不同储藏温度下大米粉理化指标对黏度特性影响

通过对储藏后大米的米粉黏度特性研究,并用SPSS统计软件对米粉的理化指标与黏度特征值进行相关性分析。比较室温和4℃低温储藏后米粉的异同,对米粉原料的选择有重要意义。试验结果表明:影响米粉的黏度的主要因素是直链淀粉、蛋白质含量和总淀粉含量、脂肪含量,直链淀粉、蛋白质含量、总淀粉含量、脂肪含量越高米粉峰值黏度越低,破损值越低,糊化温度越高,大米粉越不易糊化。室温储藏下的大米粉要比4℃下的容易糊化,室温下的大米粉蛋白质、直链淀粉、总淀粉含量减少的相对较多,故而更易糊化。     

糜子直链淀粉、蛋白质含量对其外观品质及食味品质的影响

以4个直链淀粉、蛋白质含量存在显著差异的糜子品种为实验材料,研究直链淀粉、蛋白质含量对糜子外观及食味品质的影响。结果表明：与低直链淀粉品种比较,高直链淀粉糜子品种,全粉糊化黏度、糊化时间、糊化温度较高,糜子饭吸水率、体积膨胀率、硬度较高,而糊化热焓值较低;蛋白质含量较高的糜子品种,全粉呈现低糊化黏度,糜子饭呈现低吸水率、体积膨胀率,高硬度。直链淀粉、蛋白质含量较高的糜子品种,蒸煮性差、能耗高、蒸煮时间长。因此,在糜子品质育种中,适当降低直链淀粉和蛋白质含量可以改善糜子的适口性。     

大米蛋白对大米淀粉糊化特性及鲜湿米粉品质影响的研究

以蛋白质含量不同的5种大米:银晶软黏、金丝苗、珍桂、秋优1025和越南504作为研究对象,通过测定5种大米脱蛋白前后糊化特性以及制作的鲜湿米粉的断条率、蒸煮损失和碘蓝值,研究大米蛋白对大米糊化特性及鲜湿米粉品质的影响。结果表明,脱蛋白处理明显降低大米淀粉糊化的起始糊化温度,使大米淀粉更易于糊化,但糊化温度降低的程度并不和蛋白质含量成正比;脱蛋白后大米淀粉的特性黏度以及回生值、消减值降低,而崩解值显著升高,脱蛋白处理使大米淀粉的热稳定性降低,延缓大米淀粉的老化。脱蛋白大米制作的鲜湿米粉的断条率的差异性随大米品种和大米中蛋白质含量而异,大米蛋白含量越高则脱蛋白制作的鲜湿米粉的断条率越高;而脱蛋白组制作的鲜湿米粉蒸煮损失率要高于未脱蛋白组鲜湿米粉。通过比较不同蛋白质梯度配比鲜湿米粉的碘蓝值,当蛋白质含量超过3%以后,米粉的碘蓝值较小,蒸煮品质较好。     

植物乳杆菌发酵大米粉及其淀粉特性变化

采取植物乳杆菌对整粒大米进行发酵,利用酶法分离淀粉,然后分别对大米粉及其淀粉的化学成分、糊化、凝胶及结构特性进行测定。结果表明:发酵120h后,大米中蛋白质、脂肪及灰分含量分别降低40%、28%和65%,直链淀粉质量分数由23.08%增至24.86%。发酵大米粉的糊化温度、峰值时间和回生值降低,而峰值黏度和衰减值增大;峰值黏度和衰减值随发酵时间先增后减;发酵后淀粉的糊化温度、峰值黏度、衰减值及回生值减小而峰值时间增大,发酵时间对其糊化温度、峰值黏度影响较小,而对衰减值及回生值影响较大。发酵后大米粉及其淀粉凝胶的硬度、黏附性、胶着性和咀嚼性均增加。红外光谱和X-衍射分析发现,发酵后大米粉及其淀粉未产生新官能团,但其结晶区比例稍有增加。     

基于差示扫描量热仪的大米糊化特性及回生性能的研究

利用差示扫描量热仪研究了3种大米(籼米、糯米及粳米)的糊化特性与淀粉的回生性能。实验结果表明,由于大米的组织结构不同致使其结晶熔融焓值△H及熔融起始温度To、峰值温度Tp与终止温度Te不同,另外,由于经过糊化后的米粉其支链淀粉的重结晶在储藏过程中受到环境温度和时间长短的影响,因此,结晶熔融所表现出的焓值与熔融温度除了与米粉种类有关外还具有明显的温度和时间依赖性。     

