河蚌肉营养食品加工初探

河蚌广泛存在于河流湖泊等淡水水域中。蚌肉是营养丰富的肉食品,含有丰富的蛋白质、脂肪、糖类和矿物质。蚌肉蛋白质中所含对人体和禽畜有重要意义的氨基酸有α－氨基酸、甘氨酸、亮氨酸及异亮氨酸、丝氨酸、苏氨酸、缬氨酸、谷氨酸、精氨酸、酪氨酸、苯丙氨     

养殖水温对吉富罗非鱼幼鱼血清和肝脏1H-NMR代谢组的影响

基于¹H-NMR的代谢组学方法研究饲养水温对罗非鱼的肝脏和血清代谢特征的影响。实验选用初始体重为(38.75±0.61g)的吉富罗非鱼在不同温度(22、28和34℃,分别标记为LT,MT和HT组)条件下饲养8周。结果显示:在血清中,代谢物的变化包括乳酸、脯氨酸、葡萄糖、柠檬酸、反式-4-羟基、乙醇、肌酸、亮氨酸、甜菜碱、缬氨酸、谷氨酰胺、三甲胺、甘露糖、酪氨酸和肌酐,主要参与糖酵解、胆碱代谢和脂质代谢。差异代谢物中LT组乳酸、反式-4-羟基、肌酸、葡萄糖、脯氨酸、亮氨酸和缬氨酸的含量高于MT组,HT组除葡萄糖、谷氨酰胺及甘露糖外均高于MT组。肝脏组织代谢物的变化包括麦芽糖、谷氨酸、亮氨酸、赖氨酸、精氨酸、缬氨酸、丝氨酸、谷氨酰胺、异亮氨酸、牛磺酸、酪氨酸、丙氨酸、苏氨酸、苯丙氨酸、蛋氨酸,主要参与糖代谢和氨基酸代谢。LT组15种差异代谢物含量均高于MT组和HT组,MT组麦芽糖、谷氨酸盐、赖氨酸、丝氨酸、谷氨酰胺、牛磺酸和苏氨酸浓度高于HT组。以上结果表明:低温降低了吉富罗非鱼对氨基酸及氨基酸衍生物的利用率,进而影响吉富罗非鱼的生长速度和饲料利用率;高温组实验鱼的生长表现与适温组无显著差异,但代谢组结果显示高温饲养显著影响了吉富罗非鱼的胆碱代谢和脂质代谢。     

裂壶藻蛋白肽美拉德反应产物的制备及其抗氧化特性

该研究以裂壶藻(Schizochytrium limacinum)渣为原料,采用酶解法制备得裂壶藻酶解物(S. limacinum hydrolysate, SLH),分析其美拉德反应条件,同时探究其不同超滤组分和葡聚糖凝胶柱层析组分美拉德反应产物(Maillard reaction products, MRPs)的抗氧化能力。结果表明,当还原糖为核糖、糖肽质量比为1∶1、反应pH为9、反应温度为100℃、反应时间为6 h时,SLH的MRPs还原力(5 mg·mL~(-1))为1.24,DPPH自由基清除率(12.5 mg·mL~(-1))为88.62%。将SLH经超滤后分别得到SLH-1 (5 kD)、SLH-2 (10 kD)和SLH-3 (50 kD)组,发现SLH-1组在美拉德反应前后的抗氧化能力最强。将SLH-1组经Sephadex G-25凝胶柱分离后分别得到SLH-1-Ⅰ、SLH-1-Ⅱ、SLH-1-Ⅲ和SLH-1-Ⅳ组,发现分子量较大的SLH-1-Ⅰ组经美拉德反应修饰后的抗氧化活性最好,其还原力(2 mg·mL~(-1))为0.741,DPPH自由基的清除率(5 mg·mL~(-1))为79.41%。此外,氨基酸组成分析表明美拉德反应可导致酪氨酸(Tyr)、赖氨酸(Lys)、组氨酸(His)、精氨酸(Arg)、色氨酸(Trp)等氨基酸含量明显降低,但对必需氨基酸总含量影响不大。     

