合成甜味剂对牛乳铁素抗菌活性的影响

乳铁素B是牛乳铁蛋白经胃蛋白酶酶解后得到的最重要的抗菌肽,具有很强的抗菌活性。选取大肠杆菌为实验菌株,进行了合成甜味剂对乳铁素抑菌活性影响的研究。研究表明,在牛肉膏蛋白胨培养基中,pH7.0,菌浓为107CFU/ml的条件下,纯化乳铁素B对大肠杆菌的最小抑菌质量浓度为20μg/ml;阿斯巴甜、甜蜜素、糖精钠在0～5mg/ml的质量浓度范围内,对乳铁素B的抗菌活性都有削弱的作用;而安塞蜜在0～5mg/ml的质量浓度范围内,对乳铁素B的抗菌活性没有太大的影响。     

乳铁蛋白和乳铁素的抗菌活性比较

牛乳铁蛋白是从牛乳中提取出来的一种铁结合性糖蛋白，牛乳铁素是从牛乳铁蛋白N-端水解下来的25个氨摹酸残荩。它们具有多种乍物学功能，其中的广谱抗菌性尤为引人注目。本实验以牛初乳中提取的乳铁蛋白及其水解产物乳铁素为研究对象，选取大肠杆菌为实验菌株，进行铁饱和乳铁蛋白和缺铁性乳铁蛋白、乳铁素对大肠杆菌生长抑制的比较研究。研究结果表明：铁饱和乳铁蛋白、缺铁性乳铁蛋白和乳铁索的最小抑菌浓度分别为6mg／ml、3mg／ml和15μg／ml，乳铁素的最小杀菌浓度为30μg／ml。乳铁蛋白水解后，经纯化获得的乳铁素，其抗菌能力较缺铁性乳铁蛋白增加200倍，较铁饱和乳铁蛋白增加400倍。     

六氢β-酸对李斯特氏菌抑制作用的研究

本文研究了六氢β-酸对李斯特氏菌的抑菌活性影响。结果表明:5×10~(-6)g/ml的六氢β-酸对李斯特氏菌有明显的抑制作用。温度及酸碱处理对六氢β-酸的抑菌活性影响较少,但使用环境的pH值对六氢β-酸的抑菌作用有显著影响。肉制品保藏实验表明:六氢β-酸的防腐保鲜能力明显优于目前常用的食品防腐剂乳酸链球菌素(Nisin)、山梨酸钾及苯甲酸。     

苯乳酸与食品防腐剂联合抑菌效果

以食源性病原菌Escherichia coli和Listeria monocytogenes为指示菌,研究了苯乳酸与常用食品防腐剂的联合抑菌作用。采用微量二倍稀释法和棋盘法分别测定苯乳酸与6种防腐剂的最小抑菌浓度及联合抑菌指数,并通过时间—杀菌曲线进一步考察复配较优组合的协同抑菌效果。结果显示:苯乳酸与乳酸链球菌素联用对E.coli和L.monocytogenes分别表现为无关和相加作用;苯乳酸与对羟基苯甲酸乙酯联用对2株指示菌均为相加作用;与EDTA-Na2和ε-聚赖氨酸联用对2株指示菌均为无关作用;苯乳酸分别与苯甲酸钠和山梨酸钾联用对E.coli均表现为协同作用,对L.monocytogenes均表现为相加作用。苯乳酸分别与苯甲酸钠和山梨酸钾联合使用后,苯乳酸使用剂量降低75%,苯甲酸钠和山梨酸钾的使用剂量均可以降低50%。     

食品添加剂对贮藏泡菜质地的影响

为了研究食品添加剂对泡菜质地的影响,实验分别选用了六种化学食品添加剂苯甲酸钠、亚硫酸氢钠、脱氢乙酸钠、富马酸、山梨酸钾、乙醇以及三种天然食品添加剂茶多酚、乳酸链球菌素和水溶性壳聚糖对泡菜进行处理,分别测定了其对泡菜的硬度和果胶酶的作用。结果表明:化学和天然添加剂对泡菜质地变软问题都有一定的改善作用;除苯甲酸钠和脱氢乙酸钠之外,其他的食品添加剂对泡菜中果胶酶活性都有一定的抑制作用;其中24.69mg/g山梨酸钾和0.33mg/g水溶性壳聚糖对抑制泡菜质地变软和果胶酶活性效果显著。     