RVA日本大米品质分析法研究陈化对大米糊化特性的影响

快速黏度仪广泛应用于大米淀粉糊化特性的研究。对于质量相近的大米试样,RVA日本大米糊化特性评价法具有更好的优势。本文应用该方法将粳米、籼米及糯米在4、25和36℃下分别贮藏0、1、3和6月后通过快速黏度仪研究其糊化特性。在贮藏过程中大米发生代谢活动,加上脱支酶等引起的酶促反应,使其直链淀粉含量增加而支链淀粉含量减少,从而改变了直链淀粉/支链淀粉比例,因此,在加热-保持-冷却测试过程中反映出的峰值黏度、保持黏度、衰减值、最终黏度及回生值出现增加,同时,由于陈化后水分子进入淀粉颗粒所需能量减少使得糊化温度与峰值时间有所降低。另外,由于陈化使大米组织结构发生变化及大米淀粉微晶束产生改变等物理过程,加上不同种类大米的蛋白质及淀粉等组分受陈化温度与陈化时间的影响不同,使其淀粉糊化特性上的各个特性指标表现出明显的时间与温度依赖性。     

非糯性大米淀粉和非糯性玉米淀粉性质比较

以非糯性大米和玉米淀粉为研究对象,比较分析了淀粉的化学组成、结晶特性、浊度、热性质、质构及回生性质。试验结果表明非糯性玉米淀粉浊度、淀粉糊化熔点和峰值温度、凝胶硬度、咀嚼性、弹性和凝聚性值高于非糯性大米淀粉,但其膨润力和回生焓变值低于非糯性大米淀粉。此外,在4℃贮藏过程中,非糯性玉米淀粉凝胶的熔点、峰值温度、回生焓变和回生度均高于大米淀粉。试验非糯性大米淀粉和玉米淀粉理化性质比较的试验数据结果,可为玉米淀粉改性加工及其相关产品的开发提供依据。     

鲜湿米粉品质评价及原料选择

为确定适宜鲜湿米粉加工用大米的关联性指标及阈值区间,本研究以18种大米为原料制备切条型鲜湿米粉,探讨大米主要成分质量分数、淀粉糊化特性对米粉蒸煮品质、入味性、感官品质和质构品质的影响,并利用主成分分析建立鲜湿米粉综合品质评价模型,计算米粉品质综合得分,通过逐步回归分析筛选出影响米粉综合品质的关联性指标,结合聚类分析得到适宜加工米粉的原料大米关联性指标范围。结果表明:大米的直链淀粉质量分数,淀粉糊化特性的最低黏度、最终黏度、衰减值、回生值与米粉的蒸煮品质、感官品质、质构品质显著相关(P0.05);大米主要成分、淀粉糊化特性与米粉的入味性相关性不显著(P0.05)。影响米粉综合品质的关联性指标为直链淀粉质量分数和最终黏度,适宜加工切条型鲜湿米粉的原料大米直链淀粉质量分数应大于26%,淀粉的最终黏度应大于3 852 Pa·s。     

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。     

海藻酸钠对不同直链淀粉含量的玉米淀粉物化性质的影响

采用快速黏度分析仪、差示扫描量热仪、动态流变仪、物性测试仪等,研究了海藻酸钠对3种不同直链淀粉含量的玉米淀粉糊化、凝胶及老化性质的影响。结果表明:海藻酸钠显著影响高直链玉米淀粉、普通玉米淀粉及蜡质玉米淀粉的物化性质,且对不同直链淀粉含量的玉米淀粉物化性质的影响不同。海藻酸钠使3种玉米淀粉的糊化难度增大,起始糊化温度、峰值糊化温度、终止糊化温度升高,糊化焓增加。海藻酸钠提高3种玉米淀粉的峰值黏度、末值黏度、表观黏度及损耗模量。海藻酸钠提高高直链玉米淀粉的热稳定性和抗老化性,使高直链玉米淀粉的衰减值、老化率降低。海藻酸钠阻碍高直链玉米淀粉形成凝胶,使高直链玉米淀粉的损耗角正切值升高、凝胶硬度降低。     

Effect of fertiliser on functional properties of flour from four rice varieties grown in Sri Lanka

