快速粘度分析仪及其应用

本文介绍了一种新型粘度仪（RVA）的基本工作原理、特点及其在粮食食品的品质评价和作物育种等领域中的应用成果。     

甘薯淀粉RVA测定程序初探

应用快速粘度仪(Rapid Visco-Analyser,RVA)研究了甘薯淀粉和全粉的糊化在不同测定条件下的表现。发现甘薯样品的RVA谱在很大大程度上受测定条件的影响,主要影响因素为:加热速率、95℃时的保持时间、结束温度保持时间以及剪切效应。另外起始温度保持0或1min时,样品最高粘度表现较高。加热时间一般在4min或6min时,样品最高粘度能获得最高值。冷却时间和结束温度主要影响最终粘度。冷却时间延长,样品最终粘度先升高后降低;而且随着结束温度降低,最终粘度表现递增。建议甘薯样品的RVA分析程序为:50℃保持1min,4min内加热至95℃,95℃保温5.5min,同样4min内冷却至50℃,并最终在50℃保持4min。     

多糖类食品添加剂对大米粉黏度特性的影响研究

分析多糖类食品添加剂对大米粉RVA黏度特性的影响。结果表明:大米粉的回生值随着HPMC含量的增加逐渐增加,添加HPMC的大米粉样品与未添加的样品相比,大米粉的峰值黏度、热浆黏度、最终黏度出现了增加;麦芽糊精能起到降低大米粉回生值和崩解值的作用,麦芽糊精对大米粉的峰值时间和糊化温度的影响不明显;随着瓜尔豆胶含量的逐渐增加,大米粉的峰值黏度、热浆黏度、最终黏度和回生值都逐渐增加;添加卡拉胶与未添加卡拉胶的大米粉样品相比,峰值黏度、崩解值和回生值均出现下降,而热浆黏度和峰值时间都出现了增加。     

不同改良剂对发酵米粉糊化特性及黏性米面团品质的影响

目的 基于糊化特性分析不同种类及添加量的改良剂对发酵黏性米制品品质的影响。方法 以糯米为主要原料,向其添加β-淀粉酶、大豆多糖、海藻糖、黄原胶和瓜尔豆胶,采用快速黏度分析仪(rapid viscosity analyzer,RVA)研究不同改良剂对米粉糊化特性的影响,并通过感官评价分析黏性米制品的品质。结果 抗老化效果最好的是β-淀粉酶组,且只有β-淀粉酶组的峰值黏度、最低黏度、最终黏度和衰减值均随着添加量的增加呈下降趋势,其余组均呈上升趋势。黏性最高的是大豆多糖组,衰减值最高的是黄原胶组。黏性米制品感官特性最好的是亲水胶体组,其内部结构致密、黏弹性增强; β-淀粉酶和大豆多糖组的内部较松散、黏性增大、弹性减小;海藻糖对于产品内部结构的影响较小,添加过量口感下降明显。结论 上述改良剂从不同角度改善了发酵米制品品质,经研究发现米粉的糊化特性与感官特性间存在密切关联,这为发酵糯米食品的综合利用提供了参考依据。     

Milling and flour pasting properties of waxy endosperm mutant lines of bread wheat (Triticum aestivum L)

Two waxy endosperm mutant lines, K107Wx1 and K107Wx2, derived from a bread wheat cultivar, Kanto 107, had a lower flour yield in test milling and a lower peak temperature in flour pasting measurement than their parent. Starch content in the kernel of waxy mutants was low, while fat and (1→3),(1→4)‐β‐D‐glucan content was high compared with cv Kanto 107, but protein content was similar for all of them. Waxy mutants had less α‐amylase activity than their non‐waxy parent, and had lower peak viscosity of flour paste in the pasting medium of water. A pasting test in silver nitrate solution increased peak viscosity in both waxy and non‐waxy flours. The viscosity of waxy flour paste rapidly increased above 60°C, while that of non‐waxy flour paste increased gradually at 60–80°C. The difference in pasting behaviour was attributed to the presence of amylose in starch granules. © 1999 Society of Chemical Industry     

