不同品质籼稻胚乳糊化前后微结构差异的研究

 利用扫描电镜观察品质差异较大的 4个籼稻品种稻米糊化前后的微结构 ,发现同等条件下不同部位的糊化明显不同。背部糊化最好 ,细胞完全崩解为絮状或小块状的蓬松物质 ;腹部糊化次之 ,呈较大块状或细胞结构刚被破坏 ,有的细胞轮廓仍可见 ;中部糊化最差 ,多为完整胚乳细胞。不同品种糊化后差异明显 ,米质好的品种其背、中、腹部的糊化比米质差的品种的相应部位好 ,米质较差品种的中部明显凹陷 ,而较优品种的断面较平 ,该现象同样表现在早、晚稻的对比上。品种间背部糊化的差异小于中、腹部 ,品种内米质较优的稻米背、腹、中部的差异比米质差的小。米质较好的品种的胚乳横断面可见较多断裂的细胞 ,而米质较差的品种几乎见不到断裂的细胞 ,其数目与米质优劣有一定的正相关。米质优劣与糊化时的吸水率和延长率正相关 ,吸水率和延长率高则糊化较好     

怀山药糊化特性研究及其工艺优化

[目的]研究怀山药的糊化特性,并对其工艺进行优化。[方法]以焦作怀山药为研究对象,以粘度值、黏蛋白含量及感官评价为品质指标,分别探讨糊化温度、糊化时间和料液比等因素对山药品质的影响规律,以对怀山药的糊化特性进行分析,并在单因素试验的基础上,对糊化工艺进行正交优化。[结果]山药浆糊化过程中粘度变化是淀粉糊化与黏多糖-蛋白复合物结构变化综合作用的结果;山药浆最优糊化工艺为:料液比为1∶4(W/V,g/ml,下同),糊化温度为70℃,糊化时间为15 min。[结论]该方法制备的山药浆糊化品质好,生产效率高,适于工业化深加工。     

Investigation of the high-amylose maize starch gelatinization behaviours in glycerol-water systems

The effect of glycerol on gelatinization behaviours of high-amylose maize starch was evaluated by confocal laser scanning microscopy (CLSM), scanning electronic microscope (SEM), differential scanning calorimetry (DSC), texture analyzer (TPA) and rheometer. Gelatinization of the high-amylose maize starches with glycerol content of 10% (w/w) began at 95.4 °C (T_o), peaked at 110.3 °C (T_p), and completed at 118.9 °C (T_c). The birefringence began to disappear at around 100 °C and finished at 120 °C which corresponded well to the onset and conclusion temperatures obtained by DSC. The high-amylose maize starch granules maintained original morphological structure at 100 °C and swelled to a great degree at 110 °C. The high-amylose maize starch paste formed at 100 °C showed the lowest hardness (39.92 g), while at 120 and 130 °C, showed the highest hardness (610.89 g and 635.43 g, respectively). It should be noted that in going from 100 °C to 110 °C there is a significant increase in the viscosity of the slurry solution. The identical apparent viscosity was observed when the shear rate exceed 100 s⁻¹, resulting from the high-amylose maize starch granules were completely gelatinized at 120 °C, which was consistent with DSC analysis.     

Development of new markers to genotype the functional SNPs of SSIIa, a gene responsible for gelatinization temperature of rice starch

Gelatinization temperature (GT) is an important quality predictor that determines the cooking quality of rice. GT is genetically controlled by the starch synthase IIa (SSIIa) gene. Two functional single nucleotide polymorphisms (SNPs) inside the SSIIa have already been found to be responsible for the variation of GT. One of these, GC/TT SNP at 4329/4330 bp, could be genotyped by four primers in a single PCR ( Bao et al., 2006a), but another one, G/A SNP at 4198 bp, has not been detected by a PCR-based marker. Here, we developed cleaved amplified polymorphic sequence (CAPS) and derived cleaved amplified polymorphic sequence (dCAPS) markers to detect these SNPs. A dCAPS marker that the PCR products were cleaved by the BseR I restriction endonuclease was designed to detect GC/TT SNP. Both CAPS and dCAPS markers were designed to detect G/A SNP using the restriction endonuclease Nla III and Tsp45 I, respectively. All the markers developed were co-dominant. It was known that the A allele of G/A SNP was rare among rice germplasm, but it was still in use by rice breeders. 11 rice accessions including landrace and breeding lines with A allele of G/A SNP were detected. The F₂ individuals from two crosses were used to analyze the co-segregation between the SNP alleles and the GT. The segregation ratio of two SNPs did not conform to the expected Mendelian ratio of 1:2:1, but the SNPs were co-segregated with GT. The markers developed in the present study would be useful in molecular breeding for the improvement of the quality of rice grain.     

