鲜鱼连续冻结新工艺进行鉴定

<正> 去年11月28日,在浙江奉化通过了鲜鱼连续冻结新工艺的技术鉴定。这项新工艺是由宁波地区水产公司和奉化县海带育苗厂共同设计安装的。鲜鱼连续冻结新工艺,采用管丛隧道(或盐水盘架)连续冻结,改变了目前以冷风机为主要热交换手段的隧道式冻结装置。它具有单位产量高、电耗低、投资省、设备利用率和机械化程度高等优点。从一年多试生产的情     

重金属离子除去装置在中国对虾育苗生产中的应用

自行研制的高分子吸附剂装置，在两处中等规模的中国对虾育苗场进行了应用实验。结果表明，在其他条件一致的情况下，应用装置与使用自然海水育苗对比，卵子的孵化率平均提高１１．８％，无节幼体到蚤状幼体变态率平均提高１０．２％；应用装置与使用ＥＤＴＡ（２．０ｍｇ／Ｌ）比较，卵子的孵化率平均提高７．５％，无节幼体到蚤状幼体的变态率平均提高３．６％。     

冷却介质（盐水）连续冻结装置

法国南特的MATAL公司在七十年代研制了一种连续冻结装置。这是一种采用液体冷却介质(盐水)冻结的连续冻结装置。它可以使鱼货实现单体冻结。研究这种装置的目的是为罐头工业和冷冻工业提供一种简单、安全、快速的冻结设备。     

煤矿塌陷地小型网箱养鱼试验

１９９２年，在煤矿塌陷地进行了小型网箱养鱼试验，５０只网箱总体积３００ｍ＾３，投放全雄罗非鱼种养殖１３０天，平均净产量，１２６ｋｇ／ｍ＾３，净产值４１６元／ｍ＾３。商品率９８％，饵料系数１．７３。１９９２年１１月鉴定认为，本研究达到山东省领先水平。     

黑龙滩水库网箱养草鱼种试验

网箱投喂配合饲料养草鱼种。６月３日投放平均全长５．６ｃｍ、体重２．２ｇ的鱼种，翌年４月６日出箱，平均体重达１０３．７ｇ，增重４６倍，平均产量４０．６ｋｇ／ｍ＾２饲料系数１．８６。总成活率５９．３％，其中草鱼出血病免疫组成活率平均７４．９％，对照组３０％。本文还分析了养殖效果和影响成活率的因素。     

充气养殖中国对虾试验

在６０亩试验池中，通过充气、改善水质等措施，获得亩产对虾１５３ｋｇ，比对照池提高２６．４％；平均尾重２５．１ｇ，比对照池提高２６．１％；平均每亩利税９９９３，比对照池提高４６．３％。１９９４年３月鉴定认为，本技术属省内先进水平。     

泥鳅大规模苗种生产技术

１９９８年５月至６月间进行了泥鳅的大规模苗种培育试验。５月初首先在土池中进行培育，１０００平方米共放鳅苗１３０万尾，经半个月培育仅收鳅种５０００余尾，鳅种平均全长４．３厘米。６月初继续在水泥池中进行鳅种培育试验，水泥池面积４５０平方米，放鳅苗９５万尾，经过２０天的培育收鳅种２９．４５万尾，成活率３１％，鳅种平均全长３．４。本文总结了水泥池培育鳅种成功的经验并分析了土池培育鳅种失败的原因，提出了土地     

连续冻结装置

法国Samifi Babcook公司研制成一种船用冻结输送带型冻结装置，它可以进行连续冻结或单独冻结。这种装置可用于鱼片、扇贝、对虾等的冻结。     

加州鲈鱼苗种培育技术的探讨

１９９３年我们采用小池塘、高密度进行加州鲈鱼苗种培育，共投放平均全长２．１厘米的鱼苗６．４万尾，经一个月饲养，平均全长达５．３厘米，总成活率为８３．６％，亩培苗能力达５．３万尾。同时进行投喂不同饮料的生长对比试验；投喂鲜活淼蚤的苗种比投喂鱼浆、鱼糜的苗种生长快１．２倍，成活率高１６．６％。     

对水产冷库隧道式冻结装置设计的改进意见

目前国内水产冷库的冻结装置，除少数采用搁架式排管、盐水冻结装置及平板冻结机外，多数均为隧道式冻结装置。从冻结时间来区分，有一日一冻、一日两冻等，冷风机放置位置有落地式及吊顶式之分，吹风可分成上吹风及下吹风两类。供液方式有重力及氨泵强制循环(也有上进下出及下进上出)的区别。由于过去在设计及生产管理中，对技术经济指标的统计分析工作做得不够深入细致，     

