study investigated the effects of different pH values (2, 3, 5, 7, 11) and different ionic strengths (0.1, 0.2, 0.3 mol/L) on the mechanical strength and microstructure of collagen fiber film. The experimental results showed that the pH had no significant impact on film thickness, whilst the tensile strength and elongation at break of the films exhibited a V-shaped change with increasing pH, with the highest tensile strength of 67.67 ± 2.57 MPa occurring at pH 2 (where smooth and uniform film surface was observed). With the increase of ionic strength, film thickness and roughness increased whilst the mechanical strength decreased significantly, along with a disrupted fiber arrangement. Compared with the dry film, the tensile strength of the wet film reduced greatly whilst the elongation at break increased considerably. In addition, the swellability of the film increased, as the ionic strength rose and the pH of the film-forming solution deviated from the isoelectric point of the collagen fiber.