Physiochemical,Pasting, and Thermal Properties of Starch Isolated from Different Barley Cultivars

Starches from eight different barley cultivars were isolated and evaluated for their physiochemical, thermal, and pasting properties. The amylose content varied significantly among cultivars and ranged from 21.0 to 28.3%. The majority of the starch granules were of the B-type (20 to 40 μm) in size and accounted for 50.5 to 61.6% of the total granules. The starch gel from RD-2052 showed the highest firmness (0.55 N). The pasting behavior of starch varied significantly; the PL-172 cultivar showed the highest peak viscosity (2622 cP) while it was lowest for RD-2035 (1913cP). The time to peak of pasting properties exhibited a significant (p ≤ 0.05) negative correlation with water solubility index (r =??0.74). The pasting temperature showed a significant (p ≤ 0.05) positive correlation with water binding capacity (r = 0.73) and significant negative correlation with water solubility index (r =??0.82). The highest enthalpy of gelatinization (ΔH) was exhibited by DWR-28 cultivar (4.9 J/g). Amylose content showed a significant (p ≤ 0.01) negative correlation with ΔH (r =??0.90). A significant (p ≤ 0.01) positive correlation was observed between gelatinization temperature range and water binding capacity of starch (r = 0.85).     

Effect of Initial Baking and Storage Time on Pasting Properties and Aging of Par-Baked and Rebaked Rye Bread

Part-baked rye bread with and without Ca-propionate (0.2 g/100 flour) were baked for 10, 15, 20 minutes at 230°C and stored at refrigerator temperature (4°C) for 10, 20, 30 days then second-baked for 5, 10, 15 minutes at the same temperature to give an oven-fresh end product. The effect of antimicrobial additive (Ca-propionate), part-baking, storage in refrigerator and rebaking on quality parameters such as yield of volume and crumb softness, water activity and pasting properties of rye bread crumb was evaluated. Addition of Ca-propionate increased bump area, while yield of volume and softness values of rye bread crumb decreased. The increase in initial baking time caused a decrease in the pasting temperature, water activity, and softness value and an increase in the bump area and viscosity of the rebaked bread crumb. Bump area and pasting temperature of rebaked rye bread crumb increased with longer (intermediate storage) time, while viscosity, yield of volume, water activity, and softness values decreased. A strong negative correlation was observed between pasting temperature and other parameters, which are bump area, peak viscosity, holding end viscosity, cooling end viscosity, and softness value for rye bread that was rebaked after part-baked and storing at refrigerator temperature. The re-baking rye bread after part-baking for 10 and 15 minutes and storage for 7, 14, and 21 days at refrigerator temperature gave softer crumb than the control group.     

Effect of Baking Procedure and Storage on the Pasting Properties and Staling of Part-Baked and Rebaked White Pan Bread Crumb

In this investigation, the white pan breads were part-baked for 10, 15, 20 minutes at 230°C with and without calcium propionate (0.2%), were stored at room temperature (20°C) for 3, 5, 7 days wrapped with two polyethylene bags. After storage, baking time of part-baked breads was completed to the baking time of control breads (25 minutes). Breads were subjected to softness analysis and pasting properties of bread crumb were determined using the Brabender Amylograph. Addition of Ca-propionate decreased softness value of crumb of bread rebaked after part-baked, while the peak, holding end and cooling end viscosities increased. The increase in initial baking time resulted in a decrease in the pasting temperature and softness value and an increase in the bump area and viscosity of the rebaked bread crumb. Bump area, water activity, softness value and peak, holding end and cooling end viscosities of crumb of the rebaked bread after part-baking decreased with longer (intermediate storage) time. Peak viscosity and water activity significantly correlated with softness of bread crumb rebaked following part-baking and storage at room temperature. Rebaking bread for 10 and 15 minutes after storage of 3 and 7 days at room temperature resulted in softer crumb than the control group.     

