大米抗性淀粉定量测定方法比较研究

抗性淀粉测定的方法主要有Englyst法、Berry法、S.A.法和Goni法,本文通过测定不同实验处理的大米抗性淀粉,对S.A.法和Goni法进行了比较研究。结果表明,Goni法比S.A.法具有重复性好,操作简单等明显优势。无论是S.A.法还是Goni法,酶消化处理及其反应的最适pH是影响测定结果的关键因素。      

大米抗性淀粉制备工艺研究

采用酸变性和沸水浴方法，对大米淀粉进行处理，以抗性淀粉得率作为评价指标，研究了在不同淀粉乳浓度、盐酸用量、酸解时间、沸水浴时间条件下，大米淀粉形成抗性淀粉得率的变化情况；在此基础上，进行正交实验，对正交实验结果采用极差分析，得到制备大米抗性淀粉的最佳工艺条件：酸解时间2h，盐酸用量2％，淀粉与水之比1：9，沸水浴时间2．5h。     

几种测定香蕉抗性淀粉含量方法的比较

抗性淀粉具有膳食纤维所不能及的生理功能和加工特性,是近年来变性淀粉和功能食品研究的热点,其定量分析方法目前仍没有统一的标准。文中选用了3种比较有代表性的抗性淀粉(RS)测定方法:TSA法、Berry法和Goni法,对青香蕉、生马铃薯和玉米淀粉3种原料中的RS和总淀粉含量的测定进行了比较。结果表明:Goni法模拟了人体胃肠道的生理条件,具有重复性好,操作简单等明显优势而更适合于富含抗性淀粉颗粒的青香蕉原料中RS含量的测定,用该法测得的RS含量为80.12%,其中RS2占96.63%。     

湿热法制备大米抗性淀粉的研究

湿热处理是指在淀粉含水量低于35％的条件下,对淀粉进行热处理加工的过程.研究湿热处理法对大米抗性淀粉形成的影响主要是研究浓度、温度、时间三个因素对抗性淀粉得率的影响.通过实验可知,用湿热法制备大米抗性淀粉最佳反应条件为:温度110℃,处理时间为2 h,大米淀粉水分含量为20％,抗性淀粉含量为26.7％.该方法是制备大米...     

老化因素对大米抗性淀粉制备的影响

研究老化因素对大米抗性淀粉（RS）制备得率的影响效果。先将大米淀粉制成4个不同糊化度（30％：30min和60min；60％：30min和60min）的原料粉，然后选取温度、pH、老化时间，Ca^2＋添加量作为老化因素，采用四因素三水平正交设计，根据Rs得率筛选优化组合。结果是采用30％的淀粉乳（干基），糊化30rain，在中性条件下，添加1％Ca^2＋于60℃老化12h，RS最高得率达到了19％。老化因素对RS的影响为：时间〉温度〉Ca^2＋〉pH。     

大米抗性淀粉压热处理制备工艺的研究

抗性淀粉以其显著优点及特殊的生理功能,成为食品营养学的一个研究热点。以大米淀粉为原料,制备大米抗性淀粉对大米的深加工具有重要的经济意义。以抗性淀粉得率为评价指标,通过单因素及正交试验研究了压热法制备抗性淀粉的最佳工艺参数。结果表明,对大米淀粉进行压热处理时,影响抗性淀粉得率的主次因素为:热处理温度热处理时间淀粉乳质量分数,最佳工艺条件为:热处理温度120℃,热处理时间70 min,淀粉乳质量分数30%。采用此组合进行验证性试验得抗性淀粉产率为9.54%。     

慢消化淀粉定量测定方法的比较研究

慢消化淀粉是指在人体小肠中能完全被消化吸收,但吸收速度较慢的一类淀粉。慢消化淀粉血糖指数低,具有特殊的生理功能,是近年来的研究热点;但是慢消化淀粉的定量测定仍然没有统一的标准。用了3种常用的慢消化淀粉定量测定方法:Englyst法、Shin法、Miao法,对大米淀粉、小麦淀粉和糯米淀粉3种原料中的慢消化淀粉进行定量测定,并进行比较分析。结果表明:Miao法模拟了人体胃肠道的生理条件,具有重复性好,操作简单等明显优势,适合于谷物类原料中慢消化淀粉含量的测定;用该法测得的大米淀粉、小麦淀粉、糯米淀粉的慢消化淀粉含量分别为:41·6%、49·4%、54·4%。      

