发酵牛肉调味基料对三株致病菌的抑菌作用及机理

为了研究发酵牛肉调味基料(Fermented Beef Flavorings,FBF)的抑菌作用和抑菌机理,试验采用WBL-45(木糖葡萄球菌+肉葡萄球菌+清酒乳杆菌)、VHI-41(木糖葡萄球菌+戊糖片球菌+植物乳杆菌)、清酒乳杆菌(Lactobacillus sake,LS)为发酵剂,将牛骨肉末高压浸提、酶解、发酵、美拉德反应后制作FBF,以大肠杆菌、乙型副伤寒沙门氏菌、金黄色葡萄球菌为指示菌,应用光密度法研究不同处理组FBF对三株致病菌的半数抑制浓度(Inhibitory Concentration 50,IC₅₀),同时研究FBF处理后指示菌的生长曲线,以此来评价三组FBF的抑菌作用;通过扫描电镜观察菌体形态,测定相对电导率了解胞膜通透性,阐述FBF的抑菌机理。结果表明:WBL-45组对大肠杆菌、乙型副伤寒沙门氏菌、金黄色葡萄球菌的IC₅₀浓度依次为3.75、7.5、3.75 mL/100 mL,VHI-41组和LS组FBF对三株指示菌IC₅₀浓度依次为3.75、3.75、1.88 mL/100 mL。FBF能够抑制三株指示菌的正常生长和增殖,延长延滞期,降低指示菌最大比生长速率以及稳定期的菌量,破坏细胞的正常形态,使菌体表面出现褶皱、孔洞,影响菌体营养物质的正常传递和运输,从而抑制指示菌生长。     

发酵时间和发酵剂种类对牛肉调味料风味的影响

为研究发酵剂种类和发酵时间对发酵牛肉调味基料(fermented beefflavorings,FBF)风味的影响,将发酵剂THM-17(木糖葡萄球菌+戊糖片球菌)、WBL-45(木糖葡萄球菌+肉葡萄球菌+清酒乳杆菌)、VHI-41(木糖葡萄球菌+戊糖片球菌+植物乳杆菌)及清酒乳杆菌(Lactobacillus sake,LS)分别接种于牛骨肉酶解液中发酵12 h和16 h制作FBF,同时设置不发酵的对照组,采用电子鼻、电子舌、气相色谱-离子迁移谱和气相色谱-质谱联用分析不同组别FBF的风味差异和挥发性化合物组成。结果表明:对照组与发酵组FBF的气味和滋味均存在较大差异,其中,LS组和VHI-41组FBF风味具有特殊性;含硫化合物和醛类化合物是FBF中的关键风味化合物,醇类、酮类化合物对FBF的总体风味有重要的修饰作用,2-甲基-3-呋喃硫醇和双(2-甲基-3-呋喃基)二硫及壬醛的相对含量是引起处理组FBF风味差异的关键。     

不同乳酸菌发酵剂对发酵红肠品质的影响

为研究乳酸菌发酵对红肠品质的影响,将发酵技术应用于本无发酵工艺的红肠制品中,筛选出能够提高红肠品质的乳酸菌发酵剂。分别将常应用于发酵肉制品的7 种商业乳酸菌发酵剂（木糖葡萄球菌＋戊糖片球菌（THM-17）、木糖葡萄球菌＋清酒乳杆菌＋类植物乳杆菌（PRO-MIX5）、木糖葡萄球菌＋肉葡萄球菌＋清酒乳杆菌（WBL-45）、木糖葡萄球菌＋戊糖片球菌＋植物乳杆菌（VHI-41）、木糖葡萄球菌＋戊糖片球菌＋植物乳杆菌（SHI-59）、肉葡萄球菌＋木糖葡萄球菌（WBX-43）和戊糖片球菌＋木糖葡萄球菌＋肉葡萄球菌＋乳酸片球菌（VBM-60））及8 种单菌（弯曲乳杆菌、戊糖乳杆菌、清酒乳杆菌-1、戊糖片球菌、木糖葡萄球菌、肉葡萄球菌、清酒乳杆菌-2、植物乳杆菌）以107 CFU/g的接种量接种至腌制后的肉馅中,拌馅灌肠后于35 ℃、80%湿度条件下发酵12 h,取样测定发酵后样品的乳酸菌数和细菌总数,再经干燥、蒸煮、烟熏、烘烤制得成品,测定其感官、pH值、色差、质构、亚硝酸盐、硝酸盐、生物胺及N-亚硝胺含量等指标。结果表明：15 种发酵剂中以木糖葡萄球菌和植物乳杆菌2 种乳酸菌发酵剂应用效果较好,所制得产品pH值分别为5.26和5.04,色泽美观,弹性适中,亚硝酸盐残留量（10.84、10.13 mg/kg）低,可显著抑制N-亚硝胺的形成（N-二甲基亚硝胺含量分别为1.29、2.51 μg/kg）,生物胺总量较低。由此说明,木糖葡萄球菌和植物乳杆菌能够显著提高红肠产品的安全品质。     

