玉米胚乳的特性及其应用

阐述了玉米粉质胚乳和角质胚乳的理化特性，糊化特性、α－淀粉酶的水解作用，烘焙特性等差异，旨在为玉米胚乳的应用提供理论依据。     

不同类型玉米发育过程中淀粉糊化特性的比较

采用DGC方差分析法,比较普通玉米、糯玉米和爆裂玉米籽粒生长过程中胚乳淀粉糊化特性和直链淀粉含量的变化及差异。结果表明,普通玉米和爆裂玉米RVA谱的尾部高于峰顶,而糯玉米RVA谱的尾部低于峰顶。普通玉米的低谷黏度授粉后10 d达最高,峰值黏度和最终黏度分别在20 d和30 d时最高;糯玉米的峰值黏度、低谷黏度和最终黏度均在30 d时最高,爆裂玉米均在40 d时最高。说明,普通玉米胚乳的淀粉膨胀力、耐剪切能力和淀粉胶的硬度最先达到最大,其次为糯玉米,爆裂玉米最晚。糯玉米胚乳中直链淀粉含量最低,回复值最低,最不易老化。授粉20 d后,爆裂玉米淀粉的峰值时间最长,糊化温度最高,最难糊化。相关分析发现,糯玉米的直链淀粉含量与回复值和糊化温度分别呈显著正和负相关,爆裂玉米直链淀粉含量与消减值呈显著正相关,而普通玉米直链淀粉含量与RVA特征值间不存在显著相关性,即相关性的大小受玉米类型的影响。     

沙棘果粉和酸枣粉对面粉特性的影响

为了解沙棘果粉和酸枣粉对面粉特性的影响,将沙棘果粉和酸枣粉按不同比例分别与小麦粉混合,使用快速黏度分析仪、粉质仪、物性测试仪分析2 种添加物的添加量对面粉糊化、粉质和凝胶质构特性的影响,并使用扫描电子显微镜对面筋的超微结构进行观察。结果表明：随着酸枣粉含量的增加（0%、1%、3%、5%、7%、9%）,混粉的峰值黏度、低谷黏度、最终黏度呈下降趋势,而当沙棘果粉添加量为5%～9%时,混粉的上述糊化指标明显高于对照组;吸水率、硬度、胶黏性、咀嚼性逐渐降低,而形成时间、稳定时间和粉质质量指数则先降低,后基本不变;扫描电子显微镜观察显示,2 种添加物均阻碍了面筋网络的形成。因此,沙棘果粉和酸枣粉的添加均改变了面粉的糊化、粉质、凝胶质构特性及面筋超微结构。     

酸改性麦麸粉对面粉粉质特性及面团质构特性的影响

研究超声波-酸解改性的麦麸粉不同添加量对面粉粉质特性、面团拉伸特性、面粉糊化特性以及面团质构特性的影响。结果表明：随着酸改性麦麸粉添加量的增加,面团的吸水率、形成时间呈上升趋势,稳定时间和粉质指数则先上升后下降;面团的最大拉伸阻力、拉伸阻力、拉力比数随酸改性麦麸粉添加量的增加呈上升趋势,而延伸性和拉伸面积呈下降趋势,对面团的拉伸特性具有正、反两方面的作用;峰值黏度、最低黏度、衰减值、最终黏度、回生值、糊化温度及峰值时间均呈先上升后下降的趋势;质构特性结果表明,面团的硬度、弹性、黏附性、咀嚼性、内聚性和回复性随着添加量的增加呈先增加后减少趋势。综合得出,酸改性麦麸粉添加范围6%～9%可以改善面粉粉质及质构特性。     

