Twin-Screw Extrusion Modification of a Corn Fiber and Corn Starch Extruded Blend

Surface response modeling was used to characterize the effect of extrusion processing on the functional properties of corn fiber/corn starch formulations. Process parameters evaluated included screw speed (200-500 rpm), temperature (90-150°C) and pH (3-11). Generally, the water holding capacity of starch increased with increasing extrusion temperature while the water holding capacity of the fiber decreased with increasing extrusion temperature. The foam stability decreased, while the residual moisture increased, with an increase in fiber concentration. X-ray diffraction profiles indicated that extrusion did not affect fiber crystallinity. No significant changes in the ratio of soluble to insoluble fiber were found as a result of extrusion.     

双螺杆挤压机操作参数变化对谷物产品特性的影响

对食品双螺杆挤压机的操作参数与挤出过程及谷物产品特性之间的关系作了试验研究。通过改变螺杆转速、进料速率这两个变化因素,研究模头压力、模头处物料温度、主机电流、产品膨化度、产品水溶性指数、产品吸水性指数等指标的变化规律,建立有关数学模型并进行分析。     

Shear Conversion of Corn Meal by Reverse Screw Elements during Twin-Screw Extrusion at Low Temperatures

Corn meal was extruded in a twin-screw extruder to study effects of one and two reverse-screw elements on conversion at extrusion temperatures > 60°C. Significant conversion was observed across the reverse-screw elements. The conversion was due to shear alone, since thermal effect was negligible at these low temperatures. Encompassing the reverse-screw elements were four visually distinct zones characterized by the state of the material.     

Effects of Calcium Hydroxide and Screw Speed on Physicochemical Characteristics of Extruded Blue Maize

ABSTRACT: The effects of calcium hydroxide and screw speed on expansion, pasting, crystallinity, torque, water absorption, and solubility indices upon extruded blue maize meal products were studied, using a central composite experimental design. All the characteristics measured presented a significant quadratic regression model, indicating relationship between the responses and extrusion conditions. It was found that the expansion, crystallinity, torque, water absorption, and solubility indices decreased and the Rapid Viscosity Analyzer's (RVA) pasting characteristics increased with the increase of calcium hydroxide concentrations. The Pearson correlation indicated that the responses presented strong correlation (r > 0.7, p < 0.01) between them. Extruded products with physical appearance and expansion similar to the control were found at concentrations lower than 0.1% of calcium hydroxide.     

Evaluating Energy Consumption and Efficiency of a Twin-Screw Extruder

ABSTRACT: Using the results from twin-screw extrusion of corn meal, both energy consumption and extruder efficiency were found to be significantly correlated with screw speed and specific feeding load (SFL). An increase in the SFL decreased the total specific mechanical energy, but increased the extruder efficiency. SFL influenced the extruder efficiency more than the screw speed. Increasing the screw speed from 300 to 450 rpm at a constant SFL level increased the extruder efficiency by 6 to 11%, whereas an increase of SFL from 0.0026 to 0.0038 kg rev ¹ raised the extruder efficiency by 30%. Of the mechanical energy consumed per unit mass of extrudate, over 98% were used for shearing or viscous dissipation and less than 1.5% were for pumping during twin-screw extrusion of corn meal.     

Degradation of Wheat Starch in a Single Screw Extruder: Characteristics of Extruded Starch Polymers

Wheat starch was processed in a 19 mm diameter, single screw extruder to study the physical and structural modifications that occur during extrusion cooking. Structural modification of the starch polymers was investigated using gel permeation chromatography (GPC), enzymatic digestions and dilute solution viscometry. Both the GPC and intrinsic viscosity results showed that the average molecular size significantly decreased as a result of extrusion processing. The relative amount of material excluded by Bio-Gel A150m was considerably lower for extruded samples than for unprocessed wheat starch and this size reduction of the amylopectin fraction was attributed to mechanical rupture of covalent bonds. The characterization of the structural modifications of the starch polymers is reported.     

膨化玉米粉制糖技术研究

研究了膨化玉米粉的液化、糖化和精制方法,获得了膨化预糊化、中温酶液化、筛滤法麸质分离的玉米制糖新工艺。结果表明,膨化玉米粉可使淀粉液化收率提高7.82%,糖化时间缩短16.7%,糖化最终DE值达97.4。与湿法淀粉制糖工艺相比,新工艺可降低生产成本约20%,是一条节能、节水、环保、综合效益好的制糖新技术。     

操作参数对双螺杆挤压机挤压效果影响的研究

通过实验研究了荞麦、黑米、薏米三种谷物的混合物料为原料时,双螺杆挤压机的螺杆转速、物料湿度、机筒温度三种操作参数对双螺杆挤压机的挤压膨化效果（以糊化度衡量）的影响。依据可旋转中心组合实验设计及实验数据建立了相关的统计模型,通过对响应面和等高线的分析,得出了三种操作参数的最佳取值范围。本实验研究对于开发谷物膨化食品、探索双螺杆挤压机加工谷物原料的挤压机理具有重要的现实意义。     

Effects of Extruded Sugar Bagasse Blend on Yogurt Quality

Extruded blends (EB) of whey protein concentrate 35 (WPC 35)–corn starch–sugarcane bagasse with 0%, 25%, and 50% substituted yogurt formulations were evaluated for some functional characteristics. Yogurts substituted with EB showed higher viscosity and lower syneresis index than that without EB. During storage for 48 h, the syneresis values of yogurt with and without EB decreased. The pH values and color differences (ΔE) decreased slightly in the yogurts formulated with EB. However, the color differences were not statistically significant (p > 0.05) and were also acceptable to the judges. In general, yogurts substituted with EB at different levels had sensory attributes of taste, acidity, texture, and viscosity scores similar to those observed for yogurt with no EB. Scores of yogurts were not affected significantly with substitution of EB at all the levels.     

