Nisin及其在食品工业中的应用

乳酸链球菌素(Nisin)是某些乳链球菌产生的一种活性多肽物质,是高效、无毒副作用的天然生物防腐剂,是目前世界上惟一允许使用在食品防腐上的抗菌素。综述乳酸链球菌素的结构、性质、抑菌机理及其在食品工业中的应用研究进展。     

Characterisation of the technological behaviour of mixtures of mesophilic lactic acid bacteria isolated from traditional cheeses made of raw milk without added starters

In this work, the technological behaviour in milk of a set of Lactococcus lactis strains, alone or in combination with strains of Leuconostoc spp. and Lactobacillus spp. isolated from traditional, raw milk cheeses made without commercial starters, was investigated. Small, mixture‐specific differences during milk fermentation were recorded for growth, milk acidification and production of organic acids, volatile compounds, free amino acids and biogenic amines. Four combinations appropriate for use as dairy starters were tested in pilot‐scale cheese trials. Two mixtures produced cheeses of high flavour and taste quality; these could be confidently used as starter cultures.     

基于微囊细胞耦合发酵生产Nisin泡沫分离条件的研究

研究嗜热乳链球菌（Streptococcus thermophilus）6032海藻酸盐-壳聚糖-海藻酸盐（ACA）液芯微囊细胞发酵生产Nisin泡沫分离的影响因素,探索最佳分离条件。在单因素试验的基础上,以Nisin富集比作为评价指标,采用正交试验对泡沫分离Nisin的条件进行优化。结果表明,通气速率和泡沫层高度是影响分离效果的显著因素。为获得较多的Nisin,且不影响发酵,同时兼顾分离效果,确定最佳分离条件为：分离pH值为6,泡沫层高11 cm,通气速率为0.15 L/min,分离时间60 min。在该最佳条件下,Nisin回收率为83.89%,Nisin富集比为8.4,细胞富集比为0.221。     

应用真空软包装配合生物保鲜剂加工莱豆小菜产品工艺优化研究

研究莱豆真空软包装时的杀菌工艺特性,确定可采用常压杀菌的产品的最佳杀菌工艺条件为:100℃,30min.对于需要高压杀菌的产品,则提出真空软包装配合生物保鲜剂的技术,以降低杀菌强度,保持感官品质,并采用正交实验筛选工艺条件,所得结果为:浸泡液Nisin的浓度0.2g/kg,杀菌温度106℃,杀菌时间12min,所生产的产品感官品质优良,大豆异黄酮保存率80%以上,产品理化和卫生指标符合食品卫生标准,保质期一年.     

分割托盘小包装冷却肉溶菌酶、Nisin、GNa液保鲜试验研究

在溶菌酶、Nisin、GNa保鲜剂对托盘小包装冷却肉复合性保鲜的基础上,为取得更好的保鲜实验效果,进一步开展了溶菌酶、Nisin、GNa保鲜剂正交实验研究,以研究出能应用于生产实际的托盘包装冷却肉的有效保鲜剂。通过L9(34)正交试验,结果表明,三种保鲜剂经正交实验配合使用,对非真空托盘包装保鲜冷却肉的保鲜效果非常显著,使托盘包装保鲜的冷却肉在0～4℃条件下,有效保存时间达到24天以上。经正交实验研究后得出较优的工艺条件为A3B2C2D2,即GNa液采用5000ppm,Nisin2500ppm,溶菌酶2500ppm,用乳酸调pH值至4.5。     

冷却肉天然复合保鲜剂配比的优化

根据中心复合设计原理,在琼脂扩散法得出3 种天然保鲜剂最小抑菌浓度基础上,运用Minitab14 数据统计分析软件,采用四因素二水平中心复合响应曲面分析法,确定保鲜剂的最佳配比为Nisin 0.2773g/100mL、溶菌酶0.46g/100mL、乳铁蛋白0.604g/100mL、pH5.16。pH 值与乳铁蛋白、pH 值与溶菌酶、pH 值与Nisin、乳铁蛋白与溶菌酶以及溶菌酶与Nisin 之间均存在显著的交互作用(P＜ 0.01),而乳铁蛋白与Nisin 交互作用不显著(P＞0.05)。单因素对细菌总数影响的大小次序为Nisin ＞溶菌酶＞ pH 值＞乳铁蛋白。     

