鲣鱼毛油脱胶技术的研究

以鲣鱼毛油为实验原料,研究了磷酸、硫酸、柠檬酸、醋酸4种溶液对鲣鱼毛油脱胶率的影响,以脱胶率为指标筛选得柠檬酸和醋酸脱胶效果比较好,在单因素的基础上,以脱胶剂复配比例、脱胶温度、时间、脱胶剂用量4个因素为对象,采用4因素3水平响应面分析法进一步研究得到脱胶的最佳工艺参数。结果为,柠檬酸:醋酸为1.75:1(v/v),脱胶温度为50℃,用量为油重的1.5%,时间为25 min,其脱胶率可达3.90%,所得脱胶油颜色气味较原油都有了很大改善,而且效果比普遍的磷酸脱胶效果好,可为鲣鱼油精炼加工提供一定的理论参考。     

不同磷脂酶用于植物油脱胶的研究

植物油的磷脂酶酶法脱胶,提供了一种经济节约、高效稳定、绿色环保的具有国际领先水平的油脂脱胶方法.Lecitase 10L、Lecitase Novo和Lecitase Ultra是3种可以应用于植物油脱胶的磷脂酶,对3种酶运用于不同种类植物油的脱胶效果进行了研究比较.研究结果表明,Leciiase Ultra热稳定性好、酶活性高、应用于植物油脱胶效果好且稳定,是一种更适宜于工业化应用的酶种.     

苎麻微生物脱胶技术工艺的研究

从含丰富纤维素质的土壤样品中分离筛选出对苎麻有良好脱胶性能的微生物混合物。该混合物由3株芽孢杆菌和1株球菌组成，它们都是嗜碱性脱胶菌。该脱胶茵对苎麻有很好的脱胶效果，其最适脱胶条件为：以蛋白Ag0．5％、果胶0．5％、（NH4）2SO4 0．5％、pH8．5的种子培养液培养脱胶菌，以水和0．2％（NH4）2SO4（pH8．5）组成的脱胶液与干苎麻按1：20比例混合，以5％接种量接入种子液，37℃下脱胶3d，脱胶率达到100％。脱胶茼液反复使用4次，脱胶率仍达到80％以上。     

丝瓜络纤维染色动力学研究

丝瓜络是一种物丰价廉、可降解的天然纤维素.用氢氧化钠和过氧化氢的混合液对丝瓜络进行脱胶处理后,丝瓜络束纤维变成单纤维,其纤维素、半纤维素、木质素含量分别为72.2%、15.4%、9.8%.选用活性蓝X-3G,研究了丝瓜络纤维染色动力学(包括染色速率曲线、扩散系数、半染时间和染色速率常数)并与棉纤维进行对比.结果表明:脱胶丝瓜络纤维染色性能好于未处理的丝瓜络纤维,而未处理丝瓜络纤维的染色性能好于棉纤维.     

罗布麻微生物脱胶的菌种筛选与工艺优化

为提高罗布麻微生物脱胶效率,采用透明圈法、DNS比色法以及16S rRNA分子鉴定等方法从新疆乌鲁木齐南山野生麻生长区土壤中筛选优势脱胶菌株,并设计正交试验将所筛优势菌株用于优化新疆罗布麻微生物脱胶工艺参数。试验结果表明:所筛7株菌具有较高果胶酶活、木聚糖酶活,低纤维素酶活,适用于罗布麻微生物脱胶的实际应用;7菌种主要为芽孢杆菌属,此外还有肠杆菌属、克雷伯菌属和泛菌属;在脱胶液pH值为7,浴比为1∶40,摇床转速为90 r/min的最优脱胶工艺参数下,最佳脱胶方式为7菌系复合脱胶,脱胶时残胶率可降至30.45%,脱胶效果改善,同时菌株之间形成稳定的脱胶菌群,脱胶时菌种之间的协同作用、拮抗作用会影响菌群的脱胶能力。     