抗性淀粉定量测定方法的研究

以回生淀粉为试验材料，通过凝胶渗透色谱对PPA法和TSA法的比较，发现PPA法不能充分水解慢速消化淀粉（SDS）。通过对原淀粉的测定，证明PPA法不能排除抗性淀粉粒（RS2）的干扰。另外发现对酶添加量有严格要求。所以PPA法准确性不高，重现性差，测定步骤多，时间长，测定人员必须经过长期专门培训，才能正确操作。TSA法能充分水解慢速消化淀粉（SDS），能排除RS2的干扰，准确性高，重现性好，简便、快速，酶使用量小，测定成本低。     

大米淀粉生产、性质及其应用

该文介绍大米淀粉的性质、生产技术,且对大米淀粉应用作一介绍。     

高抗性淀粉大米对方便米粉品质及GI值的影响研究

为了开发低GI方便米粉满足糖尿病和超重/肥胖人群的饮食需求,研究高RS大米对方便米粉冲泡特性、质构特性、感官评分、微观结构及GI值的影响。结果表明,高RS的添加提高了方便米粉断条率与吐浆值,降低了感官评分值;方便米粉硬度、咀嚼性有所增加,粘性、弹性、回复性先增加后减少;提高了方便米粉中RS的含量,并使其GI值降低;通过SEM分析,高RS大米较普通大米制作的方便米粉剖面结构更具连续性,结构更为致密,孔洞明显减少;通过XRD分析,添加高RS大米的方便米粉样品在14°附近有一个特征峰,普通大米制作的样品没有。本文为低GI方便米粉的开发与生产实践提供新的思路,但高RS大米对方便米粉品质及GI值的影响机理还需要进一步研究。     

Use of the resistance effect between retrograded starch and iodine for evaluating retrogradation properties of rice starch

A resistance effect between retrograded starch and iodine and its potential use for evaluating retrogradation properties of rice starch were investigated in this study. Our results showed that the resistance effect obviously occurred during the interaction of retrograded starch and iodine ions. The extent of the resistance was selected as a parameter to explore the kinetics of starch recrystallisation, indicating that the recrystallisation data obtained were suited to the Avrami equation (all correlation coefficients R > 0.99). Furthermore, the resistance was suitably employed to clarify some properties of starch retrogradation, including the rate constant (0.11 d⁻¹ ? k ? 0.17 d⁻¹) and the Avrami exponent (1.18 ? n ? 1.29). These results suggest that the resistance extent is able to provide potential data for measuring the degree of starch retrogradation.     

Evaluation of starch analysis methods for feed samples

The objectives of this work were to evaluate the efficacies of commercial starch analyses and of starch analysis extraction and gelatinisation procedures. In Study 1, accuracy and specificity of commercially available starch analyses were evaluated with six co‐operating laboratories (five commercial, one university). Results from 11 test samples showed three laboratories with recoveries of purified starch of 92 g kg⁻¹ or less. Three and four laboratories had inflated values when samples contained glucose or sucrose, respectively. Analyses appeared to have good specificity for glucose. Incompleteness of starch detection and interference by non‐starch carbohydrates can affect commercially available analyses. In Study 2, extraction with 80:20 ethanol/water (v/v; 80EtOH) or 90:10 ethanol/water (v/v; 90EtOH) to remove low‐molecular‐weight carbohydrates, and gelatinisation with heat, alkali (KOH), 6 M urea or 8 M urea were evaluated. Extraction with 80EtOH or 90EtOH reduced interference from non‐starch carbohydrates. Gelatinisation with heat was adequate for good recoveries of starch glucose for both control (non‐extracted) and 80EtOH‐extracted samples; gelatinisation with alkali was required for 90EtOH‐extracted samples. Recoveries of pure starch samples were greatest with no extraction and heat gelatinisation. 80EtOH extraction with heat gelatinisation appears to be an adequate preparation method when removal of low‐molecular‐weight carbohydrates is desired. © 2000 Society of Chemical Industry     

挤压膨化大米磷酸酯淀粉与湿法大米磷酸酯淀粉工艺及性质比较研究

以大米淀粉为原料,尿素为催化剂,分别用挤压膨化法和湿法与磷酸盐反应制得大米磷酸酯淀粉,并对其进行冻融稳定性、透明度、酯化度等比较;结果表明,挤压膨化大米磷酸酯淀粉凝沉性最弱,热稳定性最佳,冻融稳定性没湿法制品高。     

