新型微生物源天然食品防腐剂及其抑菌性能

天然食品防腐剂按其来源的不同可分为植物源天然防腐剂、动物源天然防腐剂以及微生物源天然防腐剂等类型.天然微生物源食品防腐剂由于其本身的优越性,越来越受到人们的青睐.本文主要对五种新型微生物源天然食品防腐剂(即乳球菌肤、溶菌酶、聚赖氨酸、苯乳酸及曲酸)的理化特性、抑茵机制和抑茵特性等进行了概括和论述.旨在为我国新型、安全、高效、微生物源天然食品防腐剂的研究和开发提供参考.     

微生物对食品防腐剂的抗性研究进展及应对措施

食品防腐剂是用来抑制或杀死食品中的微生物、延长食品货架期的一种添加剂。关于食源微生物对食品防腐剂的抗性研究国内未见有详细的研究报导。本文介绍了食源微生物对食品防腐剂产生抗性的研究现状及其产生机制，以期指导食品防腐剂的使用。     

天然产物对食源性致病菌的抑菌机制研究进展

在食品加工、贮藏、运输、分销和零售直到消费者的各个环节中,都存在着微生物污染的可能性,从而引起食物中毒。食品中常用防腐剂来抑制食品中微生物的生长。由于化学防腐剂的安全性受到质疑,从天然植物中提取活性成分并开发成食品防腐剂已成为各国研究热点。天然产物主要是植物的次生代谢产物,包括多酚、黄酮、生物碱等物质,对一种或多种微生物具有抑制作用。本文根据国内外学者近年来的研究成果,概括和总结了天然产物对食源性致病菌致病性、生物膜、细胞膜通透性、群体效应等的影响,并从体内的角度评价了天然产物抗菌效果;同时,对其在食品行业中的存在的问题和应用前景进行了展望,为开发绿色、营养、安全的食品防腐剂提供理论基础。     

微生物对食品防腐剂的抗性研究进展

食品腐败是影响食品安全的主要因素之一，向食品中添加防腐剂是比较普遍采用的防腐方法，食品防腐剂可以抑制微生物的生长，同时微生物对于防腐剂的作用也存在一定的抗性，本文主要介绍了微生物对食品防腐剂的抗性研究状况，为将来进行进一步的机理和应用研究提供一定的理论依据。     

微生物对食品防腐剂的抗性研究进展

食品腐败是影响食品安全的主要因素之一,向食品中添加防腐剂是比较普遍采用的防腐方法,食品防腐剂可以抑制微生物的生长,同时微生物对于防腐剂的作用也存在一定的抗性,本文主要介绍了微生物对食品防腐剂的抗性研究状况,为将来进行进一步的机理和应用研究提供一定的理论依据。     

植物多酚抑菌活性、作用机理及应用研究进展

综述了植物多酚对食源性致病微生物的抑菌效果,并从细胞形态、细胞膜电位、正常能量代谢、生物大分子合成等方面进行了抑菌机理的阐述,分析了植物多酚作为潜在的防腐剂在食品保鲜和储藏中的应用及其存在的问题。     

肉制品加工中使用的辅料——防腐剂

食品防腐剂是一类具有抑制微生物增殖或杀死微生物的化合物。防腐剂抑制与杀死微生物的机理十分复杂,在食品的生产过程中,要正确选用防腐剂,注意其种类、性质、使用范围、价格、毒性、防腐剂的并用及其他因素。目前我国常用的化学防腐剂有苯甲酸及其钠盐、山梨酸及其钾盐、丙酸盐、对羟基苯甲酸酯类、脱氢醋酸及其盐类等;常用的天然防腐剂有植物来源的食品防腐剂、动物来源的食品防腐剂、微生物来源的食品防腐剂及一些新型海洋生物型食品防腐剂等。     

微生物源天然食品防腐剂的研究进展

天然食品防腐剂按其来源不同可分为植物源天然防腐剂、动物源天然防腐剂和微生物源天然防腐剂。微生物源天然食品防腐剂由于其本身的优越性,越来越受到人们的青睐。本文主要介绍了微生物来源的天然食品防腐剂乳酸链球菌素、ε-聚赖氨酸、曲酸、溶菌酶和甲烷氧化菌素的最新研究进展,阐述了它们的理化性质、抑菌机制和应用现状,同时简单介绍了纳他霉素、抗菌肽、罗伊氏菌素和嗜杀酵母等微生物源天然食品防腐剂的应用现状,旨在为高效、无毒、天然食品防腐剂的研究提供参考。天然食品防腐剂最有发展的可能是将几种来源不同的天然食品防腐剂复配,或者将一种天然防腐剂与其他化学防腐剂复配使用,不仅可以减少防腐剂在食品中的用量,同时还可以使食品的杀菌或抑菌条件更加温和化,对人们的饮食健康非常有利。     

