连续式弹簧刷去鳞机的研制与试验

为了满足淡水鱼批量去鳞加工的需要,以前期对去鳞方法的研究结果为依据,经过方案论证,研制出了连续式弹簧刷淡水鱼去鳞机。该设备首次将弹簧去鳞刷应用于去鳞设备中,采用了两对压辊和去鳞辊组合的设计方案,实现了连续式的去鳞加工。对体长500 mm的鲢鱼去鳞,其理论生产率达到2 941尾/h,理论度电产量达到1 540尾/(kW.h)。去鳞效果试验结果表明,对鲢鱼的去鳞率平均值为61.7%,对鳊鱼为65.7%,对鲫鱼为72.2%。     

菲律宾蛤仔清洗分级整机设计及参数优化

针对捕捞后菲律宾蛤仔清洗不彻底、分级精度低、破损率高、效率缓慢等难题，本研究设计了一种菲律宾蛤仔清洗分级一体机以实现菲律宾蛤仔清洗与分级作业。确定了毛刷辊配合高压喷淋的清洗方法、滚筒式筛分的分级方式，完成了滚筒筛筛分机构、高压水喷淋结构等关键部件设计、选型。开展了清洗分级一体机作业参数的EDEM离散元仿真分析。仿真结果显示：当毛刷辊转速3 r/min、滚筒筛转速15 r/min、滚筒筛倾角3°时，分级精度为91%。经过样机作业测试，在此参数下分级精度达到91%,蛤仔破损率在1%～2%之间，其壳体附着泥沙冲洗干净。研究表明，该清洗分级一体机实现了对菲律宾蛤仔的高效率、高品质的清洗分级。     

新型滚筒式贻贝清洗设备设计

为了提高贻贝清洗工序的自动化程度和清洗效果,降低工人劳动强度,设计了一种集打散和清洗工序为一体的新型滚筒式贻贝清洗设备,利用摩擦清洗方式代替当前使用的振动清洗方式,清洗后的贻贝表面附着物和足丝连接更少,该设备提高清洗加工自动化程度和降低加工人员配置的同时,设备占地面积更小。采用Solidworks软件和Simulation模块对设备进行三维建模和相关零部件的有限元仿真,并对该设备进行样机制作和相关试验。结果显示:清洗过程中,贻贝破损数量和滚筒转速成正比,清洗所用时间和滚筒转速成反比,结合破损数量和清洗时间两曲线,确定滚筒最佳转速为30 r/min,最佳清洗时间为32s,清洗速度为375颗/min(约25 kg/min)。该设备对发展贻贝船上加工模式具有借鉴意义。     

丁香酚对罗非鱼的麻醉效果

对罗非鱼进行丁香酚药浴实验,研究丁香酚药浴浓度、药浴时间以及鱼体规格对麻醉效果的影响。结果表明:在10~120mg·L-1范围内,随着丁香酚药浴浓度的增加,罗非鱼麻醉时间逐渐缩短,苏醒时间逐渐增长,罗非鱼麻醉复苏率均为100%;丁香酚药浴浓度为45mg·L-1时,罗非鱼可以在3min内麻醉,5min内苏醒,为最适药浴浓度。在最适药浴浓度条件下,丁香酚对罗非鱼的麻醉效果与鱼的规格无相关性,且药浴时间超过120min,罗非鱼复苏率呈降低趋势,浸泡时间达到300min时,罗非鱼的死亡率为100%。     

丁香酚对罗非鱼麻醉效果的初步研究

为研究丁香酚对罗非鱼的麻醉效果,用体长(27.00±0.05)cm的罗非鱼进行了麻醉试验。结果显示,在水温25~27℃条件下,当丁香酚浓度在20~200 mg/L时,麻醉所需的时间与麻醉剂浓度呈负相关,而复苏时间与麻醉剂浓度呈正相关;在丁香酚浓度为50 mg/L的药液中药浴20 min,罗非鱼复苏所需的时间为3~4 min,在理想的复苏时间范围内;但随着药浴时间的延长,以及在空气中暴露时间的延长,深度麻醉的罗非鱼复苏所需的时间增加,且复苏率降低。试验结果表明,丁香酚是安全、有效的罗非鱼麻醉剂,其浓度在50~100 mg/L时,麻醉效果最佳,罗非鱼1~2 min即进入麻醉状态,麻醉后的罗非鱼3~4min复苏,可满足常规实验操作的需要。     

