Pasting properties of transgenic lines of a commercial bread wheat expressing combinations of HMW glutenin subunit genes

Seven transgenic lines of a commercial wheat (Triticum aestivum L.) cultivar expressing transgenic subunits 1Ax1, 1Dx5 and 1Dy10, alone or in combination have been developed. Pasting properties were determined in these transgenic lines using a Rapid Visco Analyser (RVA) in order to determine the possible impact of HMW-GS transgene expression on the starch properties. Expression of the HMW-GS transgenes increased the proportions of the corresponding 1Ax, 1Dx and 1Dy subunits affecting significantly the ratios of HMW-GS:LMW-GS and x-type:y-type HMW-GS. Starch granule size distribution varied significantly among all transgenic lines, with the Anza control and transgenic line T616 (expressing subunits 1Ax1 and 1Dy10) showing the highest and the lowest percentage of B granules, respectively. All transgenic lines increased the water-binding capacities (WBC) at 25 °C and 90 °C. Line T606 (expressing subunits 1Ax1 and 1Dx5) and line T590 (expressing subunit 1Dy10) showed the lowest and the highest values for peak viscosity, respectively. Notably, lines expressing only transgenic x-type subunits (T580, T581 and T606), with high ratios of x-type:y-type HMW-GS, had low peak viscosities, final viscosities and breakdown viscosities. Line T590 had the highest breakdown viscosity while lines T606 and T581 had the lowest.     

Effect of repeated heating and cooling cycles on the pasting properties of starch

The properties of starch and starch–lipid pastes have been explored using a novel extended Rapid Visco Analyser (RVA) profile, in which the heating and cooling cycles are repeated five times. Starches from four wheat varieties with amylose content ranging from 23 to 27%, and waxy starches of wheat, rice and maize were tested, alone and in mixtures with lauric acid and monopalmitin (glyceryl-1-monopalmitin). Gels of all of the starches formed and melted reproducibly during repeated heating and cooling in the RVA. The addition of lauric acid to the waxy starches had no effect on the multiple RVA profile. Monopalmitin caused an increase in viscosity during the heating stage of the second to the fifth cycles with the waxy starches, which was attributed to the presence of monopalmitin aggregates. Changes in the multiple cycle viscosity traces observed when monopalmitin or lauric acid was added to the amylose-containing starches were complex. It was concluded that RVA paste viscosities were determined by starch–lipid interactions, as well as by free lipid in the starch mixtures. The water solubility of the lipid and association of proteins with starch granules influence these interactions.     

不同生长期木薯块根淀粉糊化特性的差异

对木薯品种(系)SC8、南植199、C869、D346和E632在6～11个月生长期的块根淀粉糊化特性进行研究。结果表明,木薯的含粉量随生长期的延长呈先增后减趋势,不同品种的变化拐点各不相同;直链淀粉含量随生长期变化趋势因品种而异,表现出显著的品种效应和生长期差异性;峰值粘度在生长期为8个月后随生长期的延长而增加,其值与鲜薯含粉率、直链淀粉含量呈显著正相关关系;木薯淀粉糊化温度的生长期差异性显著,且变化趋势因品种的差异而略有不同,它与直链淀粉含量呈显著负相关关系。木薯淀粉恩氏粘度与直链淀粉含量呈显著正相关。     

茶叶粉对小麦面粉流变学及糊化特性的影响

为进一步提高茶叶在食品工业中的应用范围,以小麦西农538(中筋)为供试材料,分别添加0、2%、4%、6%、8%和10%的绿茶、红茶和黑茶3类茶叶粉于面粉中,并对其进行面团流变学特性及糊化特性分析。结果表明,3类茶叶粉均可显著改善面团的流变学特性及糊化特性。随着茶叶粉添加量的增加,面团吸水率均显著增大;添加2%~10%的绿茶粉及6%~10%的黑茶粉,面团的形成时间和稳定时间均显著提高,弱化度均显著降低。添加6%的绿茶粉时,面团的拉伸能量和最大拉伸阻力增幅均达到最大值,延伸度出现小幅度升高的拐点;添加4%的红茶粉,面团的拉伸面积显著增大,继续增加添加量则变化不明显;黑茶和红茶粉添加量分别大于4%和6%时,面团延伸度均显著降低。面粉中添加适量的茶叶粉可改善面粉的品质,绿茶粉的添加对面团网络结构形成速度和面团筋力的改良效果大于红茶粉和黑茶粉。面粉糊化的峰值黏度、低谷黏度、最终黏度、峰值时间、回生值随着茶叶粉添加量的增大均呈不同幅度的降低趋势;3类茶叶粉对面粉糊化的热稳定性具有不同程度的改善作用。     

Production of ß-glucan enriched flour from waxy barley

Starch (total, amylose and amylopectin), β-glucans (total, soluble and insoluble) and pasting properties of waxy and normal barley genotypes were assessed. Waxy genotypes showed higher β-glucans content, lower starch amount and higher viscosity than normal genotypes. The USA2 waxy genotype characterized by higher β-glucans content, has been subjected to dehulling, pearling, and pin-milling and then to air classification to obtain an enriched flour that showed higher dietary fiber (23.4% d.w.) and β-glucans content (15.3% d.w.) The obtained enriched flour could be used for the production of functional foods (pasta, bread, biscuits etc) that satisfy the requirements of FDA and EU Regulation.     