苎麻纤维脱胶及染色工艺研究

利用高效精练剂SB-3结合NaOH和H_2O_2对原生苎麻进行脱胶处理,优化了苎麻纤维的脱胶工艺,并探讨了苎麻纤维脱胶-染色短流程工艺。结果表明,脱胶最佳工艺为:原生苎麻先用1.5g/L H_2SO_4在50℃浸渍处理1h,再用5g/L高效精练剂SB-3、2g/L NaOH、8g/L H_2O_2在80℃处理80min。原生苎麻纤维脱胶完成后,加入少量除氧酶进行一道水洗,直接用活性染料染色,发现其染色性能与脱胶后充分水洗染色的效果相当,既缩短了流程,又减少了能耗。     

食品中单核细胞增生性李斯特菌的快速分离鉴定

单核细胞增生性李斯特菌(Listeria monocytogenes,简称单增李斯特菌)是一种重要的食源性致病菌,能引起人畜共患李斯杆菌病。本文采用两种不同的增菌分离方法从散装牛奶和猪肉中共分离得到8株单增李斯特菌。通过革兰氏染色、生化鉴定、PCR扩增hlyA基因、16SrDNA测序、血清分型等一系列实验对可疑菌株进行分析鉴定。综合实验结果和其他单增李斯特菌分离标准,探讨开发了一种快速分离鉴定单增李斯特菌的方法,该方法可在4～5d内完成单增李斯特菌的分离检测过程。      

氨基功能化磁性纳米氧化铁颗粒快速捕获和分离致病菌

为开发1种快速捕获和分离致病菌的检测技术,制备氨基功能化的磁性纳米氧化铁颗粒(Fe3O4@SiO2-NH2),研究其对4种革兰氏阳性菌(枯草芽孢杆菌、蜡样芽孢杆菌、金黄色葡萄球菌、藤黄微球菌)和4种革兰氏阴性菌(埃希氏大肠杆菌、鸡白痢沙门氏菌、宋氏志贺氏菌、阪崎肠杆菌)的吸附效果。试验结果表明,磁性纳米氧化铁颗粒对8种致病菌皆具有良好的吸附效果,动态吸附1 min内达到平衡;对8种细菌的最佳吸附pH范围为5~8,其中对革兰氏阳性菌的吸附效果优于革兰氏阴性菌;随着PBS缓冲溶液浓度和Na2SO4加入量的增加,吸附效率逐渐减小;通过透射电镜观察,磁性纳米颗粒与菌体表面具有良好的结合能力。结论:经氨基功能化处理的磁性纳米氧化铁颗粒对致病菌有广泛的吸附效果,颗粒与菌体之间的作用主要为静电吸附力。     

大麻快速脱胶菌株的选育与脱胶性能鉴定

 针对以烧碱蒸煮为中心的大麻化学脱胶工艺存在脱胶质量不稳定,纤维强度和出麻率低,环境污染严重等问题,进行了大麻脱胶菌株的选育与脱胶性能鉴定的研究。通过广泛采集菌样,初筛、复筛和诱变育种,获得了1株在16 h内完成大麻脱胶的快速脱胶菌株;在实验室条件下,该菌株进行大麻生物脱胶具有脱胶周期短,纤维产量高和品质好等特点;与传统水沤法相比,缩短脱胶周期90%以上,干茎出麻率提高2.1%,束纤维强力提高7.9%,且纤维颜色浅,质地均匀,光泽好。     

桑蚕丝绞纱染色工艺探讨

探讨采用不同工艺对桑蚕丝绞纱进行脱胶前处理及绞纱染色工艺试验,结果表明,采用酶剂脱胶、弱酸性染料及活性染料的染色工艺,均可以获得较好的真丝染色效果,采取适当的生产措施可确保染色质量达到要求。     

Chemical,antioxidant and antibacterial study of Brazilian fruits

In this study, the antioxidant capability, total phenolic content and antimicrobial activity of ethanolic extracts of seven fruits from the Brazilian Atlantic Forest were evaluated. The conditions for the extraction of crude phenolics from the fruits were determined using an experimental factorial design. Total phenolic content, 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH^?) scavenging activity and β‐carotene‐linoleic acid couple oxidation assays were used to evaluate the antioxidant properties of the extracts. In addition, antimicrobial activity was screened using two Gram‐negative bacteria (Escherichia coli and Klebsiella pneumoniae) and one Gram‐positive bacterium (Staphylococcus aureus). All native fruits assayed in this study have high potential as natural antioxidant sources. Among the seven fruits evaluated, Jabuticaba and Uvaia had the highest antioxidant activity in the DPPH^? and of β‐carotene‐linoleic acid coupled oxidation assays. In the biological assay, K. pneumoniae was the most sensitive microorganism to the fruit extracts, and the Jabuticaba extract had a slight inhibitory effect against this Gram‐positive bacterium.     