回转式活鱼分级与计数设备的设计与试验

为解决工厂化养殖水池中存在鱼苗精准化分级筛选和计数机械装备欠缺的问题,设计了一种用于活鱼幼苗分级和计数的回转式活鱼分级计数设备。通过吸鱼泵将鱼从待分级养殖池塘中抽吸到回转式活鱼分级计数装置,首先将鱼苗分级成3种规格,再通过管道内的计数装置统计各规格鱼苗个数,然后将不同规格的鱼苗放入各自养殖池塘中。分级规格参数可通过触摸控制面板调节。按照鱼体背部宽度分级,可分级的活鱼为背宽1~30 mm,精度1 mm;分级装置安装有变频电机,通过触摸屏可调节回转装置转速,调节范围6~15 r/min。选用虹鳟鱼进行试验,鱼背宽度9~26 mm。结果显示:当转速为8 r/min时,最大偏差2 mm;分级产量为9 600~14 400条/h,分级误差率4.4%~5.5%,计数误差率2.5%~4.5%。该装置可较好地满足工厂化养殖水池活鱼同时分级和计数的要求。     

牡蛎清洗试验研究与清洗设备设计

分别采用毛刷、高压水、超声波对牡蛎进行清洗,以去除杂质比重为主要指标,探讨几种方式对牡蛎清洗效果的影响,初步确定最佳清洗参数。结果表明:毛刷、高压水、超声波都能够对牡蛎进行有效清洗。模拟人工冲刷式实验最佳工艺条件为:滚刷转速20 r/min,高压水压力8 MPa,流量15 L/min,时间2~5 min;超声波清洗实验最佳工艺条件为:低频(26 KHz),处理时间5 min。此系列工艺条件下牡蛎无死亡,生态冰温保活9 d后,存活率达到95%以上。以试验参数为基础,设计一种集三种清洗方式为一体的组合式牡蛎清洗设备。     

河蟹去壳设备的设计与关键部位仿真分析

针对河蟹人工壳肉分离劳动强度大、效率低下且蟹肉易污染等问题,设计了一套河蟹去壳设备。根据河蟹的形体特征及物理特性,设计了可夹持河蟹的弹簧夹具;使用切割的方法对河蟹去背甲机构进行了设计;基于气压原理对蟹黄分离装置进行了设计;基于高压水喷射原理设计了除蟹鳃装置;并基于柔性体受压理论设计了一种仿生蟹身壳肉分离装置。为确定蟹黄气压分离装置和蟹身壳肉分离装置的最佳工作参数,以蟹黄移动距离和蟹身运动轨迹为指标分别对蟹黄气压分离装置和蟹身壳肉分离装置进行仿真试验。仿真结果显示:当气流速度为1 m/s时,可使蟹黄移动50 cm以上距离,能实现蟹黄的分离和收集;当挤压滚筒转速为30 r/min时,可使蟹身完成挤压从而分离蟹肉。该设计和研究将为后续的性能优化与提高提供参考和依据。     

鲜活海参清洗工艺试验研究

为了解决海参前处理加工环节中的清洗问题,通过引入气泡清洗技术,研发一种新型的适用于鲜活海参清洗新工艺。试验研究发现,气泡清洗能对海参周身体表进行有效的、低损伤、全方位的洗涤,而清洗强度（通入清洗水体的气流量）与清洗时间是海参清洗的重要工艺参数,并与气泡清洗后海参的洗净率和损伤率呈正线性关系。通过试验初步确定：当清洗强度为15 m^3/h,清洗1 min,海参的洗净率可达90%,而损伤率仅为5%。     

日本蟳精子超低温冷冻保存技术的研究

以精子存活率作为评价指标,采用两步降温法研究了稀释剂、抗冻保护剂和预冷时间对日本蟳精子超低温冷冻保存效果的影响。结果表明:以采用稀释剂II、15%二甲基亚砜(DMSO)作为抗冻保护剂的保存效果最佳。在液氮中保存24 h后,精子存活率可达83.76%,保存一年后可达73.81%。精液的第一次预冷时间以25 min为宜。     

Can bycatch in a flatfish gillnet fishery be reduced with rectangular mesh?