新型植物源天然食品防腐剂及其抑菌性能

食品发生腐败变质会造成巨大的经济损失,目前常采用的防腐措施就是添加食品防腐剂.食品防腐剂是食品加工、贮藏过程中必不可少的添加剂,要求具有无毒、少残留、高效、对人体无害等特点.食品防腐剂分为化学防腐剂、天然防腐剂和复合型防腐剂.天然食品防腐剂按其不同的来源又可分为植物源天然防腐剂、动物源天然防腐剂以及微生物源天然防腐剂等类型.天然植物源食品防腐剂由于其本身的优越性,越来越受到人们的青睐.本文主要对六种新型植物源天然食品防腐剂 (即香辛料提取物、中草药提取物、芦荟提取物、竹叶提取物及荸荠皮提取物) 的抑菌成分、抑菌机理和抑菌性能等进行了较为详尽的论述.旨在为我国新型、安全、高效、天然植物源食品防腐剂的研究和开发提供参考.     

动物性天然食品防腐剂的研究进展

随着生活水平的不断提高和对健康的日益关注,人们对食品防腐剂的安全性提出了更高的要求.天然食品防腐剂一般是指从植物、动物、微生物中直接分离提取的,具有防腐作用的一类物质,具有资源丰富、抗菌性强、水溶性好、安全无毒、抑菌谱广等优点,近年来成为食品保鲜防腐领域的研究热点.但是,目前天然食品防腐剂的实际使用并不多,天然食品防腐剂的研究与开发仍存在很多问题.本文主要介绍了5种动物性来源的抑菌物质,阐述了它们作为天然食品防腐剂的理化性质、抑菌机理和应用现状,并针对天然食品防腐剂在研究和应用中所遇到的问题,对天然食品防腐剂的发展方向进行了分析和讨论.     

饲用微生物制剂的研究进展

本文综述了饲用微生物制剂的定义和作用机理. 针对目前饲用微生物制剂使用效果不一致的问题分析了其影响因素, 并就饲用微生物应具备的条件, 在使用中的安全问题、功效评价等研究进展, 以及今后的研究发展方向进行了探讨.     

Effect of direct-fed microbials on rumen microbial fermentation.

Nonbacterial, direct-fed microbials added to ruminant diets generally consist of Aspergillus oryzae fermentation extract, or Saccharomyces cerevisiae cultures, or both. Results from in vivo research have been variable regarding effects of direct-fed microbials on ruminant feedstuff utilization and performance. Some research has shown increased weight gains, milk production, and total tract digestibility of feed components, but others have shown little influence of direct-fed microbials on these parameters. In vitro research with mixed ruminal microorganisms likewise has been inconsistent regarding the effects of direct-fed microbials. Several researchers observed that direct-fed microbials increased cellulolytic bacterial numbers in the rumen and stimulated the production of some fermentation end products. This suggests that direct-fed microbials may be providing growth factors for the ruminal microbes. However, other researchers have reported no effect of direct-fed microbials on in vitro fiber digestion. Recent research demonstrated that growth of the predominant ruminal bacterium Selenomonas ruminantium in lactate medium as well as lactate uptake by whole cells of Sel. ruminantium were markedly increased by an A. oryzae fermentation extract and an S. cerevisiae culture. In addition, both products increased the production of acetate, propionate, succinate, total VFA, and cell yield (grams of cells per mole of lactate). Therefore, it appears that these direct-fed microbials provide soluble factors that stimulate lactate utilization by Sel. ruminantium. Evidence is presented indicating that the malate content of the A. oryzae fermentation extract and S. cerevisiae culture may be involved in this stimulation.     

