即食龙虾仁制品的研制

以龙虾仁为原料,PET/AL/PP复合蒸煮袋作包装材料,对即食龙虾仁制品的制作工艺和制品主要栅栏因子-水分活度(Aw)的调控进行了研究.旨在开发出一种即食的龙虾仁制品,它有良好的非制冷耐贮藏性,且避免了高温杀菌给产品带来的不利影响.     

不同干燥方式下鮰鱼片的干燥特性及风味变化

本文以鮰鱼为原料,研究了不同干燥方式对鮰鱼干燥特性的影响,并利用气相离子迁移色谱(GasChromatographyIon MobilitySpectrometry,GC-IMS)、电子鼻、电子舌以及氨基酸自动分析仪等技术,对不同干燥方式对鮰鱼片风味进行了分析。结果表明,真空冷冻干燥的鮰鱼片收缩率最小,为5.44%,显著低于其他三种干燥方式(p<0.05),且其复水速率最快,用时最短;热风干燥的鮰鱼片硬度最大,达1929.70 g,与其他三种干燥方式之间有显著性的差异(p<0.05);真空干燥使得鮰鱼片的L*值为最小,a*值和b*值最大,使鮰鱼片呈现焦糖色,而真空冷冻干燥的L*值最高,a*值和b*值最低,使鮰鱼片呈现白色;热风干燥和微波干燥的鮰鱼片气味比较相似,热风干燥和真空干燥处理的鮰鱼片的滋味比较相似,而真空冷冻干燥气味和滋味都区别于其他三种干燥方式;热风干燥和真空冷冻干燥的甜味氨基酸含量分别比苦味氨基酸含量高51.97 mg/g和67.66 mg/g;微波干燥和真空干燥的苦味氨基酸含量分别比甜味氨基酸含量高3.56 mg/g和6.11 mg/g。因此,真空冷冻干燥对鮰鱼片的干燥特性影响最小,且风味有区别于其他三种干燥方式。     

不同解冻方式对熟制小龙虾理化特性的比较分析

本文比较了超声解冻、微波解冻、静水解冻、空气解冻、冰箱解冻和低压静电场解冻对带壳和去壳小龙虾理化性质的影响。以熟制小龙虾为原料,通过分析解冻时间、解冻损失率、持水力、硫代巴比妥酸值（thiobarbituric acid reactive substances,TBARS）、总巯基含量及微观结构指标,考察6种解冻方式对熟制小龙虾理化性质的影响。结果表明,6种不同的解冻方式中,微波解冻所需时间最短,而冰箱低温解冻时间最长,去壳小龙虾的解冻时间显著短于带壳小龙虾解冻时间。采用6种不同解冻方式解冻的带壳小龙虾的解冻损失率均显著低于去壳小龙虾,其中超声解冻的去壳虾肉解冻损失率最高（11.14%）。不同解冻方式对小龙虾虾肉的理化性质有显著影响,虾肉持水力、TBARS值和总巯基含量测定结果表明低压静电场解冻效果较好;经微波解冻和超声解冻的去壳小龙虾肉中总巯基含量较低（分别为0.47和0.54 μmol/g）,表明虾肉蛋白质氧化程度较高;空气解冻的小龙虾肉的TBARS值较高（去壳和带壳小龙虾肉分别为0.30和0.28 mg/kg）;扫描电镜结果显示小龙虾经低压静电场解冻后,肌肉组织结构完整性保持最好。说明冷冻小龙虾采用4 ℃低温解冻（冰箱解冻、低压静电场解冻）,更有利于其品质保持。本研究对冷冻小龙虾的综合利用提供一些理论依据。     

几种淡水虾中铅镉含量的测定

在KI-HCl-H3PO4-抗坏血酸-酒石酸钠介质中，采用二阶导数示波极谱法可得Pb^2 、Cd^2 的灵敏极谱峰，波峰电位分别为-53V和-0．67V。线性范围为0．02～6μg/ml Pb(Ⅱ)]和0．01～4μg/ml[Cd(Ⅱ)]。最低检出限0.01μg/ml Pb(Ⅱ)]和0．005μg/ml[Cd(Ⅱ)]。应用本法测定了几种常见淡水虾中的Pb^2 、Cd^3 的含量，回收率在90．2％～103．4％。实验结果表明：重金属离子的含量与虾生活的环境有关而与种类无明显相关关系，且虾各组织中重金属离子的含量也不同。     

Recognition of Dominance Status By Chemoreception in the Red Swamp Crayfish, Procambarus clarkii

We tested the hypothesis that chemical signals play a role in the recognition of dominance status in the red swamp crayfish, Procambarus clarkii. Dominance was judged on the outcome of dyadic interactions in all male or female groups of three individuals. This resulted in a dominant, intermediate, and subordinate individual within each population. A choice paradigm in a flow-through Y maze was used to judge whether crayfish were able to recognize dominance through chemical cues alone. Both individuals that interacted with the animal producing the odor and naive individuals were tested. Irrespective of sex and previous experience, individuals increased their rates of locomotion in the presence of conspecific odor. Naive males investigated the dominant arm first, spent more time at the dominant nozzle, and responded more aggressively (as measured by meral spread) to dominant male odor and subordinate female odor. Intermediate males spent more time at the dominant male nozzle and responded more aggressively to dominant male odor. Naive females spent more time at the dominant nozzle. These results show that males recognize dominant animals. Since both naive and experienced males respond to water from dominant animals, we concluded that this is recognition of dominance and not just individual recognition. This signal may be important for the formation or reinforcement of dominance relationships. Based on the change in behavior between odors, we suggest that crayfish can use chemical cues to recognize the dominance status of conspecifics.     

