龙虾下脚料中虾油的提取工艺和性质研究

采用单因素实验和响应面优化实验对龙虾下脚料中虾油的提取工艺进行研究,并对其脂肪酸组成和氧化稳定性进行了分析。结果表明:虾油提取的适宜工艺条件为78.88%乙醇、液料比(mL∶g)6.65∶1、提取温度40℃、提取时间1h、提取2次。采用逐步回归拟合,获得虾油提取率的预测模型如下:提取率/%=10.73+0.12A+0.65B-0.072C-0.43A2-0.56B2+0.027C2-0.31AB+0.012AC-0.033BC,预测最大提取率为11.04%,实测值为10.96%。通过对精炼虾油的脂肪酸分析,共检出14种脂肪酸,以总脂肪酸含量为基数,其中不饱和脂肪酸占47.98%,饱和脂肪酸占52.02%,必需脂肪酸占17.26%。EPA和DHA含量占多不饱和脂肪酸含量的7.35%,顺式脂肪酸含量占不饱和脂肪酸含量高达95.65%,说明此虾油具有很好营养价值。氧化稳定性研究表明,虾油的诱导时间为0.86 h。     

超声波辅助提取龙虾下脚料中虾油的工艺和性质研究

采用单因素实验和响应面优化实验对超声波辅助提取龙虾下脚料中虾油的工艺进行优化,并对虾油的脂肪酸组成和氧化稳定性进行了分析。实验结果表明,虾油提取的最佳工艺条件为提取温度63.79℃、液料比9.15∶1(m L/g)、乙醇浓度76.55%、超声功率158.46 W、提取时间10 min、提取1次。采用逐步回归拟合,得到提取率对提取温度、液料比、乙醇浓度、超声功率的模型如下:提取率=9.6791+0.37A+0.05B–0.48C+0.17D+0.1AB+0.135BD+0.149 25CD–0.505 26A~2–0.37406B~2–0.660 45C~2–0.403 42D~2,此时预测提取率为9.85%,实测值为9.78%。对超声法辅助提取和单一浸提法提取的虾油精炼并进行脂肪酸分析,结果表明,超声波处理对虾油的脂肪酸组成没有显著影响。氧化稳定性研究表明,超声波法辅助提取的虾油本身的抗氧化性优于单一浸提法。此研究为虾油的物理提取方法的应用和贮存提供一定的理论依据。     

南极磷虾粗虾油提取工艺优化

研究南极磷虾粗虾油的有机溶剂提取工艺。探讨不同提取剂、提取剂混合比、提取时间、提取温度和料液比对南极磷虾粗虾油得率的影响。在单因素试验基础上,通过响应面分析确定最佳的提取工艺条件为:以正己烷+乙酸乙酯为提取剂,提取剂混合比71.3:28.7、料液比1:6.6,在57.8℃提取50min;此时粗虾油得率为14.76%。     

以虾头虾壳为原料酿制虾油的影响因素研究

文章以虾头虾壳为原料酿制虾油,采用感官评定、氨态氮( AAN)、三氯乙酸可溶性氮(TCA-N)、挥发性盐基氮(TVBN)等指标,研究温度、食盐浓度、酿制过程中pH值控制对虾油酿制的影响.研究结果表明:温度和食盐浓度太高和太低均不利于提高虾油的酿制速度和品质,偏碱性的酿制环境比偏酸性的酿制环境有利于提高虾油的酿制速度和品质,其中20％食盐浓度,酿制过程中控制pH8.0,酿制温度45℃有利于虾油酿制.     

超声微波协同提取龙虾头中虾脑油的研究

以龙虾加工虾仁产生的废弃物虾头为原料,提取剂环己烷与乙酸乙酯之比为46∶54,超声微波协同提取虾头中的油脂。试验结果为:在提取温度60℃、提取时间4 min、微波功率110 W、液料比(mL/g)5∶1、超声功率140 W时,虾头出油率为5.32%,虾头油脂的提取率达98.15%。对毛虾油的主要理化指标进行了测定,达到粗鱼油二级标准。     

