Mechanical Properties of Corn-Legume Based Extrudates

The effect of extrusion conditions, including feed rate (2.52–6.84 kg/h), feed moisture content (13–19% wet basis), screw speed (150–250 rpm), and extrusion temperature (150–260°C) on the mechanical properties of corn/legume-based extrudates was studied. White bean and lentil were used in mixtures with corn flour at a ratio of 10:90 up to 90:10 (corn:legume). Simple power models were used to correlate breaking stress and corresponding strain with extrusion conditions and material characteristics. The influence of feed rate on the extrudates mechanical properties was incorporated in the mean residence time. The breaking stress of extrudates decreased with temperature, residence time, and corn to legume ratio, and it increased with feed moisture content. The corresponding strain showed an opposite trend. Screw speed did not affect the extrudate properties. The use of lentil flour led to a product with higher breaking stress. Furthermore, in a previous work, the porosity of these products was modeled and, now, it was found that breaking stress and porosity of the extrudates could be correlated by an exponential relationship.     

Structural Properties of Corn-Based Extrudates Enriched with Plant Fibers

Structural properties, such as apparent density, true density, expansion ratio, and porosity, of extruded corn grits enriched with plant fibers were measured. The effect of extrusion conditions, including feed rate (0.7–1.9 g/s), feed moisture content (13–19% wet basis), and extrusion temperature (150–230°C) on structural properties of corn-based extrudates enriched with apple and oat fibers was studied. The ratio of the two fibers to corn flour was ranging from 10 to 30% (fiber/corn). A simple power model was used to correlate porosity with extrusion conditions and material characteristics. Porosity of extrudates was found to decrease with temperature, feed moisture content and fiber to corn ratio, and to increase with feed rate for both the examined fibers. Generally, the addition of fibers led to more dense products. Comparatively, the usage of apple fiber in mixtures for the production of snacks led to a product with higher porosity than those with oat fiber.     

Physical,Functional, and Sensory Characteristics of Cereal Extrudates

Eleven cereals were processed in a twin-screw extruder to produce directly expanded extrudates. Physical and functional properties (gelatinization degree, bulk density, expansion ratio, water absorption index, water solubility index, and sensory characteristics (hardness, crispness, and bowl life) of cereal extrudates were determined. Relationships among different variables were analyzed by SPSS. Gelatinization degree positively and negatively correlated to starch and protein, respectively (p ≤ 0.01). The same relationship was observed with water absorption index at the same significance level. Water solubility index positively correlated to protein (p ≤ 0.05), negatively correlated to starch (p ≤ 0.01), amylose (p ≤ 0.01), and fat (p ≤ 0.05). Density and bowl life positively correlated to fat (p ≤ 0.01) and amylose (p ≤ 0.05), respectively. Gelatinization degree had a high correlation with water solubility index (p ≤ 0.05). As gelatinization degree increased, water solubility index decreased. Crispness positively correlated to bowl life (p ≤ 0.01).     

Functional and Structural Properties of Corn,Potato, and Cassava Starches as Affected by a Single-Screw Extruder

The aim of this study was to identify suitable starch sources that can improve the structural integrity of plant protein-based extruded feeds, specifically aquatic feeds. Extrusion trials were performed, using a single-screw extruder. Extruder temperature, screw speed, and moisture content were varied in a factorial design with a replicated central composite point. The effects of these variables on functional and structural properties of the extrudates were evaluated. Temperature had the dominant effect on all properties. Increasing extruder temperature resulted in notable increases in onset temperature of gelatinization and glass transition temperature of all extrudates. The lowest water absorption, alkaline viscosity, and the highest water solubility, in addition to the lowest Rapid Visco Analyzer profile were found for corn starch extrudates. The lowest thermal stability was observed for the potato extrudate. It is expected that cassava and potato starches can contribute better in the formation of a cohesive structure and the generation of more expanded extrudates, specifically in the production of aquafeed. The higher enthalpy transition of corn extrudates indicated the higher thermal stability of corn starch which can lead in production of more durable aquafeed extrudates.     

Physical and Processing Characteristics of Extrudates Made from Starch and d-Limonene Mixtures

In this study we examined the effect of d-limonene level of addition (0–0.5 g/100 g mixture) on the properties of starch processed through a twin screw extruder operated at different barrel temperatures (125–145°C). Limonene retention increased with increasing levels of addition, but was low overall (average recovery of 8.0%). The limonene level affected extruder torque and extrudate expansion ratio. Both decreased to a minimum at 3% d-limonene addition, but increased at higher levels of addition. The effect on extruder operation and extrudate properties was attributed to interaction between d-limonene and starch through the formation of inclusion complexes.     

