近红外光谱应用于高粱中总淀粉、直链淀粉与支链淀粉的定量分析

酱香型白酒以高粱为主要原料发酵而成,高粱中的淀粉,尤其是支链淀粉的含量对于酱香型白酒的产品质量起着至关重要的作用,因此针对其总淀粉、直链淀粉与支链淀粉的检测手段研究也应受到人们高度的重视。傅里叶变换近红外光谱法因其准确性高、稳定性好以及快速无损检测等特点,在建立总淀粉、直链淀粉和支链淀粉同时定量分析模型方面得到了较为成功的应用。结果表明,总淀粉、直链淀粉以及支链淀粉的定量分析模型相关系数分别达到0.954 9、0.923 6和0.940 1,交互验证均方根误差分别为1.027 1、0.088 5和1.264 6。可见,基于近红外光谱技术的定量分析方法可适用于高粱中总淀粉、直链淀粉与支链淀粉的同时定量分析。     

双波长法测定籼米中直链淀粉和支链淀粉含量

建立了双波长法测定籼米中直链淀粉和支链淀粉含量的方法.按照双波长测定的等吸收点波长法确定两种淀粉的测定波长和参比波长,直链淀粉的分别为596 nm和449 nm,支链淀粉的分别为533 nm和705 nm.直链淀粉浓度在20～60 mg/L线性良好,R=0.999 8;支链淀粉浓度在100～200 mg/L线性良好,R=0.999 7.籼米中直链淀粉和支链淀粉质量分数分别为24.2％和50.5％.     

淀粉结构对浆料性能的影响

研究直链淀粉和支链淀粉比例对浆料性能的影响。以高直链玉米淀粉和蜡质(支链)玉米淀粉为原料,运用光学显微镜、差示扫描量热仪研究了高直链玉米淀粉糊化所需要的条件;测试比较了不同比例的直链淀粉和支链淀粉混合浆液黏度、浆液黏附性能、浆膜性能等指标。结果表明:高直链玉米淀粉在130℃下糊化15min才能完全糊化;随着直链淀粉含量的增加,浆液的黏度下降,黏度热稳定性提高;浆膜的断裂强度、断裂伸长、耐屈曲性及磨耗增加,但对棉、涤棉粗纱的黏附力降低。认为浆料中直链淀粉和支链淀粉比例对其上浆性能有明显影响。     

粉葛直链淀粉与支链淀粉分离工艺研究

以粉葛为原料,对粉葛中直链淀粉和支链淀粉的分离工艺进行了研究。根据直链和支链淀粉的理化特性及结构的不同,采用正丁醇-异戊醇配合物沉淀法对粉葛直链和支链淀粉进行粗分离,再经正丁醇重结晶得到较纯的直链与支链淀粉,讨论了分离前对淀粉进行预处理、纯化次数、分离过程中离心时间对分离效果的影响。通过对淀粉-碘复合物光吸收特性分析和蓝值比较,表征分离得到的直链与支链淀粉的纯度。结果表明:直链淀粉纯化5次、支链淀粉纯化6次、分离前经过预处理、支链淀粉纯化时离心时间和速度为30min,5 000r/min的条件下,光谱分析测得的最大吸收波长和蓝值都落在直链淀粉与支链淀粉文献报道结果的相应数值范围内,表明此时分离效果最佳,正丁醇结晶法分离的直链和支链淀粉纯度较高。     

优化毛细管电泳法测定山药淀粉中直链/支链淀粉

以市售新鲜怀山药为原料通过石灰水浸泡法制备山药粉,并通过正丁醇反复结晶法分离纯化直链淀粉与支链淀粉。利用碘做显色剂,使用毛细管电泳法测定山药淀粉中直链淀粉与支链淀粉的含量以及比率,本文分别对柠檬酸-磷酸盐缓冲液以及醋酸-醋酸盐缓冲液等不同缓冲液作为流动相进行了对比,实验发现醋酸-醋酸盐缓冲液对于分离测定直链淀粉与支链淀粉的效果较好。随后分析了不同p H条件下的醋酸-醋酸盐缓冲液进行的分离效果进行了比较,并测定其迁移率,当p H 4.8时分离效果最佳且其迁移率达到15.4。利用最佳条件使用纯的马铃薯直链淀粉与支链淀粉标准品,得出支链淀粉的保留时间约为1.8 min,而直链淀粉的保留时间约为2.9 min,对怀山药淀粉进行分析,从而得出怀山药中直链淀粉含量为19.49%。利用重复性试验以及回收率试验该方法的准确性与精确度能达到很好的效果。     

