鲜活和死后小龙虾的冷藏特性比较

分别以鲜活和死后的小龙虾为实验对象,通过测定其在4℃冷藏和0℃冰藏期间菌落总数、pH值、总挥发性盐基氮(total volatile base nitrogen,TVB-N)含量、硫代巴比妥酸(thiobarbituric acid,TBA)值、总巯基含量等生化指标,结合感官评价和色差分析,研究小龙虾的贮藏特性.结果 ...     

高温熟制杀菌对小龙虾品质及贮藏特性的影响

以小龙虾为研究对象,采用熟制杀菌一步到位的工艺对小龙虾进行加工。通过测定不同熟制杀菌条件下小龙虾的色差、pH值、质构及感官评分变化,分析不同熟制杀菌条件对小龙虾品质的影响,确定较佳熟制杀菌工艺。结果表明：杀菌温度和杀菌时间对小龙虾产品品质有显著影响（P＜0.05）,且杀菌温度越高、时间越长,影响越大;110 ℃、10 min杀菌工艺下小龙虾的弹性、硬度、咀嚼性显著优于其他组（P＜0.05）,黄度值显著低于其他组（P＜0.05）,且感官评分最高。因此,110 ℃、10 min杀菌工艺下的小龙虾品质最好,该工艺是最优熟制杀菌工艺。同时在该工艺条件下,即食小龙虾产品4 ℃贮藏条件下的货架期为35 d。     

冷藏小龙虾优势腐败菌的筛选鉴定及细菌群落结构和多样性分析

以4℃贮藏小龙虾货架期终点筛选武汉孝感小龙虾中优势腐败菌,同时结合高通量测序方法,进一步确定小龙虾中优势腐败菌,并对小龙虾贮藏过程中菌相变化、微生物结构及其多样性进行分析。结果表明：传统培养法从腐败小龙虾中共筛选出10 株腐败菌,包括波罗的海希瓦氏菌（Shewanella baltica）、维氏气单胞菌（Aeromonas veronii）、普通变形杆菌（Proteus vulgaris）等;在属水平上,高通量测序法最终确定气单胞菌属（Aeromonas sp.）及希瓦氏菌属（Shewanella sp.）是小龙虾腐败末期相对丰度最大的2 种优势腐败菌;同时,高通量测序结果表明,随着贮藏时间的延长,小龙虾微生物群落丰富度、多样性及均匀度不断下降,这与腐败末期优势腐败菌的大量增长及生长繁殖过程中抑制其他种类微生物有关。     

Anionic Trypsins from Crayfish Hepatopancreas: Effects on Protein Degradation of Tail Meat

Four anionic trypsins, tentatively labeled trypsin A, B, C, and D, isolated from crayfish hepatopancreas, had high casein activity between pH 5.5 and 10.0. Temperature optima for hydrolysis of casein were 45°C for A and B, and 50°C for C and D. Trypsin D had the highest substrate turnover number (V_max) for casein reaction compared with the other trypsins at pH 6.8. Trypsins A and D had higher activities against myofibrilla and sarcoplasmic proteins from crayfish tail meat than did B and C. Results suggested that trypsins A and D are important in development of mushiness in crayfish tail meat compared with other trypsins present.     

基于近红外光谱技术快速检测小龙虾中的生物胺

目的 建立近红外光谱法快速检测小龙虾中总生物胺含量的方法。方法 利用近红外光谱仪采集154个不同新鲜程度小龙虾样品的近红外光谱, 使用高效液相色谱技术检测对应样品总生物胺含量; 使用KS(Kennard-Stone)算法将103个样品作为训练集, 51个样品作为预测集。采用多元散射校正(multiplicative scatter correction, MSC)、标准正态变换(standard normal variate, SNV)、小波变换(wavelet transform, WT)和1阶导数(1st)分别对样品的光谱进行处理, 利用训练集样品的光谱和生物浓度建立偏最小二乘回归(partial least squares regression, PLSR)模型, 使用竞争性自适应重加权算法(competitive adaptive reweighted sampling, CARS)进一步选择波长, 对模型进行优化。结果 经过小波变换处理之后的光谱所建立的PLSR模型具有较好的预测结果, CARS方法可以进一步提高模型的预测和解释能力, 预测集生物胺的预测均方根误差(root mean square error of prediction, RMSEP)值和决定系数(r2)分别可达55.74和0.92。结论 基于近红外光谱分析技术快速检测小龙虾总生物胺含量是可行的, 优化后的PLSR模型可以用于评价小龙虾总生物胺含量。     