BACKGROUND: Fertiliser is an essential agro‐chemical input in modern rice farming. Fertiliser affects the grain quality and yield of rice. Although much research has been carried out to investigate the influence of fertiliser (recommended NPK addition) on yield and quality of rice grain, little is known about the effect of fertiliser on thermal, pasting, gelling and retrogradation properties of rice flour. The aim of this study was to investigate the influence of recommended fertilisation on functional properties of rice flour from four popular high yielding rice varieties grown in Sri Lanka. RESULTS: Fertiliser (recommended NPK addition) increased the protein content but reduced the apparent amylose content in rice flour except in BG 357. Swelling power and amylose leaching of rice flour were also increased. Pasting onset temperature, cold paste viscosity and setback were increased but peak viscosity and granular breakdown decreased. In response to the fertiliser application, gelatinisation peak temperature was reduced in all varieties except BG 300. However, compared to pasting properties, gelatinisation parameters were not much affected by fertilisation. The extent of amylopectin retrogradation was decreased by fertiliser in BG 305 and BG 352 but unchanged in the other two varieties. Except in BG 305, fertiliser reduced the gel hardness of rice flour but increased the gel cohesiveness. CONCLUSION: It is apparent that the increased protein and reduced amylose content caused by fertiliser affect the functional properties of rice flour. Copyright © 2011 Society of Chemical Industry     

Factor analysis of the functional properties of rice flours from mutant genotypes

A set of 27 waxy rice genotypes and 52 rice genotypes with medium and high amylose contents were screened for various functional properties of flour. In this study, 68 genotypes containing various amylose contents (1.2–30.4%) were mutants of the rice variety TNG67 widely grown in Taiwan. The proximate composition, pasting, thermal and textural properties of rice flours were determined and analysed with factor analysis to assess the genetic differences. A wide variation in various functional properties was observed. Factor analysis indicated that four factors relating to amylose content, gel textural, gelatinization and protein content could explain 80% of the variability among 79 rice flours. Correlation studies and scatter diagrams also indicated the larger role of amylose with respect to protein and lipid in determining the rice flour quality. The present study can be used for readily identifying differences between rice genotypes for eating/cooking quality.     

Pasting Properties of Ohmically Heated Rice Starch and Rice Flours

ABSTRACT:  Pasting characteristics were examined for conventionally or ohmically heated rice starch and rice flours. Brown rice flour showed the greatest cooking stability and least retrogradation potential. Brown rice flour also showed the greatest pasting temperature and lowest peak viscosity, whereas commercial starch had the lowest pasting temperature. Nonstarch components of the brown rice flour, such as fat and protein, may have acted as stabilizers delaying water access into the granules and reducing swelling of the starch. Ohmic heating reduced pasting temperature for commercial rice starch, resulting in a starch that swelled faster. Furthermore, ohmic heating produced better cooking stability in white rice flour 1 and 2 than in the native sample, and caused white rice flour 2 to have less potential for retrogradation than the conventionally heated sample. At lower electric field strength (20 V/cm), ohmic heating resulted in the greatest cooking stable starches compared to higher voltages (40 and 70 V/cm) because more starch granules were disrupted from a longer cooking time, so there were fewer intact granules for pasting. Ohmic heating has been shown to alter rice starch and flour pasting characteristics with an added influence of lipids, proteins, and amylose contents.     

冰湖野米粉及其淀粉的精细结构、理化和消化特性研究

目的 探究冰湖野米粉及其淀粉的理化性质、结构特性和消化性的差异, 同时揭示不同级的冰湖野米淀粉的精细结构。方法 以3种不同级的冰湖野米和1种早籼米(对照组)为原料, 将其研磨过筛制备米粉样品, 再用焦亚硫酸钠法和甲苯法进行纯化得到对应的淀粉样品。采用体积排阻色谱分析法(Size exclusion chromatography, SEC)与荧光辅助毛细管电泳法(Fluorescence assisted capillary electrophoresis, FACE)测定冰湖野米淀粉的精细结构(直链淀粉和支链淀粉的链长分布); 利用扫描电镜、光学显微镜、X-射线衍射仪、傅里叶变换红外光谱仪和布拉班徳粘度仪等现代分析仪器对冰湖野米粉及其淀粉的理化性质和结构特性进行测定; 采用Englyst体外消化法测定冰湖野米粉及其淀粉的体外消化性。结果 研究表明, 不同级的冰湖野米粉及其淀粉的颗粒形貌特征、粘度特性、结晶结构以及直链淀粉含量无显著差异。与早籼米相比, 冰湖野米粉及其淀粉的起糊温度高, 峰值粘度低, 相对结晶度低, 热稳定性好, 慢消化淀粉和抗性淀粉含量高, 主要归因于冰湖野米的支链淀粉结构及其较高的直链淀粉含量。与冰湖野米淀粉相比, 冰湖野米粉颗粒更大, 结晶度降低, 膨胀度降低, 慢消化性增加, 主要归因于冰湖野米粉中较高的内源蛋白和纤维含量。结论 冰湖野米中的内源纤维、蛋白质、直链及支链淀粉含量对冰湖野米的粘度特性、膨胀度、结构特性以及消化性有显著的影响。     