不同筋力面筋蛋白对小麦淀粉糊化特性的影响

以3个不同小麦品种淀粉(2个普通小麦,1个糯性小麦)为实验材料,添加3种类型的面筋蛋白(强筋、中筋和弱筋),5个添加量处理(8%、10%、12%、14%、16%),分析淀粉和面筋种类及其交互作用对淀粉糊化特性的影响。结果表明:淀粉是糊化特性的决定因素,面筋蛋白质直接或通过淀粉交互作用显著影响糊化特性。淀粉和面筋蛋白类型交互作用对峰值黏度、黏度面积、稀懈值、糊化起始时间有极显著影响;淀粉和面筋蛋白含量的交互作用对除了糊化温度和糊化起始时间外的其他糊化指标都有极显著或显著的影响;面筋蛋白类型对稀懈值影响按其降低作用大小的顺序为:弱筋>中筋>强筋;面筋蛋白添加量对淀粉稀懈值和反弹值的影响因淀粉种类的不同呈现显著差异。     

Overall and Local Bread Expansion,Mechanical Properties,and Molecular Structure During Bread Baking: Effect of Emulsifying Starches

In order to determine the relationship between molecular structure of wheat bread dough, its mechanical properties, total and local bread expansion during baking and final bread quality, different methods (rheological, nuclear magnetic resonance, magnetic resonance imaging and general bread characterisation) were employed. The study was extended on wheat dough with starch modified by octenyl succinic anhydride (OSA) in order to generalise the results. The interest of investigating multi-scale changes occurring in dough at different phases of baking process by considering overall results was demonstrated. It was found that OSA starch improved the baking performance during the first phase of baking. This feature was due to a higher absorption of water by OSA starch granules occurring at temperatures below that of starch gelatinization, as confirmed by NMR, and consecutive higher resistance to deformation for OSA dough in this temperature range (20–60 °C). This was explained by a delayed collapse of cell walls in the bottom of the OSA dough. In the second phase of baking (60–80 °C), the mechanism of shrinkage reduced the volume gained by OSA dough during the first phase of baking due to higher rigidity of OSA dough and its higher resistance to deformation. MRI monitoring of the inflation during baking made it possible to distinguish the qualities and defaults coming from the addition of OSA starch as well as to suggest the possible mechanisms at the origin of such dough behaviour.     

氯化钠对马铃薯淀粉糊化特性的影响

以马铃薯淀粉为研究对象,研究氯化钠对淀粉糊特性的影响。结果表明:随着氯化钠添加量的增加,马铃薯淀粉起始糊化温度和峰值温度升高,峰值粘度和最终粘度呈现先下降后略微上升的趋势,且淀粉糊的热稳定性提高;氯化钠使淀粉糊的透明度下降,且在添加量为2%时透明度最低;马铃薯原淀粉糊不易凝沉,氯化钠的添加使淀粉糊出现较大的凝沉现象,随着氯化钠添加量的增多凝沉现象加剧,放置时间越长凝沉现象越趋于稳定;氯化钠增大淀粉的溶解度和膨胀度,且不同质量分数的氯化钠对其的影响不同;最后,氯化钠的加入提高淀粉糊的冻融稳定性。     

阿拉伯胶对马铃薯淀粉糊化及流变性质的影响

研究了阿拉伯胶对马铃薯淀粉糊化及流变性质的影响,考察了马铃薯淀粉/阿拉伯胶混合体系在盐、柠檬酸、糖等不同介质下的糊化性质.RVA结果表明在水溶液中随着阿拉伯胶含量的增加,混合体系的峰值黏度显著降低,具有更好的热稳定性,但在冷却过程中,淀粉黏度明显上升,回值略有增加.添加胶体后,马铃薯淀粉在盐溶液及柠檬酸溶液中的峰值黏度稍有降低,在糖溶液中则表现出更高的黏度.静态流变实验显示不同混合体系均表现出剪切变稀性,添加胶体后,体系假塑性增强,滞后环面积明显减小.     