Gillnets fished in North Carolina, USA, estuaries have high rates of bycatch relative to the target catch of southern flounder, Paralichthys lethostigma Jordan & Gilbert. This study tested whether rectangular‐mesh gillnets would maintain catch rates of southern flounder and reduce fish bycatch relative to conventional diamond‐mesh gillnets in two North Carolina estuaries. In the Neuse River estuary, catch rates of legal southern flounder were not different between the two mesh shapes, but the bycatch of red drum, Sciaenops ocellatus (Linnaeus) and other fish species was reduced with rectangular‐mesh net. In the Newport River estuary, southern flounder and red drum catches were reduced in rectangular‐mesh net, but the decrease was greater for red drum. Catches of sublegal southern flounder were reduced in the rectangular‐mesh net in both estuaries. Reduced catch rates of sublegal southern flounder and bycatch species suggest rectangular mesh may help manage stocks of estuarine fish species in areas where gillnets are used to target flatfishes.     

Design and evaluate a drum screen filter driven by undershot waterwheel for aquaculture recirculating systems

Micro-screen rotating drum filters are an alternative to sand filtration especially when excessive waste water is a concern. The filtering process of drum screen filters is very simple, yet very efficient and reliable due to their overall design and operation. Drum filters are designed with few moving parts to ensure a long life with low operating/maintenance costs.Micro-screening essentially captures particles on a screen fabric while letting the water pass. This paper describes a design of two an industrial-scale drum screen filters driven by undershot wheel and its performance installed in recirculating aquaculture system culturing tilapia at El-Nenaeia fish farm. These filters are consisted of a woven metal mesh of 100 μm. The design criteria for solids loading rate in the influent water is 10 kg m⁻² min⁻¹.The results indicate that the design parameters of the filter such as surface are and rotation speed were affected by the water flow rate, where the surface area and drum speed ranged from 1.58 to 27.87 m², and 1.05 to 8.40, respectively. The results also indicated that the efficiency of filter decreased during the first two months compared to the last two months of fish growth period, with an average 34.22 ± 8.85% during the first 60 days and an average 52.41 ± 16.77% during the last period. Using water wheels for driving the screen filter is very important in saving energy, where the filter with such dimensions needs 1.0 hp for driving it, which represents 18.0 kW daily.     

速冻温度对罗非鱼片品质的影响

通过测定不同冷冻方式冻罗非鱼片的理化指标,试图找到最优处理方式,并为冻罗非鱼片工厂化生产提供参考。通过设置双螺旋冷冻机不同的冷冻温度(-35℃、-38℃、-41℃、)冻结新鲜罗非鱼片,将冻结后的鱼片置于-18℃的冷库贮藏,每隔7 d对鱼片样品的pH、水分活度(Aw)、质构参数、挥发性盐基氮(TVB-N)等物理及化学指标进行检测并分析结果。数据表明,冷冻温度对鱼片色差值、失水率、硬度有较大影响,且冷冻温度越低,鱼片品质越好,对咀嚼性、弹性、TVB-N影响不大,对pH则无明显影响。综上,在现有加工工艺的冷冻温度波动范围内,选择较低冷冻温度,提高冻结速率可延缓冻罗非鱼片品质劣变速度,故建议企业加工时,将冷冻温度控制在-40℃,冷冻时间控制在40 min以尽可能保持鱼片品质。     

Effects of ferulic acid on growth performance,immunity and antioxidant status in genetically improved farmed tilapia (Oreochromis niloticus) fed oxidized fish oil

A study was conducted to characterize the effects of dietary oxidized fish oil on the growth performance, immunity and antioxidant status of genetically improved farmed tilapia (Oreochromis niloticus) and to determine the role of ferulic acid on the oxidative damage induced by the oxidized fish oil. The tilapia (13.73 ± 0.31 g) were fed four experimental diets containing untreated (peroxide value, POV: 2.2 meq/kg) and highly oxidized (POV: 120.6 meq/kg) fish oil either with or without ferulic acid (0 or 400 mg/kg) supplementation for 12 weeks. From the results, the oxidized fish oil treatments increased antioxidant enzyme activities and MDA values but decreased the weight gain and the immunological parameters in tilapia. Meanwhile, the serum biochemical indices were significantly affected by the oxidized fish oil. Besides, the addition of ferulic acid partially counteracted the free radical‐induced damage and improved the health status of tilapia. In conclusion, the oxidized fish oil may induce oxidative stress, destroy liver, dysregulate lipid metabolism as well as reduce non‐specific immunity, and eventually result in growth inhibition of tilapia. The ferulic acid supplementation partially offset the negative effects of the oxidized fish oil on tilapia.     