捕后干露对3种贝类活品品质的影响

为明确经济养殖贝类捕后早期干露耐受性,选取活力良好的菲律宾蛤仔、长牡蛎和虾夷扇贝在4℃条件下进行8 d的无水贮藏,以闭壳肌p H、糖原、腺苷三磷酸(ATP)关联化合物、磷酸精氨酸的含量和奥品脱氢酶活性为指标,研究3种贝类的品质变化规律.试验结果表明,无水贮藏期间,菲律宾蛤仔pH无明显变化(P<0.05),而长牡蛎和虾夷...     

不同生长发育阶段刺参体壁营养成分及氨基酸组成比较分析

采集稚参、幼参、成参,研究刺参在不同生长发育阶段体壁营养组成的差异,结果发现:随着刺参的生长发育,其体内的蛋白质含量逐渐升高,水分、脂肪、灰分含量逐渐降低;天冬氨酸、谷氨酸、丝氨酸、苏氨酸、甘氨酸等几种氨基酸的含量在一定的阶段内随着个体的生长发育呈现显著升高的趋势,精氨酸含量在从稚参发育到幼参的过程中较为恒定,但是到成参时显著提高,蛋氨酸和苯丙氨酸含量则一直恒定.氨基酸总量、呈味氨基酸、药效氨基酸等的含量都随个体的生长发育呈升高趋势,而7种人体必需氨基酸的含量则较为恒定.     

植物乳杆菌发酵对牡蛎成分的影响

试验结果表明,加入4%食盐能在一定程度上抑制挥发性盐基氮(TVBN)的产生,接种植物乳杆菌后牡蛎浆pH在发酵第2 d迅速下降并一直处于酸性状态(pH≈4)。蛋白质由于牡蛎自溶酶作用、微生物的利用而不断被分解,氨基酸不断地增加,而可溶性蛋白表现出波动变化。还原糖逐渐被消耗,至第10 d时所剩仅为0.07 mg/ml。表明植物乳杆菌对牡蛎的发酵过程有重要作用。为牡蛎的深加工利用提供科学依据。     

饲料中精氨酸水平对大菱鲆幼鱼生长、血浆游离氨基酸和肠道形态的影响

为研究在饲料中添加不同水平的精氨酸对大菱鲆(Scophthalmus maximus L.)幼鱼生长、血浆游离氨基酸和肠道组织结构的影响,以酪蛋白和明胶为蛋白源设计三组等氮等脂的纯化饲料,在基础配方中分别添加0%、2%、4%的晶体L-精氨酸,分别命名为LA、MA和HA处理组,用上述3种试验饲料分别饲喂初始体重为(13.30±0.01)g的大菱鲆幼鱼8周。结果显示,精氨酸不足(LA)和精氨酸过量(MA)都显著降低了鱼体的生长性能(P0.05)。随着饲料中精氨酸的添加量提高,血浆游离精氨酸浓度显著升高(P0.05)。精氨酸缺乏还造成了血浆游离蛋氨酸和苏氨酸浓度的下降,而丝氨酸和甘氨酸浓度升高(P0.05)。此外,精氨酸缺乏造成了肠道褶皱、上皮细胞和微绒毛高度的降低(P0.05)。这些结果表明精氨酸在大菱鲆的生长、氨基酸代谢和肠道健康上发挥着重要的作用。     

