鱼肉蛋白质热塑挤压组织化中过程参数的优化模型

挤压蒸煮处理可以改变鱼肉蛋白质的功能特性，这些改变与挤压机的操作参数是密不可分的。利用响应面分析方法讲究Clextral BC-45型双轴挤出蒸煮机的操作参数对鱼肉蛋白质进行热塑挤压组织化的影响。研究的3个操作参数分别是末段腔体温度，螺杆转速和喂料湿度，每一个变量设5个水平。测量作为组织化产物功能特性的持水性指数及质构特性，分别建立持水性与操作参数，质构特性与操作参数的回归拟合方程。研究结果表明喂料湿度、螺杆转速和腔体温度对挤出物质构的影响是不同的；持水性与操作参数，质构特性与操作参数的回归拟合力方程的相关系数R^2分别是1.000和0.933，拟合的统计模型可信度高。     

鱼肉蛋白质挤压过程中操作参数对挤出物水分含量及堆积密度的影响

研究了鱼肉蛋白质在双轴挤压蒸煮处理过程中,主要操作参数末段腔体温度,螺杆转速和供料水分含量对挤出物的水分含量和堆积密度两个物理性质的影响。研究的3个操作参数每一个变量设5个水平,测量相应挤出产物的水分含量和堆积密度,分别建立挤出物水分含量与操作参数,挤出物堆积密度与操作参数的回归拟合方程。结果表明,供料湿度明显影响挤出物的水分含量。供料水分含量、腔体温度和螺杆转速对挤出物的堆积密度都有影响;水分含量与操作参数,堆积密度与操作参数的回归拟合方程的相关系数R²分别是1.000和0.926,拟合的统计模型可信度高。     

双螺杆挤压机操作参数对膨化水产饲料物性的影响

利用Clextral BC－45型双螺杆挤压机对豆饼粉、鱼粉和玉米粉的混合原料进行挤压蒸煮生产水产饲料。通过改变螺杆转速、进料速率和进水速率来生产具有不同物性的水产饲料，并对所得到的饲料进行膨化度、堆积密度和水中稳定性指数的测定，同时对挤出物的浮性进行了观察。应用二次回归通用旋转设计进行试验方案设计及试验结果分析，建立回归方程来描述操作参数与膨化度、堆积密度、水中稳定性指数的关系。研究结果表明，螺杆转速、进料速率和进水速率均与膨化度和堆积密度有显著的相关关系，而与水中稳定性指数的相关关系不显著。应用所建立的回归方程可预测和控制挤压产品的膨化度与堆积密度。操作参数与水中稳定性指数的关系需进一步研究。表4参19     

北太鱿鱼挤压组织化工艺初步研究

以北太平洋鱿鱼加工废弃的边角料为原料,对低值水产蛋白资源组织化的挤压工艺进行初步研究。通过研究双螺杆挤压物料湿度、机筒温度和螺杆转速对挤出物组织化度和咀嚼度的影响,得出挤压工艺条件。结果表明:随着物料湿度的增加,挤出物咀嚼度呈逐渐降低趋势,当物料湿度达到40%时,组织化度达1.41,组织化效果较好;随着机筒温度的增加,挤出物组织化度呈先增加后降低的趋势,咀嚼度则呈现相反变化趋势,当机筒温度达到140℃时,组织化效果和咀嚼度均较好;随着螺杆转速的增加,挤出物的组织化度和咀嚼度有增大的趋势,但当螺杆转速继续升高,其组织化度略有下降,而咀嚼度下降明显。单因素试验优选的北太鱿鱼蛋白组织化挤压工艺参数为:物料湿度40%~45%、机筒温度130~140℃、螺杆转速20~30 Hz。     