对虾虾头中磷脂提取工艺的研究

为充分利用对虾加工副产物资源,采用溶剂提取法,探讨以对虾虾头为原料提取磷脂的最佳工艺和影响因素。以磷脂纯度为指标,通过单因素实验与正交实验,考察料液比、乙醇体积分数、提取时间及提取次数对磷脂提取的影响,制定出虾头磷脂的最佳提取工艺。结果表明,虾头磷脂的最佳提取工艺条件为:料液比1∶6,采用90%乙醇溶液作为提取液提取虾头2次,每次提取6 h。在最佳提取工艺条件下,虾头提取物中磷脂纯度为45.81%。该提取工艺简单、污染少、提取效率高,为低附加值海产品加工副产物的高值化利用提供有效途径。     

南极磷虾壳中虾油提取工艺优化

对比了原料不同干燥方式对虾油酸价和虾青素含量的影响,以及溶剂体系对虾油得率、磷脂得率、虾青素得率的影响。在该基础上,探究原料粉碎程度、提取温度、提取时间和料液比对虾油得率的影响,并通过正交试验优化提取工艺。结果表明:冷冻干燥法提取的虾油酸价最低,虾青素含量最高;采用95%乙醇提取,虾油、磷脂以及虾青素得率最高;以冷冻干燥、粉碎后过60目筛的虾壳为原料,95%乙醇为提取溶剂,正交优化后的最佳提取工艺为:料液比19(g/mL),提取温度50℃,震荡提取时间30 min,该条件下虾油得率(12.64±0.02)%。     

利用龙虾废弃物开发调味料的探讨

本文探讨了利用龙虾废弃物生产虾油、虾粉、龙虾酱油、虾酱的工艺流程及操作过程，以提高龙虾的综合利用效益。     

太平洋磷虾油提取工艺优化及与南极磷虾油品质的比较

采用有机溶剂浸提法,增加了乙醇复溶步骤,分别对太平洋磷虾粉以及鲜太平洋磷虾进行油脂提取单因素实验和正交实验。以虾粉为原料,用95%乙醇分别提取太平洋磷虾油和南极磷虾油,对虾油中游离脂肪酸、虾青素、磷脂及脂肪酸组成进行分析和比较。结果表明:最佳提取溶剂为95%乙醇;对于鲜虾,提取的最佳工艺条件为提取温度45℃、料液比1∶12、提取时间3 h,在此条件下油脂得率为12.99%;对于虾粉,提取的最佳工艺条件为提取温度55℃、料液比1∶10、提取时间3 h,在此条件下油脂得率为20.00%;太平洋磷虾油磷脂含量高于南极磷虾油的,为39.53%;两种虾油虾青素含量接近;太平洋磷虾油游离脂肪酸含量略高于南极磷虾油的,为9.21%;太平洋磷虾油脂肪酸种类较多,两者EPA、DHA总含量接近,南极磷虾油EPA含量较高,太平洋磷虾油DHA含量较高。     

南美白对虾虾油的提取工艺优化及影响因素研究

以南美白对虾虾头为研究对象,采用单因素和正交实验确定虾头油提取的最优条件;同时对虾头中蛋白质和含水量对虾头油提取的影响进行对比研究。结果表明:异丙醇为提取剂,虾头含水量15%,提取时间为110min,提取温度为70℃,料液比为1∶7(m∶V)。在此条件下可得到最大虾油得率为7.89%。同时脱蛋白,虾油的得率更高,达到8.00%。     

Detection of Listeria in crawfish processing plants and in raw,whole crawfish and processed crawfish (Procambarus spp.)