直链淀粉和支链淀粉的表征

直链淀粉和支链淀粉是淀粉的两大主要组分,它们在分子结构以及分子聚集态等方面的差异导致其物化特性有所不同,具有不同直链和支链淀粉组成比例的淀粉在总体应用表现也不相同。本文通过讨论淀粉最新的研究进展,对直链淀粉和支链淀粉的纯度、分子结构、相对分子质量、晶体特性、热焓特性、黏度特性等进行综述。     

普通玉米淀粉及高直链玉米淀粉工业应用的进展

玉米籽粒中含有直链淀粉和支链淀粉两种类型,普通玉米籽粒中这两种淀粉的比例约为１∶３,高直链淀粉玉米的直支比例最高可达３∶１。玉米淀粉在食品、造纸、包装、纺织、石油等领域都有重要应用,高直链淀粉具有特有的分子结构和理化性质,因而具有独特的工业加工性能及食用、医用价值,目前在世界范围内正日益得到重视。     

直链淀粉含量及检测方法与抗性淀粉增抗效应研究

直链淀粉含量及其品质对抗性淀粉的形成有着重要的影响,采用碱液分散法和碘吸光度法测量早米淀粉、葛根淀粉、青稞淀粉、绿豆淀粉、高粱淀粉、藕淀粉6种淀粉类原料的直链淀粉含量,采用循环老化工艺增抗并测定抗性淀粉含量,结果表明,抗性淀粉的得率与原料中的直链淀粉含量有密切的关系,同时,也与各淀粉中直链淀粉和支链淀粉的分子结构、平均聚合度有一定关系,与碘吸光度法相比,碱液分散法测得的直链淀粉含量能更好地预测原料淀粉增抗后的抗性淀粉得率.     

淀粉黏度性质研究最新进展

综述淀粉黏度的测定方法,对比目前常用的布拉班德黏度计(BV)法和快速黏度分析仪(RVA)法.总结影响淀粉黏度的各种因素(包括基因、生长条件、直链淀粉含量、支链淀粉结构、淀粉颗粒大小、处理方法及植物和食品中的其它成分)以及改变淀粉黏度性质的各类变性方法,并对今后淀粉黏度性质的研究进行展望.     

荧光光谱法测定淀粉中的直链淀粉

为了建立一种荧光光谱法测定淀粉中直链淀粉含量的方法,采用荧光光谱法测定了直链淀粉的激发光谱和发射光谱以及直链淀粉与支链淀粉的浓度比对荧光强度的影响。结果表明:直链淀粉的激发波长为370 nm、发射波长为422 nm;在0.10~0.70 μg/mL浓度范围内,直链淀粉荧光强度与其浓度呈良好线性关系,相关系数r=0.9996,检出限为0.026 μg/mL。用该方法测定玉米淀粉和土豆淀粉中直链淀粉的含量,加标回收率为94.5%~121.7%,相对标准偏差(RSD)为2.42%~3.24%。该方法不需加任何生化试剂,不受时间、温度、共存支链淀粉的影响,快速简便,绿色环保,检出限低,结果准确。     

不同淀粉质对米甜酒品质影响的研究

该文对不同淀粉质大米发酵酿制米甜酒进行了研究。结果表明：淀粉支直链之比越大，米甜酒的感官品质越好；支直链之比达10．44以上时，可用作米甜酒酿造；支直链之比在6．57以下时，酿制的米甜酒开始有苦涩味。     

Effects of molecular characteristics of tea polysaccharide in green tea on glass transitions of potato amylose,amylopectin and their mixtures

Tea polysaccharide (TPS) is attracting more attention gradually in many fields due to its particular biological properties. To further elucidate the functions of TPS to starch-based foods, experiments were carried out using mixed amylose/amylopectin/TPS system as a model. The effects of TPS in green tea on the glass transition temperatures (Tgs) of the mixtures with different amylose/amylopectin ratios at low water contents were investigated using high-speed differential scanning calorimetry (Hyper-DSC). The results showed that the Tgs of amylose, amylopectin and their mixtures decrease with increasing concentration of TPS. It is suggested that the addition of TPS has plasticizing effects on the structures of amylose and amylopectin on the molecular level. Based on the molecular characteristics of TPS, the results in this study indicated that TPS is a homogeneous and spherical polymer with branch in solution, which can increase free volume and molecular movement of amylose and amylopectin chains. TPS can also produce greater electrostatic repulsion and decrease association among macromolecules, thereby resulting in the decrease of the Tgs of amylose, amylopectin and their mixtures.     

