斑点叉尾鮰鱼皮明胶制备工艺的优化

以斑点叉尾鱼皮为原料,采用低浓度氢氧化钠短时间浸泡鱼皮制备明胶。用中心组合实验设计(CCD)展开实验,以研究自变量氢氧化钠浓度(%,X1)、碱浸泡时间(h,X2)、水抽提温度(℃,X3)和水抽提时间(h,X4)对变量凝胶强度(g,Y)的影响。采用响应面分析优化工艺条件为:X1=0.889%,X2=25.794h,X3=49.295℃,X4=4.902h时,指标Y有最大值620.988g。测定了最优工艺条件下所得明胶的产率、凝胶强度和氨基酸组成。      

Uptake and elimination routes of inorganic mercury and methylmercury in Daphnia magna

Mercury (Hg) is an important environmental pollutant due to its highly toxic nature and widespread occurrence in aquatic systems. The biokinetics of Hg in zooplankton have been largely ignored in previous studies. This study examines the assimilation, dissolved uptake, and efflux of inorganic mercury [Hg(II)] and methylmercury (MeHg) in a freshwater cladoceran, Daphnia magna, and models the exposure pathways of Hg(II) and MeHg in the daphnids. The assimilation efficiencies (AEs) of both Hg species decreased significantly with increasing algal carbon concentrations. The dissolved uptake of Hg(II) and MeHg was proportional to the ambient concentration (ranging from environmentally realistic to high concentration over a 3-4 orders of magnitude variation), whereas MeHg had a slightly higher uptake rate constant (0.46 L g(-1) h(-1)) than Hg(II) (0.35 L g(-1) h(-1)). Surprisingly, the efflux rate constants of Hg(ll) and MeHg were rather comparable (0.041 -0.063 day(-1)). The release of both Hg(II) and MeHg via different routes (excretion, egestion, molting, and neonate production) was further examined at different food concentrations. It was found that regeneration into the dissolved phase was important for D. magna to eliminate both Hg species, but maternal transfer of Hg(II) (11-15%) and MeHg (32-41%) to neonates represented another important pathway for the elimination of Hg(II) and MeHg from the mothers. Modeling results suggest that food is an important source for MeHg exposure (47-98%), but water exposure represents 31-96% of Hg(II) accumulation in D. magna, depending on the variation of Hg bioconcentration factor in ingested food. Furthermore, MeHg predominates the bioaccumulation of Hg in D. magna even though MeHg constitutes only a small percentage of the total Hg in the water. The results strongly indicate that maternal transfer of Hg(II) and MeHg in freshwater zooplankton should be considered in manytoxicity testings and risk assessment in aquatic food chains.     

斑点叉尾鮰鱼皮明胶水解方法的研究

研究了利用斑点叉尾鮰鱼皮明胶水解制取抗氧化活性肽的方法,比较了不同的水解方法,不同底物,不同的蛋白酶对水解产物抗氧化活性的影响。结果表明酶解法适合生产胶原蛋白活性肽,酶解产物具有不连续的分子量分布及较好的抗氧化活性。不同底物酶解制取的产物的抗氧化活力不同,其中以酸法明胶利用碱性蛋白酶酶解的产物活力最高,平均分子量小于4000Da。     

斑点叉尾鮰鱼片的加工工艺、营养成分及质构分析的研究

通过对斑点叉尾鮰鱼片的加工工艺、操作要点的介绍和对鱼片的营养成分、质构的详细分析,得出:斑点叉尾鮰鱼片中含有多种人体必须氨基酸,氨基酸总量14.93%,粗蛋白质含量15%,粗脂肪含量3%。经工厂化加工的鱼片无刺,解决了吃鱼被卡带来的烦恼。冻斑点叉尾鮰鱼片是一种营养价值高、食用方便的产品,具有良好的市场前景。     

Absorption, distribution and elimination of fumonisin B1 metabolites in weaned piglets

