干热处理对藜麦淀粉结构和理化性质的影响

以高筋小麦粉为原料添加酵母制作面团,在温度28℃、湿度80%条件下发酵1～6 h,提取小麦淀粉。研究发酵时间对小麦直链淀粉含量、损伤淀粉含量、粒径、颗粒表面结构、糊化及消化特性的影响。结果表明：面团发酵1 h后直链淀粉含量和损伤淀粉含量均显著低于原淀粉(P<0.05)。快速黏度分析结果表明,发酵1 h的小麦淀粉峰值黏度、热浆黏度和冷浆黏度最低。发酵处理后淀粉的粒径均小于原淀粉,其中发酵5 h的平均粒径最小。扫描电镜结果表明,发酵6 h的小麦淀粉颗粒表面出现破裂现象。体外消化实验表明,发酵5 h和6 h小麦淀粉的消化速率最高,发酵后抗性淀粉含量低于原淀粉,而慢消化淀粉含量高于原淀粉(P<0.05)。     

Production and Measurement of Starch Damage in Flour. Part 3. Effect of Type of Damage on Baking Performance

Baking trials were conducted on two blends of 10% starch and 90% high protein flour. In both blends the flour component was identical but the starches had been ground in different ways to produce high levels of different types of damage. The levels of damage in the starches, and hence the blends, were similar if measured enzymically but different if measured by an amylose extraction method. Only small differences in baking properties were revealed.     

Physiochemical and Rheological Characterization of Sorghum Starch

Starch was isolated from the seeds of 3 sorghum cultivars and compared with commercial wheat starch. The amylose content of sorghum starches was in the range of 22.0–27.8%. Sorghum starches had less total lipids than wheat starch (1.66%) but there was no difference between sorghum Milo and Sorghum “100”. The water binding capacity of sorghum Dabar did not differ from that of wheat (100%) whereas differences in swelling power were observed, over a range of temperatures, between wheat and sorghum starches except for Sorghum “100” at 70°C. Sorghum starches showed single-step viscoamylographic curves with pronounced pasting peaks, good pasting stability and good set-back on cooling.     

玉米淀粉与玉米变性淀粉性质比较研究

测定了玉米淀粉、羟丙基淀粉、羧甲基淀粉、淀粉磷酸酯的冻融稳定性、透光率、膨胀度、粘度、糊化特性等主要物理性质并进行了比较。试验结果表明：变性淀粉与玉米淀粉的性质不同，由于变性淀粉引进了羟丙基、羧甲基、磷酸基团等亲水性基团，使淀粉极性增强，亲水能力增大，使其都具有较强的冻融稳定性、抗凝沉性，较高的膨胀度、透明度，因此变性淀粉具有更广阔的应用性。     

颗粒状冷水可溶淀粉糊性质的研究

在常压下,用醇解法制备了不同溶解度的颗粒状冷水可溶淀粉系列,并对玉米、木薯和马铃薯原淀粉及其不同溶解度的颗粒状冷水可溶淀粉糊的性质进行了研究。试验证明,相对于原淀粉糊,醇解法制备的颗粒状冷水可溶玉米淀粉糊的表观粘度和冻融稳定性有所提高,凝沉性降低;颗粒状冷水可溶木薯和马铃薯淀粉糊的表观粘度、凝沉性和冻融稳定性均降低。三种颗粒状冷水可溶淀粉糊的透明度大大提高,且随着溶解度提高其透明度增大。     

Preparation and Properties of Physically Modified Banana Starch Prepared by Alcoholic‐Alkaline Treatment

Granular cold‐water‐soluble (GCWS) starches were prepared from banana starch treating it with 40 and 60% aqueous ethanol at two controlled temperatures (25 and 35 °C). GCWS starches prepared at 25 °C and with 40 and 60% aqueous ethanol had the lowest cold‐water solubility, that prepared with 40% aqueous ethanol at 35 °C and stored at room temperature showed low tendency to retrogradation, as assessed by transmittance. Solubility and swelling profiles were similar for GCWS starches and the freeze‐thaw stability of GCWS starches was increased as compared with native starch. The apparent viscosity of GCWS banana starches was higher than that of its native starch counterpart.     