The foodborne pathogen Listeria monocytogenes represents a major concern to the food industry and particularly to producers of ready-to-eat (RTE) foods because of the severity of human listeriosis infections and because of the ubiquitous nature of this organism. Although several studies on the prevalence and sources of L monocytogenes in various RTE seafoods have been conducted, limited information is available on the presence and potential sources of this organism in RTE crawfish products. We thus monitored the presence of L monocytogenes and other Listeria spp. in the processing environment, in raw, whole crawfish, and in cooked crawfish meat from two processing plants. Samples were collected from the two plants throughout one crawfish season (April to June 2001) at 5 and 8 separate visits, respectively. At each visit, 6 raw, whole crawfish, 6 finished product samples (crawfish meat), and 14 mid- or end-of-processing environmental sponge samples were collected and tested for L. monocytogenes and Listeria spp. Of the 337 samples tested, 31 contained Listeria spp. Although Listeria innocua was the predominant Listeria spp. found (20 samples), four samples were positive for L monocytogenes. L. monocytogenes was detected in three raw material samples and in one environmental sample. Listeria spp. were found in 29.5% of raw, whole crawfish (n = 78) and in 4.4% of environmental samples (n = 181) but in none of the finished product samples. Among the environmental samples, Listeria spp. were found in 15.4% of the drains (n = 39) and in 5.1% of the employee contact surfaces (gloves and aprons) (n = 39) but in none of the samples from food contact surfaces. Even though a high prevalence of Listeria spp. was detected on raw materials, it appears that the heat treatment during the processing of crawfish and the practices preventing postprocessing recontamination can significantly reduce Listeria contamination of RTE crawfish meat.     

Bacteria associated with processed crawfish and potential toxin production by Clostridium botulinum type E in vacuum-packaged and aerobically packaged crawfish tails

Refrigerated vacuum-packaged storage has been shown to increase significantly the shelf life of fresh fish and seafood products, but the effect, if any, on the outgrowth and toxin production of Clostridium botulinum type E on cooked crawfish is unknown. Microflora associated with live crawfish reflect the microbial populations of the harvest water and sediments in which they are living. The presence or absence of specific pathogens in either vacuum-packaged or air-permeable bags of cooked crawfish have not been thoroughly evaluated. This study evaluates the potential survival and outgrowth of biological hazards in both vacuum-packaged and air-permeable-packaged cooked crawfish held at 4 and 10 degrees C for 30 days. During shelf-life studies of vacuum-packaged and air-permeable-bagged cooked crawfish, a total of 31 bacterial species were isolated and identified from crawfish samples using both selective and nonselective media. The only pathogens isolated from both vacuum-packed and air-permeable bags of processed crawfish samples during shelf-life studies were strains of Aeromonas hydrophila and Staphylococcus aureus. C. botulinum type E and Clostridium perfringens species were not isolated from any of the uninoculated crawfish samples. Cooked crawfish were inoculated with 10(3) C. botulinum type E spores per g of crawfish tail meat to determine whether cooked crawfish tails would support the growth of C. botulinum type E strains and produce toxin at refrigerated temperatures. Spore-inoculated crawfish tails were vacuum packaged in both a high barrier film and an air-permeable bag and stored at 4 degrees C and 10 degrees C for 30 days. C. botulinum toxin E was not detected in any of the spore-inoculated packages throughout the shelf-life study until day 30. Microbiological data from this study should be useful in the development and implementation of the hazard analysis and critical control point plans for processed crawfish tails.     

出口淡水小龙虾产品生物危害风险管理措施研究

针对出口淡水小龙虾产品存在的生物显著危害,从多方面对风险管理措施进行了评价研究,并提出了在综合运用各种风险管理措施的基础上建立和运行HACCP体系的建议。     

Chlorine dioxide wash of shrimp and crawfish an alternative to aqueous chlorine

This study compared the biocidal effect of chlorine dioxide spray with traditional chlorine wash on shrimp and crawfish tail meat. Treatments included aqueous chlorine (hypochlorite) (10–40 mg l⁻¹) and chlorine dioxide (10–40) mg l⁻¹ combined with and without a high-pressure prewash (600 psi). Standard aerobic and psychrotrophic bacteria were evaluated for up to 21 days. Samples treated with chlorine dioxide in both treatment techniques had lower aerobic and psychrotrophic counts (P<0·001) than any combination of other treatments tested. Reductions were from 1 to 4 log₁₀ (increasing as initial concentration of chlorine dioxide increased). Pressure application increased the effectiveness of both sanitizers and water wash by at least 0·5 log. Chlorine residuals of 18–51 mg g⁻¹ were present in aqueous chlorine treatment of \ge30 ppm. No chlorine residuals were present following chlorine dioxide treatments.     