Impact of brown foxtail millet (Setaria italica) flour on thermo-mechanical properties of flours from different rice varieties

The physical, functional and thermo-mechanical properties of rice flours prepared from long, round and medium rice grain and of foxtail millet (Setaria italica) flour were investigated. The impact of foxtail millet flour addition on the thermo-mechanical properties to the rice flours was also explored. Rice flour from long grain had higher amylose content (26.37%), while the rice flour from round grain had better hydration properties compared to the other rice flours. The dough from long grain rice flour exhibited higher starch gelatinisation temperature and cooking stability and lower starch retrogradation compared to the other investigated rice flours. Foxtail millet flour addition to the rice flours exerted a lower impact on the thermo-mechanical properties of the dough based on rice flour from long grain compared to the other investigated rice flours. These differences might be due to the differences in terms of starch properties and proximate composition of the flour samples.     

Effect of Raw Material Preparation on Rice Vermicelli Quality

The physicochemical properties of high amylose rice flour prepared from wet milling and dry milling were examined and the rice vermicelli quality made from these flour samples was evaluated. The effect of flour particle size on rice vermicelli quality was also determined. The milling method affected chemical compositions and all physicochemical properties of the flour. A higher degree of starch damage occurred in drymilled flour. Rice vermicelli made from dry‐milled flour had higher cooking losses and softer texture than that made from wet‐milled flour and the commercial reference products. Flour particle size influenced both cooking and textural quality of rice vermicelli but did not influence the water absorption index. Flours with larger particle sizes gave vermicelli with higher cooking loss and less desirable texture than flours with smaller particle sizes. Flour with particle sizes less than 200 mesh produced acceptable vermicelli in terms of cooking and textural quality.     

鲜湿面条的煮面时间及其与面粉糊化特性的关系

通过对不同类型小麦品种鲜湿面条的煮面时间及其与面粉品质的关系研究,结果表明:随着煮面时间的延长,面条评分呈先上升后下降的趋势,不同类型小麦品种的面条评分分别在不同煮制时间达到最大值;同时,随着煮制时间的延长,糯小麦面粉开始糊化温度逐渐下降,而黑小麦76、豫麦34、豫麦49、豫麦50呈先上升后下降的趋势,且均在一定时间后保持平缓的趋势。最佳煮面时间和面粉品质的相关分析表明,最佳煮面时间和直链淀粉含量、最终粘度、反弹值、糊化温度呈显著正相关,和稀懈值呈显著负相关;糊化特性能较好的预测最佳煮面时间。同时,评委感官评价测得的最佳煮面时间和糊化温度测定法有极显著相关性。     

Morphology and physicochemical changes in rice flour during rice paper production

Rice flour samples from four steps of rice paper processing were prepared from rice grain, Chainart 1 variety: wet-milled flour (WMF), 24 hour soak-milled flour (24SF), 48 hour soak-milled (48SF), and dried rice paper (DRP). Decrease in protein, fat and amylose content occurred during prolonged fermentation but increase of ash content due to addition of salt occurred. Because of lactic acid bacteria activity, increases occurred in titratable acidity as lactic acid in soaking water during fermentation. Scanning electron microscopy revealed that starch granule surfaces wilted and showed corrosion channels with longer fermentation. Pasting and thermal properties of the four samples were significantly different; 24SF and 48SF showed lower peak viscosity, breakdown and final viscosity. Increasing fermentation time increased gelatinization temperature, endothermic energy and relative crystallinity. The results suggest that lactic acid and enzyme hydrolysis during fermentation in rice paper processing caused significant decrease in amorphous structure and increase in crystallinity in rice starch.     

粳米与籼米组合对婴幼儿米粉食用品质的影响

研究了粳米和籼米不同搭配组合的基本理化指标、蒸煮特性、糊化特性和质构特性.结果表明,直链淀粉含量对食用品质具有重要影响.蒸煮特性上,直链淀粉含量越低,吸水率及膨胀体积越小,米汤pH、碘显色值和干物质含量越高,蒸煮及冲调性越好;糊化特性上,直链淀粉含量越低,峰值黏度和崩解值越高,回复值及衰减值越低,口感越好;质构特性上,...