Chlorination of Cake Flour and Its Effect on Starch Gelatinization

The influence of a defined chlorination on the gelatinization behaviour of different cake flours in sucrose solutions (30–60% w/w) was investigated. Besides microscopic examinations, methods were developed for the estimation of hot paste viscosity and “amylose”

1 “Amylose” will throughout this paper mean linear polymers of glucose long enough to give a blue colour with iodine, but not necessarily native amylose as exists within the starch granule.

exudation from starch granules. The findings have shown that the amount of “amylose” which is exuded from starch granules during heating, as well as paste viscosity, increases with the chlorination of flour. High positive correlations were obtained between “amylose” exudation, hot paste viscosity and cake crumb firmness. It is proposed that this increased “amylose” exudation is, via an increase of gel strength, to a large extent responsible for the prevention of high ratio cake collapse. Besides reducing “amylose” exudation the high sucrose concentrations prevailing in cake batters were also found to inhibit greatly starch breakdown by malt and fungal amylase activity.     

贵州主产区不同品种荞麦淀粉性能的比较

选取贵州省主产区威宁县种植的11 种荞麦提取淀粉,测定了不同品种荞麦淀粉的理化性能、流变性能及体外模拟消化.结果表明,不同品种荞麦淀粉在理化、流变及消化性上均呈现出一定的差异性.其中,黔苦8 号、黔苦5号、贵甜荞1 号、贵黑米16 号荞麦淀粉具有较高的透明度;定苦1 号、黔黑荞1 号、黔苦3 号荞麦淀粉呈现较好的冻融稳...     

Effect of the Hard-to-Cook Phenomenon on Some Physicochemical Properties of Bean Starch

Two bean varieties of outstanding agronomic performance were seeded, harvested and a portion stored for 135 days under high temperature and humidity. These varieties were Negro Qro and Canario with black and light yellow seeds, respectively. Hard-to-cook (HTC) defect developed in aged seeds as assessed by the Mattson cooker and Instron texturemeter. Fresh and HTC beans were used in order to determine physicochemical changes in starch and to evaluate its contribution in textural defects. The damaged starch content, water absorption and swelling were higher for isolated starches from HTC seeds than for the controls. Starch damage was generated by enzymatic attack and/or by mechanical action during milling. Pasting properties examined with the Brabender viscograph showed that peak viscosity increased and stability and retrogradation capacities declined after storage. These results might be ascribed to the starch damage and also to changes undergone by the residual impurities of isolated starches. In agreement with the previous observations, scanning electron microscopy of starch isolated from HTC samples revealed the presence of some swollen granules and many others with fissures, while those from controls had smooth surfaces and with no evidence of damage. Differential scanning calorimetry (DSC) evaluations showed that gelatinization temperatures and transition enthalpies were not significantly influenced by storage; results in agreement with birefringence studies. It is suggested that the changes in the starch from defective seeds were not sufficient to modify the gelatinization performance.     

Production and Measurement of Starch Damage in Flour. Part 2. Damage Produced by Unconventional Methods

The relationship between two parameters of starch damage namely enzyme susceptibility and amylose extractability was examined in starch and in hard and soft flours ground by three unconventional methods. Variations in the relationship were as great in the starch series as in the flours, demonstrating that the effects of particle properties on the efficiency of one or other method of determination were not responsible. It is suggested that the two parameters are capable of independent variation since, in a single granule complete digestibility arises following a single “once for all” event, while for extractability that event marks the beginning of a process which can be further increased by suitable treatment. Types of starch damage can be defined in terms of ratio between extractability and digestibility and micrographs are presented which display granules afflicted by different types of damage.     