The absorption, distribution and elimination of fumonisin B₁ (and B₂) after oral administration of Fusarium verticillioides (MRC 826) fungal culture, mixed into the experimental feed for 10 days, was studied in weaned barrows. In order to determine the absorption of FB₁ from the feed marked by chromium oxide, a special T-cannula was implanted into the distal part of pigs' ileum. During the feeding of toxin-containing diet (45 mg FB₁ kg^-1) and until the tenth day after the end of treatment, the total quantity of urine and faeces was collected and their toxin content analysed. At the end of the trial, samples of lung, liver, kidney, brain, muscle, and fat were also collected and their fumonisin content analysed by LC-MS. The fumonisins appeared to decrease the reduced glutathione content in blood plasma and red blood cell haemolysate, possibly associated with in vivo lipid peroxidation. From a data set of 80 individual data and the concentration and rate of C_r and fumonisins (FB₁, partially hydrolysed FB₁ and aminopentol) in the chymus, it could be established that the accumulative absorption of fumonisin B₁ was 3.9% ± 0.7%. In the chymus, the FB₁ conversions into aminopentol and partially hydrolysed FB₁ were 1.0 and 3.9%, respectively. The degree of metabolism in faeces was variable, although the main product was the partially hydrolysed form, with very small amounts of the aminopentol moiety being recovered. In the investigated tissues the FB₁ conversion to aminopentol and partially hydrolysed FB₁ was 30 and 20%, respectively.     

Absorption,distribution and elimination of fumonisin B1 metabolites in weaned piglets

The absorption, distribution and elimination of fumonisin B₁ (and B₂) after oral administration of Fusarium verticillioides (MRC 826) fungal culture, mixed into the experimental feed for 10 days, was studied in weaned barrows. In order to determine the absorption of FB₁ from the feed marked by chromium oxide, a special T-cannula was implanted into the distal part of pigs’ ileum. During the feeding of toxin-containing diet (45 mg FB₁ kg^?1) and until the tenth day after the end of treatment, the total quantity of urine and faeces was collected and their toxin content analysed. At the end of the trial, samples of lung, liver, kidney, brain, muscle, and fat were also collected and their fumonisin content analysed by LC-MS. The fumonisins appeared to decrease the reduced glutathione content in blood plasma and red blood cell haemolysate, possibly associated with in vivo lipid peroxidation. From a data set of 80 individual data and the concentration and rate of C _r and fumonisins (FB₁, partially hydrolysed FB₁ and aminopentol) in the chymus, it could be established that the accumulative absorption of fumonisin B₁ was 3.9% ± 0.7%. In the chymus, the FB₁ conversions into aminopentol and partially hydrolysed FB₁ were 1.0 and 3.9%, respectively. The degree of metabolism in faeces was variable, although the main product was the partially hydrolysed form, with very small amounts of the aminopentol moiety being recovered. In the investigated tissues the FB₁ conversion to aminopentol and partially hydrolysed FB₁ was 30 and 20%, respectively.     

Chlordane and toxaphene residues following cooking of treated channel catfish fillets

The reduction in residues of chlordane and toxaphene following cooking (frying, baking, and smoking) of fillets obtained from treated Channel catfish (Ictalurus punctatus) was determined. On average, cooking reduced moisture content by 17% and increased fat content by 28 to 274%. Frying reduced chlordane residues by 56 to 86% on a dry basis (db) or 84 to 92% on a percent fat basis (fb) when raw fillets were compared to cooked fillets. Baking and smoking reduced chlordane significantly less (P < 0.05) than frying with reductions in residues of 12% and 9% (db) or 30% and 33% (fb), respectively. Frying reduced toxaphene residues by 40 to 49% (db) or 65 to 77% (fb), while baking and smoking reduced toxaphene by 35% and 24% (db) or 51% and 59% (fb), respectively.     

