Effect of Germination and Fermentation on in vitro Starch and Protein Digestibility of Pearl Millet

Germination of pearl millet grain for 24 hr significantly improved its in vitro starch and protein digestibility. Fermentation of pearl millet sprouts by mixed culture combinations of yeasts and bacteria (Saccharomyces diastaticus and Lactobacillus brevis; Saccharomyces diastaticus and Lactobacillus fermentum; Saccharomyces cerevisiae and Lactobacillus brevis; and Saccharomyces cerevisiae and Lactobacillus fermentum) resulted in a significant increase in protein and starch digestibility. The pearl millet sprouts fermented with mixed culture containing S. diastaticus and L. brevis had the highest in vitro starch digestibility, while the sprouts fermented with the culture containing 5. cerevisiae and L. fermentum had the highest in vitro protein digestibility.     

Degradation of Starch Granules by Alpha-Amylase of Streptomyces precox NA-273

The action of purified α-amylase of Streptomyces precox NA-273 on starch granules of normal maize and potato was studied. The hydrolysis was followed by measuring total soluble carbohydrates and glucose released. Patterns of degradation were observed by scanning electron microscopy (SEM). The main soluble product was maltose, small amounts of glucose and higher oligosaccharides were always observed. By SEM, attack started small pits on the surfaces of maize starch granules, pits increased in number and in size, and pores penetrated into the inner portions of the granules toward the center. The enzyme seemed to degrade the inner portion of starch granules better than the well-known general α-amylases.     

发芽状况及热处理对小麦淀粉品质影响的研究

以面筋强度不同的７ 个小麦品种为材料,分析不同发芽状况与热处理对小麦淀粉品质的影响。结果表明：发芽使α－ 淀粉酶活性激增,表现为降落值（ＦＮ）、膨胀势下降。７０ ℃、９０℃处理的发芽小麦,较未经热处理芽麦的降落值、膨胀势增高,说明适当高温处理能降低α－ 淀粉酶的活性。发芽及热处理对小麦淀粉含量影响较小。面筋强度不同的小麦品种表现基本一致     

发芽小米淀粉热分解机制及动力学研究

发芽是改善谷物品质的绿色加工方法。为了探究发芽对小米淀粉热力学性质的影响,采用差示量热扫描法、热重分析法对发芽小米淀粉的热分解机制及其动力学行为进行了研究。结果表明,小米发芽后淀粉糊化温度升高,糊化焓、回生度、回生速率均减小;未处理及发芽处理小米淀粉热分解均是一个连续的过程,热分解温度范围为295~360℃,分解速率最快的温度范围为298.49~305.01℃;发茅小米淀粉活化能、指前因子、焓值、熵值(绝对值)及吉布斯自由能均较未处理小米淀粉减小;未处理及发茅小米淀粉热分解最概然机制函数均为G(α)=lnα,最概然机制为单分子消除反应,为一级反应。     

Honey Amylase Activity and Food Starch Degradation

ABSTRACT: Honey amylase was evaluated for potential to degrade food starch and cause viscosity loss. Honey was assayed for amylase activity with diastase number (DN). A viscosity assay, developed with unmodified waxy maize starch, measured honey amylase rate of viscosity decrease (RVD). The relationship between DN and RVD was linear (R²= 0.98). Modified waxy maize starches showed resistance to honey amylase. Honey heat treatment at 85 °C reduced amylase activity 2 to 5 DN, but confirmed enzyme heat resistance. Optimum pH for honey amylase was confirmed at pH 5.3 to 5.6. RVD activity declined as pH decreased. Preventing food viscosity loss involved selecting honey with lowered DN and/or using modified starches. Complete control of activity was achieved in barbecue sauce at pH < 3.9.     