高效液相色谱法同时检测小麦粉中6种非法添加剂

目的：建立高效液相色谱法同时测定小麦粉中6种非法添加剂,包括硫脲、曲酸、间苯二酚、苯甲羟肟酸、三聚硫氰酸三钠盐、噻二唑。方法：样品经70%乙腈水溶液提取,采用Thermo Hypersil-Gold C18色谱柱,以甲醇-0.1%磷酸水溶液为流动相进行梯度洗脱, 采用二极管阵列检测器检测。结果：6种目标化合物均在0.5~20μg/mL范围内线性关系良好, 相关系数均≥0.999。方法检出限均为0.2μg/g;平均回收率为62.9%~100.1%, 相对标准偏差为1.16%~2.65% (n=6)。结论：该方法检测效率高、稳定性好, 具有良好的应用前景。     

Combining Partial Least Squares (PLS) Discriminant Analysis and Rapid Visco Analyser (RVA) to Classify Barley Samples According to Year of Harvest and Locality

The aim of this study was to evaluate the usefulness of the Rapid Visco Analyser (RVA) instrument combined with pattern recognition methods as tools to differentiate commercial barley samples from two South Australian localities and three harvests. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and stepwise discriminant analysis were applied to classify samples based on the RVA profiles using full cross validation (leave-one-out) as the validation method. The PLS-DA models correctly classify 96.3 and 97.8 % of the barley samples according to harvest and locality, using the profiles generated by the RVA instrument. Analysis and interpretation of the eigenvectors and loadings from the PCA or PLS-DA models developed verified that the RVA profiles contain relevant information related to starch pasting properties that allows sample classification. These results suggest that RVA coupled with PLS-DA holds necessary information for a successful classification of barley samples sourced from different localities and harvests.     

Effect of sowing time on protein quality and starch pasting characteristics in wheat (Triticum aestivum L.) genotypes grown under irrigated and rain-fed conditions

The effect of varying sowing time on wheat flour protein quality and starch pasting characteristics was studied in two genotypes differing in their water requirements for two years under irrigated and rain-fed conditions. Delayed sowing associated with high temperature during grain filling resulted in an overall increase in total grain protein. Low temperature prevailing under early sown conditions enhanced insoluble glutenin (IG) but reduced total protein accumulation in both the genotypes. IG and residue proteins increased but soluble glutenin and amylose decreased under rain-fed conditions. Amylose, hold- and final viscosity (FV) increased but setback decreased with change in normal sowing time. Peak viscosity (PV) increased under late sown conditions. Pasting temperature, setback, FV and breakdown (BD) were enhanced under rain-fed conditions. This study inferred that by selecting suitable irrigation practices and different sowing times for subjecting the crop to desirable temperature range, flour properties of given cultivars can be manipulated.     

Application of the Rapid Visco Analyser as a Rheological Tool for the Characterisation of Mash Viscosity as Affected by the Level of Barley Adjunct

The application of the Rapid Visco Analyser (RVA) as a laboratory scale rheological tool for the characterisation of mash viscosity is the subject of this study. Studies were conducted to simulate an industrial mashing process, taking into account temperature/time, grist loads, adjunct amounts and enzyme levels. The RVA was used to characterise the effects of different ratios of malt: barley adjunct. The method was found to have the ability of not only detecting the major viscosity changes which occur during starch gelatinisation/liquefaction processes, but also the minor viscosity changes which were found to occur during the proteolytic and saccharification steps. Clear correlations were found between the level of barley adjunct and the output rheological data points of the peak viscosity at 50°C (PV50, R² = 0.9931), the rate of viscosity breakdown at 50°C (BR50, R² = 0.9522), the peak viscosity prior to gelatinisation (PVG, R² = 0.9988), the area recorded under the gelatinisation curve (PGA, R² = 0.9928) and the peak viscosity breakdown rate (VBR, R² = 0.9783). The developed RVA rheological method is a useful tool for characterising grain quality (adjunct level) with regard to macromolecular viscosity compounds and the grains endogenous enzymatic capabilities.     