挤压蒸煮操作参数对鱼蛋白高水分模拟产物组织化效果的影响

对高水分鱼蛋白的挤压组织化进行研究, 以双轴挤压设备操作参数中的进料水分、腔体温度、螺杆转速、进料速率和电机转速为影响参数, 挤压模拟产物的纤维化程度、硬度、弹性、咀嚼性和色泽为响应因素, 通过中心组合设计及响应面分析法, 探讨了高水分挤压重组技术对鱼蛋白模拟肉类产物特性的影响。结果表明: 首先, 高水分组织化模拟产物具有明显的天然肉类的纤维结构、方向性、弹性和口感。其次, 进料水分对产物的纤维化度、硬度和咀嚼性影响相当显著(P<0.01), 对模拟物色泽中的L^*和a^*影响显著(P<0.05), 进料水分的增加使产物的纤维化度、硬度、咀嚼性和a^*降低, 但提升产物 L^*; 腔体温度对产物的咀嚼性和a^*影响特别显著(P<0.01), 对硬度影响显著(P<0.05), 升高腔体温度会增加的产物咀嚼性和a^*, 硬度则先上升后下降; 进料速率对产物的纤维化度影响极其显著(P<0.01)。     

膨化参数对饲料淀粉糊化度和蛋白质体外消化率的影响

试验采用胃蛋白酶-胰蛋白酶两步法和β-淀粉酶法分别测定饲料蛋白质体外消化率和淀粉糊化度,探讨了膨化工艺参数对二者的影响。结果表明：物料水分含量、喂料速度、螺杆转速和机筒温度的适度增加都使淀粉糊化度、蛋白质体外消化率增大;机筒温度过高反而使蛋白质体外消化率减小。适宜的膨化条件为：调质后水分26%-30%,喂料速度30-60 r/min,螺杆转速150-250 r/min,机筒温度120-135℃。在此条件下,饲料的淀粉糊化度为90%-92%,蛋白质体外消化率为90%-92%。     

低值鱼蛋白挤压组织化模拟产品质构特性的研究

运用栅栏技术,合理设置栅栏因子,通过栅栏因子间交互作用,形成有效的防止食品腐败变质的栅栏,研发出感官、品质良好的中间水分组织化模拟食品。采用二次旋转组合试验设计方法进行试验设计,以山梨糖醇、蔗糖和食醋为栅栏因子调节参数,以产品最大剪切力为响应参数,建立3个调节参数与产品最大剪切力的回归拟合方程,同时分析感官评定值咀嚼感与仪器测定值最大剪切力之间相关性。研究结果表明,山梨糖醇、蔗糖和食醋对产品最大剪切力显示出不同影响趋势,拟合方程相关系数r2=0.8504,拟合模型具有较高的可信度;感官评定值咀嚼感与仪器测定值最大剪切力之间存在极显著的线性相关关系,可以用仪器测定值最大剪切力来判断感官评定值咀嚼感。     

海水冷却条件对鱼糜脱水温升抑制的数值模拟

在鱼糜脱水工序内增加海水冷却系统，能够对加工过程中挤压发热引起的温升起到较好的抑制作用，并可控制鱼糜出料温度，提高鱼糜品质。基于螺杆挤压脱水、温升和非均匀流换热模型，应用有限元法对挤压脱水过程中的鱼糜冷却效果进行数值模拟，比较不同海水循环方式和冷却参数对鱼糜冷却效果的影响。研究表明：在螺杆内使用一定条件的循环冷海水冷却鱼糜，平均温降可达到5℃以上。对比生产试验与数值模拟结果，数据基本吻合。     

俄罗斯鲟鱼稚幼阶段生长发育规律的研究

应用Visual Basic语言程序，对俄罗斯鲟鱼生长的系统测量数据进行回归分析计算，得出体长、体重的拟合曲线和方程，表明其体长呈直线增长，体重呈加速度增长。     

辊道式鱼类分级机的设计与模拟仿真

随着中国水产养殖业的发展，对水产养殖的机械化、智能化程度要求不断提高。针对国内目前对于鱼类分级机械研究和应用较少，人工分级工作效率低等问题，设计了1台参数可调的辊道式鱼类分级机，以构建的大泷六线鱼模型为研究对象，通过EDEM仿真开展辊轴转速、直径和倾角对分级准确率的单因素和多因素响应面试验，分析分级过程中辊轴参数对鱼体分级准确率的影响以优化其工作参数。结果显示：辊轴转速、倾角和直径均对分级准确率有显著影响。其中，辊轴转速和倾角以及转速和直径之间存在交互影响，当分级辊轴转速为3.4 r/s,倾角为7.8°,直径为2.68 mm时，分级准确率最高，准确率为90.5%。本研究为EDEM仿真方法在水产机械领域的应用提供了参考，并为鱼类分级机的设计及优化提供了新的思路。     