不同杂粮添加对籼米粉粉质特性及挤压米粉品质特性的影响

本文选择绿豆、荞麦、高粱、薏米四种杂粮分别添加到籼米粉中,替代比例为25%。通过快速黏度测定仪、动态流变仪、质构仪和扫描电镜,研究了杂粮添加对米粉糊化特性、流变特性、凝胶质构和微观结构等特性的影响。利用挤压重组技术生产挤压杂粮米粉,研究了杂粮添加对挤压米粉蒸煮特性、质构特性的影响。结果表明,杂粮粉与籼米粉混合后,荞麦混合粉在淀粉糊化过程中表现出最高的峰值黏度和最终黏度,分别为4241和4705 cP,而薏米混合粉峰值黏度和回生值最低,分别为2438和1369 cP;添加杂粮后的凝胶结构呈现出较多的孔状,其中荞麦粉混合凝胶的硬度和弹性值最大,分别为16.60 g和0.89;添加杂粮后,挤压米粉的膨胀率、蒸煮损失、断条率均有所增加;添加荞麦粉后米粉的质构特性接近籼米米粉,而添加薏米粉的米粉质构特征值表明挤压米粉的品质显著降低(p<0.05)。利用挤压技术开发挤压杂粮米粉不仅可以提高米粉的营养价值,同时也有助于推动传统主食食品米粉的工业化发展进程。     

氯化钠对不同品种红小豆淀粉特性的影响

从3种不同品种的红小豆中提取的淀粉为原料,通过分析淀粉及添加氯化钠后的淀粉糊的粒径、黏度值、回生值、热焓值、凝胶性等特性,探究氯化钠对淀粉糊化特性的影响。结果表明:低直链淀粉含量的大红袍中淀粉相较于宝清红和珍珠红淀粉,表现出较高的糊化起始温度、最终黏度、热焓值;较低的峰值黏度、较小的粒径;对比添加2%氯化钠前后,3种红小豆淀粉糊化后的平均粒径、峰值黏度、衰减值和回生值显著下降(P0.05);糊化温度、淀粉的凝沉性显著增大(P0.05);氯化钠对凝胶特性的影响体现在凝胶强度显著降低(P0.05),同时淀粉凝胶的黏度减小。     

豆粉对小麦粉粉质特性和糊化特性的影响

将豆粉和小麦粉按不同比例混合,采用Mixolab混合实验仪和快速黏度分析仪分析不同豆粉对小麦粉粉质及糊化特性的影响。结果表明:随着豆粉添加量的增加,面团的稳定时间和形成时间减少,面团蛋白弱化度增大,峰值黏度、低谷黏度、最终黏度、回生值不断减小;C2值、峰值黏度、低谷黏度、最终黏度、糊化温度和糊化时间与5种豆粉添加量显著负相关(P<0.05)。其中,绿豆粉对小麦粉的粉质特性影响较大,黄豆粉和黑豆粉对小麦粉的糊化特性影响较大。     

普鲁兰多糖对籼米粉凝胶及老化特性的影响

探究不同添加量的普鲁兰多糖(0%、2%、4%、6%、8%)对籼米粉糊化特性、流变特性、凝胶质构以及微观结构的影响。结果表明,普鲁兰多糖的添加使米粉的糊化特性、流变特性、凝胶质构和微观结构发生显著变化。随着普鲁兰多糖添加量的增加,混合粉的峰值黏度、最低黏度、崩解值、回生值、弹性模量、黏性模量均逐渐降低,糊化温度略有升高,表明普鲁兰多糖抑制了大米淀粉的糊化;X-射线衍射的分析表明普鲁兰多糖的添加降低了淀粉的重结晶度,抑制了淀粉老化;普鲁兰多糖添加后的凝胶呈现出多孔状结构,表明淀粉连续性的凝胶结构被破坏,从而导致凝胶的硬度、弹性、黏聚性、胶着度、咀嚼性逐渐降低。     

马铃薯淀粉糊化和凝胶特性与马铃薯粉品质的关系

为了研究马铃薯粉生产过程中原料淀粉的糊化和凝胶特性对马铃薯粉品质的影响,通过快速黏度分析仪和质构仪对6种不同的马铃薯淀粉的糊化和凝胶特性进行了测定,并对这些特性之间的关系,以及这些特性与马铃薯粉品质之间的关系进行了探讨。结果表明:马铃薯淀粉的糊化特性和凝胶特性之间存在密切关系,且糊化和凝胶特性与鲜湿马铃薯粉品质密切相关。淀粉的糊化特性与马铃薯粉的感官品质和断条率存在显著关性,按显著程度(r值大小)排序依次是:回生值谷值黏度峰值黏度最终黏度崩解值糊化温度。淀粉的凝胶特性对马铃薯粉的感官品质和断条率存在显著相关性,按显著程度(r值大小)排序依次是:咀嚼性凝胶强度、黏性硬度回复性弹性。在鲜湿马铃薯粉的生产过程中,可以采用马铃薯淀粉的回生值、凝胶的咀嚼性、黏性和凝胶强度作为原料的衡量标准。本研究为马铃薯粉生产的原料选取和品质改善提供了理论参考。     

