湛江对虾副产物酶解制备抗氧化肽

以湛江对虾加工副产物虾头为研究对象,研究虾头的酶解条件和酶解产物的抗氧化活性,选用木瓜蛋白酶和胃蛋白酶分别对虾头酶解,制备高活性的抗氧化肽。在单因素的基础上,以清除DPPH自由基为指标,研究时间、温度、加酶量、pH对酶解产物抗氧化活性的影响。结果表明,与木瓜蛋白酶相比,胃蛋白酶酶解产物的抗氧化效果更好;通过正交试验,确定胃蛋白酶酶解产物的最佳条件为温度32℃、酶解时间1 h、pH 1、加酶量为1.33×10-5kat/g(以底物计),在此条件下酶解产物的抗氧化活性最高,对DPPH自由基清除率为89.12%。     

黑龙江高粱水提物中原花青素的结构表征

旨在对水提取黑龙江产高粱中的原花青素进行鉴定。通过正交实验优化提取工艺,大孔树脂柱层析纯化,并采用UV、IR、MS进行鉴定。结果表明用水作提取剂提取高粱外种皮中原花青素的最佳工艺条件:时间60min,温度90℃,料液比1∶20,pH值为5,大孔树脂分离纯化得到产品纯度达98.48%,纯化产物为聚合度小于6的低聚体原花青素。     

利用动物血发酵酱油

各种屠宰动物血是一种资源量很大的蛋白质,营养丰富,在食品开发方面,大规模利用动物血的报道不多,本文报道了一种利用动物血制作酱油的新工艺。利用动物血制作酱油的主要优点是质量高、成本低。采用本文报道的工艺制作的血酱油成功地消除了血的腥臭气,并且酱香浓郁,产品的各项主要指标均达到了优质酱油的水平,氨基氮含量达到1.1g/100mL,为屠宰动物血的大规模利用提供了一条新的途径。利用酵母和乳酸菌进行后处理,对血酱油的质量提高具有重要意义,并对增香处理的工艺条件进行了初步探索。     

Properties of gum exudates from selected Albizia species from Tanzania

Gum samples from three selected Albizia species from Tanzania have been analysed and their commercial potential determined by comparing their properties with those of Albizia zygia and Acacia gums. The properties of the gum exudates from Albizia amara, Albizia pertesiana and Albizia harveyi have been found to be similar to those of A. zygia gum except that their aqueous solutions possess slightly lower viscosity and higher levels of tannin. The Albizia gums were much less soluble in water than Acacia gums; however, their methoxyl contents and acid equivalent weights (AEW) were similar to those of some Acacia gums.     

Formation of Anthocyanins from Cells Cultured from Different Parts of Strawberry Plants

Anthocyanin formation and structural identification were investigated in the cultured strawberry, Fragaria unannssa cv Shikinari. Friable callus tissues were obtained from apical meristems, leafs, and petioles grown on LS agar medium with 2,4-dichlorophenoxyacetic acid and benzyladenine. Using these calli, effects of auxins and cell inoculum size on pigment production were studied in suspension culture. Anthocyanin was produced under 8000 lux after preculture for 3 wk under 800 Iux in suspension culture. The main extracted pigment was identified as a peonidin-3-glucoside and the second major pigment was a cyanidin-3-glucoside by FABMS and NMR. Anthocyanin production was stimulated by 2,4-dichlorophenoxyacetic acid and its yield was about three times that of indole-3-acetic acid. An inoculum rate of 2g (fresh weight)/100 mL LS medium resulted in highest pigment production. The callus derived from the leaf was much higher in anthocyanin production than the others tissues of strawberry.     

Isolation and Properties of Starch from Wild Yam from Zimbabwe

Wild Yam (Dioscorea dumetorum) was collected during the wet as well as dry season in the bush of Zimbabwe. Starch from its tubers was isolated in behavioral conditions and properties were determined such as size of granules, content of water, amylose, phosphorus, proteins and lipids, characteristics of gelation of its gels and thermal properties (TG, DTG, DTA).     