国产Nisin部分特性的研究

研究温度、pH、蛋白酶、保存条件对国产Nisin抑菌活性的影响,以及抑菌谱等,结果表明温度、pH会显著影响Nisin活性,在酸性条件下,Nisin对温度较稳定,随PH值的增加,温度越高,Nisin活性下降越显著,温度越低越有利于保存,干制品比溶液易保存,国产Nisin对胃蛋白酶不敏感,但对胰蛋白酶敏感,国产Nisin对革兰氏阳性细菌有抑制作用,而对革兰氏阴性细菌、霉菌和酵母没有作用。     

Antibacterial activity of zinc oxide nanoparticle suspensions on food‐borne pathogens

Nanoparticles (NPs) are increasingly recognised for their utility in biological applications including nanomedicine and food safety. The present study investigated the antibacterial activity of zinc oxide (ZnO) when tested against the Gram‐negative bacteria Escherichia coli as well as the Gram‐positive bacterium Staphylococcus aureus, and the effect was more pronounced with the Gram‐positive than with the Gram‐negative bacteria. ZnO NPs also exhibited a preferential ability to suppress growth of E. coli and S. aureus in milk. This study suggested that the application of ZnO NPs as antibacterial agents in food systems and medicine may be effective at inhibiting certain pathogens.     

芦荟汁抗菌作用研究

用一系列真菌和细菌试验了芦荟汁的抑菌作用。结果表明 :芦荟汁对G+和G- 氏细菌 ,以及部分霉菌的生长有较强的抑制作用 ;芦荟汁还具有热稳定性强 ,抑菌浓度低 ,抑菌pH范围广的特点。对酵母的抑制作用不明显。     

Damage to Pork Liver Caused by Repeated Freeze-Thaw Cycling and Refrigerated Storage

The effects of freezing and thawing (F-T) and refrigerated storage (R-S) on pork liver were examined. Intact cells were isolated from the tissue and analyzed for membrane integrity and the tissue extracts were analyzed for protein content. Significant (p < 0.05) differences were noted in the number of isolated intact cells and in tissue protein content between F-T and R-S or fresh livers. Differences in cell membrane integrity were also noted between fresh and R-S livers. Repeated freezing and thawing appears to break down the liver structure differently than does refrigerated storage.     

Molecular Analysis,Biochemical Characterization,Antimicrobial Activity,and Immunological Analysis of Proteus mirabilis Isolated from Broilers

Proteus mirabilis, a Gram‐negative bacterium, is ubiquitous in the environment and is considered as the normal microflora in the human gastrointestinal tract. However, this bacterium is an opportunistic pathogen in humans, often causing urinary tract infections. Moreover, Proteus has been frequently isolated from food animals, including poultry. Whether this bacterium contributes to the foodborne illness in humans is unclear. In this report, P. mirabilis isolates recovered from broilers during housing in the units were characterized, their antimicrobial activity was assayed, and broiler immune response to the soluble proteins was determined. Cecal contents and fecal droppings were treated according to the standard protocol for isolation. Speciation based on biochemical reactions and the antimicrobial activity of the isolates were carried out using commercial kits. Immunoblot was assayed to determine immune status of broilers against P. mirabilis. A total of 10 isolates of P. mirabilis were selected for further characterization. These isolates could grow in pH 6.0 and 1% NaCl conditions. They were resistant to sodium lactate, troleandomycin, rifamycin SV, vancomycin, but sensitive to nalidixic acid, cefotaxime and novobiocin. Moreover, the CTX, ACC, CMY‐1, BIC, NDM, VEB, qnrB and qnrD genes were detected by PCR amplification in all isolates. Sera from broilers harboring this bacterium reacted to the P. mirabilis soluble proteins, but not from litter‐ and age‐matched P. mirabilis negative and SPF chickens, indicating that this bacterium infected chickens that could have humoral immune response against P. mirabilis. This study provides a rationale for further monitoring P. mirabilis during poultry production to determine whether this bacterium poses potential threats to public health.     