Isolation and Characterization of Starch from Pearl Millet (Pennisetum typhoidium) Flours

Pearl millet, an underutilized crop, is a relatively good source of nutrients and has varied uses over cereals. New applications must be explored to popularize the millet. In the present study, flour and isolated starch from pearl millet cultivars—Kalukombu and Maharashtra Rabi Bajra (MRB)—were investigated for physicochemical properties, nutritionally important starch fractions and x-ray diffraction. The yield of starch was significantly low (Kalukombu: 34.5 g/100 g and MRB: 39.4 g/100 g) with traces of non-starch components (protein, fat, and ash) indicating its purity. Starch could be classified as non-waxy type based on low amylose content (2.86–4.96 g/100 g). Low amylose lead to fragility of swollen starch granules which disintegrated easily at 65°C as observed in swelling power and solubility. Isolated starch was characterized with low water- and oil-holding capacity which could be attributed to the low protein content and absence of fiber in the starch. However, MRB starch showed higher oil uptake compared to flour, possibly due to its larger surface area that increased oil uptake. X-ray diffraction patterns showed sharp peaks at 2θ values 15 and 23º and a diffused peak at 2θ of 17 and 18º which is characteristic of A-type pattern. Low resistant starch (RS) and high readily digestible starch (RDS) content observed in the isolated starch could be attributed to the A-type pattern of starch which is more susceptible to enzyme hydrolysis and also due to elimination of structural obstruction to amylase hydrolysis during the process of starch isolation and gelatinization.     

Effects of Germination and Pure Culture Fermentation by Yeasts and Lactobacilli on Phytic Acid and Polyphenol Content of Pearl Millet

Germination of pearl millet at 30°C for 24 hr reduced phytic acid significantly (P<0.05) which, on fermentation with mixed pure cultures of Saccharomyces diastaticus, Saccharomyces cerevisiae, Lactobacillus brevis, and Lactobacillus fermentum at 30°C for 72 hr, was eliminated or reduced to negligible levels in fermented sprouts. Concentration of polyphenols did not change on germination. The fermentation of sprouts by combinations of S. cerevisiae with L. brevis and S. cerevisiae and L. fermentum did not change polyphenol whereas S. diastaticus with L. brevis (SdLb) increased and S. diastaticus with L. fermentum combinations decreased the polyphenol in the sprouts.     

小麦和酿酒大麦发芽过程中主要酶活的比较研究

对小麦、大麦发芽过程主要酶(α-淀粉酶、β-淀粉酶、植酸酶、过氧化物酶和多酚氧化酶)活力的动态变化进行比较研究.结果表明,在发芽过程中,小麦和大麦中几种酶的酶活力变化具有较高的一致性,即发芽前4d酶活不断增加,随后出现下降趋势.     

高静压处理对小米淀粉和小米全粉中淀粉颗粒结构和糊化特性的影响

将小米淀粉及其全粉经300,450,600 MPa压力处理20 min,探讨不同高静压处理条件对小米淀粉及其全粉中淀粉颗粒结构和糊化特性的影响,为优化小米淀粉品质特性提供理论依据。结果表明：小米淀粉颗粒在较高的压力水平下发生明显膨胀,颗粒之间形成弱凝胶,黏度变化不大,崩解值和回生值下降。小米全粉中淀粉颗粒在较高压力水平下与表面物质络合,崩解值下降而回生值升高,说明高静压处理可以改善小米淀粉及其全粉中淀粉的颗粒结构和糊化特性。     

Physico-chemical Properties of Native and Malted Finger Millet,Pearl Millet and Foxtail Millet Starches

The physico-chemical properties of starches isolated from native and malted finger millet, pearl millet and foxtail millet were studied. Malt starches, as compared with native starches, contained a majority of smaller granules, slightly more amylose, and exhibited higher gelatinisation temperature, lower swelling power, higher solubility in water as well as in dimethyl sulfoxide and lower intrinsic viscosity. The in-vitro digestibility of starches from native and malted millets was more or less similar but it was different for different starches: pearl millet starch was more susceptible whereas finger millet starch was slighly resistant for amylolysis.     