微生物发酵对牛肉调味基料的增香作用

以牛骨肉末为原料,在传统肉味香精的制备工艺中增加发酵技术,研究比较不同菌种发酵对牛肉调味基料的赋香效果。将牛骨肉末经过热压浸提、酶解后分成5组:不接种发酵剂的对照(CK)组;分别接种0.02%意大利萨科WBL-45(肉葡萄球菌+木糖葡萄球菌+清酒乳杆菌)、WBX-43(肉葡萄球菌+木糖葡萄球菌)、BOM-13(清酒乳杆菌)和THM-17(木糖葡萄球菌+戊糖片球菌)的实验组,30℃发酵12 h后进行美拉德反应制成牛肉调味基料。采用感官评定结合电子鼻和电子舌对其挥发性气味和滋味成分进行分析。结果表明,经发酵处理得到的牛肉调味基料在气味和滋味上与CK组之间差异显著(p<0.05),而4种菌株之间比较,接种THM-17对牛肉调味基料的赋香作用更为明显。实验说明,选用适宜菌株进行微生物发酵对牛肉调味基料具有明显的赋香效果,从而为工业化生产调味基料提供了新思路和新方法。     

发酵牛肉调味基料在牛肉饼中的应用效果

冷冻牛骨肉末经热-压浸提、酶解、发酵和美拉德反应后制成发酵牛肉调味基料（fermented beef flavoring,FBF）,以新鲜牛前肩肉为原料,加入不同比例腌制剂制成牛肉饼,分别为阴性对照（negative control,NC）组（既不添加NaNO2又不添加FBF）、阳性对照（positive control,PC）组（添加不同比例的NaNO2）及实验组。对牛肉饼进行感官评价后于20 ℃条件下贮藏,测定贮藏期间牛肉饼的红度值（a*）、pH值、硫代巴比妥酸反应物（thiobarbituric acid reactive substance,TBARs）值及亚硝酸盐残留量。结果表明：与NC组相比,PC组和实验组牛肉饼色泽红润,口感香嫩,风味得到明显改善;只添加FBF的实验组牛肉饼a*较高,TBARs值和亚硝酸盐残留量较低;同时添加NaNO2和FBF的牛肉饼口感、色泽及风味等品质均有所提高,且20 g/kg FBF和0.05 g/kg NaNO2复配制成的牛肉饼品质最好。     

冰鲜鸡肉中3 种主要致病菌的共修复- 增菌条件研究

研究冰鲜鸡肉中鼠伤寒沙门氏菌(S. typhimurium)、单增李斯特菌(L.monocytogenes)和大肠杆菌(E. coli) O157:H7的共修复-增菌条件。通过传统技术和PCR技术相结合的方法,研究肉鸡屠宰浸烫脱毛工艺对3种目标菌的热激损伤及共修复-增菌条件,并利用共修复-增菌结果,对生产线和超市的冰鲜鸡肉样品中3种目标菌的污染状况进行调查。结果表明：肉鸡屠宰浸烫脱毛工艺条件能使部分S. typhimurium、L.monocytogenes和E. coli O157:H7处于亚致死状态;TSB-YE培养基对热损伤S. typhimurium、L.monocytogenes和E. coli O157:H7的修复效果最好,且对前两种菌的修复时间为2h,对后一种菌的修复时间为4h;TSB-YE培养基在16h对3种致病菌的共增菌效果最好;运用共修复-增菌条件,对80份实际样品中的3种致病菌检出率分别为：S. typhimurium 22.5% (18/80)、L.monocytogenes 11.3% (9/80)和E. coli O157:H7 18.8% (15/80)。     

