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Mechanical properties of bacterial cellulose synthesised by diverse strains of the genus Komagataeibacter
Food Hydrocolloids ( IF 10.7 ) Pub Date : 2018-08-01 , DOI: 10.1016/j.foodhyd.2018.02.031
Si-Qian Chen , Patricia Lopez-Sanchez , Dongjie Wang , Deirdre Mikkelsen , Michael J. Gidley

Abstract Bacterial cellulose (BC) has several current and potential future uses in the food industry because of its ability to form hydrogels with distinctive properties. The texture of BC hydrogels is determined by both the cellulose fibre network and the internal dispersed water. In this study, mechanical properties of hydrated BC synthesised by six different strains of Komagataeibacter genus were investigated with regards to their extensibility, compressive strength, relaxation ability, viscoelasticity and poroelasticity. The stress/strain at failure and Young's modulus were assessed by uniaxial tensile testing. The compressive strength, relaxation ability and viscoelasticity were measured via a series of compression and small amplitude oscillatory shear steps. A poroelastic constitutive modelling simulation was used to investigate the mechanical effects of water movement. The morphology of the BC fibril network under compression was observed via scanning electron microscopy. Results showed that the mechanics of BC were highly dependent on the cellulose concentration, as well as the morphology of the fibril network. BC synthesised by ATCC 53524 was the most concentrated (0.71 wt%), and exhibited high tensile properties, stiffness and storage moduli; whereas comparatively low mechanical properties were noted for BC produced by ATCC 700178 and ATCC 10245, which contained the lowest cellulose concentration (0.18 wt%). Small deformation responses (normal stress, G′) scaled with cellulose concentration for all samples, whereas larger deformation responses (Young's modulus, poroelasticity) depended on both cellulose concentration and additional factors, presumably related to network morphology. Increasing concentration and compressive coalescence of fibres in the integrated BC network reduced both the relaxation of the normal stress and the movement of water. This research aids the selection of bacterial strains to modulate the texture and mechanical properties of hydrated BC-based food systems.

中文翻译:

由驹形杆菌属不同菌株合成的细菌纤维素的机械性能

摘要 细菌纤维素 (BC) 在食品工业中具有多种当前和潜在的未来用途,因为它能够形成具有独特特性的水凝胶。BC 水凝胶的质地由纤维素纤维网络和内部分散的水决定。在这项研究中,研究了由六种不同的驹形杆菌属菌株合成的水合 BC 的机械性能,包括它们的延伸性、压缩强度、松弛能力、粘弹性和多孔弹性。破坏应力/应变和杨氏模量通过单轴拉伸试验进行评估。通过一系列压缩和小振幅振荡剪切步骤测量压缩强度、松弛能力和粘弹性。多孔弹性本构建模模拟用于研究水运动的机械效应。通过扫描电子显微镜观察压缩下 BC 原纤维网络的形态。结果表明,BC 的力学高度依赖于纤维素浓度以及原纤维网络的形态。由 ATCC 53524 合成的 BC 浓度最高(0.71 wt%),并表现出较高的拉伸性能、刚度和储能模量;而由 ATCC 700178 和 ATCC 10245 生产的 BC 的机械性能相对较低,其中含有最低的纤维素浓度 (0.18 wt%)。所有样品的小变形响应(法向应力,G')与纤维素浓度成比例,而较大的变形响应(杨氏模量,多孔弹性)取决于纤维素浓度和其他因素,大概与网络形态有关。在集成的 BC 网络中增加纤维的浓度和压缩聚结减少了法向应力的松弛和水的运动。该研究有助于选择细菌菌株以调节基于水合 BC 的食品系统的质地和机械特性。
更新日期:2018-08-01
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