生物发酵处理对小米淀粉分子结构及糊化特性的影响

采用0.2 g/100 m L NaOH溶液提取发酵后的小米淀粉,研究自然发酵及优势菌(乳酸菌、酵母菌)发酵后对小米淀粉颗粒特性、结晶度、官能团、分子质量、糊化及老化特性的影响。结果如下:乳酸菌、酵母菌发酵后,淀粉颗粒表面有明显的侵蚀迹象,而自然发酵淀粉颗粒表面侵蚀迹象较轻;乳酸菌发酵后小米淀粉的结晶度较自然发酵增加1.49%而酵母菌发酵减少0.33%;发酵并未改变小米淀粉官能团区的峰位,但特征峰强度减弱,乳酸菌、酵母菌发酵后小米淀粉指纹区图谱消失;未发酵小米淀粉重均分子质量为1.5×10~4~5.9×10~5 g/mol,自然发酵分子质量在2.1×10~4~5.4×10~5 g/mol,乳酸菌发酵分子质量为1.6×10~4~5.3×10~5 g/mol,酵母菌发酵分子质量为1.6×10~4~4.7×10~5 g/mol,乳酸菌、酵母菌发酵后支链淀粉长链及直链淀粉比例减少而中间及短支链淀粉的比例相对增加;乳酸菌、酵母菌发酵96 h糊化温度较自然发酵下降0.84℃和1.13℃,热焓值上升1.00 J/g和0.78 J/g;二者的回生值较自然发酵分别下降743、471 mPa·s。自然发酵的优势菌(乳酸菌、酵母菌)使小米淀粉的分子结构、糊化及老化特性发生明显变化,并在小米自然发酵过程中起主导作用。     

燕麦发芽过程中淀粉理化特性的变化

以山西产裸燕麦为原料,在控制的条件下发芽72 h,每间隔12 h取样,测定燕麦淀粉的颗粒结构、溶解度等理化特性。结果表明,燕麦发芽过程中,其淀粉颗粒仍保持了原淀粉的外貌形态和X-射线衍射A型图谱特征。发芽处理使燕麦淀粉的溶解度增加,膨胀度减小,同时会导致淀粉冻融稳定性变差,易于老化。但适度的发芽可增加淀粉的透明度,增强淀粉糊的热稳定性和冷稳定性。     

Degradation of Wheat Starch in a Single-Screw Extruder: Mechano-Kinetic Breakdown of Cooked Starch

Wheat starch was processed in a 19 mm diameter split-barrel laboratory extruder under varying conditions of barrel temperature (79–121^oC), screw speed (50, 100 rpm) and moisture content (25, 30%). Final product and samples removed from along the barrel length were examined for changes in molecular size by dilute solution viscometry. Final products were also examined for paste viscosity and estimated degree of cook. A mathematical model was developed which relates the residence time of the starch in the barrel, the nominal shear stress acting on the starch and the degree of cook of the product to the extent of molecular degradation of the starch. Solution viscometry was found to be more rapid than gel permeation methods previously used to determine the extent of molecular changes.     

Effects of Wheat Starch Contents on Malt Qualities

The relationships between wheat starch content and wheat malt qualities were studied in the present work. Six wheat varieties that were typical in starch, protein content and amylopectin/amylose ratio were selected from 12 wheat varieties and germinated under the same conditions. The decreased degree of total starch content after malting had a positive correlation (r = 0.8020, P < 0.1) with the amylopectin/amylose ratio of the raw wheat. Extracts of wheat malts were influenced by starch content and the amylopectin/amylose ratio of the raw wheat. When the amylopectin/amylose ratio was in the range 3.65:1?3.93:1, extracts of the malts had significant positive correlation (r = 0.967, P = 0.002) with the starch content of the raw wheat. In this investigation a suitable amylopectin/amylose ratio (3.65:1 to 3.93:1), a high starch content and a low protein content were the characteristics of a wheat variety suitable for malting.     