食品的两段冻结技术

在食品冻结中采用２个蒸发温度的新技术，即在冻结的第１阶段采用较高的蒸发温度，提高制冷系数（ＣＯＰ），在第２阶段中采用较低的蒸发温度以使食品达到所需的最终冻结温度。利用卡诺定理研究该技术中的各项参数并进行优化。结果表明，通过对制冷装置的适当操作和调整可达到节能效果，最大节能值（Ｅｓ）可达３５．６％。     

冻结速率和冻藏温度对鲢肉蛋白质冷冻变性的影响

研究了冻结和冻藏温度对鲢肉肌原纤维Ca-ATPase活性和盐溶性蛋白溶解度的影响并作了冷冻切片观察，结果发现，冻结速率对具有一定细胞形态的鲢肌蛋白质的冷冻变性有一定的影响，对无完整细胞形态的碎鱼肉和鱼糜基本无影响，而冻藏温度对鱼肌、碎鱼肉和鱼糜蛋白质冷冻变性都有显著的影响，即温度越低，变性越小，而抗冻剂可有效防止蛋白质的冷冻变性，尤其是使鱼糜肌原纤维蛋白质的稳定性大大提高。     

冰点调节剂对军曹鱼冰点的控制研究

研究几种冰点调节剂对于军曹鱼（Rachycentroncanadum）冰点的影响。选取氯化钙（CaCl2）、氯化钠（NaCl）和维生素C（Vc）3种冰点调节剂,利用单因素比较法得出使用4％CaCl2浸泡处理60min可使军曹鱼冰点降至-1．21oC;用2％NaCl浸泡处理军曹鱼90min可使军曹鱼冰点由-1．01cC降至-1．36℃;使用0．5％V,溶液浸泡处理30min可使其冰点降至-1．30℃。因此选取NaCl和Vc 2种较好的冰点调节剂进行复配,再通过正交试验确定两者结合使用的最佳配比。结果显示,使用3％NaCl和0．3％V。共同处理军曹鱼60min为最佳,可使其冰点降至-1．62℃,下降了60．4％。     

Preservation of Tilapia (Oreochromis aureus) Fillet by Isochoric (Constant Volume) Freezing

ABSTRACT

The aim of this work was to evaluate the effects of isochoric freezing on the quality of tilapia fillet. Isochoric freezing was compared to chilling, super-chilling, and freezing. Isochoric freezing showed muscle color alterations similar to the other preservation methods. All preservation methods resulted in softer fillets, with the isochoric frozen fillet having the most similar texture to that of the fresh sample. Thiobarbituric acid reactive substances (TBARS) for isochoric samples were similar to those of fresh samples. However, there was a 53%, 55%, and 34% increase in TBARS for chilled, super-chilled, and frozen samples, respectively. Total volatile basic nitrogen (TVB-N) content was 1.4 times higher for isochoric samples than for fresh samples. For chilled, super-chilled, and frozen samples, TVB-N content was 3.0, 1.9, and 1.3, respectively, times higher than for fresh samples. Microstructural analysis indicated that isochoric samples showed less cell damage compared to those using other methods. Subfreezing temperatures in conjunction with no ice formation during isochoric freezing contributed to improved quality of tilapia fillet. This study may find application in the commercial preservation of fish to increase shelf life and allow for expanded distribution of raw fish. This study might also be a potential solution to “food desert” areas, where residents have low access to fresh healthy foods.     

Quality of Atlantic Cod Frozen in Cell Alive System,Air-Blast,and Cold Storage Freezers

ABSTRACT

Gutted Atlantic cod, packed in cartons, were frozen immediately after killing in a magnetic field (cell alive system). The results were compared with traditional air-blast freezing or by putting the cartons directly in a cold storage room (without forced convection of air). After frozen storage, external and fillet properties were compared. In spite of differences in freezing rates, only minor differences were found among treatments. The mechanism for the freezing of fish in the magnetic field, under the current conditions, appeared to be similar to that of traditional freezing methods.     