山黄麻作为造纸原料的基础评价

本研究对产自云南省西双版纳1.5年生的山黄麻（Trema orientalis）进行制浆造纸基础评价。结果表明,山黄麻的木质部纤维平均长度接近1.2 mm,综纤维素和酸不溶木素的含量分别为78%和21%。采用硫酸盐法制浆,在最高蒸煮温度160℃、NaOH用量21%、升温时间90 min、保温时间90 min的条件下,细浆得率为52.7%,再经氧脱木素-二氧化氯-过氧化氢加氧气强化的碱抽提（ODEop）短程漂白后,其纸浆得率99.6%,白度85.0%,漂白浆的抗张指数为79.0 N·m/g、耐破指数为5.15 kPa·m²/g、撕裂指数为5.81 mN·m²/g。     

Mechanical and Structural Properties of Expanded Extrudates Produced from Blends of Native Starches and Natural Fibers of Henequen and Coconut

The aim of this research was to evaluate the effects of barrel temperature (130‐180ºC), feed moisture (14.6‐24.5%) and fiber content (0.0‐15.0%) on the physicochemical and structural properties of starch‐derived loose‐fill packaging materials (LFPM). Two blends were analyzed: one of corn starch and henequen fiber (Agave americana) (CS‐HF), and the other of potato starch and coconut fiber (PS‐CF). An experimental laboratory extruder with a 2.9 mm internal diameter die‐nozzle was used, and a hybrid central composite design was employed to study the LFPM, and the influence of some extrusion variables on mechanical properties, i.e. tensile strength (ϵ),stress (σ), flexion modulus (E_f), and structural properties; expansion index (EI), water absorption capacity (WAC), crystallinity by X‐ray diffraction, viscosity profiles and scanning electronic microscopy (SEM). In both extruded blends feed moisture was the most significant variable, increasing the values of EI and ϵ, and decreasing the values of σ and E_f when the feed moisture was decreased. The blend of PS‐CF had the highest values of EI, ϵ, σ and E_f,, and is the more appropriate for the preparation of LFPM. X‐ray diffraction analysis of the LFPM samples suggested the formation of almost completely amorphous structures, similar to those of commercial LFPM prepared from polystyrene. This research indicated that blends from natural sources like corn starch with henequen, and potato starch with coconut fibers have the potential to be used in the preparation of LFPM with similar characteristics to commercial LFPM, with the additional advantage of being biodegradable.     

原料大米特性与米粉产品品质关系的研究

对17种大米原料及其所加工成的米粉品质进行了分析,并对大米原料特性与米粉的加工性能、烹煮性能和感观品质之间的相关性进行了探讨,确立了米粉的原料标准。结果表明：大米直链淀粉含量与米粉的蒸煮品质、搓粉散粉质量和综合评价显著正相关;大米胶稠度、糊化等级与米粉的断条率显著正相关,与搓粉散粉质量和成品含水量显著负相关。大米直链淀粉含量、胶稠度和糊化等级等可以作为米粉原料标准的主要指标。     

植物蛋白肉的原料开发、加工工艺与质构营养特性研究进展

植物蛋白肉以植物蛋白质为主要原料,通过重塑蛋白质的解离聚合行为形成类肉纤维结构,同时添加油脂、色素、粘合剂等非动物来源食品配料,加工定制出接近真实动物肉的形态色泽与风味口感。由于能够有效解决肉类供应不足问题,食品安全性高、生产方式绿色可持续,植物蛋白肉作为肉类替代食品发展迅猛,受到食品工业的广泛关注。本文将对植物蛋白肉所用的蛋白质等原料组成、挤压法等加工工艺开发以及成型产品的质构特性与营养组分研究进行综述,以期为国内植物蛋白肉的生产研发与应用推广提供参考。     

Thermal Properties of Raw Hemp Fiber as a Loose-Fill Insulation Material

The article presents the possibilities of using hemp fiber as a loose-fill insulation material. The article presents the results of research concerning raw hemp fiber obtained from the Polish crop of industrial hemp of Bia?obrzeskie variety. The analysis involved evaluation of thermal conductivity in function of bulk density and air permeability, the properties important for insulation materials. The results of laboratory investigation were used to create the numerical simulation models of heat transfer in the frame wall partitions filled with hemp fibers. The study showed that with the increase of bulk density, the thermal conductivity and air permeability of material decrease. The obtained lambda values are comparable with the characteristic values for conventional thermal insulation materials. The results of heat transfer and temperature distribution reveal that hemp fibers characterize with strongly air permeance, what affects on the need for additional barriers against air filtration.     