斑点叉尾鮰鱼头水解物的风味成分分析

对斑点叉尾鮰鱼头和鱼头酶解物干燥粉的风味成分进行了分析和比较,研究结果表明,斑点叉尾鮰鱼头和鱼头酶解物中都含有丰富的氨基酸和核苷酸。相对于新鲜的斑点叉尾鮰鱼头,鱼头酶解物中的风味氨基酸、游离氨基酸和核苷酸的含量都更高。斑点叉尾鮰鱼头酶解物中含有对风味贡献比较大的钾、钙、钠、镁等无机元素,而有害的铅、汞等重金属元素的含量均低于国家标准规定。对新鲜的斑点叉尾鮰鱼头、鱼头酶解物的挥发性风味成分分析结果表明,鱼头在酶解时产生了大量风味物质。在斑点叉尾鮰鱼头酶解物检测发现34种挥发性成分,其中呈现风味的主要成分之一杂环类化合物含量达到85.09%,使得鱼头酶解物干燥粉具有远高于新鲜鱼头的浓郁鱼香味。此实验结论可为斑点叉尾鮰鱼头的利用提供一定理论依据。     

斑点叉尾鮰鱼皮胶原蛋白的理化特征研究

选用斑点叉尾鮰（Ictalurus punctatus）鱼皮为材料,用乙酸和乙酸-胃蛋白酶,分别提取鱼皮中的酸溶性胶原蛋白（acid-solubilise collagen,ASC）和酶溶性胶原蛋白（pepsin-solubilise collagen,PSC）,并对其理化性质特征进行研究。研究发现,提取得到的ASC纯度高达93.11%,PSC纯度高达93.46%;紫外吸收分析表明,ASC和PSC的吸收峰值均在233nm处;蛋白图谱中两种胶原蛋白均由两种不同的α链（α1）2α2组成,具备I型胶原蛋白的特征;ASC和PSC的傅里叶红外图谱相似,具有完整的三螺旋结构;ASC的变性温度为34.2℃,PSC的变性温度为33.9℃。      

酶法脱脂对鮰鱼品质及干燥特性的影响

为推动鮰鱼加工产业的发展,采用碱性脂肪酶对鮰鱼进行脱脂处理,通过感官评价、理化指标以及色差、质构和硫代巴比妥酸法(TBARS)等方法研究鮰鱼品质和干燥特性的变化。结果表明:随着脱脂率的升高,鱼片土腥味物质含量降低,腥味感官评分显著下降(p<0.05);50℃热风干燥34 h后,脱脂率为55%的干制品的硬度降至(391.98±39.15)g,低于未脱脂样品(p<0.05),色泽变得明亮红润、有光泽,并且在整个干燥过程中干燥速率高于对照组,脂肪氧化程度低于对照组(p<0.05)。酶法脱脂有利于提高新鲜鮰鱼片及其干制品的品质,为鮰鱼精深加工提供理论基础。      

斑点叉尾鮰鱼皮胶原蛋白的理化特征研究

选用斑点叉尾鮰(Ictalurus punctatus)鱼皮为材料,用乙酸和乙酸-胃蛋白酶,分别提取鱼皮中的酸溶性胶原蛋白(acid-solubilise collagen,ASC)和酶溶性胶原蛋白(pepsin-solubilise collagen,PSC),并对其理化性质特征进行研究研究发现,提取得到的ASC纯度高达93.11％,PSC纯度高达93.46％;紫外吸收分析表明,ASC和PSC的吸收峰值均在233nm处;蛋白图谱中两种胶原蛋白均由两种不同的α链(α1) 2α2组成,具备Ⅰ型胶原蛋白的特征;ASC和PSC的傅里叶红外图谱相似,具有完整的三螺旋结构;ASC的变性温度为34.2℃,PSC的变性温度为33.9℃.     