抗冻剂对蒸煮小龙虾虾仁冻融后品质的影响

目的:提升冷冻蒸煮小龙虾虾仁的冻藏品质.方法:将虾仁浸泡在不同配比复合磷酸盐、海藻糖与山梨糖醇抗冻剂中,测定虾仁冻融后的解冻损失率、水分含量及分布、持水力、盐溶性蛋白、总巯基含量、质构特性并观察微观结构变化以评价各抗冻剂的效果,选择效果较好的抗冻剂作为水平因素设计正交试验优选适宜的抗冻剂配比.结果:1.5%复合磷酸盐、8%海藻糖或10%山梨糖醇具有较好的抗冻效果;复配抗冻剂组(1%复合磷酸盐+6%海藻糖+6%山梨糖醇)具有最佳的抗冻效果,在此条件下解冻损失率为9.97%,显著低于单一抗冻剂组(15.95%,17.44%,16.78%);复配抗冻剂组显著提高了虾仁与水的结合能力,较好地抑制了冻融过程中冰晶对肌肉组织的破坏.结论:复配抗冻剂组(1%复合磷酸盐+6%海藻糖+6%山梨糖醇)可有效提升蒸煮小龙虾虾仁的抗冻能力.     

Impact of intervention strategies on Listeria contamination patterns in crawfish processing plants: a longitudinal study

Two ready-to-eat crawfish processing plants were monitored for 2 years to study the impact of Listeria control strategies, including employee training and targeted sanitation procedures, on Listeria contamination. Environmental, raw material, and finished product samples were collected weekly during the main processing months (April to June) and tested for Listeria spp. and Listeria monocytogenes. Before implementation of control strategies (year 1), the two processing plants showed Listeria spp. prevalences of 29.5% (n = 78) in raw, whole crawfish, 5.2% (n = 155) in the processing plant environment, and 0% (n = 78) in finished products. In year 2, after plant-specific Listeria control strategies were implemented, Listeria spp. prevalence increased in raw crawfish (57.5%, n = 101), in the processing plant environment (10.8%, n = 204), and in the finished product (1.0%, n = 102). Statistical analysis showed a significant increase in Listeria spp. prevalence (P < 0.0001) and a borderline nonsignificant increase in L. monocytogenes prevalence (P = 0.097) on raw material in year 2. Borderline nonsignificant increases were also observed for Listeria spp. prevalence in environmental samples (P = 0.082). Our data showed that Listeria spp. prevalence in raw crawfish can vary significantly among seasons. However, the increased contamination prevalence for raw materials only resulted in a limited Listeria prevalence increase for the processing plant environment with extremely low levels of finished product contamination. Heat treatment of raw materials combined with Listeria control strategies to prevent cross-contamination thus appears to be effective in achieving low levels of finished product contamination, even with Listeria spp. prevalences for raw crawfish of more than 50%.     

影响酶法回收螯虾加工下脚料中虾青素及蛋白质的因素研究

通过测定螯虾加工下脚料中虾青素和蛋白质在不同保藏条件、预处理条件和酶解条件下的含量变化,研究了这些因素对酶法回收虾青素和蛋白质的影响。结果表明,破碎的下脚料在空气中保藏12d后虾青素残留仅37.5%,在阳光下照射3d虾青素残留18.2%,在真空、冷冻、避光的保藏条件下虾青素损失较少;酶解前预热处理蛋白质回收率可提高5%,但虾青素回收率下降5.6%;破碎后虾青素及蛋白质的回收率大幅提高,超声波处理有助于二者的回收率;酶解反应的最适条件为温度55℃,pH8.5,反应时间2h,酶底比3750U/g蛋白质。     

β-hydroxyacyl-CoA-dehydrogenase (HADH) differentiates unfrozen from frozen-thawed crawfish (Procambarus clarkii) and trout (Salmo gairdneri) meat

An enzymatic method for differentiation of unfrozen from thawed crawfish ( Procambarus clarkii ) and trout ( Salmo gairdneri ) has been developed. The method is based on the release of the β-hydroxyacyl-CoA-dehydrogenase (HADH) during freezing. The HADH activity mean values were 7.9 and 78.9 for unfrozen and thawed trout, respectively. In the case of crawfish, these values were 12 and 70 respectively. Statistical analyses showed significant differences ( P 0.001) in both species. Trout could be distinguished with a high confidence level, but for crawfish this level was slightly lower.