Brown Cynthia A, Wang Baowu, Oh Jun-Hyun
Department of Food and Nutritional Sciences, 200 D Campbell Hall, Tuskegee University, Tuskegee, Alabama 36088, USA.
J Food Prot. 2008 Feb;71(2):319-24. doi: 10.4315/0362-028x-71.2.319.
The objectives of this research were to develop and characterize edible chitosan film containing lactoferrin as a natural antimicrobial agent, and to investigate the combination effects of lactoferrin with lysozyme in chitosan film against the growth of Escherichia coli O157:H7 and Listeria monocytogenes. Chitosan films containing lactoferrin, lysozyme, or nisin were fabricated, and the antimicrobial concentrations were 0.5, 1, or 2 mg in a circular disc of chitosan film. Three concentrations of lactoferrin or EDTA (0.28, 0.56, or 1.12 mg per disc) were also incorporated into the chitosan film containing lysozyme to investigate the combination effects of lactoferrin. The water barrier properties of the chitosan films containing lactoferrin were characterized. The antimicrobial activities against E. coli O157:H7 and L. monocytogenes were determined using the agar diffusion assay and cell count assay. The chitosan films containing lactoferrin less than 1 mg per disc did not alter the water vapor permeability of the chitosan film. Although the film containing lysozyme exhibited significant antimicrobial activity, the incorporation of lactoferrin alone into chitosan film did not exhibit significant antimicrobial activity against both E. coli O157:H7 and L. monocytogenes. However, the combination of lactoferrin with lysozyme-containing chitosan film significantly decreased the growth of E. coli O157:H7, exhibiting a comparable effect to that of the combination of EDTA with lysozyme (P < 0.05). Furthermore, the combination of lactoferrin with lysozyme in chitosan film exhibited greater reduction in the growth of L. monocytogenes than did the combination EDTA with lysozyme, resulting in an approximate 3-log reduction.
本研究的目的是开发并表征含有乳铁蛋白作为天然抗菌剂的可食用壳聚糖薄膜，并研究壳聚糖薄膜中乳铁蛋白与溶菌酶联合对大肠杆菌O157:H7和单核细胞增生李斯特菌生长的影响。制备了含有乳铁蛋白、溶菌酶或乳链菌肽的壳聚糖薄膜，抗菌剂在壳聚糖薄膜圆片中的浓度分别为0.5、1或2 mg。还将三种浓度的乳铁蛋白或乙二胺四乙酸（EDTA）（每片0.28、0.56或1.12 mg）加入含有溶菌酶的壳聚糖薄膜中，以研究乳铁蛋白的联合作用。对含有乳铁蛋白的壳聚糖薄膜的阻水性能进行了表征。采用琼脂扩散法和细胞计数法测定了对大肠杆菌O157:H7和单核细胞增生李斯特菌的抗菌活性。每片含乳铁蛋白低于1 mg的壳聚糖薄膜未改变壳聚糖薄膜的水蒸气透过率。虽然含溶菌酶的薄膜表现出显著的抗菌活性，但单独将乳铁蛋白加入壳聚糖薄膜中对大肠杆菌O157:H7和单核细胞增生李斯特菌均未表现出显著的抗菌活性。然而，乳铁蛋白与含溶菌酶的壳聚糖薄膜联合使用显著降低了大肠杆菌O157:H7的生长，其效果与EDTA和溶菌酶联合使用相当（P < 0.05）。此外，壳聚糖薄膜中乳铁蛋白与溶菌酶联合使用对单核细胞增生李斯特菌生长的抑制作用比EDTA与溶菌酶联合使用更强，导致菌数减少约3个对数级。
