Effect of acid concentration and treatment time on acid–alcohol modified jackfruit seed starch properties

The properties of starch extracted from jackfruit (Artocarpus heterophyllus Lam.) seeds, collected from west Assam after acid–alcohol modification by short term treatment (ST) for 15–30 min with concentrated hydrochloric acid and long term treatment (LT) for 1–15 days with 1 M hydrochloric acid, were investigated. Granule density, freeze thaw stability, solubility and light transmittance of the treated starches increased. A maximum decrease in the degree of polymerisation occurred in ST of 30 min (2607.6). Jackfruit starch had 27.1 ± 0.04% amylose content (db), which in ST initially decreased and then increased with the severity of treatment; in LT the effect was irregular. The pasting profile and granule morphology of the treated samples were severely modified. Native starch had the A-type crystalline pattern and crystalline structure increased on treatment. FTIR spectra revealed slight changes in bond stretching and bending. Colour measurement indicated that whiteness increased on treatment. Acid modified jackfruit seed starch can have applications in the food industry.     

高速混合条件下不同增塑剂对热塑性淀粉结构及性能的影响

目的:研究在一定高速混合温度下增塑剂种类对材料的结构与性能产生的影响,为今后TPS在降解材料领域的应用提供依据。方法:通过高速混合的方法制得三种不同增塑剂(甘油、甲酰胺、尿素)增塑的热塑性淀粉(TPS)样品,对保存在室温及65RH%湿度下的样品的各项性能进行测试。结果:SEM结果说明:增塑剂能在一定程度上破坏和改变淀粉颗粒的形态。XRD测试表明:甲酰胺塑化的TPS(FPTPS)和尿素塑化的TPS(UPTPS)的耐回生性能好于甘油塑化的TPS(GPTPS)。TG测试表明:三种塑化剂塑化的热塑性淀粉的热稳定性次序为甘油<甲酰胺<尿素。FTIR谱图可得出几种塑化剂与淀粉形成氢键的能力为:尿素>甲酰胺>甘油。结论:甲酰胺和尿素作为淀粉增塑剂,其塑化的热塑性淀粉的综合性能要优于甘油。     

物理化学方法在淀粉研究中应用

该文介绍物理化学方法:差示扫描量热技术(DSC),扫描电子显微镜(SEM),核磁共振 (NMR)和X-射线衍射(XRD)等技术在研究淀粉结构,糊化,老化和玻璃化转变中应用。     

物性学研究方法在变性淀粉研究中应用

该文介绍物性学研究方法,如扫描电子显微镜(SEM)、X–射线衍射技术(XRD)、差式扫描量热技术(DSC)、核磁共振技术(NMR)等在研究变性淀粉颗粒形貌、糊化特性、老化特性和乳化能力等方面应用。     

Effect of Temperature and Starch Concentration on the Intrinsic Viscosity and Critical Concentration of Sago Starch (Metroxylon sagu)

Intrinsic viscosity and critical concentration of sago starch dispersions were studied at different temperatures and presence of solutes (sodium chloride, glucose and sucrose). Ubbelohde capillary viscometer was used to measure relative viscosity. Intrinsic viscosity decreases with an increase in temperature but the critical concentration remained fairly constant over the range of temperature studied. Sodium chloride enhanced the intrinsic viscosity but sugars somehow reduced it. Critical concentration is defined as the point where the starch molecules start to entangle with each other and abruptly enhance viscosity. Sodium chloride enhanced the molecular entanglement and lowered the critical concentration.     

"起荧"翡翠的矿物学特征及光学原理研究

采用X射线粉末衍射仪（XRD）、傅里叶变换红外光谱仪（FTIR）、X射线能谱仪（EDS）和扫描电子显微镜（SEM）等测试仪器对目前珠宝市场价值较高的“起荧”翡翠样品进行了矿物学、岩石学研究,并对其“起荧”现象的光学原理进行了初步探讨。研究结果表明,翡翠（包括硬玉质翡翠和绿辉石质翡翠）的“起荧”现象与其化分成分无必要关联。翡翠发生“起荧”现象的必要条件为：1．翡翠饰品应整体或局部被切磨成弧面琢型,其弧面琢型的高度对“起荧”现象的强弱有一定的影响;2．翡翠饰品的表面抛光精良;3．翡翠的矿物颗粒大小基本上在0．05～0．14mm范围内。     

酶改性玉米淀粉表征及流变性质的研究

以玉米淀粉为原料,采用中温α-淀粉酶水解制取改性玉米淀粉.通过正交试验确定其制备工艺条件,并对此条件下得到的改性玉米淀粉进行了研究.扫描电镜观察结果表明,样品具有2～6 μm的粒径;x-粉末衍射图表明,样品保留了部分A型特征峰.以其中的一种改性玉米淀粉为代表,测定了其乳化稳定性和粘度流变特性,与原淀粉相比粘度显著的下降、油水比15/35乳化液稳定性好,可以作一种良好的食品添加剂应用于食品工业中.     