正交实验法分析薪棒螺旋挤压热成型工艺及优化

通过正交试验研究了成型温度、原料含水量、挤压压力和挤压滞留时间对薪棒的密度、表层松散程度、各截面层致密度情况及表层炭化程度的影响，发现压力、含水量与温度是影响薪棒质量的3个重要因素。通过对实验结果的分析，为薪棒质量缺陷的消除和参数的设定提供了有益的参考。     

Effects of Product Formulation, Processing, and Meal Composition on In Vitro Estimated Iron Availability from Cereal-Containing Breakfast Meals

The effects of breakfast cereal composition, breakfast cereal processing, and breakfast meal composition on relative iron availability from breakfast meals were estimated using an in vitro method. Addition of wheat bran and germ to cereals and meals reduced iron availability. Presweetening caused a slight increase in iron availability. Comparisons among meals containing cereals that were similar except for type of processing showed that processing may affect iron availability. Addition of orange juice to breakfast meals caused a dramatic enhancement of iron availability. Ascorbic acid fortified apple and grape juice increased iron availability but the effect was small compared with the orange juice effect. Studies with purified organic acids showed that ascrobic and citric acids present in the juices caused the observed enhancement of iron availability. Citric acid was a more potent enhancer than ascorbic acid.     

玉米蛋白深加工现状及发展趋势

玉米蛋白粉作为湿法生产玉米淀粉的下脚料,来源广泛,价格低廉,对玉米蛋白进行深加工可以提高其附加值。文中介绍了玉米蛋白的主要组成成分、营养价值,重点综述了国内外玉米蛋白深加工的新方法和新工艺,包括加工生产醇溶蛋白、玉米分离蛋白以及具有多种保健功能的玉米蛋白肽等。     

Functional and Biochemical Alterations of Fish Meal,Soybean Meal,and Distillers Dried Grains with Solubles as Affected by a Single-Screw Extruder

The goal of this study was to investigate the effect of extrusion-forced structural changes on the extent of functional and biochemical changes of three selected protein sources that are predominantly used in aquafeed, i.e., fish meal (FM), soybean meal (SBM), and distillers dried grains with solubles (DDGS). The samples were individually extruded in a single-screw extruder using a factorial design with replicated central composite points at a temperature of 80, 110, and 140 °C; screw speed of 80, 150, and 220 rpm; and moisture content of 150, 225, and 300 (g/kg). Extrusion temperature and feed moisture significantly affected the nitrogen solubility in water (NSI), sodium dodecyl sulfate, and 2-mercaptoethanol solvents. Screw speed had only a minor effect on this value (P?<?0.05). Solubility results indicated that the contribution of hydrophobic and ionic interactions were more significant than that of the disulfide bonds, particularly for FM and SBM extrudates. For all extrudates, the highest peak viscosity was observed at the highest temperature and lowest screw speed. Extrusion processing led to considerable increase in T _g of 79 % and 67 % for the DDGS and SBM samples, and a reduction of 19 % for the FM sample, respectively. Extrusion processing increased relative protein digestibility (RPD) of the SBM extrudates the most, followed by those of DDGS and FM. Overall, the severity of the extrusion conditions adversely affected available lysine content (AL) and L* color score, but relatively increased RPD of the extrudates. SBM extrudates had the lowest reduction in AL. Despite the decrease in AL, the results for both plant-based protein extrudates were comparable in quality to those of FM. The outputs of this study provide viable information for feed formulator and feed technologist in feed and food industries.     

Enhancing an Extruded Puffed Snack by Optimising Die Head Temperature,Screw Speed and Apple Pomace Inclusion

Extrusion cooking is recognised as a smart technology for food processors. It requires low cost, high temperature, short-time process and few ingredients to create a puffed snack. The only drawback is that it contains multiple parameters that need to be rigorously trialled to develop an optimal process. This study investigated the effects of two extruding parameters (die head temperature and screw speed) and examined the addition of apple pomace into a corn flour-based extruded snack formulation. A response surface design was utilised. A D-optimal design was chosen, which generated 21 combinations; within these combinations, the control formulation existed. Extrudate characteristics, i.e. bulk density and porosity, textural properties, cooked starch properties and moisture, were analysed. Screw speed was found to have the greatest effect on extrudate quality, e.g. bulk density increased as the screw speed increased (p?<?0.001). Both apple pomace addition and screw speed impacted expansion ratio; as they increased, expansion decreased (p?<?0.0001). The optimised and validated formulation contained the following parameter levels: 7.7 % apple pomace, 150 °C die head temperature and a screw speed of 69 rpm. As apple pomace and corn flour are naturally gluten free, the extruded product would appeal to people who suffer from intolerances, allergies and coeliac disease.     

