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.     

Effects of feed processing conditions and acid salts on nutrient digestibility and physical quality of soy‐based diets for Atlantic salmon (Salmo salar)

Two experiments were conducted to investigate effects of feed processing conditions and potassium diformate (KDF) supplementation on apparent digestibility of nutrients in Atlantic salmon (Salmo salar) and physical quality of extruded feed. In Exp. 1, diets with raw or expander pretreated full‐fat soybean meal (FFSBM) at 100 or 120 °C were extruded at 110 °C. Expander pretreatment significantly (P < 0.05) improved the digestibility of arginine, glutamine and tyrosine in Atlantic salmon. The higher digestibility of expander pretreated FFSBM was confirmed in mink (Mustela vison). In Exp. 2, diets with defatted soybean meal (SBM) were extruded at 110, 130 or 150 °C. The results showed that increasing extrusion temperatures significantly (P < 0.05) improved the digestibility of most major nutrients and amino acids in Atlantic salmon. In general, KDF supplementation to FFSBM and SBM diets did not affect digestibility of nutrients in Atlantic salmon or mink. Expander pretreatment and increasing extrusion temperatures increased pellet expansion, while KDF supplementation reduced pellet expansion.     

HJS-90型颗粒活性炭挤出机的研制

本文分析了国内各种类型的颗粒活性炭挤出机存在的优缺点,介绍了HJS-90型挤出机的工作原理及结构设计。该机采用不等长同向旋转的双螺杆,兼有单螺杆和双螺杆挤出机的特点。试验表明,使用该机,喂料容易,螺杆自洁性好,出料均匀,生产效率高,使用寿命长。     

饲料膨化机能耗问题的研究

设计并使用一种电测方法，对饲料膨化机能耗总是进行了测定，分析和研究。探讨了膨化机主要工艺参数对功耗的影响，建立了相尖的数学模型，为其它类型膨化设施斩经济性能分析提供了一定的理论和方法依据。     

基于CFX的新型豆粕单螺杆挤出机数值模拟分析

单螺杆挤出机是加工以豆粕为原料的膨化食品行业中使用的关键设备。普通单螺杆挤出机存在混合不充分、比能耗低的缺点,为了提高其性能,运用ANSYS/CFX软件对具有三角屏障混炼元件以及反向螺纹元件的新型单螺杆挤出机的流道进行流场分析。研究分析豆粕在其流道中的运动情况,包括速度矢量图、速度流线图、宏观压力图,并和具有普通单螺杆元件挤出机进行对比分析,结果表明:新型组合式单螺杆挤出机的建压能力较好,可切断重排豆粕的速度流线,有利于豆粕更好地混合。研究结果可为单螺杆挤出机设计提供参考。     

挤压参数对组织化大豆蛋白持水性的影响

试验以脱脂低温豆粕为原料,以德国布拉本德双螺杆挤压实验室工作站（DSE-25型）为设备,研究了挤压温度、物料含水率以及螺杆构型对产品持水性的影响。结果表明：物料含水率和螺杆构型对产品持水率有极显著影响（p〈0.01）;挤压温度对产品的持水率没有显著影响;挤压温度、物料含水率和螺杆构型对产品吸水率有极显著影响（p〈0.01）。影响产品持水率程度的大小顺序为物料含水率、螺杆构型、挤压温度;影响产品吸水率程度的大小顺序为螺杆构型、挤压温度、物料含水率。产品吸水率随着挤压温度的升高而增加。产品的持水率和吸水率随着物料含水率的提高先增加,随后略有降低。与配备输送元件的构型相比,配备反向元件、齿型盘和捏合块的构型显著增加了产品的持水性。工艺参数和螺杆构型对大豆组织化蛋白的吸水率的影响相对较大,对持水率影响相对较小。产品良好的组织结构是提高产品持水性的必要条件。     

挤压膨化参数对豆粕保水性的影响

文章利用双螺杆挤压膨化机对大豆进行挤压加工,采用响应面设计方法建立模孔直径、物料含水率、螺杆转速以及套筒温度与豆粕保水性之间的数学模型。结果表明,各参数对豆粕保水性的影响由大到小依次为物料含水率(x2),套筒温度(x4),螺杆转速(x3),模孔直径(x1);经过遗传算法优化,得到高保水性豆粕的最佳参数为模孔直径14.8 mm,物料含水率18%,螺杆转速106 r.min-1,套筒温度91.5℃。得到豆粕保水性的最大值为318.99。     

Characterization of by-products of sunflower culture – commercial applications for stalks and heads

The by-products of sunflower production were characterized. The sunflower heads contain a strong smelling essential oil (EO) (0.2%) and pectins (22%). The galacturonic acid (GA.A.) content of the pectins depends on the extraction conditions (water-soluble pectins: 67%, soluble in ammonium oxalate/oxalic acid: 74%, in hydrochloric acid: 33%). They are all slightly methylated (degree of methylation (DM) <20%). The stalks may be readily separated into two parts: fiber (external part, 90%) and the pith (internal part, 10%). The mechanical properties of paper pulp obtained by thermomechanical treatment in a twin-screw extruder of the whole stalks or depithed stems were investigated. The pulps had high values of ring crush test (RCT) and concora medium test (CMT), which make them suitable for the manufacture of cardboard. Low-density materials can be also shaped with ground pith. The role of water-soluble substances in the cohesion of these materials is discussed. Its mechanical properties, which are comparable to those of polystyrene, were determined. They may find application in the packaging and packing industries.     

双螺杆挤压生产谷物早餐过程中维生素的稳定性

为了揭示维生素在谷物早餐挤压膨化过程中的变化规律,提高维生素在挤压膨化过程中的稳定性及为谷物早餐维生素强化提供理论依据,采用高效液相色谱分析法,研究了5种维生素(V—A,V—D3,V—B1,V—B2,V-B6)在谷物早餐双螺杆挤压膨化过程中的变化．结果表明,谷物早餐的组成体系和挤压膨化条件对维生素的稳定性存在关联性;谷物早餐在物料水分16％,进料量100kg／h,挤压温度700℃／120℃／140℃,螺杆转速700r／min的挤压条件下,V—D3,V—B1,V—B2,V-B6等表现出较好的稳定性,损失小于15％,但维生素A的稳定性较差,损失率超过30％;谷物早餐中的维生素含量随着进料量减小、物料水分升高、螺杆转速减慢,挤压腔体温度上升等挤压因素的变化而减小．     

颗粒饲料的水中保形和致腐性评价研究

对市售大黄鱼饵料、颗粒饲料、冰鲜鱼在水中的滞留进行相关的生化和微生物特性研究,重点对颗粒在水中的溶胀率、散失率、挥发性盐基氮(TVB-N)、BOD、COD、菌落总数进行测定。结果表明颗粒饲料的保形性比市售大黄鱼饵料要好,但由于颗粒饲料营养成分丰富,小分子物质比较多,在水中容易溶出,使得其对水质的影响较大,腐败容易发生。