黄原胶对莲藕淀粉糊化性质及流变与质构特性的影响

为探究亲水性胶体对淀粉性质的影响,将不同比例的黄原胶添加到莲藕淀粉中,研究两者复配后莲藕淀粉的糊化、流变、质构特性及微观结构的变化。结果表明：黄原胶提高了淀粉糊终值黏度、糊化峰值时间并降低淀粉的崩解值和回生值,复配体系有更好的热稳定性和抗老化性。添加不同比例的黄原胶使莲藕淀粉糊的剪切应力不同程度降低,稠度系数K增大,流体指数n降低,加入黄原胶后的淀粉糊仍为假塑性流体,但是具有更好的增稠作用;加入黄原胶提高了淀粉的贮能模量、损耗模量,降低了损耗角正切值tanδ,体系的黏弹性和稳定性增强,其中莲藕淀粉与黄原胶配比为8.0∶2.0（g/g）的复配体系增稠效果、黏弹性、稳定性最好。复配体系的硬度、内聚性、黏着性、咀嚼性降低,弹性略有增大,添加黄原胶形成的凝胶质地更柔软。扫描电子显微镜观察到添加黄原胶后淀粉内部形成更加均匀稳定的结构。     

复合酶制剂对甜酒酿面包发酵烘焙特性的影响

选用中国特色传统甜酒曲制作的甜酒酿进行面包制作,通过面团流变学分析、生物化学分析、激光共聚焦 显微观察、感官评定等多种手段对甜酒酿面团及面包的品质进行综合评估,与普通小麦面包进行对比,并使用天然 酶制剂来提高含甜酒酿面包的发酵烘焙特性。结果表明：含甜酒酿面团游离巯基含量增加,蛋白酶活力较强,甜酒 酿对面包面团面筋网络结构的形成有破坏作用,会导致面包内聚性、弹性下降,降低口感评分。但甜酒酿能给面包 带来更加诱人的色泽,其特有的酒香使面包更加可口,通过酶制剂的作用,面团面筋网络结构得到强化,含酶甜酒 酿面包品质全面提升,比普通小麦面包更受欢迎。     

纤维素纳米晶体对甘薯淀粉糊化特性和流变特性的影响

采用快速黏度分析仪以及流变仪分析纤维素纳米晶体对甘薯淀粉短期回生的影响。结果表明:随着0.03、0.06、0.09、0.12、0.15 g的纤维素纳米晶体添加到1.5 g甘薯淀粉中,其回生值明显低于纯淀粉。静态剪切流变测试结果表明,复合体系符合幂定律模型,是一种假塑性流体,剪切应力随着纤维素纳米晶体添加量增加而呈现降低趋势,稠度系数K减少,流体指数n增大。动态黏弹性测试结果表明,纤维素纳米晶体增强了体系的流体性。纤维素纳米晶体是一种有前景的淀粉短期回生抑制剂。     

黄原胶对木薯淀粉糊化特性及其糊稳定性的影响

研究黄原胶对木薯淀粉糊化特性,热、酸条件下的黏度稳定性及冻融稳定性的影响。结果表明：复配体系的峰值黏度、热糊稳定性、冷糊稳定性显著提高;黄原胶能明显改善木薯淀粉耐热和耐酸稳定性;抑制淀粉的回生,提高淀粉的冻融稳定性;通过电子显微镜观察木薯淀粉颗粒结构变化,进一步验证了黄原胶对木薯淀粉糊化特性及稳定性的改善作用。     

Effect of Phenolic Compounds on the Pasting and Textural Properties of Wheat Starch

Pasting and textural properties of wheat starch were systematically investigated in the presence of 25 phytochemicals including phenolic acids, flavonoids, coumarins, stillbenes and tannins with a wide structural diversity. Overall, most of these phenolic compounds significantly changed functional properties of starch. Trans‐cinnamic acid increased the peak viscosity most by 37 RVU whereas catechin decreased it most by 14 RVU. All the phenolic compounds considerably increased the breakdown with the greatest effect by chlorogenic acid (135 RVU) and the least by chrysin (6 RVU). Esculetin caused the maximum increase in setback (38 RVU), and 3‐hydroxybenzoic acid caused the maximum decrease (103 RVU). All the phenolic compounds significantly reduced the peak time with the greatest effect by trans‐cinnamic acid. Chrysin and 3‐hydroxybenzoic acid most increased and decreased the hardness of starch gels stored at 23°C for 48 h by 3.9 and 24.2 g. Most of the phenolic compounds increased the adhesiveness with the greatest effect by 3‐hydroxybenzoic acid (72 g·s). pH changes of the starch suspension caused by the addition of phenolic compounds and their structural diversity affected these functional properties of wheat starch to different extents. This study may provide a basis for the use of phytochemicals in functional and starch‐based staple foods.     