不同活力种子对玉米产量与淀粉品质的影响

以玉米杂交种安科985和隆平206为材料，分析不同种子活力水平(相对发芽率100%、80%和60%)间玉米籽粒产量、淀粉粒度分布和黏度特性的差异。随着种子活力的降低，2个玉米品种穗长、百粒重、穗粒重、产量都呈降低的变化趋势，玉米胚乳大型淀粉粒组体积分布与数量分布的百分比显著减小(P<0.05),而淀粉粒表面积百分比显著增大(P<0.05),可见低活力种子不利于玉米胚乳淀粉粒个体体积增大。活力对籽粒淀粉含量的影响最大，蛋白质含量次之，脂肪含量相对较小。大型淀粉粒组(直径>16μm)的表面积分布百分比与淀粉稀懈值和峰值黏度呈显著负相关(P<0.05)。低活力种子，通过影响胚乳淀粉粒度分布，即减小大型淀粉粒比例，从而降低了玉米淀粉最终黏度、峰值黏度等糊化参数。     

Endosperm Properties and Extrusion Cooking Behavior of Maize Cultivars

Understanding the association between industrial quality and biochemical and biophysical properties of commercial maize cultivars may help breeders develop cultivars best adapted to diversified processing requirements, and processors choose cultivars best for specific requirements. The suitability of cultivars for extrusion cooking is important in this regard. To supply information useful to maize breeders and processors, biophysical (endosperm texture and hardness) and biochemical (protein and starch composition) properties of kernels, grits and extruded curls of several commercial maize cultivars were determined and related to extrusion performance. Results show that extrusion alters protein hydrophobicity and degree of aggregation, though differently between cultivars. Under conditions of this study, grits from harder maize expand more, consume less energy upon extrusion, and cook more rapidly than do grits from softer maize. These behaviors appear related to differing protein compositions and endosperm textures of cultivars. Results also suggest that reversed-phase high-performance liquid chromatography of zeins (the storage prolamin proteins of maize) may be valuable for predicting end-use properties of extruded maize products, and as a quality estimator during maize breeding.     

Endosperm Structure and Physicochemical Properties of Starches from Normal,Waxy, and Super-Sweet Maize

Maize is a main botanical source used for extraction of starch in the world market. New maize cultivars with different amylose contents and special starch metabolism characteristics have been generated. Three types of maize cultivars, namely, normal maize, waxy maize (wxwx homozygous mutant), and super-sweet maize (sh2sh2 homozygous mutant), were investigated to determine differences in endosperm structures, morphologies, and physicochemical properties of starches. Maize kernels exhibited significantly different contents of total starch, soluble sugar, and amylose. Normal maize kernels contained the largest proportion of floury endosperm, followed by waxy maize and then super-sweet maize. Normal maize starch and waxy maize starch were larger in size than super-sweet maize starch. Normal maize starch and waxy maize starch were spherical and polygonal in floury and vitreous endosperms, respectively. Super-sweet maize starch was spherical both in floury and vitreous endosperms. Waxy maize starch showed the strongest birefringence patterns, the highest crystallinity and the largest proportion of ordered structure in external region of granules, and the largest proportion of double helix components, followed by normal maize starch and then super-sweet maize starch. Waxy maize starch showed the highest peak viscosity, trough viscosity, breakdown viscosity, gelatinization temperatures (i.e., gelatinization conclusion temperature, gelatinization onset temperature, gelatinization peak temperature, and gelatinization enthalpy). By contrast, super-sweet maize starch showed the lowest corresponding values for these parameters.     