拖网网目尺寸及其速度效应的探讨

拖网的网目大小(特别是网具前部)对拖速有直接影响，而拖速又对捕捞效率产生重要作用。从理论上说，不但存在着没有渔获效果的临界低速，而且应有一个具有良好渔获效果的最佳拖速．在渔船功率与网具尺度不变的条件下，网目大小的确定应以保证拖网达到最佳拖速为目的。网目可按下式确定：     

利用热泵装置干燥罗非鱼片试验研究

为了充分利用热泵干燥装置的优势,以罗非鱼片为试验材料,研究了干燥温度、风速、物料厚度及形状等因素对罗非鱼片干燥特性的影响,获得了不同风速、不同厚度、不同温度条件下鱼片干燥曲线。结果表明,热泵干燥过程中各因素的合理匹配能有效提高罗非鱼片的干燥速度,强化热泵干燥的良好效果。不同厚度的鱼片只有找到匹配的温度和风速条件,才能使干燥阶段达到传热传质的平衡状态,在降低临界湿含量的同时维持后期的干燥速度,避免局部干缩而影响物料品质和外观。越薄的鱼片越易找到匹配的条件,厚3 mm鱼片更容易找到匹配的干燥条件。     

加工鱼产品种类的电泳鉴定

介绍了几种鱼的白肌在乳酸脱氢酶和蛋白电泳表型上种的特异特征。链,镛,草,青,尼罗罗非鱼白肌乳酸脱氢酶的谱带数不同,活性强度亦不同;蛋白质电泳图谱的迁移率也有差异。这类特征可为加工产品的种类鉴定提供可靠判据。鱼类电泳鉴定技术的标准化及其应用将为规范鱼品加工业,检验鱼产品提供理想的检测手段。     

Effect of towing speed and net mouth size on catch efficiency in framed midwater trawls

ABSTRACT:   To investigate fish density using rigid-mouth, towed net gear, such as a framed midwater trawl (FMT), it is necessary to know the catch efficiency. The catch efficiency with an FMT is described as the rate of fish entering the net (entering rate) versus the rate of fish retention, i.e. the mesh selectivity. This study investigated the change in the catch efficiency under several towing conditions using three types of FMT of different net mouth areas (4.0, 12.3, and 16.0 m²) with the same mesh size. The catch efficiency of the FMT was evaluated by comparing catch per unit effort obtained from each towing condition. The catch efficiency of FMT varied with towing speed and net mouth area. Particularly, the effect of net mouth area on the catch efficiency was greater than that of towing speed. Additionally, under the same towing condition, the catch efficiency for large length fish was lower than that for small length fish.     

Effects of dietary animal proteins on growth and body composition of the red drum (Sciaenops ocellatus)

Two experiments were conducted to determine the nutritional value of various dietary proteins for juvenile red drum. In the first 8-week feeding trial, diets containing similar quantities of lipid, carbohydrate, available energy and ash with 35% crude protein from either lyophilized whole-body croaker (Micropogon undulatus), striated beef muscle, red drum processing waste or commercially processed menhaden (Brevoortia tyrannus) fish meal were fed to juvenile red drum in brackish (6 ppt) water along with a control diet containing lyophilized muscle of red drum. The control diet produced significantly (P<0.05) greater weight gain (WG), feed efficiency (FE), and protein efficiency ratio (PER) values than all other diets; intermediate responses were observed for fish fed diets containing protein from red drum waste and whole-body croaker, while diets containing striated beef muscle and menhaden fish meal yielded the lowest values. Some differences in tissue indices and body composition of red drum including hepatosomatic index, whole-body ash and lipid, as well as liver lipid and glycogen were induced by the various diets. In the second 8-week feeding trial, the control diet containing red drum muscle was compared with similar diets containing protein from whole-body croaker and menhaden fish meal. Again the control diet produced the greatest WG, FE, and PER values followed by whole-body croaker and then menhaden fish meal. Effects of the dietary proteins on tissue indices and body composition were limited. The excellent protein quality and low-temperature processing of lyophilized red drum muscle resulted in superior performance of red drum relative to the other evaluated protein products, and lyophilized whole-body croaker provided better performance than commercially processed menhaden fish meal.