茶槲寄生“螃蟹脚”醇提正丁醇萃取相对金黄色葡萄球菌抑菌机理的研究

本文研究了茶槲寄生“螃蟹脚”醇提各萃取相的抑菌作用及正丁醇萃取相（NVBEs）对金黄色葡萄球菌的抑菌机理。采用滤纸片扩散法测定抑菌圈直径（DIZ）的大小,对倍稀释法测定最小抑菌浓度（MIC）和最低杀菌浓度（MBC）,来评价“螃蟹脚”醇提各萃取相对金黄色葡萄球菌（S. aureus）、大肠杆菌（E. coli）、鼠伤寒沙门氏菌（S. typhimurium）、单核细胞增生李斯特菌（L. monocytogenes）4种食源性腐败菌的抑制性;通过光学显微镜和扫描电镜观察、胞膜通透性、胞壁完整性和酶活性等实验,研究了NVBEs抑菌机理。结果表明,“螃蟹脚”醇提各萃取相对S. aureus、E. coli、S. typhimurium和L. monocytogenes均有明显抑制效果,其中NVBEs抑菌活性较好,对S. aureus抑制效果最好,DIZ为9.84±0.57 mm,MIC为3.52 mg/mL,MBC为7.04 mg/mL。抑菌机理结果表明：NVBEs可增加S. aureus细胞壁及细胞膜的通透性,破坏菌体细胞结构,引起细胞内含物如核酸和蛋白质等外泄;引起遗传物质DNA的改变,使菌体细胞形态结构出现异常;影响菌体酶的代谢活动,从而抑制细菌的生长。     

接种乳酸菌发酵剂对风干肠加工过程中理化性质及安全品质的影响

为研究乳酸菌发酵剂对风干肠在加工过程中理化性质及安全品质的影响,本试验分别将SHI-59(木糖葡萄球菌、戊糖片球菌、植物乳杆菌)、WBL-45(木糖葡萄球菌、肉葡萄球菌、清酒乳杆菌)、PRO-MIX5(木糖葡萄球菌、清酒乳杆菌、类植物乳杆菌)复合型商业发酵剂接种到肉馅中,3个接菌组分别用SHI、WBL、PRO表示,经过...     

微生物亚硝化抑制剂对风干肠发酵成熟期间微生物菌落变化的影响及其感官评价分析

为研究微生物亚硝化抑制剂（microbial nitrosation inhibitor,MNI）对风干肠发酵和成熟过程中微生物群落动态变化及感官特性的影响,该试验设计4组风干肠,MNI组：添加MNI;MNIP组：添加MNI并接入PRO-MIX5商业发酵剂（木糖葡萄球菌、清酒乳杆菌、类植物乳杆菌）;FBFAP组：发酵牛骨调味基料和复配抗氧化剂（fermented beef flavorings and compound antioxidant,FBFA）并接入PRO-MIX5;CK组。结果表明：在发酵阶段,4组风干肠乳酸菌数逐渐增多,MNI组和MNIP肉馅分别在发酵的15 h、12.5 h达到发酵终点即pH降到5.4~5.6,乳酸菌数分别为8.99 lg cfu/g、8.91 lg cfu/g,显著高于CK组发酵终点（22 h）的乳酸菌数8.88 lg cfu/g（p<0.05）。到成熟终点时,革兰氏阴性腐败微生物在MNI组的相对丰度占比最低（19.35%）,对肠杆菌科和假单胞菌的抑制率分别为30.43%、27.22%,仅次于MNIP组37.00%、33.79%,优于CK组和FBFAP组。综合分析,MNI能作为促生长因子,促进肉馅中乳酸杆菌属菌的生长,在接种有发酵剂PRO-MIX5的风干肠中加入MNI对腐败微生物的抑制效果优于FBFAP。单独添加MNI或MNI与PRO-MIX5协同作用均能提高风干肠微生物安全性和感官性能,说明MNI在提高风干肠安全品质方面具有广阔的应用前景。     