微波辅助干制对双孢菇提取物腌制鲍肌肉品质的影响

为探究微波辅助干制对鲍肌肉品质的影响,本实验考察了干制过程中微波处理对经30% NaCl和5%双孢菇提取物腌制的鲍肌肉褐变强度、荧光强度、还原糖、氨基酸组成、糖蛋白等理化性质和挥发性风味的影响。结果显示,在干制过程中,未微波（WMT）组和微波（MT）组鲍肌肉的荧光强度值和褐变强度值均逐渐增加,在105 d时达到最大值后开始下降。经120 d干制的WMT组鲍肌肉还原糖含量由7.24下降至5.58 mg/g,而MT组鲍肌肉还原糖含量由7.24增加至14.05 mg/g。WMT和MT组鲍肌肉总氨基酸含量由39.69 g/100g分别增加至44.06和41.54 g/100g。在干制30 d后,电泳图谱中出现明显高分子化合物和糖蛋白聚集物。相比WMT组,MT组鲍肌肉傅里叶变换红外光谱中不仅酰胺A带的波数下降更加显著,而且酰胺Ⅰ带和酰胺Ⅱ带吸收峰强度更强。不管是否微波处理,干制90 d的鲍肌肉的电子鼻中W2W（芳香成分、有机硫化物）和W2S（醛醇酮类化合物）传感器响应值明显大于未干制的样品。气相色谱-质谱联用仪测定的壬醛和1-辛烯-3-醇在干制90 d时明显下降,而芳樟醇含量明显增加。在相同干制时间内,MT组鲍肌肉中芳樟醇含量高于WMT组样品。研究表明在干制过程中微波处理可以促进鲍肌肉美拉德反应程度,进而生成良好的挥发性气味,结果将为利用微波辅助改良干鲍的制备工艺提供理论参考。     

不同日龄吉林地方黑羽鸡肌肉品质与上市时间分析

目的 研究不同日龄吉林地方黑羽鸡肌肉品质，确定最佳的上市时间。方法 试验选择同日龄的800羽吉林地方黑羽鸡为研究对象，随机分为4个重复，每个重复200只。所有鸡在90日龄时离地进行平养。分别在90、120、150日龄时，随机选取公母鸡8只，进行屠宰，采集胸部肌肉，检测胸肌的pH值、剪切力、水分、干物质、氨基酸、脂肪酸、肌苷酸。结果 母鸡、公鸡的剪切力随着日龄的增长逐渐增大，150日龄均显著高于90和120日龄(P<0.05);母鸡的肌肉干物质在150日龄时显著高于90和120日龄(P<0.05);公鸡肌肉的呈味氨基酸中甘氨酸、丙氨酸、天门冬氨酸、酪氨酸、苯丙氨酸在120日龄时显著显著高于90和150日龄(P<0.05),苏氨酸、丝氨酸、胱氨酸、蛋氨酸、亮氨酸、赖氨酸、精氨酸、脯氨酸在120日龄时显著高于90日龄(P<0.05);母鸡的呈味氨基酸谷氨酸、丙氨酸、天门冬氨酸在150日龄时显著高于90和120日龄(P<0.05),苏氨酸、丝氨酸、蛋氨酸、亮氨酸、赖氨酸、脯氨酸在150日龄时显著高于90日龄(P<0.05);公鸡肌苷酸在120日龄时显著高于1...     

低酸性和酸化即食紫菜热杀菌工艺优化研究

为优化即食紫菜(Porphyra spp.)的杀菌工艺、开发高品质即食湿态紫菜产品,分别测定了低酸性和酸化紫菜(pH≤4.6)两类产品高压热处理(110、115、121℃)和常压热处理(85、90、95℃)过程中的传热曲线,结合保藏实验和微生物分析确定了两种杀菌方式对应的产品安全杀菌时间(F值),并进一步探究了相同杀菌强度F值下不同温度-时间组合对紫菜感官和营养品质的影响。结果表明,紫菜在高压热杀菌F0=3 min时可达到商业无菌,酸化后紫菜在常压热杀菌F89.38.39=5 min时可满足保藏要求。与高压热杀菌相比,酸化结合常压杀菌有利于维持紫菜的色泽和质构。在相同杀菌强度F值下紫菜的韧性、硬度和感官评分随杀菌温度升高而增加。营养成分方面,高压加热组中,随温度升高可溶性糖和游离氨基酸总量降低,常压组中在90℃杀菌时游离氨基酸总量最高。综合比较,酸化组杀菌参数采用90℃、11.5min,低酸性组杀菌参数采用115℃、10 min时即食紫菜的质构、感官和营养品质较优。     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.