玉米原料酒精厂液化糖化工艺

介绍了国外３种液化糖化工艺，比较了优缺点，对我国酒精工业中液化糖化工艺的改进，提出了笔者自己的看法     

挤压改性绿豆粉对小麦粉加工及其面条品质特性的影响

研究了添加挤压改性绿豆粉对挤压改性绿豆-小麦混合粉粉质特性、面团流变特性和所制备面条品质的影响。首先采用双螺杆挤压机处理绿豆粉,随后将挤压改性绿豆粉以不同添加量(10%~60%)添至小麦粉中,制备面条。然后采用粉质拉伸仪、RVA黏度仪、流变和质构仪对混合粉的粉特性、面团流变性能以及面条的质构特性进行分析。结果表明,随着挤压改性绿豆粉添加量的增加,绿豆-小麦混合粉面团的形成时间、稳定时间、粉质质量指数急剧下降,混合粉的粉质特性明显降低,且与小麦粉相比,混合粉的起始糊化温度、峰值黏度、谷值黏度、最终黏度、崩解值及回生值呈明显的下降趋势;随着挤压改性绿豆粉添加量的增加,混合粉面团的G'和G″降低,面团的网络结构受到破坏;对于挤压改性绿豆-小麦混合面条,随着挤压改性绿豆粉添加量的增加(<40%时),其干物质吸水率和损失率有所提高,蒸煮面条的硬度、弹性、胶粘性、咀嚼性和回复性有所降低,综合感官评分降低,当挤压改性绿豆粉添加量≤ 20%时,整体可接受度接近小麦面条。最后分析三者之间的相关性发现,挤压改性绿豆粉的添加量、挤压改性绿豆-小麦混合粉的粉质特性、黏度特性与其制作面条的品质有明显的相关性。综上所述,挤压改性绿豆粉的添加改变了小麦面团的特性和面条的品质,其添加量不宜超过20%。     

Material Properties and Glass Transition Temperatures of Different Thermoplastic Starches After Extrusion Processing

Four different starch sources, namely waxy maize, wheat, potato and pea starch were extruded with the plasticizer glycerol, the latter in concentrations of 15, 20 and 25% (w/w). The glass transition temperatures of the resulting thermoplastic products were measured by Dynamic Mechanical Thermal Analysis (DMTA). Beside mechanical and structural properties also the transition temperatures of the materials were evaluated during tensile and impact tests. Above certain glycerol contents, dependent on the starch source, a lower glass transition temperature T_g resulted in decreased modulus and tensile strengths and increased elongations. Lowering the T_g at different glycerol contents did not influence the impact strength. When the amylose/amylopectin ratio increased a decrease in T_g was found. For pea, wheat, potato and waxy maize starch the T_g was 75 °C, 143 °C, 152 °C and 158 °C, respectively. Therefore products with higher percentages of amylose are more flexible. The shrinkage of the specimens made by injection molding was considerable compared to the specimens made by pressing.     

竹浆造纸污泥的特性及资源化利用

分析了造纸污泥的特性,包括含水率、有机物含量、pH值、干污泥中纤维含量、干污泥中灰分含量、湿污泥中纤维长度及分布、干污泥中C、H、N元素含量、污泥灰分中金属离子含量等。结果显示,污泥含水率较高,有机物含量大,其中大多是纤维,pH值为中性;污泥中纤维长度较短,大部分（约66%）纤维的长度在0.20 mm以下;污泥中蛋白质含量不高;污泥中有毒重金属含量低于国家标准。同时,对造纸污泥的资源化利用进行了探讨。     

Viscoelastic Behaviour and Microstructural Modifications in Acrylic Fibres and Yams as a Function of Textile Manufacturing Processing Conditions

Tensile tests on acrylic yarns and fibres extracted from various steps of textile processing reveal mechanical and thermal modifications due to the manufacturing operations. To examine this, viscoelastic modelling based on mechanistic models for fitting experimental data of tensile tests were investigated. Crystalline/amorphous distribution was assessed by the differential solubility technique, and the models account for changes in property values due to microstructure modifications.     

Chemical, Physical and Sensory Characteristics of Peanut Milk as Affected by Processing Conditions

The influence of processing conditions on chemical, physical and sensory characteristics of aqueous extracts of peanuts (peanut milk) prepared for lactic bacterial fermentation was investigated. Soaking peanuts in 1.0% NaHCO₃ before extraction resulted in a lighter colored milk, and homogenization enhanced lightness. Cooking peanuts before grinding reduced total solids and protein contents of milk. Hexanal concentration was greatly reduced by cooking peanuts for 10 min. The most satisfactory conditions for preparing peanut milk consisted of soaking peanuts in 0.5% NaHCO₃, cooking for 10 min and homogenizing the extract at 4000 psi.     