直投式发酵剂生产四川泡菜的研究

通过分析接入乳酸菌直投式发酵剂和自然发酵四川泡菜发酵过程中亚硝酸盐含量、乳酸菌菌数和产品品质的动态变化,确定直投式菌剂发酵泡菜时的菌粉添加量和食盐用量。结果表明:添加4%食盐,接入0.04%直投式发酵剂,室温25℃,发酵7d后制得的泡菜酸甜适口,色泽好。添加到直投式发酵剂终产品中的亚硝酸盐含量显著低于自然发酵组,仅为2.11μg/mL,且其乳酸菌菌数远高于自然发酵组,肠膜明串珠菌和植物乳杆菌菌数分别达到6.42×107cfu/mL和3.13×107cfu/mL。     

Characterization of lactic acid bacteria isolated from a Greek dry-fermented sausage in respect of their technological and probiotic properties

A total of 147 lactic acid bacteria was isolated from two types of naturally fermented dry sausages at four different stages of the ripening process studied in order to select the most suitable strains according to their technological characteristics including probiotic properties and antimicrobial activity against food-borne pathogens. Identification of the isolates revealed that 90% were lactobacilli, 4% enterococci, 3% Pediococcus sp. and sporadic isolates of Weissella viridescens, Leuconostoc pseudomesenteroides, and Leuconostoc sp. The isolated strains of Lactobacillus sakei (49 isolates), Lactobacillus curvatus (24 isolates) and Lactobacillus plantarum (7 isolates) were further characterized. All strains could grow at 15?°C, whereas the majority of the strains was able to grow in the presence of 6.5% NaCl and on acetate agar. The enzymatic potential of the strains was evaluated using the API ZYM system. During in vitro investigations all strains exhibited high leucine and valine aminopeptidase activities and moderate acid phosphatase and phosphohydrolase activities. Some strains showed very weak lipolytic activity. The enzyme profiling is an important factor for selection of strains as starter cultures. A large majority of the strains tolerated 0.1% bile salts whereas 58% of Lactobacillus curvatus strains and all Lactobacillus plantarum strains were resistant to 0.3% bile salts. All Lactobacillus sakei strains and the majority of Lactobacillus curvatus and Lactobacillus plantarum strains exhibited an anti-listerial activity against three Listeria monocytogenes strains. A percentage of 75, 50 and 29% of Lactobacillus sakei, L. curvatus and L. plantarum strains, respectively, could inhibit two Staphylococcus aureus strains. The contribution of the selected strains to a possible inhibition of Listeria monocytogenes and S. aureus in situ on fermented meats would be of considerable interest to enhance the hygienic quality of these products.     

干酪乳杆菌发酵荔枝汁在模拟胃肠道中耐受能力及其抑菌性的研究

以干酪乳杆菌发酵荔枝汁为研究对象,在人工胃液、人工肠液环境下对干酪乳杆菌的存活性能进行研究;同时,采用琼脂扩散法,研究其对六种常见食源性致病菌(肠炎沙门氏菌、宋氏志贺氏菌、大肠埃希氏菌O157:H7、单增李斯特氏菌、金黄色葡萄球菌和阪崎肠杆菌)的抑菌性,以及探究酸和酶等因素对发酵液抑菌性的影响。结果表明:在模拟胃肠消化中,干酪乳杆菌在pH 1.5、pH 2.0、pH 3.0和pH 4.0的人工胃液中培养4 h后,活菌数分别达到了260 CFU/mL、8.63×107 CFU/m L、9.57×107 CFU/m L和1.15×108CFU/m L;在人工肠液中消化12 h后,活菌数均在107 CFU/m L以上。在抑菌试验中,经去酸、去过氧化氢和酶解等不同处理的发酵液对肠炎沙门氏菌等五种常见食源性致病菌具有明显的抑制效果,而对阪崎肠杆菌均未表现出抑制作用,其中胞外多糖、H2O2和蛋白肽类物质对五种常见的致病菌是主要的抑菌物质。研究结果为干酪乳杆菌发酵荔枝汁能否在胃肠道中发挥有益作用提供体外实验的理论依据以及在当地食品工业的开发应用提供科学依据。     

具有潜在抑制肠道致病菌的乳酸菌的筛选

以西北地区发酵食品分离出的106株乳酸杆菌为材料,通过其代谢产物对肠道致病菌生长的抑制作用、菌体HT-29细胞的粘附作用和抑制宋内志贺氏菌(S.sonnei)对HT-29细胞的黏附作用筛选出了具有抑制肠道致病菌作用的三株乳酸杆菌,为进一步的体内实验奠定了基础.     

