细菌纤维素基自组装可食性纳米乳液膜的可控构建及其对鲜切果蔬的保鲜机制

Bacterial cellulose, a kind of natural edible nanofiber, has many properties including self-assembly properties, high purity, high mechanical strength and high water holding capacity. In our previous studies, the bacterial cellulose/pectin composite membranes have been prepared in situ synthesis method, which have many properties that the cell walls of fruits and vegetables have. And it has been found that it has certain fresh-keeping effects on the fresh-cut fruits and vegetables, but its fresh-keeping properties and mechanisms needs to be further investigated. In the present study, bacterial cellulose will be used as film-forming substrate and Ca2+ will be used as the film forming-inducer. Then the nano emulsion edible film will be formed by self-assembly under the inducer. The interactions between the particles of the blend film forming suspensions will be studied during their self-assembly, to reveal the effects of the components of film forming suspensions on the self-assembly properties. The relationship among the self-assembly properties, the Three-dimensional network structure and properties (water resistance, gas barrier and antibacterial properties) of film will be established by partial least squares, so as to realize the three dimensional structure-function controllable regulation of nano membrane materials. In order to further investigate the effects and preservation mechanisms of three dimensional controllable nano film on the fresh-cut fruits and vegetables, 8 kinds of fresh-cut fruits and vegetables with different physiological properties will be used as the standard samples, the fresh-keeping effects of three dimensional controllable nano film on the fresh-cut samples, including water metabolism, browning degree and microorganisms disseminated, will be studied. And the relationship between the fresh-keeping effects and properties of the films will be investigated to reveal its fresh-keeping mechanism. This research will provide the important theoretical foundation and technical support for building suitable fresh-keeping coating materials for different of fresh-cut fruits and vegetables.

细菌纤维素是一种具有良好自组装特性及超纯、高机械强度、高保水等特性的天然可食性纳米纤维。申请人前期利用原位合成法已成功获得具有果蔬细胞壁特性的细菌纤维素/果胶复合膜，且初步发现其具有一定的保鲜作用，但其保鲜性能及保鲜机制急需进一步研究。本课题拟采用细菌纤维素作为成膜基质，利用Ca2+的诱导交联作用自组装形成纳米乳液膜。通过研究膜自组装过程中成膜液粒子间互作，揭示成膜液组分对纳米膜自组装行为的影响规律，并运用偏最小二乘法分析建立成膜液的自组装行为与膜的三维网络结构及其阻水、阻气、抑菌三大性能之间的关联性，从而实现自组装纳米膜的可控构建。为进一步探明膜的保鲜作用机制，选择8种生理特性不同的鲜切果蔬作为标样，通过研究膜对标样的呼吸强度、水分代谢、切面褐变及微生物侵染等规律与膜的结构及其性能之间的关联性来揭示其保鲜调控机理，该研究为构建适合不同鲜切果蔬的保鲜涂膜材料提供重要的理论基础和技术支持。

随着社会的发展和人们生活水平的不断提高，人们对果蔬的消费需求提出了更高的要求，即要求新鲜、方便、营养、安全的洁净果蔬商品，因此，可食性保鲜膜的研发是当前鲜切果蔬保鲜领域的一个重要发展方向。为此，本项目构建了细菌纤维素纳米纤维（BCNs）作为纳米填料的可食性纳米乳液复合膜。项目首先构建了BCNs胶体颗粒稳定的Pickering乳液，应用流变仪、激光粒度仪及共聚焦显微镜等测定乳液的物理性质及微观结构，明确了Pickering 乳液的稳定机制。其次，以BCNs作为纳米填料构建BCNs/魔芋胶复合型Pickering乳液膜。运用流变仪、小角衍射、透射电镜等测试分析成膜共混液中粒子间互作，分析孔径分布情况与孔隙率，表征复合膜的微纳结构，并测定复合膜的疏水、阻气等性能，建立复合膜的宏观性质与其微观结构及其性能之间的关联性，从而实现了纳米乳液膜的可控构建。该项目大致完成了项目计划书的主要研究内容，达到了预期的研究目标，并取得了重要的研究成果，特别在细菌纤维素纳米纤维作为纳米填料方面获得创新的发现。通过该项目的实施在国际食品类SCI主流刊物上发表相关性学术论文10篇。其中1篇SCI论文成为ESI前1%高被引论文。该项目的完成对于可食性保鲜膜的研发及鲜切果蔬的保鲜都具有较重要的理论意义。