三个籼型杂交水稻糊化温度的遗传分析

本文以KOH扩散法分析了汕优3号、汕优6号、赣化2号等三个杂交水稻双亲、F_1和F_2的糊化温度。结果表明五个供试亲本分别归属于二种不同的糊化温度类型。珍汕97A、献党1号的平均糊化温度级别是1.68、1.88,为典型的高糊化温度类型;而IR661、IR26、IR24的平均糊化温度级别为6.13、6.94、6.14,是典型的低糊化温度类型。三个F_1无论是高×低,还是低×高,它们的平均糊化溫度级别是1.73、1.65、1.71,均表现为高糊化温度。三个F_2糊化溫度分离都呈偏态双峰曲线分布。根据各组合中高、中、低三种类型的籽粒数,可以得到12:1:3的分离比,经X~2测定,三个X~2值都小于PO.01,无显著性差异。因此,可以认为,高糊化温度是个显性性状,是由二对基因控制的,而且,基因间具有上位效应。另外,利用高糊化温度是显性的特点,测定了赣化2号(IR24×献党1号)组合的种子纯度。结果表明,杂种和母本间的差异显著。因此,通过糊化温度测定可以测定该组合F1杂种的纯度。同时,本文还针对杂交水稻米质差的情况,提出了改进意见。     

葡萄糖和蔗糖对莲籽淀粉糊化特性的影响

通过差示扫描量热法（DsC）研究葡萄糖和蔗糖对莲籽淀粉糊化特性的影响。试验结果表明,葡萄糖和蔗糖均可使莲籽淀粉的糊化起始温度（To）、糊化峰值温度（Tp）、糊化终止温度（Tc）和糊化热焓值（△H）升高,其上升幅度与糖浓度呈正相关。     

10种玉米胚乳突变基因型淀粉糊化的热力学特性

玉米淀粉粝化过程的热力学特性对于淀粉在食品和非食品工业中的利用具有重要意义，本文以近等基因系为材料，采用差热扫描分析仪（ＤＳＣ）研究了ｏｈ４３和Ｂ３７遗传背景的＋／＋；ａｅ／ａｅ；ｄｕ／ｄｕ；ｓｕ２／ｓｕ２；ｗｘ／ｗｘ；ａｅ／ａｅ；ｄｕ／ｄｕ；ａｅ／ａｅ，ｗｘ／ｗｘ；ｄｕ／ｄｕ，ｓｕ２／ｓｕ２；ｄｕ／ｄｕ，ｗｘ／ｗｘ；和ｓｕ２／ｓｕ２ｗｘ／ｗｘ胚乳突变基因型对淀粉糊化的热力学性状的效应。结果表明，     

橡实与木薯、玉米淀粉理化性质的对比研究

[目的]研究橡实淀粉的组成成分、结构及理化性质。[方法]采用理化检测方法对橡实淀粉的性质进行了研究,较系统地考察了橡实淀粉的组成、颗粒、淀粉糊等方面的性质。[结果]橡实淀粉中淀粉含量为59.61%,直链淀粉的含量为31.40%;其颗粒相对玉米淀粉颗粒较小,与木薯淀粉相近;晶体结构为C型;橡实淀粉的溶解度、膨胀度比玉米淀粉低,与木薯淀粉相近;橡实淀粉糊凝沉速度居于玉米淀粉和木薯淀粉之间。DSC分析显示,橡实淀粉的糊化温度(61.72℃)较木薯淀粉(70.22℃)和玉米淀粉(66.78℃)低,这说明橡实淀粉较玉米淀粉和木薯淀粉易糊化。[结论]研究可为橡实资源的开发利用提供基础数据。     

Accelerated ageing of wheat grains: Part II-influence on thermal characteristics of wheat starch and FTIR spectroscopy of gluten

Wheat quality characteristics are influenced by different factors such as moisture content, storage time and temperature. In this study accelerated ageing of wheat grains was carried out by increasing moisture content (16, 18 and 20%) and keeping the samples in different temperatures (30, 40 and 50 °C) for different periods (2, 5 and 8 days). After milling, the thermal properties of starch and structure of gluten were investigated using Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR); respectively. The experimental set up was designed using response surface methodology and the three distinct factors were combined by central composite design. Results showed that increasing moisture content caused a decrease in onset, peak and end set temperatures of gelatinization while increasing storage time and temperature increased these parameters. By progressing storage time the band intensity of thiol groups decreased while that of disulfide groups of gluten increased indicating an improvement in gluten quality. Increasing moisture content from 16 to 20% and higher storage temperature (50 °C) decreased intensity of disulfide bands.