不同防腐剂对过氧化氢酶防腐效果的研究

将不同的食品防腐剂添加到由肝脏抽提制备的过氧化氢酶 溶液中,试验其防腐效果。通过对乳酸链球菌素、氯化钠、 苯甲酸钠、尼泊金复合酯、山梨酸钾的单一、组合对比防腐 买验,得到两组防腐效果好且不影响酶活的防腐剂组合 为:尼泊金复合酯(1‰)、乳酸链球菌素(0.5‰)、氯化钠 (10％)和尼泊金复合酯(3‰)、乳酸链球菌素(0.5‰)。     

乳酸链球菌素用于虾肉糜保鲜的研究

乳酸链球菌素是某些乳链球菌产生的一种多肽,对引起食品腐败的大多数革兰氏阳性菌有很好的抑制作用,是一种高效、无毒副作用的天然食品防腐剂.本文研究了乳酸链球菌素对虾肉糜保鲜的作用效果.结果显示,乳酸链球菌素能够有效地抑制虾肉糜中TVC、PC以及TVB-N值的上升;将乳酸链球菌素与山梨酸钾联合使用,保鲜效果更明显;试验结果还表明,保鲜剂的添加对虾肉糜的感官几乎没有影响.     

常用防腐剂在鱼糕保鲜中的应用研究

通过单因素试验,从七种防腐剂中筛选出对鱼糕防腐保鲜效果较好的四种防腐剂:乙二胺四乙酸二钠、山梨酸钾、对羟基苯甲酸乙酯、Nisin(乳酸链球菌素).再通过正交试验分析得其四种防腐剂的最优组合方案为:乙二胺四乙酸二钠0.03%、山梨酸钾0.05%、对羟基苯甲酸乙酯0.01%、Nisin(乳酸链球菌素)0.02%.     

苯乳酸菌发酵液在牛肉保鲜中的应用研究

以苯乳酸发酵液作为鲜牛肉保鲜剂,检验了其对几种食品中常见微生物如金黄色葡萄球菌、芽孢杆菌、大肠杆菌等的抑菌效果,对比了其与一些常用防腐保鲜剂如苯甲酸钠、山梨酸钾与乳酸链球菌素的作用差异。结果表明:采用3%(v/v)浓度的苯乳酸菌发酵液进行鲜牛肉保鲜效果较好,其贮存天数可达10d以上。苯乳酸发酵液对金黄色葡萄球菌和芽孢杆菌的抑菌效果最强,对大肠杆菌、沙门氏菌与酵母菌稍差,而对霉菌的抑制作用则较弱,其抑菌作用与Nisin接近。     

丁香和肉桂挥发油的提取、主要成分测定及其抗菌活性研究

本文采用水蒸汽蒸馏法提取丁香和肉桂的挥发油,并对所得挥发油主要成分进行气相测定,通过体外抗菌试验,比较了这两种挥发油及其主要成分和目前常用化学防腐剂苯甲酸钠和山梨酸钾对金黄色葡萄球菌、大肠杆菌、枯草芽孢杆菌、沙门氏菌和志贺氏菌等5株食品中常见污染菌的抗菌作用。结果表明丁香油中丁香酚含量为78.1%,肉桂油中肉桂醛含量为86.8%;这两种挥发油及其主要成分丁香酚和肉桂醛的抗菌作用均强于两种化学防腐剂,其中肉桂油与其主要成分肉桂醛表现出的抗菌活性最强,最小抑菌浓度(MIC)为200～1600mg/L;仅为苯甲酸钠和山梨酸钾MIC(6400～25600mg/L)的1/64～1/16;丁香油及其主要成分丁香酚的抗菌活性次之,MIC为800～1600mg/L,相当于苯甲酸钠和山梨酸钾MIC的1/16～1/8。     