Studies on Rye Starch Properties and Modification. Part II: Swelling and Solubility Behaviour of Rye Starch Granules

Rye starch shows the typical inhibited swelling behaviour of triticeae starches with an onset of swelling at rather low temperature (50–55°C). Swollen rye starch granules exist as individuals even after swelling at 100°C. The total dispersion of rye starch needs temperatures above 120°C with pressure cooking. On heating of the rye starch suspension preferentially amylose is leached. Defatting of rye starch exhibits no influence on swelling power but results in higher solubility and in increased amylose leaching. The drying procedures applied here resulted in stronger assoziation of the polymer molecules in the starch granule leading to higher swelling temperatures and a reduced solubility. Shiftings of the crystalline/ amorphous-ratio of the starch granules as caused by different drying procedures, had no influence on the results of swelling power investigation but the highest swelling enthalpy as well as Brabender viscosity were exhibited by a sample dried at room temperature. It is proved to be possible to change the swelling behaviour of rye starch to “potato starch type” by slight chemical modification like succination.     

Characteristics and “Fodal”-Factor of Mango Seed Kernel Starch

Starch prepared from mango seed kernels is characterized by a low protein and fat content. Infrared studies proved the presence of amine and carboxyl groups of amino acids at wave numbers of 1485 and 1650 cm⁻¹ respectively, whereas the phosphate group had been detected at 1150 cm⁻¹. The contents of amylose and amylopectin were 39.9 and 60.1 respectively, reducing value was 1.54 and the alkali number was 10.10. The percentage of soluble material associated with starch was 2.11, whereas the percentage of branching of the mango seed kernel starch was 4.23. The glucose residues per end group were 23.62 and those per a segment were 11.81. Corn starch showed approximately the same values, whereas rice starch showed different results. The intrinsic viscosity was 1.72, 1.83 and 1.33 for mango seed kernel, corn and rice starches respectively, and the corresponding “Fodal” factors were 0.947, 0.983, and 0.992. X-ray analysis indicates that mango seed kernel starch possesses an “A” type of X-ray diffraction diagram.     

Physicochemical Properties of Ginkgo Kernal Starch

Native starch was isolated from ginkgo kernels, its physicochemical properties were investigated using some physical methods. Ginkgo starch granules were mostly oval in shape with a central Maltese cross and average long axis of 11 μm. Ginkgo starch contained 29.9% amylose content and exhibited an A-type crystallinity with 27.2% crystalline degree. Ginkgo starch had significantly higher gelatinization conclusion temperature, temperature range, and enthalpy than potato and rice starches. Ginkgo starch showed lower hot viscosity and higher breakdown viscosity than potato and rice starches. Ginkgo starch possessed markedly higher swelling power and resistance to α-amylase and amyloglucosidase hydrolysis than rice starch.     

Effect of Storage on Starch Content and Modification of Cassava Starch

The effect of storage on yield and modification of starch using hydrochloric acid and acetic anhydride were studied. Yield of starch from fresh roots (24.4%) was significantly greater than yield (16,2%) from roots stored at room temperature for six days. On a dry weight basis the amount of starch in the roots decreased over a six day storage period. The proximate composition of cassava starch on dry weight basis was 0.24% ash, 0.13% fat, 0.49% protein, 0.15% crude fibre and 98.4% starch. The isolated starch was treated with different concentration of hydrochloric acid to produce acid thinned and dextrinized starches and different concentration of acetic anhydride to produce acetyl substituted starches. The alkali number of acid thinned and dextrinized starches increased with acid treatment while the viscosity decreased. The degree of substitution increased with the concentration of acetic anhydride used. The cold water solubility of the acid thinned and acetyl substituted starches were similar to that of native starches while the solubility of the dextrinized starches increased with the acid concentration. The viscosity of the acetyl substituted starches increased with the degree of substitution.     