Properties of Starches Isolated from Sorghum Floury and Corneous Endosperm

Decorticated grains of three sorghum cultivars of intermediate grain hardness were individually dissected to separate the floury and the corneous endosperm fractions. The starch and polymeric components (amylose and amylopectin) of each of the endosperm fractions were isolated and subsequently characterized. Results indicate that there exist major differences in the properties (granule size distribution, gelatinization temperature, iodine binding capacity, and rate of lintnerization) of the starch and starch components from the endosperm fractions. Close relationships between the starch properties and the strength of the alkali gel of the corresponding endosperm fraction were observed.     

Comparison of Endosperm Starch Granule Development and Physicochemical Properties of Starches from Waxy and Non-Waxy Wheat

Starch granule development and physicochemical properties of starches in waxy wheat and non-waxy wheat were investigated in this article. Starch granules in waxy wheat endosperm showed an early developmental process. Compared with non-waxy wheat starch granules (round-shaped), waxy wheat starch granules (ellipse-shaped) were larger and contained more B-type granules. According to the granule size, starch granules were divided into two groups in waxy wheat, but were divided into three groups in non-waxy wheat. Compared with non-waxy wheat starch, waxy wheat starch had higher swelling power, gelatinization temperatures (To, Tp, Tc), and relative degree of crystallinity. They showed similar ordered structures on external regions of starch granules. Additionally, waxy wheat starch had a higher proportion of double-helical components and a lower proportion of single-helical components than non-waxy wheat starch. Based on the previous results, it was concluded: (1) waxy wheat and non-waxy wheat not only differed in starch granule development, but also in physicochemical properties of starches; (2) waxy wheat had more potential value for producing traditional products than non-waxy wheat.     

Physicochemical and Biochemical Characterization of Starch Granules Isolated of Pigmented Maize Hybrids

In this study, the morphological and physicochemical of pigmented maizes as well as the initial characterization of the corresponding starch granule enzymes are described. Starch granules were isolated from blue, black, and white maize. They were analyzed using scanning electron microscopy, particle size distribution, pasting characteristics, sorption isotherms, differential scanning calorimetry, and two‐dimensional gel electrophoresis. The morphology of the starch granules of pigmented maizes was different from the granules of white maize; the pattern was related to the endosperm type of these varieties. The average starch granule size was higher for black than for white and blue maizes. The average gelatinization temperature was similar in the three starches, but the pigmented maizes had higher gelatinization enthalpy; black maize starch showed the lowest enthalpy of retrogradation. These results indicated that the starches from the three maizes analyzed had different organization level. Black maize starch showed the highest peak viscosity followed by white and blue maize starches. In the gel electrophoresis three starch granules presented one main spot at pI of 5 and MW of 60 kDa that corresponds to the granule‐bound starch synthase. Blue and white starches presented some spots near 97 kDa at pI of 5.3–5.7 (white maize) and 5.1–5.5 (blue maize), spots that were not observed for black maize starch. The morphological and physicochemical characteristics of maize starch are related to the enzymes involved in its biosynthesis.     

筛分细度对糯玉米淀粉理化特性的影响

以糯玉米为材料,分析了不同筛分细度(100目、200目和400目)对淀粉理化特性的影响。结果表明,随着分样筛孔径的变小,淀粉中小颗粒的比例增多,结晶度升高,但淀粉颗粒并未受到破坏。淀粉的膨胀势和溶解度以过细筛(400目)处理下最大。筛分细度对淀粉的峰值时间、糊化温度和析水率影响较小,但细筛使其他黏度特征值显著升高。DSC研究表明,起始温度、峰值温度和终值温度以过200目筛时较高,过100目和400目时较低,过细筛(400目)处理下淀粉热焓值较高,回生值较低。     