Antibacterial activity of Lactobacillus sake isolated from dry fermented sausages

Lactic acid bacteria isolated from Spanish dry fermented sausages were screened for antagonistic activities under conditions that eliminated the effects of low pH and hydrogen peroxide. From 720 isolates tested 119 were inhibitory to Lactobacillus fermentum CECT285. The isolates showing the largest inhibitory activity exhibited an antagonistic effect against several other lactobacilli and the selected foodborne pathogens Staphylococcus aureus and Listeria monocytogenes. Comparison of the antimicrobial spectra of the supernatants suggested that the inhibitory compounds were not identical. The isolates were tentatively characterized as Lactobacillus sake. One of the isolates, L. sake 148 was chosen for further study. The compound excreted by L. sake 148 was active against various lactobacilli and several Gram-positive foodborne bacteria, but not against the Gram-negative bacteria tested. The antagonistic effects were almost eliminated by treatment with proteases, whereas they were heat resistant and bacteriostatic rather than bacteriocidal.     

ISOLATION AND CHARACTERIZATION OF BACTERIOCIN-PRODUCING MICROORGANISMS FROM AGOS-OS

Agos-os, a fermented meat and sweetpotato mixture, was produced and analyzed for its microbial characteristics. pH decreased during fermentation. Mold and anaerobic bacterial counts increased while yeasts and aerobic bacterial counts decreased during the third and seventh day of fermentation. Six isolates with the widest zones of inhibition on the indicator lawn were selected for bacteriocin production. These isolates had exactly the same morphological, physiological and biochemical characteristics. The ribosomal RNA sequence was 99.5% identical with Enterococcus faecalis VRE 1492. The identification was confirmed through DNA homology test by the EMBL Genbank, Canada. This bacterium produced the L-isomer lactic acid. The amount of bacteriocin produced by the bacterium was optimized by growing the bacterium at different growth media, initial pH and fermentation time. Maximum production of bacteriocin was achieved in MRS (De Man Rugosa and Sharpe) medium (with glucose) at pH 7.50. The crude bacteriocin inhibited the growth of gram-positive bacteria such as Lactobacillus sake 15521 and Listeria innocua. The gram-negative bacteria such as Escherichia coli DH 5-alpha (with plasmid, PUC) , Salmonella typhii and Staphylococcus aureus were weakly inhibited. Other microorganisms such as Lactobacillus curvatus D31685 , Lactobacillus confusius M23036 , Lactococcus lactis MG1363 , Leuconostoc paramesenteroides S67831 , Pediococcus pentosaceus M58834 , Saccharomyces cerevisiae SS553 (wild type) and Escherichia coli JM109 (no plasmid) were not inhibited.     

Preventive effect of fermented Maillard reaction products from milk proteins in cardiovascular health

The aim of this study was to determine the dual effect of Maillard reaction and fermentation on the preventive cardiovascular effects of milk proteins. Maillard reaction products (MRP) were prepared from the reaction between milk proteins, such as whey protein concentrates (WPC) and sodium caseinate (SC), and lactose. The hydrolysates of MRP were obtained from fermentation by lactic acid bacteria (LAB; i.e., Lactobacillus gasseri H10, L. gasseri H11, Lactobacillus fermentum H4, and L. fermentum H9, where human-isolated strains were designated H1 to H15), which had excellent proteolytic and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities (>20%). The antioxidant activity of MRP was greater than that of intact proteins in assays of the reaction with 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt and trivalent ferric ions; moreover, the effect of MRP was synergistically improved by fermentation. The Maillard reaction dramatically increased the level of antithrombotic activity and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) inhibitory effect of milk proteins, but did not change the level of activity for micellar cholesterol solubility. Furthermore, specific biological properties were enhanced by fermentation. Lactobacillus gasseri H11 demonstrated the greatest activity for thrombin and HMGR inhibition in Maillard-reacted WPC, by 42 and 33%, respectively, whereas hydrolysates of Maillard-reacted SC fermented by L. fermentum H9 demonstrated the highest reduction rate for micellar cholesterol solubility, at 52%. In addition, the small compounds that were likely released by fermentation of MRP were identified by size-exclusion chromatography. Therefore, MRP and hydrolysates of fermented MRP could be used to reduce cardiovascular risks.