鱼类冷加工过程的能量匹配

以鱼类冷加工过程放热的动态特性为依据,以冷加工时间为目标函数,按照鱼体热物性非单值性特点,对冻结室温、货间风速、鱼类品别及其几何尺寸和冻结速度之间的关系进行分析研究。论证用“三段法”取代“焓差法”计算货物负荷,把最大冰结晶生成带放热量作为制冷能量配置主要依据的可行性。提出按照鱼体放热特点适时变换风速和保持室温稳定的制冷能量配置方案,以期在维持必要的冻结速度、保证冻品质量的前提下,实现节能运行之目的。     

Fuzzy-logic-based feeder system for intensive tilapia production (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>)

In high-fish-density aquaculture systems, tilapia producers are compelled to provide 100% of food required to obtain profitable growth rates. It is well known that fish have a low food conversion rate and feeding represents the most important expenditure, approximately 40% of total production cost. Therefore, precise quantities of food should be provided to avoid water pollution and economic losses due to food waste when water conditions are inadequate for fish feeding. A way to control food provisions in this work was determined by the conditions of temperature, dissolved oxygen, fish age, and body weight, since these variables have a direct effect on fish metabolism and growth. Thus, a change in metabolism is reflected in a modification of energy requirements and, as a consequence, in variations of food consumption. In this work, a new feeder with fuzzy-logic control algorithms is proposed for fish feeding; this technique allows farmer knowledge to be taken into account in a series of if–then-type rules. To define these rules the temperature and dissolve oxygen were considered in order to provide precise food quantities. The results show minimal differences in growth (P > 0.05) between treatments, important food saving of 29.12% (equivalent to 105.3 kg), and lower water pollution (reduced water dissolved solids and ammonium components) compared with timed feeders. This system provides an important contribution to sustainability of intensive aquaculture systems, increasing productivity and profitability, and optimizing water use.     

文蛤和波纹巴非蛤冷冻变性的比较研究

利用IMP热电偶测温系统及组织切片技术、食品化学特性的常用分析方法以及测定表征蛋白质变性的盐溶性蛋白溶解度和Ca2 ATPase活性,对文蛤和波纹巴非蛤在冷冻后的组织结构、食品化学特性、蛋白质变性的影响进行了比较研究。结果表明:冻结会使贝肉组织结构发生较大变化,水分流失,非蛋白氮显著增加,但冻结对贝肉蛋白质冷冻变性的影响不明显;在冻藏后贝肉蛋白质发生了较大变性。在相同冷冻条件下,文蛤在上述3方面受到的影响均比波纹巴非蛤受到的影响大,说明文蛤比波纹巴非蛤更容易发生冷冻变性。     

Assay performance during validation of freezing channel catfish Ictalurus punctatus (Rafinesque) infected with a Gram‐negative bacterium

Recovery of bacteria from infected fish during population sampling can be affected by factors including the type of assay, method of specimen preservation and concentration of bacteria present. Consequently, before use in field sampling, methods should be validated. The three objectives of this study were, first, to determine whether a channel catfish Ictalurus punctatus (Rafinesque) fingerling classified as positive for Gram‐negative Edwardsiella ictaluri infection according to bacterial culture before freezing was also classified as positive after freezing, second, to determine how direct culture from the kidney (DIRECT), culture of homogenate (HOMOG) and standard PCR (PCR) agree with bacterial culture in terms of classifying fish as positive or negative and third, to estimate diagnostic sensitivity (dSe) and diagnostic specificity (dSp) for DIRECT, HOMOG and PCR. In fresh and frozen fish, as bacterial concentration decreased, the ability of each assay to detect positive fish also decreased, especially when there were <10⁴ colony‐forming units per gram (CFU g^?1) tissue. HOMOG proved to be the most reliable at correctly classifying catfish, whether they were subclinically or clinically infected. PCR assay was the least reliable. Overall, values for this study population for dSe were 0.66, 0.92 and 0.43, and for dSp were 0.86, 0.91 and 0.95, for DIRECT, HOMOG and PCR respectively.     

Processing and Digestion of Press Juices from Different Fish Muscles; Temperature and Lyophilization Effects on Their Anti-Oxidative Properties

Press juices (PJs) from seven, mostly underutilized, fish were tested for their anti-oxidative properties. The effects of thermal processing, freezing, and lyophilization of fresh PJs on these properties were investigated. Lyophilized samples were further subjected to in vitro digestion. It was concluded that thermal processing significantly affected only the ferric ions reducing ability, while freezing affected the anti-oxidative properties of only certain species. Lyophilized samples from Dactylopterus volitans and Trachinus draco were able to delay significantly the onset of hemoglobin-mediated oxidation. Finally, the exposure of the PJs to different pH values during in vitro digestion seemed to play an important role in their 1,1-diphenyl-2-picrylhydrazyl (DPPH)% inhibition ability.