Effect of Sodium Dodecyl Sulphate on the Physicochemical,Thermal and Pasting Properties of Cassava Starch

The effect of different concentrations of sodium dodecyl sulphate (SDS) on cassava starch properties after complexation and in situ addition were studied. The swelling volume of the starch‐SDS complexes increased to a maximum of 100 mL/g with increase in concentration of SDS (even at 0.004 mol SDS) with a corresponding decrease in solubility. During in situ addition also, a similar but gradual behaviour was observed for swelling volume and solubility. The apparent and total amylose contents showed an irregular trend. The soluble amylose content decreased with increase in concentration of SDS. In vitro enzyme digestibility of starch‐SDS complexes was significantly lowered compared to that of native starch. The water‐binding capacity showed an initial decrease followed by a significant increase at higher concentrations of SDS. DSC studies showed that in addition to the gelatinisation endotherm, a peak corresponding to the melting of the starch‐SDS complex was obtained in the case of in situ addition of the surfactant. The peak viscosity of starch during in situ addition of SDS exhibited a rapid increase except at the highest concentration. The peak viscosity of starch‐SDS complexes underwent an initial reduction followed by a gradual increase at higher concentrations. The breakdown, setback and pasting temperature were also affected.     

Production and Measurement of Starch Damage in Flour. Effect of Starch Damage on Hot Pasting Properties

Aqueous suspensions were made of wheat starches damaged, by different methods, to varying degrees. Apparent viscosities of the hot pastes declined as damage levels increased and the relationships between these factors were examined. Measured as “extractability”, starch damage had a linear relationship with apparent viscosity for starches damaged by both methods. Starch damage measured as “digestibility” had different relationships with apparent viscosity for each type of damage involved. Evidence was found for the association of amylolytic enzymes with the starches used in the experiments.     

粳稻米淀粉糊化性质及其级分的研究

以3种粳稻米为原料，测定了粳稻米淀粉的RVA黏度特性、DSC热力学指标，以及对稻米淀粉进行高效液相色谱分析。结果表明：3种粳稻米淀粉的RVA峰值黏度、回生值差异较大，其余各项指标相差不大；DSC吸热曲线表明粳稻米淀粉起始糊化温度在65℃以下。吸热焓值略有差异；支链淀粉、中阃级分、直链淀粉在淀粉中的含量分为60％、22％、18％左右。     

Effect of Added Pentosans Isolated from Wheat and Rye Grain on some Properties of Bread

 Water-soluble and water-insoluble pentosans extracted from wheat and water-soluble pentosans extracted from rye were added in concentrations of 0.5%, 1.0%, 1.5%, and 2.0% to flour samples having different qualities. The effects of these pentosans on the physical and technological properties of the dough and bread and bread staling were then determined. Results show that all three pentosans markedly increased the water absorption and loaf volume, and retarded bread staling. Water-soluble rye pentosans in particular showed the most desirable effects. Received: 14 March 2000     

均质及大米蛋白对大米淀粉糊化和质构特性的影响

利用均质机在20～100 MPa压力下处理大米淀粉(RS),在添加或不添加大米蛋白(RP)情况下,考查大米淀粉理化性质、糊化和质构特性的变化。研究结果表明:随着处理压力的增加,RS的溶解度、膨胀率和透光率分别从1.90%、3.37%、6.27%上升至2.88%、5.38%、14.17%,凝沉性则下降;添加大米蛋白后,同一处理压力下,淀粉的溶解度、膨胀率下降,凝沉性上升。糊化特性分析发现,均质处理后,RS的最终黏度、崩解值和回生值分别下降了17.75%、24.47%和16.45%,说明其热稳定性提升,抗老化能力增强;原淀粉和60 MPa压力处理后的淀粉在添加氯化钠后糊化温度上升,黏度、降落值、回生值均有所下降,添加大米蛋白后淀粉黏度下降,回生值上升。质构特性分析发现,随处理压力的增加,淀粉凝胶的硬度从1 743 g下降到1 398 g,弹性则变化不大,大米蛋白使淀粉的硬度下降而弹性升高。