3种常用防腐剂对秀丽隐杆线虫毒性作用的研究

目的研究苯甲酸钠、山梨酸钾、尼泊金甲酯3种常用防腐剂在食品常规剂量下对秀丽线虫的毒性作用。方法分别用1 g/L山梨酸钾、1 g/L苯甲酸钠、0.25 g/L尼泊金甲酯处理秀丽线虫24、48、72 h,观察秀丽线虫身体弯曲频率、头部摆动频率、触碰反应及体长;同时观察各组线虫的后代数目和寿命。结果 3种防腐剂均能显著降低线虫的生殖能力(P0.01)及线虫头部摆动频率(山梨酸钾作用24、48 h,P0.01;尼泊金甲酯和苯甲酸钠作用24、48、72 h,P0.01)。尼泊金甲酯能够显著降低线虫身体弯曲频率(作用48、72 h,P0.05)。尼泊金甲酯作用72 h,苯甲酸钠作用48、72 h后,线虫触碰反应迟钝(P0.05)。山梨酸钾作用24 h时线虫体长增加(P0.05),作用72 h时线虫体长减少(P0.05);尼泊金甲酯作用24、48 h时线虫体长增加(P0.05),但其效果随作用时间的增加而减弱;苯甲酸钠作用72 h时明显抑制线虫的体长发育(P0.05)。3种防腐剂的长期作用对线虫寿命无显著性影响。结论常规剂量的苯甲酸钠、山梨酸钾、尼泊金甲酯对秀丽线虫有一定的生殖毒性和神经毒性。     

低温等离子体及防腐剂对解淀粉芽孢杆菌芽孢灭活效果的影响

为了研究低温等离子体及防腐剂对解淀粉芽孢杆菌（Bacillus amyloliquefaciens）芽孢杀死率的影响,分别采用不同质量浓度的单一和复合防腐剂加入到含有菌悬液的培养基中,采用不同功率与时间低温等离子体对菌体进行处理,考察不同质量浓度防腐剂及不同功率与时间低温等离子体对解淀粉芽孢杆菌芽孢致死率的影响。结果表明,单一防腐剂抑制效果由大到小顺序为脱氢乙酸钠＞乳酸链球菌素＞山梨酸钾,脱氢乙酸钠在质量浓度为4 mg/mL时,芽孢抑制率可达97%;脱氢乙酸钠∶乳酸链球菌素（1∶1）、脱氢乙酸钠∶山梨酸钾∶乳酸链球菌素（1∶2∶1）复合防腐剂抑制效果较好,质量浓度为0.5 mg/mL时芽孢抑制率可达90%以上;低温等离子体在相同功率下,时间越短,抑菌效果越好,最佳抑菌效果条件为300 W、50 s。     

苯甲酸钠和山梨酸钾的复配抑菌效果研究

采用液体培养法和比浊法研究苯甲酸钠和山梨酸钾的3种复合配伍(1∶1∶2∶3∶3∶2)对大肠杆菌和金黄色葡萄球菌的抑菌效果,运用SPSS16.0统计软件对所测数据进行统计分析,从中筛选最佳抑菌配伍及最佳抑菌浓度.结果表明,这两种防腐剂的3种复合配伍对两种菌的生长都有显著的抑制作用,且随质量浓度增加抑菌作用逐渐增强.苯甲酸钠和山梨酸钾复合配比为3∶2时,对大肠杆菌的抑菌效果较好;复合配比为2∶3时,对金黄色葡萄球菌的抑菌效果较好;3种复合配伍的最佳抑菌浓度均为1.0 g/L.     