淀粉老化过程机理及淀粉抗老化剂应用的研究进展

淀粉老化是淀粉糊化过程中分解的直链淀粉和支链淀粉重新连接并形成更加有序结构的过程。淀粉老化是食品老化的主要原因,对淀粉质食品的感官、储存质量、风味等有不利影响。随着食品行业发展,延长食品货架期、保持食品原有风味及口感愈来愈重要。本文介绍了淀粉老化过程,并从老化动力学、热力学和淀粉晶体等方面探讨淀粉老化机理并综述淀粉老化机理研究方法,在此基础上,介绍抗老化剂在食品体系中的应用,为有效抑制淀粉老化,延长食品的货架期提供理论支持。     

食品添加剂对薯类食品品质影响的研究进展

随着我国"马铃薯主食化"战略的提出,薯类食品的研究开发受到重视。薯类淀粉支链淀粉含量和直链淀粉聚合度高,蛋白含量低,不易形成网络结构。添加薯类淀粉会导致食品的黏度增加,严重影响外观及口感,是薯类食品生产应用中的一个大问题。食品添加剂可以有效解决产品的感官品质差等问题,是近年研究的热点。分析总结了不同种类食品添加剂对薯类食品品质的影响,并对薯类食品未来的科学研究方向进行展望,为食品添加剂在薯类食品中的应用提供理论基础和指导意义。     

Application and Opportunities of Pulses in Food System: A Review

Pulses are highly nutritious seeds of pod-bearing leguminous plants, specifically dry peas, lentils, and chickpeas. US farmers harvest about 2.6 million pounds of pulses every year but 75% of this is being exported internationally because of its increased consumption in the developing countries. In the current scenario, increasing costs of production, bad economy, and fluctuating food commodity prices have made a strong case for US producers to seek opportunities to increase domestic consumption of pulses through value-added products. Pulses are the richest sources of plant proteins and provide approximately 10% of the total dietary requirements of the proteins world over. Pulses are also high in dietary fibers and complex carbohydrates leading to low GI (glycemic index) foods. Pulses help to lower cholesterol and triglycerides as leguminous fibers are hypoglycosuria because of consisting more amylose than amylopectin. Pulses provide tremendous opportunities to be utilized in the processed foods such as bakery products, bread, pasta, snack foods, soups, cereal bar filing, tortillas, meat, etc. These show excellent opportunities in frozen dough foods either as added flour or as fillings. Pulses in view of their nutrient profile, seem to be ideal for inclusion in designing snack foods, baby, and sports foods.     

Simultaneous,rapid, spectrophotometric determination of total starch,amylose and amylopectin

A novel spectrophotometric method for the simultaneous measurement of total starch, amylose and amylopectin in lipid-free samples has been developed using a diode-array spectrophotometer. It involves measurement of the spectrum of the amylose/amylopectin-iodide complexes at six wavelengths and calculation of amylose and amylopectin concentrations using multi-component analysis and a spreadsheet computer program. This method appears to offer some advantages to previous ‘iodine-blue colour’ assays for the measurement of amylose.     

Some Observations on the Stability of Amylose and Amylopectin in Aqueous Solution

Results are presented for a series of light-scattering experiments on the stability of the starch components, amylose and amylopectin, in 0.33 M KCl. Potato, regular maize amylose, and the amylose from two amylomaize starches have been studied. The findings are generally in agreement with previous studies in this area, but in the case of amylopectin, contrary to the findings of Čeh and Vene, no retrogradation has been observed.     

Form and functionality of starch

Starch is a macro-constituent of many foods and its properties and interactions with other constituents, particularly water and lipids, are of interest to the food industry and for human nutrition. Starch varies greatly in form and functionality between and within botanical species, which provides starches of diverse properties but can also cause problems in processing due to inconsistency of raw materials. Being able to predict functionality from knowledge of the structure, and explain how starch interacts with other major food constituents remain significant challenges in food science, nutrition, and for the starch industry generally. This paper describes our current understanding of starch structure that is relevant to its functionality in foods and nutrition. Amylose influences the packing of amylopectin into crystallites and the organization of the crystalline lamellae within granules, which is important for properties related to water uptake. Thermal properties and gel formation appear to be influenced by both amylose content and amylopectin architecture. While amylose content is likely to have an important bearing on the functional properties of starch, subtle structural variations in the molecular architecture of amylopectin introduces uncertainty into the prediction of functional properties from amylose content alone. Our ability to relate starch granule structure to suitability for a particular food manufacturing process or its nutritional qualities depends not only on knowledge of the genetic and environmental factors that control starch biosynthesis, and in turn granule morphology, but also on how the material is processed.