Effects of Particle Size and Processing Variables on the Properties of an Extruded Catfish Feed

Abstract

A catfish feed was extruded to determine how particle size, moisture content and screw speed affected the pellet durability, water stability index, and buoyancy. Increasing moisture content from 250 to 300 g/kg required less die pressure, specific mechanical energy and product temperature to produce durable pellets that were stable in water. Increasing screw speed from 200 to 400 rpm also lowered die pressure, due to a lower filled length of the extruder screw channels, but increased specific mechanical energy and product temperature; the resulting pellets had a lower apparent bulk density, but a higher degree of starch gelatinization and water stability index. Reducing particle size from 1200 to 700 m decreased die pressure and apparent bulk density, but increased product temperature, degree of starch gelatinization, pellet durability index and water stability index.     

Water‐soluble protein level in fishmeal affects extrusion behaviour,phase transitions and physical quality of feed

The aim of this research was to investigate the effect of water‐soluble protein (WSP) as a plasticizer in the fish feed extrusion process and the impact on physical pellet quality. A three‐factor central composite design was used to study the influence of the variables WSP in the feed mix, and steam and water addition in the extruder. Regression models with r² in the range of 0.862–0.976 (P < 0.001) were established for specific mechanical energy (SME), pellet hardness, cutting strength, sectional expansion index, length, bulk density, oil adsorption capacity and extrudate flow‐starting temperature (T_f). Addition of WSP had a positive effect on SME and improved the physical pellet quality, while moisture had the opposite effect. Expansion parameters showed a complex relationship and were influenced by all the studied process variables. Increase in WSP and moisture content had a comparable effect on T_f reduction. This opens up the possibility to obtain a satisfactory ‘cook’ at reduced moisture level with a potential for significant reduction of the energy consumption during drying of the extrudate. Overall conclusion from the experiment is that WSP can be used as a processing aid for the fish feed industry, serving multiple purposes as nutrient, plasticizer and binder in extruded fish feed.     

Structural and Rheological Characteristics of Alginate from Sargassum cristaefolium Extracted by Twin Screw Extruder

This study aimed to investigate the effects of process extrusion on the characteristics of Sargassum cristaefolium sodium alginate (SCSA) extracted using twin-screw extruder. Box-Behnken Design (BBD) from response surface methodology (RSM) was established to understand the effects of temperature, screw speed, and pH on the multiple-responses of alginate characteristics including intrinsic viscosity, yield, and molecular weight. The results revealed that temperature, screw speed, and pH significantly affected (P < .05) all responses. The optimum extraction condition was found at temperature of 58.18°C, screw speed of 77.99 rpm, and pH 10.11. At this condition, the response of residence time distribution was 7.07 ± 0.029 min, yield of 34.01 ± 0.12%, intrinsic viscosity of 460.13 ± 14.75 mL/g, and molecular weight of 217.94 ± 7.14 × 10³ g/mol. This alginate had mannuronic acid to guluronic acid (M/G) ratio of 0.28, and the L-guluronic acid block was 0.78, which was higher than the D-mannuronic acid block. Rheological characterization of SCSA in aqueous solution was shear-thinning pseudoplastic, and alginate gel in 1 M CaCl₂ was more elastic than liquid.     