南五味子乙醇提取物对食品腐败细菌的抑菌活性研究

目的:研究南五味子乙醇提取物的体外抑菌活性,以期为寻求新的天然食品防腐剂提供实验依据。方法:以抑菌圈直径、最低有效抑菌浓度等为指标,以金黄色葡萄球菌、乙型副伤寒沙门氏菌等7种食品腐败细菌作为供试菌,研究南五味子乙醇提取物的体外抗菌活性。结果:南五味子乙醇提取物对供试菌的抑菌圈直径均>20mm,且对革兰氏阳性细菌的抑制效果强于革兰氏阴性细菌。乙醇提取物对供试菌的MIC值和MBC值分别为金黄色葡萄球菌3.125,6.25mg/mL,蜡样芽孢杆菌1.562,3.125mg/mL,大肠杆菌25,25mg/mL,变形杆菌12.5,25mg/mL,枯草芽孢杆菌、乙型副伤寒沙门氏菌、宋内氏志贺氏菌、铜绿假单胞菌的MIC值和MBC值均为12.5mg/mL。提取物对供试菌的抑菌率随抑菌作用时间的延长,提取物浓度的增加而升高。提取物对蜡样芽孢杆菌抑菌能力大于苯甲酸钠和山梨酸钾;对金黄色葡萄球菌的抑菌能力与苯甲酸钠相同,稍差于山梨酸钾。结论:南五味子乙醇提取物对食品腐败细菌具有显著的抑菌活性,有望开发成天然食品防腐剂。     

涂布抑菌防霉包装纸及其性能研究

将山梨酸钾、脱氢乙酸钠、苯甲酸钠分别溶于聚乙烯醇溶液制得抗菌液,再将抗菌液涂布于牛皮纸上制备得到包装用抑菌纸。采用抑菌圈法检验该抑菌纸对大肠杆菌和金黄色葡萄球菌的抑制效果,研究了涂布抗菌液后对抑菌纸的抗拉强度、撕裂强度、水蒸气透过系数、氧气透过量和微观结构的影响。结果表明,抑菌纸的抗拉强度、撕裂强度、水蒸气透过系数、氧气透过量均有改善,微观结构更加致密均匀,且具有良好的抑菌性能,抑菌效果随抗菌剂浓度的增加而提高,可用于食品的包装。     

Effect of preservatives on Shiga toxigenic phages and Shiga toxin of Escherichia coli O157:H7

Toxin synthesis by Shiga toxin-producing Escherichia coli (STEC) appears to be coregulated through the induction of the integrated bacteriophages that encode the toxin genes. These phages might be the principal means for the dissemination and release of Shiga toxins. We evaluated the effect of three common food preservatives, potassium sorbate, sodium benzoate, and sodium propionate, on the propagation of the phages and Shiga toxins. We tested each preservative at four concentrations, 1, 1.25, 2.5, and 5 mg/ml, both on free phages and on lysogenic phages in bacteria. We also evaluated the expression of a lambdoid phage, which was exposed to increasing concentrations of preservatives, by measuring β-galactosidase activity from SPC105, a transductant strain. Furthermore, we tested the effect of the preservatives on cytotoxigenic activity of Shiga toxin on Vero cells. We detected an increase of the inhibitory effect of the phage lytic activity, both in lysogenic and free phages, as the preservative concentration increased. However, the inhibition was higher on the lysogenic phages release than on free phages. Sodium benzoate and potassium sorbate were about equal at inhibiting phages; they were more effective than sodium propionate. A significant decrease of lacZ expression, encoded in a lambda phage, was observed. We also found a reduction in Shiga toxin titer caused by exposure of E. coli O157:H7 to 5 mg/ml sodium benzoate or potassium sorbate. These results imply that these three preservatives, used to inhibit microbial spoilage of foods, also act to inhibit lytic activity and dispersion of a phage carrying the gene encoding powerful Shiga cytotoxins. Also notable was the inactivation of Shiga toxin activity, although this effect was detected using concentrations of preservatives greater than those allowed by the Argentine Food Code.     