Nisin/β-环糊精包合物的制备工艺和抑菌活性研究

为改善乳酸链球菌素(Nisin)的水溶性,采用饱和水溶液法,用β-环糊精(β-cyclodextrinβ-CD)对其进行包合。通过正交实验得到其最优条件为pH=3,摩尔比Nisin∶β-CD=1∶2,包合温度40℃,此时Nisin最优包合率达到34.46%。傅里叶变换红外光谱分析与差式扫描量热分析表明,Nisin和β-CD形成包合物,结构发生变化。在抑菌实验中,Nisin/β-CD包合物对金黄色葡萄球菌和枯草芽孢杆菌的抑菌活性与Nisin相比无显著性差异。     

Antimicrobial films and coatings for inactivation of Listeria innocua on ready-to-eat deli turkey meat

Edible antimicrobial coating solutions incorporating chitosan, lauric arginate ester (LAE) and nisin were developed to reduce foodborne pathogen contamination on ready-to-eat (RTE) meats. RTE deli meat samples were directly coated with the solutions, or treated with solution-coated polylactic acid (PLA) films. The antimicrobial efficacy of the coatings and films against Listeria innocua inoculated onto the surface of RTE meat samples was investigated. Antimicrobial coatings with 1.94 mg/cm² of chitosan and 0.388 mg/cm² of LAE reduced L. innocua by ca. 4.5 log CFU/cm². Nisin (486 IU/cm²) showed less effectiveness than LAE (0.388 mg/cm²) and addition of nisin to the antimicrobial coatings or films containing LAE (0.388 mg/cm²) did not enhance the total antimicrobial effectiveness. Combining antimicrobial coatings or films with flash pasteurization (FP), which uses short burst of steam under pressure, further reduced L. innocua, achieving over a 5 log reduction. There was no significant difference in the effectiveness of antimicrobial films versus the coatings (p > 0.05). These data show the potential use of antimicrobial packaging alone, or in combination with FP, in preventing foodborne illness due to post-processing contamination of RTE meat products.     

Antibacterial activity of chitosan grafting nisin: Preparation and characterization

Nisin grafted chitosan was prepared by using microbial transglutaminase as biocatalyst. The transglutaminase-catalyzed reaction displayed high efficiency, high selectivity, mild reaction condition and environmental friendliness. The results revealed that the degree of substitution (DS) of nisin–chitosan could be controlled by adjusting the reaction time, the reaction temperature and the molar ratio of nisin to chitosan. And nisin–chitosan in different pH showed excellent solubility. In addition, in vitro antibacterial activity assessment, nisin–chitosan with the concentration of 0.008 mg/mL showed pronounced inhibitory effect against Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria (Escherichia coli). Furthermore, L929 mouse fibroblasts were cultured with nisin–chitosan, and the methylthiazol tetrazolium (MTT) assay showed that nisin–chitosan with the concentration from 0.005 to 0.01 mg/mL displayed low toxicity. The results may contribute to finding the application of nisin–chitosan in pharmaceutical and food industry fields.     

The antimicrobial effects and synergistic antibacterial mechanism of the combination of ε-Polylysine and nisin against Bacillus subtilis

The aim of the present study was to evaluate the combined effects of ε-Polylysine (ε-PL) and nisin and investigate the synergistic action of these compounds against Bacillus subtilis (B. subtilis).The combination of ε-PL and nisin showed synergistic anti-microbial activity against Escherichia coli (E. coli), B. subtilis and Staphylococcus aureus (S. aureus). SEM and TEM microscopy revealed that combined treatment with ε-PL and nisin synergistically damaged the morphology of tested bacterial cells. Propidium iodide (PI) infiltration experiments indicated that combined treatment with ε-PL and nisin synergistically enhanced the permeability of the bacterial cell membrane, likely reflecting the inhibition of both Na⁺K⁺- and Ca⁺⁺ Mg⁺⁺-ATPase activities through these compounds. The fluorescence spectrum showed an interaction between ε-PL and DNA, but not between nisin and DNA. The mode of ε-PL in binding with DNA was similar to that of ethidium bromide (EB). These results indicated that the uptake of ε-PL into cells was promoted through nisin, and subsequently, ε-PL interacted with the intracellular DNA achieving a synergistic effect.