Value added products from fermentation of sugars derived from agro-food residues

BackgroundGlobally, significant amounts of agro-food residues are generated, most of which are burned as waste disposal. Given the abundance of this biomass, it can be used as raw material for the production of biofuels and valuable chemicals through biochemical conversion. Research in this field has gained importance given concerns regarding limitation of fossil resources, environmental problems and sustainability and preference towards natural, biodegradable and environmentally friendly products. Furthermore, the accessibility of alternative substrate sources for fermentative production of these high-value products has been one of the primary goals of industrial biotechnology research in the past two decades.Scope and approachThe present review is focused in the production of high value products through microbial fermentation of sugars from agro-food residues. Research in this field is interesting due to concerns regarding limitation of fossil resources. On the one hand, for the production of these bioproducts it is important the accessibility of alternative substrate and, on the other hand, the selection of the right microorganism to obtain the desired product. For this reason, the novelty of the present work is that details all different bioproducts which can be obtained through fermentation of sugars derived from agro-food residues, describing raw materials, pretreatments, mode of operation, conditions and microorganisms used, together with the production yields.Key findings and conclusionsThe use of renewable and environmentally sustainable agro-food residues as raw material for the production of bio-based products has gained interest recently. For this purpose, the application of a suitable pretreatment to improve biomass digestibility and the optimization of biomass hydrolysis for the production of fermentable sugars is crucial to make bio-based products competitive with petroleum-based ones. The combination of pretreatments together with the employment of microorganisms tolerant to inhibitors generated during the pretreatment or able to ferment pentose sugars in hydrolysates have turned out to be interesting approaches. Regarding hydrolysis and fermentation, SHF and SSF are the predominant strategies, although CBP and SSCF have gained recognition recently. The final bioproduct cost depends on the productivity, yield per quantity of substrate, cost of raw material and the recovery method. In this way, for the commercialization of these bioproducts, some technical challenges are still needed, including the reduction of the pretreatments and enzymes costs, the design of strains with tailored capabilities, downstream processes optimization, waste treatment, etc.     

四个不同产地淫羊藿热裂解产物对比分析

采用裂解色谱法研究比较4个产地淫羊藿的裂解组分。结果表明:4个产地的淫羊藿裂解产物分别为云南6 8个、吉林4 8个、辽宁5 1个、四川5 6个,主要为酚类、酮类、醛类、烯烃、芳烃、萜类、杂环类化合物;主要裂解产物为苯酚(相对含量在5%～8%之间),其他为环戊烯酮类、苯酚衍生物、2,3-二氢-苯并呋喃等;不同地域的同种药材其裂解产物分布基本相同,但各组分的含量差异却很大;高效液相色谱法测定不同地域淫羊藿中淫羊藿甙含量表明:云南为5.49%、四川为12.85%、辽宁为1.95%、吉林为2.82%,差异比较大。     

Exfoliation of Helicobacter pylori from gastric mucin by glycopolypeptides from buttermilk

In the human stomach, Helicobacter pylori, an ulcer pathogenic bacterium, colonizes the gastric mucosal layer primarily. The ability of glycopolypeptides (GPP) prepared from buttermilk to exfoliate H. pylori bound to gastric mucin was investigated. The GPP were prepared from buttermilk by digestion with trypsin, papain, pancreatin, bromelain, or pepsin. Helicobacter pylori ATCC 43504T and 43579 adhered more strongly to all of the GPP tested than to whole buttermilk, the soluble fraction of buttermilk, gastric mucin prepared from mouse stomach, or commercial pig gastric mucin. The GPP digested with trypsin, papain, or pancreatin were significantly more adherent. When the GPP concentration was 10 mg/mL, bound H. pylori ATCC 43504T, 43579, and 5 clinical isolates were exfoliated markedly from immobilized porcine gastric mucin following treatment with GPP digested with trypsin or pancreatin. This ability of GPP did not correlate with sialic acid content, indicating that sialic acid content is not important in the exfoliation of this microorganism. Such an ability may depend on the structure or number of sugar chains, or the position of sialic acid. We conclude that GPP promote the exfoliation of H. pylori bound to gastric mucin and prevent the de novo adherence of this microorganism. As such, GPP are a promising food material for preventing H. pylori infection.     

罗非鱼胶原肽制备中钙回收工艺的研究

对比柠檬酸和乳酸对罗非鱼骨与鱼鳞中钙的溶解能力,选择乳酸作为罗非鱼骨、鳞胶原肽制备过程中脱钙的酸化剂.当采用20%乳酸,料液比1:9、35℃下酸解骨鳞原料10h时,骨磷钙的溶出率为88.12%.乳酸钙上清液在0.1MPa下真空浓缩,浓缩比达到6.2:1-6.7:1时,将浓缩液循序降温至5℃并保持3h,使乳酸钙结晶析出.经回液分离、精制、干燥后,得到纯度为98.3%的乳酸钙晶体.     

Frequency of isolation of Campylobacter from roasted chicken samples from Mexico City

The presence of Campylobacter spp. was investigated in 100 samples of roasted chicken tacos sold in well-established commercial outlets and semisettled street stands in Mexico City. From 600 colonies displaying Campylobacter morphology only 123 isolates were positive. From these isolates, 51 (41%) were identified as C. jejuni, 23 (19%) as C. coli, and 49 (40%) as other species of this genus. All of the 27 positive samples came from one location where handling practices allowed cross-contamination of the cooked product. The results indicate that these ready-to-consume products are contaminated with these bacteria, representing a potential risk for consumers, especially in establishments lacking adequate sanitary measures to prevent cross-contamination.     