不同处理方式下膨化玉米粉的冲调性能分析

该研究以膨化玉米粉为原料,分析磷酸化、酶处理、食用胶干热和复合处理对膨化粉吸水性指数、水溶性指数、分散时间、结块率、黏度、粒径和色度的影响。结果表明,磷酸化热处理对膨化粉黏度无显著影响;食用胶干热处理黏度增加;酶处理及其与磷酸化、食用胶干热复合处理吸水性指数和黏度显著降低,水溶性指数大于磷酸化和食用胶干热处理。α-淀粉酶处理粉的水溶性指数从30.4%增至80.98%,吸水性指数从4.96降至1.21。黄原胶α-淀粉酶、α-淀粉酶正磷酸钠复合处理膨化粉结块率分别为1.63%、1.46%,低于正磷酸钠、α-淀粉酶、中性蛋白酶、黄原胶干热处理粉结块率,分别为5.57%、5.60%、6.16%、5.58%,两种复合处理方式下黏度较稀,分别为83.33 mPa·s、100 mPa·s;正磷酸钠、黄原胶干热处理黏度分别为2243.33 mPa·s、306.33 mPa·s,正磷酸钠联合中性蛋白酶处理黏度、结块率分别为546.67 mPa·s、4.89%,黏度适中,结块率低于单一处理,此时分散时间、粒径分别为4.81 s、131.14μm,呈淡黄色。综合分析,正磷酸钠中性蛋白酶复合处理下膨化米粉冲调...     

膨化玉米对断奶仔猪肠黏膜形态和腹泻的影响

通过2个饲养试验,研究了膨化玉米对断奶仔猪肠黏膜形态和腹泻的影响.试验一分别用普通玉米和膨化玉米为主要能量原料的饲料饲喂断奶仔猪做2种处理,每个处理6个重复,定时观察猪只排粪情况和粪便性状.结果表明,膨化玉米可显著降低断奶仔猪腹泻率和腹泻指数.试验二分别用普通玉米和膨化玉米为主要能量原料的饲料饲喂断奶仔猪做2种处理,每个处理6个重复,分别在断奶后第14天和第28天各屠宰1头公猪.取十二指肠、空肠前、中、后段以及回肠做组织切片,观察其黏膜厚度、绒毛高度、隐窝深度和绒毛宽度.结果表明,断奶后14 d,与普通玉米组相比,膨化玉米组显著提高了十二指肠的绒毛高度,显著降低了空肠中段的隐窝深度,显著增加了十二指肠、空肠前段、后段和回肠的黏膜厚度.断奶后28 d,与普通玉米组相比,膨化玉米组显著增加了十二指肠的黏膜厚度.     

挤压剪切活化对添加耐高温α-淀粉酶脱胚玉米淀粉结构和理化特性的影响

本研究通过偏光显微镜、扫描电子显微镜、热台显微镜、X射线衍射、差示扫描量热分析、傅里叶变换红 外光谱分析等手段,研究原脱胚玉米、挤压脱胚玉米和添加耐高温α-淀粉酶挤压脱胚玉米的淀粉结构及性质变化, 并探究其相互关系,揭示挤压剪切活化对脱胚玉米的淀粉颗粒机械力化学效应。研究表明：与原脱胚玉米和挤压脱 胚玉米相比较,挤压处理对添加耐高温α-淀粉酶脱胚玉米的淀粉结构及性质产生显著影响,酶解力和糊化度增大,碘 蓝值、直链淀粉含量减小。添加耐高温α-淀粉酶挤压脱胚玉米淀粉颗粒形貌破坏,偏光十字破坏,结晶度变小;升温糊 化过程中,焓变降低;挤压使淀粉颗粒的结晶结构破坏,淀粉颗粒发生聚集,破损淀粉颗粒易糊化和裂解。     

Effects of Heat and Fermentation on the Extractability of Minerals from Soybean Meal and Corn Meal Blends

Autoclaving (121°C for 30 min) soybean meal reduced phytate phosphorus by 17.5%; phosphorus soluble in 0.03N HCl decreased 27.1%, and iron decreased 17.2%. Heat treatment increased (P < 0.05) extractability of zinc and potassium (soluble in 0.03N HCl) in soybean meal. A natural lactic acid fermentation of corn meal decreased phytate phosphorus by 77.8% and increased phosphorus soluble in 0.03N HCl by 37.9%. Phosphorus and iron from corn meal soluble in 0.03N HCl decreased in quantity when soybean meal was added. There was little difference in the % magnesium, zinc and potassium soluble in 0.03N HCl whether in corn meal or corn meal-soybean meal blends.     

加工参数对挤压膨化食品膨胀度的影响

膨胀度是衡量挤压膨化食品品质的一个重要指标.首先介绍了膨胀度的表示方法,然后详细论述了挤压设备、原料特性和挤压操作条件对膨胀度的影响.