荞麦壳水提物调控糖尿病大鼠肠道菌群结构的研究

为研究荞麦壳水提物对糖尿病大鼠粪便菌群的影响,选取12只Wistar大鼠,糖尿病模型建立后随机分为糖尿病组和荞麦壳组,每组6只,于第5周末无菌采集大鼠粪便,对粪便菌群16SrRNA的V1-V3区进行扩增,利用Miseq高通量测序平台测定基因序列,最后进行比对、分类。结果表明,荞麦壳水提物组和糖尿病组大鼠粪便中菌群结构及多样性有较大差别,在目(Order)的水平上,荞麦壳组Lactobacillales含量高于糖尿病组,糖尿病组Clostridiales含量高于荞麦壳组;在属(Genus)的水平上,荞麦壳组Lactococcus、Blautia、Prevotella、Klebsiella含量高于糖尿病组,糖尿病组Ruminococcaceae_uncultured、Ruminococcaceae_unclassified、Clostridium_sensu_stricto_1、Turicibacter和Oligella含量较荞麦壳组增加。说明糖尿病导致肠道菌群紊乱,大鼠通过饮用荞麦壳水提物可改善肠道菌群的结构。     

Prevalence and enumeration of Escherichia coli O157 in steers receiving various strains of Lactobacillus-based direct-fed microbials

The objective of this research was to evaluate the effect of daily dietary inclusion of specific strains of Lactobacillus acidophilus on prevalence and concentration of Escherichia coli O157 in harvest-ready feedlot cattle. Five hundred yearling steers were housed in pens of 10 animals each. At arrival, steers were randomly allocated to one of five cohorts. Four of the cohorts were fed various strains and dosages of Lactobacillus-based direct-fed microbials throughout the feeding period. Fecal samples were collected from the rectum of each animal immediately prior to shipment to the abattoir. E. coli O157 was detected using selective enrichment and immunomagnetic separation techniques. For positive samples, E. coli O157 concentration was estimated using a most-probable-number (MPN) technique that included immunomagnetic separation. Prevalence varied among the cohorts (P < 0.01). The prevalence in the controls (26.3%) was greater (P < 0.05) than that in cattle supplemented with L. acidophilus strains NP51, NP28, or NP51-NP35 (13.0, 11.0, and 11.0%, respectively). The greatest E. coli O157 concentration was also observed in the controls (3.2 log MPN/g of feces); this concentration was greater (P < 0.05) than that observed in positive animals receiving NP51, NP28, or NP51-NP35 (0.9, 1.1, 1.7 log MPN/g of feces, respectively). Specific strains of Lactobacillus-based direct-fed microbials effectively reduced the prevalence and concentration of E. coli O157 in harvest-ready cattle, whereas others did not. When using direct-fed microbials to reduce carriage of E. coli O157 in cattle, it is important to select appropriately validated products.     

果寡低聚糖的营养及应用研究进展

果寡低聚糖是一种新型饲料添加剂，可以促进肠道内双歧杆菌及乳酸杆菌等有益微生物的增殖，同时抑制沙门氏菌与大肠杆菌等病原的增殖，从而改善肠道微生态；它还可以改善脂质代谢，对蛋白质的代谢也有一定的影响；同时，它也可以促进日粮中钙、镁、磷及铁的吸收；另外，它还可以为肠粘膜细胞提供能源，增进肠粘膜细胞的增殖，促进肠道发育。果寡低聚糖在动物生产中具有重要的应用价值。     

市场上发酵菜中亚硝酸盐含量的调查研究

蔬菜发酵主要是多种微生物并存的一种发酵过程,形成亚硝酸盐不可避免。本实验通过对市场上发酵菜中亚硝酸盐含量的调查分析,结果表明：市场上发酵菜中亚硝酸盐的含量依次为辣椒类（30.44mg/kg）〉萝卜类（27.45mg/kg）〉白菜类（26.92mg/kg）〉黄瓜类（14.65mg/kg）。发酵菜均不同程度地含亚硝酸盐,以辣椒类最多,其次是萝卜类和白菜类,含量最少的是黄瓜类。所检测的20个样品中有5个样品的亚硝酸盐超标,超标率为25%。各类发酵菜中亚硝酸盐的含量与pH、肠道菌数量有关,pH值较低的发酵菜中肠道菌数量少,亚硝酸盐含量也低;相反,pH值较高的发酵菜中肠道菌数量多,亚硝酸盐含量也较高。一定含量范围内的食盐对亚硝酸盐含量影响不大。     