普通、甜、糯玉米果穗不同部位籽粒淀粉理化特性和颗粒分布差异

以普通玉米、甜玉米和糯玉米为材料,研究了淀粉糊化特性、热力学特性和颗粒分布等在果穗不同部位(基部、中部和顶部)间的变异情况。结果表明,甜玉米淀粉的糊化特征值各项指标均为顶部籽粒较高;普通玉米淀粉的峰值黏度和崩解值亦为顶部籽粒较高,回复值在各部位间无显著差异。糯玉米淀粉崩解值为顶部籽粒最高,峰值黏度和回复值在各部位间相对稳定。甜玉米淀粉转变温度(起始温度、峰值温度和终值温度)均为基部籽粒较高,而普通玉米在各部位间差异较小,糯玉米以中部籽粒较高,热焓值在3个类型玉米各部位间变化不一。淀粉颗粒体积均呈双峰分布,>17 μm的体积比例以顶部籽粒最低,中部籽粒最高,<17 μm的体积比例以顶部籽粒最高,中部籽粒最低。碘结合力在糯玉米不同部位间差异较小,而甜玉米和普通玉米以顶部籽粒最低。相关分析表明,淀粉颗粒体积分布和碘结合力等指标与糊化和热力学特征值存在一定的相关关系,表明果穗不同部位淀粉糊化和热力学特性的差异主要由颗粒分布及淀粉链长分布变化所致。     

小麦淀粉与面条质量关系的研究进展

小麦淀粉品质对白盐面条的质量（尤其是煮后的感官特性）有重要影响。直链与支链淀粉的含量及比例是影响面条质量的重要因素,是造成不同小麦品种淀粉糊化和膨胀特性及面条质量差异的物质基础。较低直链淀粉含量的小麦粉具有较好的糊化和膨胀特性,制作的面条煮制时吸水率高,烹调损失低,具有较高的感官评分。优质白盐面条的直链淀粉含量应在22%左右。峰值黏度、稀懈值、峰值时间是影响面条质量的重要糊化参数,这3项参数高的小麦粉适合制作优质面条。高膨胀势或膨胀体积的小麦粉制作的面条中等偏软,光滑且富有弹性,可以作为面条用小麦的重要选择标准。一般认为,直链淀粉含量较低、峰值黏度和稀懈值高、峰值时间长、膨胀势或膨胀体积高的小麦粉适合制作优质白盐面条。其中,直链淀粉含量、峰值黏度和膨胀势是优质面条小麦评价的关键品质性状。     

Temperature during grain ripening affects the ratio of type-II/type-I protein body and starch pasting properties of rice (Oryza sativa L.)

The starch and protein properties of rice grain are important factors for sake brewing and these properties are reported to be influenced by temperatures during grain ripening. Amylose content, nitrogen content, protein composition, pasting properties measured by a Rapid Visco Analyser (RVA), and their relationship to temperatures during ripening were investigated in a rice cultivar, Yamadanishiki, which was grown under various conditions in the same experimental field. The average temperature after heading was significantly correlated with amylose content and RVA properties, but not with nitrogen content. Under high temperatures during ripening, a decrease in prolamin, which accumulated in type I protein body (PB-I), and an increase in glutelin, which deposits in type II PB (PB-II), were recognized. The ratio of PB-II/PB-I and RVA pasting temperatures were distinctly increased as the temperature became higher. High temperatures during grain ripening would lead to difficulties in digesting steamed rice grains by Aspergillus oryzae, together with ease in digesting rice protein. The average temperature of 11–20 days after heading showed a higher correlation coefficient than that of 1–10 or 21–30 days, implying that temperatures during the middle stage of grain development would be important in determining the rice component that relates to brewing properties.     

Pasting,thermal and rheological properties of octenylsuccinylate modified starches from diverse small granule starches differing in amylose content

Waxy maize (a standard starch of normal granule size) and five small granule starches from different botanical sources (rice, wheat B type, oat, quinoa and amaranth) were subjected to 2-octenyl-1-succinic anhydride (OSA) modification. Changes of pasting, gel texture, thermal and rheological properties were investigated. Different small granule starches showed quite different property changes after OSA modification. Pasting viscosity was generally increased in OSA starches, among which OSA oat starch had notably high peak and breakdown viscosity but low setback viscosity. Gel hardness of rice, wheat B type, oat and quinoa starches was reduced by OSA treatment, whereas that of waxy maize and amaranth starches was increased. Amylose content was considered to be the major factor influencing pasting, gel and thermal property of OSA starches. Esterification increased pseudoplastic flow behavior of all starches, while OSA oat starch uniquely had reduced flow consistency coefficient. The dynamic rheological properties were also changed differentially among OSA starches. Viscoelastic properties of rice, wheat B type, oat and quinoa starches were increased after OSA treatment, whereas those of waxy maize and amaranth starches were decreased. This study showed that diverse functionalities from OSA small granule starches may fulfil different demands in product development.     

小麦籽粒淀粉合成动态及糊化特性的基因型差异

为了明确不同基因型小麦品种籽粒灌浆过程中的淀粉合成动态,为小麦的高产优质栽培提供参考信息,对6个不同基因型小麦籽粒形成过程中淀粉组分的变化及淀粉糊化特性进行了分析。结果表明,非糯性小麦的直链淀粉含量随着花后天数的增加呈上升的趋势,糯性小麦则呈先上升后下降的趋势,所有品种的支链淀粉含量均呈上升的趋势;不同基因型小麦直链、支链淀粉积累速率均呈单峰曲线图,不同品种直链淀粉最大积累速率出现的时间不同,而支链淀粉最大积累速率出现的时间均在花后21d;不同小麦品种的峰值粘度、低谷粘度、最终粘度均随着花后天数的增加而上升;不同品种淀粉糊化特性不同:糯性小麦之间在糊化时间、反弹值上无差异,而在峰值粘度、低谷粘度、最终粘度、稀懈值上的差异达显著水平;对于非糯性小麦,豫麦50和其他品种的多数糊化参数差异达显著水平;糯小麦和非糯小麦在糊化参数上的差异达1%显著水平。