高效液相色谱法检测鮰鱼体内丁香酚的残留

目的建立测定斑点叉尾鮰中丁香酚残留量的高效液相色谱法,幵探究高、中、低3个不同丁香酚浓度在鱼体内的残留规律。方法样品先经过冷冻干燥法将鱼肉冻干,磨成粉状过筛,称0.5g冻干鱼粉经5mL乙腈超声重复提取3次, 280 nm条件下,高效液相色谱技术进样检测,采用外标法定量。结果丁香酚标样在0.15～20.0 mg/L浓度范围内,线性关系良好,线性相关系数达到0.99996。在添加浓度为0.40-3.20 mg/kg时,加标回收率在78.67%～90.54%,相对标准偏差为3.37%～5.54%,方法的检出限为0.045 mg/kg。同时収现麻醉时所用的丁香酚溶液浓度越高,丁香酚在鱼体内积累越多,用60 mg/L丁香酚溶液麻醉过的鮰鱼,体内丁香酚完全代谢需6～8 d,而用40、16 mg/L丁香酚溶液麻醉过的鮰鱼,仅需4～6 d。结论本方法具有操作简便、快速、准确、所用试剂价格低廉的特点,适用于斑点叉尾鮰中丁香酚残留量批量检测。     

Absorption, distribution and elimination of fumonisin B(1) metabolites in weaned piglets

The absorption, distribution and elimination of fumonisin B(1) (and B(2)) after oral administration of Fusarium verticillioides (MRC 826) fungal culture, mixed into the experimental feed for 10 days, was studied in weaned barrows. In order to determine the absorption of FB(1) from the feed marked by chromium oxide, a special T-cannula was implanted into the distal part of pigs' ileum. During the feeding of toxin-containing diet (45 mg FB(1) kg(-1)) and until the tenth day after the end of treatment, the total quantity of urine and faeces was collected and their toxin content analysed. At the end of the trial, samples of lung, liver, kidney, brain, muscle, and fat were also collected and their fumonisin content analysed by LC-MS. The fumonisins appeared to decrease the reduced glutathione content in blood plasma and red blood cell haemolysate, possibly associated with in vivo lipid peroxidation. From a data set of 80 individual data and the concentration and rate of C(r) and fumonisins (FB(1), partially hydrolysed FB(1) and aminopentol) in the chymus, it could be established that the accumulative absorption of fumonisin B(1) was 3.9% +/- 0.7%. In the chymus, the FB(1) conversions into aminopentol and partially hydrolysed FB(1) were 1.0 and 3.9%, respectively. The degree of metabolism in faeces was variable, although the main product was the partially hydrolysed form, with very small amounts of the aminopentol moiety being recovered. In the investigated tissues the FB(1) conversion to aminopentol and partially hydrolysed FB(1) was 30 and 20%, respectively.     

茶园中草甘膦在靶标杂草和非靶标茶树中的吸收、转运、分布和代谢

化学除草剂能快速抑制草害, 弥补人工除草工作效率不高的不足, 降低成本、增加效益, 在茶园中广泛应用; 其中草甘膦因其高效、广谱特性使其成为茶园除草的主要用药。近年来, 随着人们对茶饮农药残留的关注, 草甘膦的毒性作用、对生态环境的破坏、对人类健康的隐患等, 逐渐成为研究的重点。本文对草甘膦在茶园中的应用, 以及在靶标杂草和非靶标茶树中的吸收、转运、代谢机制和规律进行了综述, 以期为减轻草甘膦对非靶标茶树的药害研究提供参考, 并对草甘膦对非靶标茶树影响的研究方向做出展望。     