Effect of extrusion cooking temperature on the microstructure of extruded pellets

ABSTRACT:   The microstructure of extruded pellets (EP) for fish under various extrusion cooking temperatures was studied by using a twin-shaft extruder. As the extrusion cooking temperature increased, the expansion rate increased and the bulk density of EP decreased. The liquefaction of the material started because of the increase in inner material temperature, the decrease in inner material pressure, and the decrease in main motor amperage. Thus, the microstructure of EP changed depending on the extrusion cooking conditions, that is, the extrusion cooking temperature effected greatly the liquefaction of the material. Generally, when the extrusion cooking temperature increased, the expansion rate increased, but a suitable temperature was found for a maximum expansion rate. The microstructure of the EP was caused by the liquefaction of the material and the microstructure effects on the function of EP. For example, the water holding capacity was affected by the inner bubble structure of an EP. These functions affect the character of the feed. EP produced under suitable conditions can have additional functions for feed.     

Extruder Texturized Foods from Underutilized Fish Tissue

Underutilized fish tissue alone or in combination with cereal grain flours can be processed by high-temperature-short-time (HTST) plasticating extruders to produce shelf-stable, texturized food products with a range of rheological and nutritional properties. This study has provided guidance for: (I) The design of processes for (a) expanded snack foods to be eaten from the hand with protein contents of 10 to 30%, and (b) meat extenders, or substitutes, with protein contents of 50 to 90%; and (II) The evaluation of the effects of independently controlled variables (feed composition and extruder operating parameters) on product characteristics. The primary purpose was to generate information to guide the prediction of extrudate properties from known extrusion system parameters and to determine optimal sets of extrusion conditions for given types of products.     

Performance factors, body composition and digestion characteristics of gilthead sea bream (Sparus aurata) fed pelleted or extruded diets

The effects of steam pelleting or extrusion of a commercial feed on performance of 2 g (small) and 40 g (large) gilthead sea bream was studied. In addition the apparent digestibility of diets, gastric evacuation time (GET) and trypsin and amylase activities were measured in large fish. Fish size significantly increased protein and energy productive value, body protein and lipid, liver glycogen and liver lipid, however decreased daily growth index, feed intake and feed utilization, body moisture and hepatosomatic index. Extrusion processing decreased feed intake, more strongly for small fish, and increased daily growth index, feed utilization, protein and energy productive value, body protein and lipid. Digestibility of starch and energy increased with extrusion and GET of extruded feed was double that of steam-pelleted conditioned feed (i.e. 544 min versus 284 min). Digestive enzyme activities approached maximum values after 240 min for the pelleted diet, while those of the extruded continued to increase, at higher rates for amylase than trypsin. Pelleted diet indicated higher moisture for stomach digesta, while the moisture of the intestinal precipitate indicated a higher water-binding capacity for the extruded diet. The overall results indicate a better assimilation of the extruded diet, which could result from its prolonged gastric evacuation.     

Effects of physical properties of diets on evacuation time of digesta and plasma free amino acid patterns in yellowtail

SUMMARY: The periodical changes of feed digesta contents in the digestive tracts and plasma free amino acid levels of yellowtail, Seriola quinqueradiata (average weight 690 g) were investigated at 0, 3, 6, 12, 18, 24, 30, and 48 h after feeding on three different types of diets. The diets were: (i) extruded pellets prepared using a large-sized twin screw extruder (SDP); (ii) pellets processed using a small-sized twin screw extruder (EP); and (iii) single moist pellets (SMP). Three types of experimental fish meal diets were formulated so as to have an almost similar ingredient composition, and were supplemented with crystalline methionine, lysine, and tryptophan. Digesta contents in the stomach of fish fed the SDP diet during the experimental period were highest, whereas fish fed the SMP diet were lowest, and the stomach digesta evacuation time was different for the different types of diets. This might be caused by the differences in the chemical and physical properties of the diets. The evacuation times of the feed digesta contents of the stomach influence those of the intestine. Three crystalline amino acids added to the diets seemed to be absorbed effectively into blood plasma immediately after feed intake irrespective of the diet types. Periodical changes in the plasma levels of methionine seemed to be linked to the feed digesta contents of the stomach. Therefore, it is suggested that utilization of supplemented methionine might be affected by diet characteristics which, in turn, influence the stomach digesta evacuation times.