植物精油蒸气与空气负离子在食品保藏中的应用研究进展

植物精油属于GRAS物质,具有较高的安全性,将其应用到食品的防腐保鲜中可以减少化学合成抗菌剂对人体产生的不良影响。精油的蒸气形式可以在不与食品直接接触的情况下对多种细菌、霉菌和酵母产生抑制作用,其主要抑菌成分为单萜烯和醛类,通过疏水性作用于细胞达到抗菌效果。植物精油蒸气与食品包装相结合,可以降低精油对于食品感官的影响并为食品提供抑菌保护。空气负离子能提高精油蒸气对微生物细胞的破坏作用,高浓度的空气负离子还能抑制微生物的活性,将精油与空气负离子结合使用,可以把对食品品质的影响降到最低,并提供更好的抑菌效果。     

多糖对免疫系统调控的研究进展

多糖是一类重要的生物信息大分子,广泛存在于动植物和微生物体内。目前,多糖对机体免疫系统的调控作用已获得学术界的普遍认可。多糖对免疫系统的调控机制主要是与免疫细胞表面的模式识别受体如甘露糖受体、Toll样受体、Dectin-1、清道夫受体、补体受体等结合,激活免疫细胞,通过促进单核巨噬细胞的吞噬功能、调控淋巴细胞的增殖和转化、增强对补体系统的活化、诱导细胞因子分泌等实现对机体免疫系统功能的调控。此外多糖对神经-内分泌-免疫系统网络的平衡调控也是其发挥免疫调控作用的重要途径。多糖的生物学活性及其免疫调控作用机制一直以来是国内外科研工作者研究的重要课题。本文主要对近年来国内外对多糖基于免疫系统的免疫调控作用及其机制的研究进行综述。     

Pre-harvest interventions to reduce carriage of E. coli O157 by harvest-ready feedlot cattle

Escherichia coli O157 is an important cause of food-borne illness. The primary reservoir for this organism is cattle and at present the major site of control is within abattoirs. Recent data have highlighted the importance of the pathogen load entering abattoirs on harvest-ready feedlot cattle. The likelihood for in-plant intervention failure increases as the proportion of cattle carrying E. coli O157 within a pen increases. Pre-harvest reduction of E. coli O157 colonization will require targeted intervention strategies and should reduce contamination of carcasses thereby enhancing public health. Several pre-harvest interventions show substantial promise, such as specific strains of direct-fed microbials, vaccine technology, sodium chlorate, and neomycin sulfate, whereas others such as Brown Seaweed or chlorination of water have little or no detectable benefit. Selection of validated interventions strategies will be important as efforts to control pre-harvest carriage of E. coli O157 increase.     

Dietary supplementation with Lactobacillus- and Propionibacterium-based direct-fed microbials and prevalence of Escherichia coli O157 in beef feedlot cattle and on hides at harvest

The objective of this study was to describe the prevalence of Escherichia coli O157 in the feces and on the hides of finishing beef cattle fed a standard diet and those fed diets supplemented with direct-fed microbials. Two hundred forty steers received one of four treatments throughout the feeding period: (i) control: no added microbials; (ii) HNP51: high dose of Lactohacillius acidophilus strain NP 51 (10(9) CFU per steer daily) and Propionibacterium freudenreichii (10(9) CFU per steer daily); (iii) HNP51+45: high dose of NP 51 (10(9) CFU per steer daily), P. freudenreichii (10(9) CFU per steer daily), and L. acidophilus NP 45 (10(6) CFU per steer daily); or (iv) LNP51+45: low dose of NP 51 (10(6) CFU per steer daily), P. freudenreichii (10(9) CFU per steer daily), and NP 45 (10(6) CFU per steer daily). Samples were collected from each animal and analyzed for the presence of E. coli O157 using immunomagnetic separation methods on day 0 (feces), 7 days before harvest (feces), and at harvest (feces and hide). At the end of the feeding period, cattle receiving HNP51 were 57% less likely to shed detectable E. coli O157 in their feces than were the controls (P < 0.01). For animals receiving HNP51+45 and LNP51+45, fecal prevalence did not differ from that of the controls. The prevalence of positive hide samples was least among cattle receiving HNP51+45 (3.3%); these animals were 79% less likely (P < 0.06) to have a positive hide sample than were the controls (prevalence = 13.8%). There was poor agreement of the culture results between fecal and hide samples collected from the same animal (kappa = 0.08; confidence interval = -0.05 to 0.2). Cattle supplemented with a high dose of NP 51 had reduced E. coli O157 prevalence in both fecal and hide samples, indicating that this treatment may be an efficacious preharvest intervention strategy.