天然抗氧化剂对斑点叉尾鮰内脏精炼鱼油的抗氧化效果研究

以过氧化值(POV)为指标,采用Schaal烘箱法研究了D-异抗坏血酸钠、迷迭香、茶多酚对斑点叉尾鮰内脏精炼鱼油的抗氧化效果,结果表明当抗氧化剂的添加浓度为0.02%时,抗氧化性能由大到小顺序为茶多酚>迷迭香>D-异抗坏血酸钠,茶多酚的抗氧化效果与其浓度呈剂量效应关系。添加维生素C和柠檬酸对茶多酚的抗氧化效果均有协同增效作用,但维生素C对茶多酚抗氧化能力的增效略大于柠檬酸。     

Pathogenicity and production of virulence factors by Listeria monocytogenes isolates from channel catfish

Pathogenicity of four channel catfish Listeria monocytogenes isolates (CCF1, CCF4, HCC7, and HCC23) was examined in a comparative manner with virulent type strains L. monocytogenes ATCC 19115 and EGD and avirulent type strain ATCC 15313 in BDF and A/J mice. Isolates HCC7 and CCF1 (both serovar 1) caused similar percent mortalities and 50% lethal concentration values when compared with virulent type strains and were therefore considered pathogenic. The presence of the virulence factors listeriolysin (LLO), phosphotidylcholine-phospholipase (PC-PLC), and phosphotidylinositol-phospholipase (PI-PLC) was determined using specific activity tests. The virulent catfish isolates were positive for production of LLO, PC-PLC, and PI-PLC. However, catfish isolate HCC23 was not virulent in mice despite being hemolytic, suggesting that not every hemolytic L. monocytogenes strain is virulent. With the exception of HCC7, all virulent strains displayed enhanced LLO production in a special stress medium, whereas almost undetectable LLO activity was present when catfish isolates and virulent type strain L. monocytogenes were grown in a rich medium such as brain heart infusion. Avirulent strains were found to lack or have decreased expression of LLO, PC-PLC, or PI-PLC.     

斑点叉尾鮰内脏粗鱼油的精制及其理化指标和脂肪酸组成的分析

斑点叉尾鮰内脏粗鱼油通过脱胶、脱酸、脱色、脱臭工艺精制后,外观澄清透明,略显淡黄色,并有淡淡的鱼腥味,除碘价低于我国水产行业精制鱼油的一级标准(SC/T 3502-2000),其它各类指标均符合精制鱼油的一级标准。对脂肪酸的组成和含量进行分析,斑点叉尾鮰内脏精制油含有19种脂肪酸,主要是由C14～C22组成,其中饱和脂肪酸6种,单不饱和脂肪酸5种,多不饱和脂肪酸8种,其含量分别为20.37%6、5.20%和13.66%。∑n-3/∑n-6的比值也较为合理,表明斑点叉尾鮰内脏精制油的脂肪酸组成有利于人体健康。     

Factors controlling the bioavailability of ingested methylmercury to channel catfish and Atlantic sturgeon

The bioavailability of ingested methylmercury (CH3Hg(III) was investigated in vitro using the gastric and intestinal fluids of channel catfish, Ictalurus punctatus, and Atlantic sturgeon, Acipenser oxyrinchus. Gastric fluid collected from each species was incubated with CH3Hg(II)-spiked sediment or bloodworms, after which the intestinal fluid of each species was added and incubated further. The proportion of CH3Hg(II) solubilized from bloodworms and sediment appeared to be controlled by complexation to amino acids in both the stomach and the intestinal fluids during the digestive process,with the more thorough digestion of bloodworm organic material enhancing CH3Hg(II) solubilization. A greater proportion of CH3Hg(II) was solubilized by the sturgeon fluids compared to the catfish fluids, especially for the sediment incubations. These differences corresponded to the relative amount of amino acids in the fluids of these fish. A comparison of the catfish gastrointestinal solubilization incubations and a CH3-Hg(II) bioaccumulation experiment with bloodworms revealed that the solubilization incubations may be a reasonable surrogate measurement of the bioavailability of CH3Hg(II) to fish. Overall, it appears that digestive processes is the most important controlling factor in the bioavailability of CH3Hg(II) to fish.