小米淀粉与玉米淀粉糊性质比较研究

对小米淀粉和玉米淀粉糊性质进行较详细比较研究,包括透明度、冻融稳定性、凝沉性、膨胀力、酸解、酶解,和介质对糊粘度性质影响。结果表明,小米淀粉与玉米淀粉相比,糊的凝胶稳定性好、持水力强、膨胀力高、糊化温度高、热焓变值大、但透明度较差、冻融稳定性不佳、热稳定性差;且氯化钠及糖溶液对小米淀粉糊粘度性质影响较大。     

Steep-Out Moisture,Malting Loss,and Diastatic Power of Pearl Millet and Sorghum as Affected by Germination Time and Cultivar

Ten pearl millet cultivars and sorghum (control) were steeped for 12 hours with one hour air rest and germinated for 96 hours. The germinative properties and steep-out moisture content of the grain were determined. Green malt moisture, malting loss, vegetative loss, total malting loss, and diastatic power were also determined during germination at intervals of 24 hours. Data obtained from the study were statistically analyzed using analysis of variance of a randomized complete design and 11 × 5 factorial experiments to determine differences among germination time and cultivar. Means were separated using Duncan Multiple Range Test. Correlation analysis was determined with computer using statistix, version 4.1. Results indicated that grains had good germinative properties and wide variations of steep-out moisture content among the cultivars. Green malt moisture, metabolic loss (malting loss), vegetative loss (seedling yield), total malting loss, and diastatic power increased significantly (P < 0.05) with an increase in germination time and varied widely among cultivars. This information could serve as a guide for selection of suitable pearl millet cultivars for malting.     

Effects of Protein in Wheat Flour on Retrogradation of Wheat Starch

Albumins, globulins, gliadins, and glutenins were isolated from wheat flour and the effects of those proteins on retrogradation of wheat starch were investigated. The results showed that only glutenins retarded retrogradation of wheat starch and other 3 proteins promoted it. The results of IR spectra proved that no S–S linkage formed during retrogradation of wheat starch blended with wheat proteins. Combination of wheat starch and globulins or gliadins through glucosidic bonds hindered the hydrolysis of wheat starch by α‐amylase. The melting peak temperatures of retrograded wheat starch attached to different proteins were 128.46, 126.14, 132.03, 121.65, and 134.84 °C for the control with no protein, albumins, glutenins, globulins, gliadins groups, respectively, and there was no second melting temperature for albumins group. Interaction of wheat proteins and starch in retrograded wheat starch greatly decreased the endothermic enthalpy (△H) of retrograded wheat starch. Retrograded wheat starch bound to gliadins might be a new kind of resistant starch based on glycosidic bond between starch and protein.     

变性淀粉用于麦草浆造纸

本文研究了不同种源、不同取代度、不同离子型的多种变性淀粉对麦草浆湿部化学与成纸性能的影响。指出对麦草浆造纸来说，变性淀粉是物美价廉的助剂，兼有助留、助滤与增强的功能。     

Some Effects of Starch Lipids on the Thermal and Rheological Properties of Wheat Starch

Thermal and rheological properties of starches from two different wheat varieties were examined in relation to differences in surface distribution of lipids in the starch granules. The lipids present on the outside of the granules were extracted by isopropanol and the lipids in the amylose lipid complexes were extracted by water-saturated butanol. These amylose lipid complexes influence both the thermal properties of the starch, measured by differential scanning calorimetry, and the viscosity of the starch. The starch with the greatest amount of lipids extractable by water-saturated butanol began to gelatinize at a higher temperature and the gelatinization enthalpy was lower. Furthermore the viscosity began to increase at a higher temperature and the maximum viscosity was achieved at a higher temperature for this starch.     

超声处理对小米淀粉结构及理化性质的影响

在相同超声温度及时间下,研究了不同超声功率0、25、50、100、150、200、250 W对小米淀粉聚集态结构及理化性质的影响,测定了超声处理时小米淀粉的水解率、颗粒形貌、晶体结构、官能团结构、粒径大小、流变学特性、糊化特性的变化规律。结果表明:超声处理导致小米淀粉水解率和粒径增大,250 W超声处理40 min小米淀粉水解率为1.037%,平均粒径由9.96 μm增大到12.10 μm,且表现出更好的稳定性;超声处理未引起小米淀粉结晶类型和分子结构改变,但导致分子有序度略微下降;超声处理改变了小米淀粉糊的流动性,其剪切应力和表观黏度随超声功率增加而降低;小米淀粉在超声处理后峰值粘度、最低粘度、终值粘度、崩解值和回生值均显著降低,热稳定性增加。超声波技术广泛应用于变性淀粉加工,本研究的结果可为小米淀粉的改性研究提供理论基础。