Effect of Various Chemical Treatments of Prosopis juliflora Fibers as Composite Reinforcement: Physicochemical,Thermal, Mechanical,and Morphological Properties

ABSTRACT

The present environmental regulations enforced by the government authorities have made the investigators around the globe to make use of more and more green materials particularly in composite systems. In this context, natural fibers play an important role and proven to be excellent reinforcements in polymer matrices. However, these natural fibers have got one major limitation: their incompatible hydrophilic behavior which affects their bonding with hydrophobic matrixes. Researchers over the years have come up with several fiber surface modification processes to overcome this defect. So, in this present study, the effect of various chemical treatments like alkaline, benzoyl peroxide, potassium permanganate, and stearic acid on Prosopis juliflora fibers has been discussed. These various chemical treatments on the fiber surfaces impacted on their structure, composition, and properties which were discovered through chemical analysis, Fourier transform-infrared, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and tensile testing.     

Comparative study of degumming of silk varieties by different techniques

Different varieties of silk differ from each other in their chemical composition as well as the physical, chemical and mechanical properties. Silk degumming is a primary important process, which needs to be carried out uniformly to a sufficient level to get good quality in further processes such as dyeing. In the present study, we have compared the efficiencies of five different degumming treatments for eri, tasar and mulberry silk fabrics using conventional, ultrasonic and microwave techniques. Among the various treatments, soda ash plus hydrogen peroxide and enzyme (papain) degumming recipies gave the best results in terms of weight loss and absorbency. As compared to the conventional technique, the treatments under ultrasonication and microwave enhanced the efficiency. The microwave technique was found to be superior, with the advantage of drastic reduction in treatment time, better retention of tensile strength and smooth appearance of silk. The dye uptake also increased after degumming. The molecular conformation of the different silk varieties, as estimated by FTIR spectroscopy, and the crystalline structure, as elucidated by X-ray diffraction, remained unchanged. SEM showed distinct morphological changes on degumming.     

环氧氯丙烷增塑大豆蛋白的机理研究

本文利用傅立叶红外光谱仪(FTIR)对环氧氯丙烷增塑的大豆蛋白内部分子结构进行了深入分析,利用扫描电子显微镜(SEM)对不同增塑剂增塑的大豆蛋白材料断面概貌进行了比较,总结了环氧氯丙烷增塑大豆蛋白材料表现出高强度、低吸水率和低伸长率特点的原因以及环氧氯丙烷增塑大豆蛋白的机理。     

氦气/氧气常压等离子射流处理对羊毛织物性能的影响

以氦气和氧气分别为载体和反应气体,对羊毛织物进行常压等离子射流处理.测定处理前后羊毛织物的润湿时间和表观色深K/S值,利用SEM和FTIR分析等离子体处理前后纤维表面形态和化学成分的变化.结果表明:羊毛织物经常压等离子射流处理后,纤维表面鳞片受到不同程度的破坏且粗糙度增加,纤维表面羟基等极性基团有所增加,从而使织物吸湿性和染色性得到显著改善.     

Fat Mimicking Properties of Citric Acid Treated Sweet Potato Starch

Fat mimicking properties of citric acid treated sweet potato starch were investigated in this present study. Citric acid treated sweet potato starch was prepared by treating the native sweet potato starch with 3% citric acid for 6 h at a temperature of 45°C. Dextrose equivalent value of citric acid treated sweet potato starch was 2.05%. A significant increase in amylose content was noticed in citric acid treated sweet potato starch possibly due to the lyses of amylopectin fractions. The melting temperature of citric acid treated sweet potato starch was 51.44°C, which was close to the melting point of fat. Citric acid treated sweet potato starch exhibited superior water holding capacity and in vitro digestibility. Gel strength and enthalpy (?H) of citric acid treated sweet potato starch were comparatively lower than native sweet potato starch; correspondingly, citric acid treated sweet potato starch confirmed a low pasting profile. Native sweet potato starch and citric acid treated sweet potato starch exhibited a shear-thinning behavior. Acid treatment did not alter the granule size of native sweet potato starch (≈8 µm). Hence, this study concluded that citric acid treated sweet potato starch would be used as a potential fat replacer in food preparations due to its fat mimicking properties.