大米淀粉物化特性与糊化曲线的相关性研究

以不同品种的大米淀粉为原料，采用快速黏度分析仪（RVA）研究不同品种大米淀粉的糊化曲线的差异，碘兰值和酶解力等物化特性对糊化特性的影响。结果表明，不同品种大米淀粉的碘兰值、酶解力存在差异，以籼米淀粉的碘兰值最大，其次是粳米淀粉和糯米淀粉。粳米淀粉和糯米淀粉酶解力相对较大。糊化温度、最终黏度、最低黏度、回升值与碘兰值均呈不同程度的正相关。峰值黏度、最低黏度、最终黏度、回升值、糊化温度与酶解力呈不同程度的负相关。采用碘兰值、酶解力的指数模型描述大米淀粉的糊化特性可达到很高的拟合精度。     

Pasting Properties of Potato Starch and Waxy Maize Starch Mixtures

The pasting viscosity, morphological properties, and swelling properties of potato starch and waxy maize starch mixtures at different ratios were investigated. Pasting analysis of the starch mixtures (7% solids in water, w/w) using a Rapid Visco Analyser showed linear changes in peak viscosity and pasting temperature according to the mixing ratios of both starches, but not in breakdown and setback. The pasting profile revealed that the starches rendered mutual effects during pasting, more significantly when the amounts of potato and waxy maize starches were similar. The volume fraction of swollen granules and the presence of amylose appeared to be important parameters in the mutual effects of both starched during pasting. Under a light microscope, the swelling of potato starch granules was delayed by the presence of waxy maize starch. Overall results indicate that new pasting properties can be generated by mixing starches of different botanical sources.     

Cationized Starch Derived From Pre‐Oxidized Starch For Textile Sizing and Printing

Maize starch was subjected first to oxidation using H₂O₂ in presence and absence of ferrous sulfate as catalyst and then to cationization using 3‐chloro‐2‐hydroxypropyl trimethyl ammonium chloride. A thorough investigation of the chemical and rheological characteristics of the oxidized starch and oxidized‐cationized starch samples was made. It was found that these modified starches display characteristics, which qualify them to function as excellent sizing agent and to less extent as thickeners for printing polyester fabric with disperse dyes. The differences among the oxidized samples prepared in acidic and alkaline media in presence and absence of ferrous sulfate with respect to carboxyl and carbonyl group content were explained on the basis of the different mechanisms involved in the oxidation reaction of starch. The amenability of the different oxidized starch samples to cationization and variation in the apparent viscosity after cationization of the oxidized starches were also reported.     

Synthesis and Characterization of Hypochlorite Oxidized Starches

Egyptian rice and maize starches were treated with sodium hypochlorite at different concentrations. The oxidized starches so obtained were monitored for carboxyl content and rheological properties. In addition, the extent and rate of the oxidation reaction was assessed by investigating the chlorine consumption. Results indicated that the extent and rate of oxidation of rice starch, expressed as chlorine consumption, are much higher than those of maize starch. The opposite holds true for the carboxyl content. Pastes of rice and maize starches before and after oxidation exhibit non-Newtonian thixotropic behaviour but their apparent viscosity decreases by increasing the hypochlorite concentration. At any event, however, the apparent viscosity of rice starch is substantially higher than that of maize starch. Storing the pastes for 24 h adversely affect the apparent viscosity particularly with oxidized starches prepared using higher hypochlorite concentrations.     

Physicochemical Characteristics and Functional Properties of Starch from a High β-Glucan Waxy Barley

The physicochemical properties and functional characteristics of starch from a high β-glucan waxy barley were compared with those of starches isolated from normal and high amylose barleys. Amylose content of the starches ranged from 1.9 to 34.8%. There was no relationship between amylose content and water binding capacity and gelatinization temperature of the starches. Amylose content and swelling power as well as enzyme susceptibility were negatively correlated. Waxy barley starches had a lower solubility than amylose-containing starches. High amylose barley starch registered no swelling in the Amylograph. Amylose content in starch proved to be very important for good bread- and cake baking quality. Waxy starches did not produce acceptable breads and cakes. The starch from the high β-glucan barley variety “Shonkin” will be suitable as a thickening agent, but not as an ingredient in bakery products.