Prediction of Listeria spp. growth as affected by various levels of chemicals, pH, temperature and storage time in a model broth

The effects of concentration of NaCl (0.5 to 12.5%), methyl paraben (0.0 to 0.2%), sodium propionate (0.3%), sodium benzoate (0.1%), potassium sorbate (0.3%), pH (>5.9) temperature (4 to 30°C), storage time (up to 58 d) and inoculum (>10⁵ to >10⁻² per ml) on the log₁₀ probability percentage of one cell of Listeria spp. to initiate growth in a broth system were evaluated in a factorial design study. At pH 5.96 and temperature ranging from 4 to 30°C the concentrations of sodium propionate, potassium sorbate, and sodium benzoate examined allowed growth of L. monocytogenes with lag phases at 4°C of 18, 27 and 21 days, respectively. For 0.1 and 0.2% methyl paraben growth of all Listeria spp. was initiated at 8°C and 30°C, respectively. At pH 6, concentration of 12% NaCl supported the growth of L. monocytogenes at 8 to 30°C, whereas 12.5% inhibited all Listeria species. Four regression equations were derived relating probability of growth initiation to temperature, concentrations of NaCl and preservatives storage time, and Listeria species specific effects. From these equations, the number of cells needed for growth initiation can be calculated. The impact of this type of quantitative study and its possible application on the development of microbial standards for foods is discussed.     

Combinations of antimycotics to inhibit the growth of molds capable of producing 1,3-pentadiene

Some species of molds are capable of degrading sorbic acid to produce 1,3-pentadiene, a volatile compound with an unpleasant hydrocarbon-like odor. The effectiveness of reduced concentrations of sorbate, in combination with other antimycotics, to control the growth of these molds has not been described. We did a study to evaluate potassium sorbate, sodium benzoate, calcium propionate, disodium ethylenediaminetetraacetic acid (EDTA), and natamycin, alone and in combination, for their effectiveness in preventing the growth of five molds isolated from Parmesan cheese and a lemon-flavored drink subjectively judged to contain 1,3-pentadiene. Growth of Penicillium brevicompactum, Penicillium roqueforti, Paecilomyces variotii, Aspergillus niger, and Cephaloascus fragrans on model agar media containing Parmesan cheese (PRM agar) (pH 5.5) and lemon-flavored drink (LD agar) (pH 2.6) supplemented with antimycotics was studied. All molds grew well at 21 degrees C on PRM agar containing potassium sorbate (3500microg/ml), calcium propionate (3000microg/ml), or natamycin (20microg/ml). Combinations of potassium sorbate (250-1000microg/ml), calcium propionate (250-1000microg/ml), and/or natamycin (10-18microg/ml) greatly inhibited or prevented growth of molds on PRM agar, indicating their potential as preservative systems at pH values resulting in large percentages of the acids in dissociated forms. Three of the five molds grew on LD agar containing potassium sorbate or sodium benzoate at a concentration of 200microg/ml. Growth did not occur within 70 days on LD agar containing EDTA (30microg/ml) in combination with potassium sorbate and sodium benzoate at 50 and 175microg/ml, respectively, or 175 and 50microg/ml, respectively. Results of this study show that preservative systems containing a reduced concentration of potassium sorbate, in combination with other antimycotics, particularly natamycin, have potential for controlling the growth of molds thought to be capable of producing 1,3-pentadiene.     

Antimicrobial Activity and Synergistic Effect of Cinnamon with Sodium Benzoate or Potassium Sorbate in Controlling Escherichia coli O157:H7 in Apple Juice

ABSTRACT: Antimicrobial effects of cinnamon, sodium benzoate, potassium sorbate, and combinations were examined against Escherichia coli O157:H7 in apple juice at 8°C and 25°C. E. coli O157:H7 was reduced by 1.6 log colony-forming units (CFU)/mL at 8°C and 2.0 log CFU/mL at 25°C by 0.3% cinnamon. At 8°C, 5.2 log CFU/mL of E. coli O157:H7 was eliminated in 11 d by 0.3% cinnamon with 0.1% sodium benzoate, and in 14 d by 0.3% cinnamon with 0.1% potassium sorbate. At 25°C, 5.3 log CFU/mL E. coli O157:H7 was eliminated in 3 d by the same combinations. A synergistic effect was observed between cinnamon and preservatives against E. coli O157:H7 at 8°C and 25°C.