Unlocking the potential of pasting properties to predict extrudate characteristics of corn grits blends with high amylose corn starch,potato starch,or rice flour

The development of new production lines of extruded ready-to-eat (RTE) snacks often results in high losses of edible food due to the trial-and-error approach in industry. Being able to predict extrudate characteristics of new formulations before having to run trials on industrial scale would be beneficial for reducing waste and having a more efficient development process. With this study, the correlation between pasting properties of seven blends of flours/starches and extrudate characteristics was investigated (100% corn grits, 25% and 50% replacement of corn grits with high amylose starch, potato starch, and rice flour). The predictive power of pasting characteristics on extrudate's moisture content, water absorption and solubility index, sectional expansion index (SEI) and hardness was studied. Results indicated the potential of predicting SEI, water solubility index (WSI), and water absorption index (WAI) of RTE-snacks. WSI and WAI were, respectively, negatively correlated with peak temperature (R² = 0.897), and positively with peak temperature and positively with trough viscosity (R² = 0.855). One can conclude that the rheometer can be a useful tool to gain insight into the characteristics of the extrudate, although further research with enlargement of the dataset is necessary to make the rheometer effectively deployable for potentially other extrudate characteristics.     

Viscoelastic properties and pasting characteristics of fermented maize: influence of the addition of malted cereals

Investigations were conducted on the viscoelastic properties and pasting characteristics of fermented maize with malted cereals and their suitability for infant feeding. A 3 × 3 × 2 factorial experimental design with malting time, cereal malt concentration and cereal type was used. Maize, millet, and sorghum malts were added to fermented maize to reducing its bulk density. Samples were analysed for their viscoelastic properties and pasting characteristics using Brabender Viscoamylograph. Sorghum malt in comparison to millet and maize malts was not effective in terms of lowering the hot and cold paste viscosities of the fermented maize. Maize and millet malts liquefied the dough considerably during both the hot and cold paste viscosities. The effect of 4‐day malted millet was most pronounced whilst the highest activity of maize malt was observed with the 3‐day malted flours. The addition of maize and millet malts to fermented maize were most effective in lowering the viscoelastic properties of the resulting porridges.     

超高效液相色谱-串联质谱法同时测定小麦粉中4种新型非法添加剂

目的 建立超高效液相色谱-串联质谱法同时测定小麦粉中4种禁用成分.方法 样品经80％乙醇:乙腈(1:1,V:V)提取除杂后上机分析.采用Atlantis T3色谱柱、5 mmol乙酸铵+0.1％甲酸水溶液和甲醇为流动相进行梯度洗脱,采用多反应监测模式进行定性、定量分析.结果 4种化合物在各自线性范围内线性关系良好,相关...     

反应程序和淀粉浓度对糯玉米和普通玉米淀粉快速黏度测定谱特征值的影响

以糯玉米品种渝糯7号和普通玉米品种农大108为材料,研究了不同的反应程序和淀粉浓度对其快速黏度测定(RVA)谱特征值的影响,同时比较了糯玉米和普通玉米淀粉在不同反应程序和淀粉浓度条件下的差异。结果表明:(1)玉米淀粉的RVA特征值在不同反应程序下发生了改变,但其没有改变糯玉米和普通玉米之间的差异,在不同反应程序下,相对于普通玉米淀粉,糯玉米淀粉的峰值黏度和沉降值较高,而谷值黏度、终值黏度、回复值、峰值时间和糊化温度较低。(2)糯玉米和普通玉米淀粉的RVA特征值受到浓度影响,随着淀粉浓度的增加,峰值黏度、谷值黏度、沉降值、终值黏度和回复值随之增加,峰值时间略有降低,浓度太低时淀粉不能糊化,在能糊化条件下则随着浓度的增加而降低。在低浓度条件下,糯玉米淀粉的峰值黏度高于普通玉米,而在较高浓度(11%)条件下,糯玉米淀粉的峰值黏度则低于普通玉米淀粉。     

Small and large deformation rheology for hard wheat flour dough as influenced by mixing and resting

ABSTRACT:  The effects of mixing and resting on the physicochemical properties of doughs prepared with strong and weak hard wheat flours were investigated, specifically concerning aspects related to their rheological behavior and molecular mobility. Small deformation dynamic tests showed that, during the initial resting period, the complex modulus G * decreased and phase angle decreased for undermixed dough, whereas overmixed dough showed opposite trends. G * values for optimally mixed dough did not vary during the resting period investigated. This was more obvious for the strong dough. Large deformation tests more clearly showed differences among optimal, under-, and overmixed dough, and also between doughs prepared with strong and weak flour. Optimally mixed dough exhibited the highest peak stress and strain for both samples. In addition, the peak stress of dough prepared with the strong flour was higher than that of dough prepared with weak flour. Inconsistent results between small and large deformation tests implied that small and large deformation tests reflected different structural aspects of dough. NMR measurements were performed to estimate the relaxation properties of the sample upon resting. Decreased water mobility during resting, indicated by decreasing T ₁ relaxation time, was possibly attributed to increasing molecular interactions caused by continued hydration. Evidence of additional molecular interactions created by mixing was also observed.     

