College of Food Science, Sichuan Agricultural University, Yaan 625014, China.
College of Food Science, Sichuan Agricultural University, Yaan 625014, China; School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China; California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.
Int J Biol Macromol. 2020 Feb 15;145:1031-1038. doi: 10.1016/j.ijbiomac.2019.09.195. Epub 2019 Nov 4.
The physical and antimicrobial properties of sodium alginate or sodium carboxymethylcellulose films containing cell-free supernatant of Lactococcus lactis ATCC 11454 were evaluated in this study. The antimicrobial activity of the films against Staphylococcus aureus ATCC 6538, and Escherichia coli ATCC 25922 was evaluated. Cell-free supernatants were obtained by centrifugation and filtration of Lactococcus lactis cultures in MRS broth; the filtrates were freeze-dried, and rehydrated (4, 8, or 12 mg/mL) to produce collagen film. The thickness, tensile strength, color, moisture content, solubility, and water vapor permeability of the films were measured to examine the effects of cell-free supernatants on film matrices. Noticeable antimicrobial activity was observed against Staphylococcus aureus, and Escherichia coli upon the addition of 12 mg/mL cell-free supernatants. Our results indicate that the incorporation of cell-free supernatant changed the physical properties of the edible films. Gradual and significant (p < 0.05) increase in color difference and solubility were observed with the addition of increasing concentrations of cell-free supernatant. Antimicrobial films were brown in color and with variable moisture contents. Sodium alginate films were better than sodium carboxymethylcellulose films for most of the evaluated parameters. In summary, collagen films containing cell-free supernatants are interesting alternative natural antimicrobial films for functional food packaging.
本研究评估了含乳球菌（Lactococcus lactis）ATCC 11454 无细胞上清液的海藻酸钠或羧甲基纤维素钠膜的物理和抗菌性能。评估了这些膜对金黄色葡萄球菌（Staphylococcus aureus）ATCC 6538 和大肠杆菌（Escherichia coli）ATCC 25922 的抗菌活性。通过离心和过滤 MRS 肉汤中的乳球菌培养物获得无细胞上清液；过滤液经冷冻干燥，然后再水合（4、8 或 12 mg/mL）以产生胶原蛋白膜。测量膜的厚度、拉伸强度、颜色、水分含量、溶解度和水蒸气透过率，以研究无细胞上清液对膜基质的影响。添加 12 mg/mL 无细胞上清液后，明显观察到对金黄色葡萄球菌和大肠杆菌的抗菌活性。我们的结果表明，无细胞上清液的加入改变了可食用膜的物理性质。随着无细胞上清液浓度的增加，颜色差异和溶解度逐渐显著（p < 0.05）增加。抗菌膜呈棕色，水分含量不同。就大多数评估参数而言，海藻酸钠膜优于羧甲基纤维素钠膜。总之，含无细胞上清液的胶原蛋白膜是功能性食品包装中一种有趣的天然抗菌膜替代品。