种植密度对沿淮玉米籽粒淀粉粒度分布与糊化特性的影响

分析不同种植密度对沿淮玉米籽粒中淀粉粒度分布与糊化特性的影响。以豫单132、京科968等13个玉米杂交品种为材料,设置56 250 株/hm2、67 500 株/hm2、77 250 株/hm2等3个种植密度,分析不同种植密度对玉米籽粒品质、淀粉粒度分布与糊化特性的影响。结果表明,在种植密度56 250~77 250 株/hm2范围内,随着种植密度的增加,玉米籽粒的蛋白质和脂肪含量呈递减趋势,淀粉含量呈递增趋势,即淀粉/蛋白质比率增加。玉米籽粒大型淀粉粒体积和表面积百分比显著增加,小型淀粉粒却显著降低。增加种植密度后玉米淀粉的峰值黏度、低谷黏度、最终黏度和稀懈值等黏度参数均呈显著升高。相关分析表明,玉米籽粒峰值黏度等黏度参数与小、大型淀粉粒体积百分比呈正相关,与中型淀粉粒体积百分比呈显著或极显著负相关。说明种植密度影响玉米籽粒淀粉粒度分布、淀粉黏度参数和组分含量。     

Properties of starch from root tuber of Stephania epigaea in comparison with potato and maize starches

The dry root tuber of Stephania epigaea contained 36.5% starch, indicating a good starch source. In this study, starch was isolated from S. epigaea. Its morphology, physicochemical, and functional properties were investigated and compared with potato and maize starches. S. epigaea starch had small spherical granules with centric hila and large ellipsoidal granules with eccentric hila, and granule sizes varied from 7 to 40 μm. The starch had 33.9% amylose content and B-type crystallinity. The gelatinization onset, peak, and final temperatures were 59.4, 62.3, and 66.2°C, respectively, and were lower than those of potato and maize starches, but the enthalpy (16.3 J/g) was higher than that of potato and maize starches. The peak, hot, final, and breakdown viscosities were 2227, 1623, 2149, and 594 dPa s, respectively, and were significantly higher than those of maize starch and lower than those of potato starch. S. epigaea starch was more susceptible to amylase hydrolysis and in vitro digestion than potato starch and less than maize starch. This study would be useful for the applications of starch from S. epigaea in the food and non-food industries.     

糯玉米淀粉形成过程中理化特性的变化

为阐明糯玉米淀粉形成过程中理化特性的变化趋势。以6个糯玉米品种为材料,研究了其在花后7 d(淀粉初始期)、22 d(乳熟期)、40 d(成熟期)的淀粉理化特性。结果表明,新形成的淀粉粒为圆型或椭圆型,表层光滑,而鲜食期和成熟期淀粉粒呈不规则的多面体,表层粗糙。淀粉粒径和尖峰强度随生育进程推进逐渐加大(升高)。最大吸收波长和碘结合力以新形成的淀粉粒最高,其次是成熟期。RVA和DSC特征参数在不同生育阶段的变化品种间有显著差异。总体上,随着发育进程推进,淀粉峰值黏度、崩解值、热焓值和回生热焓值先升后降,而回生值、糊化和峰值温度逐渐下降。淀粉形成过程中淀粉粒形态、大小、晶体结构和链长分布发生变化,改变了淀粉糊化和热力学特性。     

Comparison of Morphology and Physicochemical Properties of Starch Among 3 Arrowhead Varieties

Arrowhead (Sagittaria trifolia var. sinensis) is a source of starch worldwide, but arrowhead starch has been rarely studied. In this work, starch was separated from arrowhead corm. The morphology and physicochemical properties of starch were then investigated and compared among 3 different arrowhead varieties (Purple‐corm, Hongta, and Japanese). Results showed that starches from the 3 varieties similarly featured an oval shape containing a visible polarization cross, a C_A‐type crystalline structure, and an ordered structure in the external granule region. However, starch content, granule size, crystal characteristics, and pasting properties differed among the 3 varieties. Japanese arrowhead exhibited the highest starch content and degree of ordered structure in the external granule region, as well as onset, peak, and final gelatinization temperature. Purple‐corm arrowhead starch demonstrated the highest amylose content and relative degree of crystallinity, smallest granule size, and lowest swelling power and solubility. Purple‐corm arrowhead starch also showed the highest gelatinization enthalpy, as well as peak, trough, final, and setback viscosities. This starch further presented the lowest breakdown viscosity and degree of hydrolysis by HCl and porcine pancreatic α‐amylase. These findings can provide useful references for arrowhead variety selection in food and nonfood industries.