小龙虾肉脯的工艺优化

本文以质构、色差、感官评分为指标,研究糖盐比、TG酶添加量、烤制温度、烤制时间对小龙虾肉脯品质的影响。在此基础上,以感官评分和硬度为响应值,采用响应面设计优化工艺条件,得到的最佳工艺参数为：100 g小龙虾肉,糖盐比7.5∶2.5（10.0 g）、TG酶添加量2.00 U/g、烤制温度145℃、烤制时间9 min,此工艺加工而成的小龙虾肉脯产品片形整齐,厚薄均匀,色泽淡红清亮,咸甜适宜,有较好的弹性,硬度、咀嚼性适中,感官评分为89.00分,硬度为540.45 N,试验结果值与理论预测值误差分别是0.84%、0.46%,模型拟合度好,试验结果可靠。     

Metal Residues in Farm-Raised Channel Catfish, Rainbow Trout, and Red Swamp Crayfish from the Southern U.S.

ABSTRACT: Farm-raised channel catfish (Ictalurus punctatus), rainbow trout (Oncorhynchus mykiss), and red swamp crayfish (Procambarus clarkii) were collected from production and processing sites across the southern U.S. and analyzed for barium, cadmium, copper, chromium, silver, lead, arsenic, selenium, and mercury. Average metal residues were much lower than recommended safety limits. Residues of barium, copper, and mercury were slightly higher in crayfish than catfish or trout. Selenium was higher in crayfish and trout than catfish, and lead was higher in catfish and trout than crayfish. Residues of mercury in all samples were much lower than the FDA's Action Limit (1 ppm) for mercury in the edible tissue of fish.     

Chemical sex discrimination in the crayfishProcambarus clarkii: Role of antennules

Chemical sex discrimination of conspecifics by male and female crayfish (Procambarus clarkii) was tested. Intact female subjects were more attentive in the presence of stimulus water from males than from females and showed more aggressive postures in the presence of stimulus water from females than from males. Intact males showed more aggressive postures in the presence of stimulus water from males than from females. Females and males with only one inner antennule ramus and one outer ramus performed discrimination and localization almost as well as intact subjects. Subjects with only the two inner rami or only the two outer rami were disadvantaged in either responding to the stimuli or localizing them. The relevance of this outcome to previous conflicting reports on the use of antennules in sex discrimination in crayfish is discussed.     

小龙虾基体中氯霉素残留降解因素分析

目的 研究温度和氯霉素初始浓度对小龙虾中氯霉素降解的影响.方法 将氯霉素初始添加浓度为0.5、5.0、50μg/kg的小龙虾阳性模拟样品放置在?18、4、25和37℃恒温条件下,分别在2、4、6、12、24、36、48 h时测定其氯霉素残留量.结果 温度对小龙虾中氯霉素降解影响较为显著(P<0.01),本质在于微生物降...     

克氏原螯虾不同可食部位风味成分分析

以克氏原螯虾为研究对象,分别测定克氏原螯虾熟制前后基本营养成分、可食组织得率的变化,运用电子鼻、固相微萃取-气相色谱-质谱联用、气相色谱-离子迁移谱（gas chromatography ion mobility spectrometry,GC-IMS）等技术结合游离氨基酸含量研究克氏原螯虾不同可食部位风味成分的变化。结果表明：克氏原螯虾的重要可食部位是尾肉与肝胰腺,且含有大量蛋白质与脂肪;其中克氏原螯虾肝胰腺熟制前后气味差异远大于尾肉熟制前后气味差异;熟制前后克氏原螯虾尾肉和肝胰腺中共检出59 种挥发性物质,结合GC-IMS分析可知,虾肉熟制后出现新的风味物质,并且一些原有物质（乙酸乙酯、丁酸甲酯和3-辛酮等）含量升高,肝胰腺熟制后挥发性有机物种类（醛类、酮类以及少量醇类和呋喃等物质）减少,含量大部分降低,也有少量物质（乙醇、丙醛、丁醛和戊醛等）含量升高;克氏原螯虾肝胰腺熟制后游离氨基酸总量明显升高,达119.63 mg/g,而尾肉熟制前后游离氨基酸总量相比肝胰腺熟制前后变化较小,但含量很高,达237.51 mg/g。