仙人掌多糖提取与多糖胶囊的制备

本研究以仙人掌浓缩清汁为原料,进行仙人掌多糖提取的单因素及正交提取试验,并将提取的仙人掌多糖制备成多糖胶囊。正交提取试验结果表明,仙人掌汁浓缩5倍,乙醇与仙人掌汁的比例为1:3,醇析温度为-18℃时,仙人掌多糖的提取得率最高;仙人掌多糖胶囊制备方法:以95%乙醇作为仙人掌多糖的粘合剂制粒,6%～8%HPMC溶于60%乙醇中作包衣液,在35～40℃下包衣,干燥2h后装胶囊,可获得品质较好的仙人掌多糖胶囊。     

江蓠藻渣膳食纤维制备工艺

目的:研究从江蓠藻渣中制备膳食纤维的工艺。方法:采用梯度离心法脱除助滤剂,得到藻渣粗纤维;再以可溶性膳食纤维得率为指标,利用复合植物水解酶对其进行酶解改性,在单因素试验基础上,采用正交试验对酶解工艺条件进行优化。结果:梯度离心条件分别为2500r/min、10min,3500r/min、5min,可得到纯净的藻渣粗纤维,回收率为25.4%,同时回收得到60.2%的助滤剂;藻渣粗纤维酶解改性的最佳工艺条件为料液比1:30(g/mL)、加酶量20FBG/g、pH4.5、酶解时间2.5h、酶解温度55℃,酶解改性后总膳食纤维得率为20.34%(相对于藻渣,干质量计),膨胀力10.25mL/g,持水力541.6%。结论:梯度离心结合复合植物水解酶制备江蓠藻渣膳食纤维可行,可为江蓠藻渣的高值化利用提供理论基础。     

Production of Trehalose from Starch by Thermostable Enzymes from Sulfolobus acidocaldarius

The optimum conditions for the production of trehalose from starch were investigated using two thermostable enzymes, maltooligosyl trehalose synthase (MTSase) and maltooligosyl trehalose trehalohydrolase (MTHase), from Sulfolobus acidocaldarius ATCC 33909. The optimum pH was 5.5 and the optimum temperature was 55—57°C using isoamylase from Pseudomonas amyloderamosa as a debranching enzyme. The addition of CGTase to the reaction mixture during the saccharification process caused an increase in trehalose and a decrease in maltose and maltotriose. Isoamylase was better than pullulanase as a debranching enzyme. The yield of trehalose was independent of the type of starch used. Under optimum conditions, the yield of trehalose from corn starch at 30% concentration was more than 82%.     

茶叶籽粕蛋白功能特性研究

以大豆分离蛋白为对照,研究碱法和酶法提取茶叶籽粕蛋白的功能特性。结果表明：酶法提取茶叶籽粕蛋白的溶解性、吸油性、乳化能力和乳化稳定性、起泡性、凝胶脆度优于碱法提取茶叶籽粕蛋白,而后者的吸水性、泡沫稳定性则优于前者,两者所形成蛋白凝胶的黏性和硬度相当。碱法和酶法提取的茶叶籽粕蛋白的乳化能力和乳化稳定性稍优于大豆分离蛋白,但起泡性和泡沫稳定性则不及大豆分离蛋白,溶解性与大豆分离蛋白相当,它们形成凝胶的最低质量分数分别为13%和15%,凝胶的黏性和硬度低于大豆分离蛋白。pH值、蛋白质量分数、NaCl浓度等因素对茶叶籽粕蛋白功能特性均有不同程度的影响。     

Comparison of the microflora isolated from spoiled cold-smoked salmon from three smokehouses

The microflora on spoiled, sliced and vacuum packed, cold-smoked salmon from three smokehouses was quantified and characterized in two independent experiments. Large variations in the microflora were observed both within (i.e. among vacuum packs from the same batch) and among the smokehouses. Lactic acid bacteria dominated the microflora, which reached 10⁷ cfu g⁻¹. Total viable counts of microorganisms alone were not related to quality, though spoilage characteristics were typical for microbiological spoilage. Among the lactic acid bacteria, Lactobacillus curvatus (ca 52–55%) was the most common species in both experiments with Lactobacillus saké, Lactobacillus plantarum, Carnobacterium spp. and Leuconostoc spp. present in smaller numbers. In some cases, large numbers of Enterobacteriaceae were also present and identified species were Serratia liquefaciens, Enterobacter agglomerans and Hafnia alvei. The microflora on cold-smoked salmon appeared to be related to the source of contamination i.e. the raw material and/or the smokehouse rather than being specific for the product, thus rendering the identification of the specific spoilage organisms difficult.     