果胶酶酶解预处理对马铃薯泥干燥特性及生粉加工特性的影响

为提高马铃薯生粉的干燥效率,考察了果胶酶酶解预处理不同时间(60~180min)对马铃薯泥热风干燥特性及制备的酶解马铃薯生粉(pectinase-treated native potato flour,PNPF)理化性质和加工特性的影响。结果表明:果胶酶酶解处理降低了马铃薯泥果胶含量和初始含水量,提高了薯泥干燥速率,干燥时间缩短了6.32%~7.81%;果胶酶酶解预处理制备的生粉中果胶、灰分、蛋白质含量显著降低,直链淀粉、支链淀粉和总淀粉含量显著提高,淀粉相对结晶度和生粉碘蓝值降低;同时酶解预处理制备的生粉与未处理生粉相比,具有较高的溶解度和溶胀度,持油性显著降低,持水性提高了40.49%~49.58%,冻融析水率降低了26.23%~62.11%,其中酶解预处理180min制备的生粉(PNPF180)冻融稳定性提升幅度最大;糊化特性分析结果表明,PNPF峰值温度降低,峰值时间缩短,崩解值上升,最终黏度和回生值下降。果胶酶酶解预处理可改善马铃薯泥热风干燥特性,缩短干燥时间,同时显著改善马铃薯生粉基本理化性质及加工特性。     

超声辅助2,2,6,6-四甲基哌啶-1-氧自由基催化制备绿豆氧化淀粉及其结构与性质分析

以绿豆淀粉为原料,次氯酸钠为氧化剂,2,2,6,6-四甲基哌啶-1-氧自由基(2,2,6,6-tetramethyl-piperidine-1-oxyl,TEMPO)为催化剂在超声作用下制备绿豆氧化淀粉并对其结构性质进行分析。通过单因素试验,确定氧化淀粉制备最佳工艺条件为氧化剂物质的量与淀粉含有葡萄糖单元物质的量比1.5∶1、反应pH 8.5～9.0左右,在此工艺条件基础上研究超声处理对于氧化淀粉结构与性质的影响。结果表明:超声频率25 kHz时,淀粉氧化度最高,粒径最小;扫描电子显微镜观察结果显示,原淀粉颗粒光滑完整,氧化淀粉颗粒破碎缩小,表面出现孔洞及凹陷;傅里叶变换红外光谱结果显示在1 613～1 637 cm^-1出现了明显的羧基吸收峰,说明淀粉被成功氧化;X射线衍射结果显示与原淀粉相比,氧化淀粉的衍射峰及位置都没有变化,淀粉晶型未改变;淀粉经氧化后,黏度、粒径、Zeta电位、溶解度、透光率等性质发生较明显变化,利于绿豆淀粉的应用。     

以大豆糖蜜为原料高产乙醇酵母的筛选鉴定及其发酵特性研究

从大豆糖蜜中进行高产乙醇酵母的筛选和鉴定,并对其发酵特性进行研究。从大豆糖蜜中通过菌种的富集分离,TTC平板法初筛,耐乙醇能力及乙醇发酵能力的测定,筛选出一株乙醇产量达9.07%(V/V)的菌株P14。通过个体形态、菌落特征、生理生化及26S rDNA D1/D2区序列分析将菌株P14鉴定为酿酒酵母。研究了大豆糖蜜浓度及添加氮源和无机盐对酿酒酵母P14发酵生产乙醇的影响及酿酒酵母P14对大豆糖蜜中低聚糖的利用,结果表明大豆糖蜜浓度、添加氮源和无机盐对乙醇发酵影响显著,最佳的大豆糖蜜浓度为40%,添加氮源为1.2 g/L的蛋白胨;补加的无机盐为0.4 g/L MgSO4。在此培养基中发酵72 h后,糖蜜中90.10%的葡萄糖,91.23%的蔗糖,92.56%的棉籽糖和96.97%的水苏糖被酵母利用。因此大豆糖蜜中筛选出来的酿酒酵母P14具有较强的利用大豆糖蜜中的大豆低聚糖发酵产生乙醇的能力。     

Mechanical Properties of Pear as a Function of Location and Orientation

Abstract

This study provides data on the fundamental mechanical properties of pear tissue and its relationship with specimen orientation and location. The compression tests were performed on Dangshan pear using the Instron Universal Testing Machine. The values of failure stress, failure strain, failure energy, and Young's modulus on the specimen orientation and location in pear were obtained. The four mechanical properties are significantly affected by specimen orientation, latitude, and depth, but not affected by the longitude of the specimen.