A Decade after Invasion: Evaluating the Continuing Effects of Rusty Crayfish on a Michigan River

In 2004, we revisited a Michigan stream invaded by rusty crayfish (Orconectes rusticus) to determine if this species continued to expand its downstream range and negatively impact the stream food web. Compared to a 1992 study, we predicted that rusty crayfish would increase in density and downstream distribution from a small lake, resulting in further reduction of in-stream resources such as organic matter, benthic invertebrates, and periphyton. To determine current crayfish distributions and impacts, we conducted a longitudinal survey of crayfish abundance, ran a 28-d leaf breakdown experiment, and sampled benthic substrates. Leaf packs of sugar maple (Acer saccharum) leaves were placed at three sites with differing crayfish densities (high, intermediate, and none). Breakdown rates were compared across the three sites and for two treatments (closed leaf bags excluding crayfish and open bags allowing crayfish access). Benthic invertebrates were sampled from leaf bags and invertebrates and periphyton were sampled from cobbles. In contrast to 1992, we found that the maximum downstream distance of rusty crayfish declined from 4 km to less than 3 km downstream from the lake. Leaves in open bags decayed significantly faster (k = 0.143) than did leaves in closed bags at all sites (k = 0.079) (p = 0.0005). The site lacking crayfish had significantly higher densities of invertebrates compared to both high and intermediate crayfish density sites (p = 0.005). Although we found that rusty crayfish reduced standing stocks of leaves and invertebrates, we did not detect measurable changes in periphyton biomass. Therefore, rusty crayfish have not dispersed further downstream since 1992, but where present, these omnivores significantly reduce resource availability via the consumption of leaf material and benthic invertebrates.     

Chemical detection of “self” and conspecifics by crayfish

Stimulus waters were used to examine behaviorally chemical communication in female crayfishProcambarus clarkii. Animals detected conspecifics. Response to stimulus water drawn from the animal's own tank, self water, mimicked either response to distilled water or response to water drawn from the tank of another animal. The response to self water depended on the relative concentration of substance(s) in self water stimuli to that of the same substance(s) in the test animal's tank.     

Chemical Defenses of Freshwater Macrophytes Against Crayfish Herbivory

We measured feeding preferences of the crayfish Procambarus clarkii for fresh tissue from four species of freshwater macrophytes (Habenaria repens, Saururus cernuus, Ceratophyllum demersum and Typha angustifolia). We then determined the role of plant chemical defenses in generating these preferences by incorporating crude aqueous and organic extracts from each species into palatable foods and comparing feeding on these foods to feeding on control foods lacking these extracts. Tissue toughness, dry mass and ash-free mass per volume, and percentages of carbon, nitrogen, and phenolics were also measured for each of the four macrophytes. Although it had a low nutritional value, Ceratophyllum was the preferred food when it was offered as fresh tissue; it did not produce a chemically deterrent extract. The lipophilic crude extract from Typha significantly deterred crayfish feeding, but this highly nutritious plant was preferred when offered in an agar-based diet lacking structural defenses. Habenaria and Saururus were low preference foods that did not appear to be structurally defended; each species contained both lipophilic and water-soluble extracts that significantly deterred feeding. Fractionation of the lipophilic crude extract from Saururus indicated the presence of at least three deterrent compounds. From the orchid Habenaria, we isolated and identified a novel bis-p-hydroxybenzyl-2-alkyl-2-hydroxysuccinoate metabolite, habenariol, that appeared to explain most of the feeding deterrent activity present in the lipophilic extract of this species. The concentration of the metabolite in frozen collections of this plant doubled if we allowed the material to thaw before placing it in extraction solvents.     

超声辅助酶法提取虾黄油脂及其脂肪酸组成分析

以克氏原鳌虾虾黄为原料,研究超声辅助酶法提取其油脂的工艺,并运用气相色谱（gas chromatography,GC）法分析其脂肪酸组成。虾黄油脂提取的优化条件为水料比3∶1 （ mL/g）、添加质量分数0.6%的复合蛋白酶、在52 ℃条件下、用150 W的超声波处理125 min,虾黄油脂的提取率可以达到77.86%。提取的虾黄油脂经GC分析,检测出从C14～C24共26 种脂肪酸,其中饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸占脂肪酸总量的相对含量分别为40.67%、31.47%和27.92%,ω-3和ω-6系列脂肪酸占脂肪酸总量的9.68%。