Characterization of Antibiotic Resistance Genes from Lactobacillus Isolated from Traditional Dairy Products

Lactobacilli are widely used as starter cultures or probiotics in yoghurt, cheese, beer, wine, pickles, preserved food, and silage. They are generally recognized as safe (GRAS). However, recent studies have shown that some lactic acid bacteria (LAB) strains carry antibiotic resistance genes and are resistant to antibiotics. Some of them may even transfer their intrinsic antibiotic resistance genes to other LAB or pathogens via horizontal gene transfer, thus threatening human health. A total of 33 Lactobacillus strains was isolated from fermented milk collected from different areas of China. We analyzed (1) their levels of antibiotic resistance using a standardized dilution method, (2) their antibiotic resistance gene profiles by polymerase chain reaction (PCR) using gene‐specific primers, and (3) the transferability of some of the detected resistance markers by a filter mating assay. All Lactobacillus strains were found to be resistant to vancomycin, but susceptible to gentamicin, linezolid, neomycin, erythromycin, and clindamycin. Their susceptibilities to tetracycline, kanamycin, ciprofloxacin, streptomycin, quinupristin/dalfopristin, trimethoprim, ampicillin, rifampicin, and chloramphenicol was different. Results from our PCR analysis revealed 19 vancomycin, 10 ciprofloxacin, and 1 tetracycline‐resistant bacteria that carried the van(X), van(E), gyr(A), and tet(M) genes, respectively. Finally, no transferal of the monitored antibiotic resistance genes was observed in the filter mating assay. Taken together, our study generated the antibiotic resistance profiles of some milk‐originated lactobacilli isolates and preliminarily assessed their risk of transferring antibiotic gene to other bacteria. The study may provide important data concerning the safe use of LAB.     

不同来源红缘拟层孔菌粗多糖的抗氧化活性

采用1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基、2,2’-联氮基双(3-乙基苯并噻唑啉-6-磺酸)（2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid),ABTS）阳离子自由基、羟自由基清除实验和铁氰化钾还原法,对3 种不同产地（吉林、黑龙江、云南）红缘拟层孔菌子实体（Fomitopsis pinicola fruiting body,分别记为JFPF、HFPF、YFPF）、红缘拟层孔菌菌丝体（Fomitopsis pinicola mycelium,FPM）及其发酵液（Fomitopsis pinicola fermentation broth,FPFB）粗多糖的体外抗氧化活性进行对比研究;并采用紫外线和H2O2氧化损伤酵母细胞保护实验模型,评价上述5 种粗多糖对氧化损伤酵母细胞的保护作用。结果表明：这5 种红缘拟层孔菌粗多糖均表现出不同程度的体外抗氧化活性,并均能明显提高氧化损伤酵母细胞的存活率,且呈一定的剂量依赖效应;其中,YFPF粗多糖对DPPH自由基、ABTS阳离子自由基、羟自由基的清除能力及还原能力在5 种粗多糖中较强;在质量浓度为5 mg/mL时,其对3 种自由基的清除率分别为78.78%、99.24%、64.38%,还原能力为0.84。FPM粗多糖对氧化损伤酵母细胞保护作用最强,可明显提高氧化损伤酵母细胞的存活率,当其质量浓度为20 mg/mL时,紫外和H2O2氧化损伤酵母细胞的存活率分别为75.48%、48.38%。因此,不同来源红缘拟层孔菌粗多糖的抗氧化活性存在差异,这为红缘拟层孔菌的开发利用提供理论依据。     

四川泡菜中植物乳杆菌亚硝酸盐还原酶基因克隆与表达

目的:对植物乳杆菌中亚硝酸盐还原酶基因进行克隆并表达,并测定酶的活力。方法:根据Gen Bank中亚硝酸盐还原酶（NIR）基因序列,设计引物。提取植物乳杆菌的DNA,采用PCR技术扩增nir基因,TA克隆构建获得重组质粒p MD19-nir,分析其核苷酸序列同源性。通过双酶切连接到表达载体p ET-32a（+）中,获得重组表达载体p ET-32a-nir,构建成功后转化到E.coli BL（DE3）中进行表达研究。经IPTG诱导表达,得重组蛋白,超声波破碎,提取粗酶液,测定酶活力。结果:克隆的目的基因序列长度为1638 bp。获得重组蛋白分子量为80 ku,酶活力为4.2 U/mg。结论:成功克隆了植物乳杆菌中的亚硝酸盐还原酶基因,成功的导入到E.coli BL（DE3）中,表达产物有酶活。