稻米蛋白质测定方法的比较与分析

分别利用凯氏定氮法和双缩脲法对10个稻米样品的蛋白质含量进行测定。比较发现,两种方法的测定结果并不相同,并表现出双缩脲法的测定结果较凯氏定氮法小约10%～20%的规律。提出利用已标定蛋白质含量的稻米为标样,基于双缩脲反应原理,进行蛋白质测定的分析方法,结果表明,该法可获得较高的检测精度。     

纱线信号时频分析方法比较

阐述了一种新的时频分析方法——基于Hilbert-Huang变换的Hilbert时频谱分析,并将其应用到纱线信号分析中。以毛条信号为例,将短时Fourier变换、小波分析和Hilbert谱分析方法进行比较,指出Hilbert谱分析能对信号的时频分布做出比短时Fourier变换和小波分析更为精确的描述,从而能更准确地揭示纱线信号中能量在时域和频域同时变化的过程。通过对纱线信号进行时频分析,可以得到每个瞬间的频率变化,进而对其进行在线谱分析,可以实时监测工艺及设备状况的变化,及时发现生产过程中的异常。     

Comparison of calibration methods for the quantification of Basmati and non-Basmati rice using microsatellite analysis

The accurate quantification of non-Basmati rice in Basmati rice is central to the successful prosecution of adulteration, where non-Basmati rice has been substituted for Basmati rice. The current method and three alternatives of constructing calibration curves for the measurement of non-Basmati rice in Basmati rice using microsatellite analysis were investigated. The methods compared involved power regression, linear regression (with and without log₁₀ transformation) and hyperbolic regression of the ratio of Basmati to non-Basmati peak areas. Assessments were made using error uncertainty, standard error at the agreed limit of adulteration, and 95% confidence intervals for five example data sets. The linear regression of the ratio of peak areas to the ratio of content proportions was found to give the most precise calibration and thus enhanced quantification of the level of adulteration of Basmati rice with non-Basmati rice.     

Comparison of calibration methods for the quantification of Basmati and non-Basmati rice using microsatellite analysis

The accurate quantification of non-Basmati rice in Basmati rice is central to the successful prosecution of adulteration, where non-Basmati rice has been substituted for Basmati rice. The current method and three alternatives of constructing calibration curves for the measurement of non-Basmati rice in Basmati rice using microsatellite analysis were investigated. The methods compared involved power regression, linear regression (with and without log(10) transformation) and hyperbolic regression of the ratio of Basmati to non-Basmati peak areas. Assessments were made using error uncertainty, standard error at the agreed limit of adulteration, and 95% confidence intervals for five example data sets. The linear regression of the ratio of peak areas to the ratio of content proportions was found to give the most precise calibration and thus enhanced quantification of the level of adulteration of Basmati rice with non-Basmati rice.     

大米淀粉组成与挤压特性之间的相关性研究

分析11种大米的淀粉组成和挤压特性,探讨总淀粉、直链淀粉含量以及淀粉直/支比与膨化度、吸水性、水溶性、容重、硬度等挤压特性之间的相关性。结果表明:直链淀粉含量与吸水性呈显著正相关(r=0.879)、与水溶性呈显著负相关(r=-0.876),与膨化度之间也具有一定的相关性(r=0.530),与容重及硬度无显著相关性;淀粉直/支比与吸水性(r=0.848)呈显著正相关,与水溶性呈显著负显著(r=-0.827),与膨化度具有一定的相关性(r=0.512),但与容重及硬度无显著相关性。大米的直链淀粉含量以及淀粉直/支比与膨化度、吸水性等挤压特性具有相关性,直链淀粉含量和淀粉直/支比可作为大米挤压加工中原料选择和复配的依据。     

陈化进程中大米淀粉与谷蛋白的相互作用

为进一步阐明大米陈化机理,本研究以荧光和紫外光谱等为手段,探讨加速陈化过程中大米淀粉-谷蛋白混合物的相互作用,及其对复合物溶解性、起泡性和消化性能的影响。结果显示,陈化过程中谷蛋白溶解度和起泡性逐渐下降,且随着大米淀粉的加入进一步降低。紫外及荧光分析表明,陈化过程中,淀粉的加入影响了陈化进程中谷蛋白的三级结构,色氨酸和酪氨酸残基周围微环境发生改变,蛋白质分子与淀粉相互缔合,且随着陈化的进行愈加紧密,造成荧光发射峰红移并产生荧光猝灭,以及谷蛋白与淀粉消化性能的下降。随着淀粉含量增加,谷蛋白的消化率降低速率增大,与此相应,谷蛋白比例增加也迫使淀粉消化率下降。