Textural and pasting properties of potatoes (Solanum tuberosum L.) as affected by storage temperature

Fresh tubers from five potato (Solanum tuberosum L.) cultivars were stored at different temperatures (4, 8, 12, 16 and 20 °C) and 80–90% relative humidity for 18 weeks after harvest to examine the effect of storage temperature on their textural and pasting properties. Texture profile analysis was performed on raw and cooked potatoes using an Instron universal testing machine to measure textural parameters such as fracturability, hardness, cohesiveness, adhesiveness and springiness. Both raw and cooked potato tubers showed a considerable reduction in all textural parameters upon storage, irrespective of the storage temperature employed. Raw potatoes showed a decrease in fracturability and hardness with increasing storage temperature, whereas their cooked counterparts showed the opposite trend. The extent of change in the textural properties of both raw and cooked potatoes also varied among the different cultivars. Fresh and stored tubers from all cultivars were freeze‐dried, ground into flours and analysed for amylose content and pasting properties. The amylose content of flours prepared from potatoes stored at 4 and 8 °C was observed to be considerably lower than that of flours prepared from potatoes stored at 16 and 20 °C. Pasting characteristics such as peak viscosity, setback and final viscosity increased with increasing storage temperature, while the reverse was observed for pasting temperature, when studied using a rapid visco analyser. Breakdown in viscosity of the flour pastes from all cultivars was considerably reduced during storage, irrespective of the storage temperature employed. Copyright © 2006 Society of Chemical Industry     

绿豆—小麦混合粉加工特性及其挂面品质研究

将绿豆粉和小麦粉按不同比例混合,研究绿豆粉对绿豆—小麦混合粉加工特性及其所制得挂面品质的影响。结果表明,随着绿豆粉添加量的增加,混合粉的湿面筋含量降低,稳定时间减少,面筋网络结构形成不足,耐搅拌能力下降,峰值粘度、最低粘度、衰减值、最终粘度、回生值、峰值时间不断减小,糊化温度不断提高,混合粉的加工品质趋于恶劣;挂面的烹调时间、烹调损失率上升,吸水率先升后降,添加量为30%时达到最大值,硬度、弹性、胶粘性、咀嚼性和回复性逐渐上升,断裂距离比先增后减,添加量为30%时达到最大值,在绿豆粉添加量超过50%以后,挂面无法制作。     

Rheological properties of wheat flour and quality characteristics of pan bread as modified by partial additions of wheat bran or whole grain wheat flour

The use of bran and whole grain flour changes dough rheology and causes difficulties in manufacturing bakery products. The aim of this study was to analyse the influence of substituting refined wheat flour (WF) by wheat bran (WB; 5%, 10%, 20%, 30% and 40%) or whole grain wheat flour (WGWF; 10%, 20%, 30%, 40% and 50%) on dough rheological properties and pan bread quality characteristics. The addition of WB and WGWF increased water absorption and resistance to extension and decreased stability, extensibility and peak viscosity. Effects with WB were more pronounced. The presence of WB or WGWF increased crumb moisture content, firmness and hardness and decreased specific volume of pan bread. It is important to set new farinographic and extensographic standards when using WB and WGWF, allowing for a correct correlation between rheology and quality characteristics of bakery products, as the same standards used for WF are not valid.     

喷雾干燥法制备面粉改良剂茶多酚微胶囊研究

以面粉改良剂茶多酚为研究对象,选用海藻酸钠、壳聚糖以及氯化钙为包埋壁材,采用喷雾干燥法对茶多酚进行微胶囊化研究。通过单因素实验以及响应面优化分析得出如下结论,喷雾干燥最佳技术条件:进风温度180℃,空气流量750L/h,出风温度100℃。茶多酚最佳包埋参数为:复合壁材比例海藻酸钠2.5%、壳聚糖0.8%、氯化钙4.5%,芯材与壁材质量比为2∶1,最大包埋率为73.8%。包埋颗粒近似球形,直径介于2～10μm之间,分布均匀无粘连。微胶囊稳定性实验表明,在5℃下,茶多酚较为稳定,最佳储存期为22d。