From undefined red smear cheese consortia to minimal model communities both exhibiting similar anti-listerial activity on a cheese-like matrix

Starting from one undefined cheese smear consortium exhibiting anti-listerial activity (signal) at 15 °C, 50 yeasts and 39 bacteria were identified by partial rDNA sequencing. Construction of microbial communities was done either by addition or by erosion approach with the aim to obtain minimal communities having similar signal to that of the initial smear. The signal of these microbial communities was monitored in cheese microcosm for 14 days under ripening conditions. In the addition scheme, strains having significant signals were mixed step by step. Five-member communities, obtained by addition of a Gram negative bacterium to two yeasts and two Gram positive bacteria, enhanced the signal dramatically contrary to six-member communities including two Gram negative bacteria. In the erosion approach, a progressive reduction of 89 initial strains was performed. While intermediate communities (89, 44 and 22 members) exhibited a lower signal than initial smear consortium, eleven- and six-member communities gave a signal almost as efficient. It was noteworthy that the final minimal model communities obtained by erosion and addition approaches both had anti-listerial activity while consisting of different strains. In conclusion, some minimal model communities can have higher anti-listerial effectiveness than individual strains or the initial 89 micro-organisms from smear. Thus, microbial interactions are involved in the production and modulation of anti-listerial signals in cheese surface communities.     

新疆圆柏叶内生菌的分离及其抑菌特性研究

对新疆圆柏叶内生菌进行分离,确定分离条件,分离纯化得到7 株菌株,采用打孔法对这7 株菌的发酵液进行抑菌实验。结果表明：其中两株菌的发酵液对枯草芽孢杆菌、金黄色葡萄球菌呈现较强的抑菌活性。通过形态学观察和革兰氏染色,确定1 号菌株为革兰氏阳性球菌,2 号菌株为革兰氏阴性球菌,均无荚膜,无芽孢,不产酸,不产气,淀粉水解为阴性。     

The effect of cooking on the antibacterial activity of the dialdehyde starch suspensions

Dialdehyde starch (DAS) has been found to show a significant antibacterial activity after cooking. A study of the antibacterial efficiency of the DAS suspensions was performed on a Gram‐negative bacterium Escherichia coli and a Gram‐positive bacterium Staphylococcus aureus. After heating at 90–95°C in deionized water for 2 h, the as‐prepared DAS aqueous suspension (DAS‐AS) demonstrated strong antibacterial activity against the test bacteria, whereas the DAS granular suspension showed very limited antibacterial activity. The antibacterial activity of the DAS suspension is mainly attributed to the reactivity of its dialdehyde functional groups, which is related to the dispersion and the pH values of the test media. The physicochemical changes of DAS‐AS were determined by particle size, dispersibility, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and UV–Vis measurements. Upon heating, the dispersibility of DAS in deionized water significantly increased. Meanwhile, the granules of DAS were disintegrated with significantly decreasing the DAS particle size. The soluble parts of DAS‐AS and the as‐received DAS (DAS‐R) had similar molecular weight distribution as determined by GPC analysis. DAS‐AS had more soluble materials in GPC medium (DMSO) than DAS‐R, suggesting that DAS‐AS and DAS‐R were different. Chemical changes of DAS during cooking such as the formation of the conjugated aldehyde and carboxylic acid functions were observed by the FTIR and UV–Vis spectroscopic analysis.     

Ultrastructure of Pork Liver after Freeze-Thaw Cycling and Refrigerated Storage

Pork liver was subjected to repeated freezing (-20°C) and thawing (+ 5°C) to simulate conditions of temperature abuse of frozen liver during commercial transport. Ultrastructure was compared to that of refrigerated pork liver. Liver cells deteriorated more with freezing and thawing (F-T) than with refrigerated storage (R-S). After one cycle F-T, hepatocyte organelles were damaged and cytoplasmic components appeared in the sinusoids. After four cycles F-T, membranes were extensively damaged and sinusoids contained organelles. The tissue organization was stable during six days of refrigerated storage, although cell structure deteriorated. Evidence from ultrastructure indicated that drip from F-T liver and R-S liver arose from different kinds of tissue damage.