酸湿热处理小麦面粉的性质及酶解动力学研究

本文采用水热反应釜酸湿热处理小麦面粉,分析了小麦面粉处理前后基本成分变化、显微形貌、热力学性质、糊粘度曲线、结晶性质、红外图谱和酶解动力学方程。研究表明,经过酸湿热处理后的作用产物,蛋白质含量减少,部分颗粒出现浅层裂痕,偏光十字模糊;差示扫描量热分析显示,处理产物与原面粉相比吸热峰后移,吸热焓ΔH降低了2.976 J/g;布拉班德粘度曲线表明,产物的起糊温度由82.6℃增加到87℃,峰值粘度由82 BU降到63 BU;X射线衍射分析显示产物结晶度增大3.8%;红外图谱变化不大。酶解动力学研究发现,在模拟体外消化条件下,α-淀粉酶对小麦面粉处理前后样品的降解遵循Michaelis-Menten规律,产物的α-淀粉酶酶解动力学方程为V=0.161[S]/(1.093+[S]),与处理前比,米氏常数Km及最大反应速率Vm均降低。     

西米柠檬酸酯淀粉物化性质研究

利用扫描电子显微镜、红外光谱仪、聚焦光束反射测量仪、X射线衍射仪和布拉班德粘度计对西米柠檬酸酯淀粉性质进行测定和分析,并与西米原淀粉进行比较。结果表明,西米淀粉经柠檬酸酯化后,其表面被侵蚀,甚至有颗粒已破碎;酯化后淀粉颗粒平均粒径从30.8μm减至27.1μm;柠檬酸酰基引入会破坏淀粉颗粒结晶,淀粉相对结晶度从24.5%显著降至11.6%;通过对淀粉糊粘度分析发现,西米淀粉与柠檬酸在酯化作用下发生交联,其浆液在粘度测定过程中不发生糊化和胶凝。     

酯化交联淀粉反应及性质的研究(Ⅱ)——糊粘度曲线

测定了三氯氧磷变性木薯淀粉制得的酯化交联淀粉糊的粘度性质 ,如糊的粘度曲线、抗剪切和抗酸碱的特性。变性淀粉的交联度和取代度是影响其糊粘度性质的内在因素     

醇水相湿热处理对玉米淀粉颗粒性质的影响

采用醇水相湿热处理对玉米淀粉进行研究,考察了处理温度范围为70-90 ℃内淀粉颗粒偏光十字,形貌,粒径分布,结晶结构及糊性质等性质变化。随着湿热处理温度升高,发现：淀粉颗粒偏光十字消失增多,最终颗粒破碎;颗粒平均粒径由23.6 μm持续增加至50.4 μm,其中小颗粒（〈10 μm）数目减少,中等颗粒（10-30 μm）和大颗粒（30-100 μm）数目均有不同程度的增加;淀粉颗粒表面出现小孔和凹坑,最终颗粒成团,干燥粉碎之后破碎成片状;淀粉的X射线衍射在衍射角15°,18°和23°处峰强度逐渐降低,但在衍射角20°处峰强度增加。淀粉的Brabender粘度曲线显示,湿热处理后玉米淀粉糊化起始温度由80.5 ℃升高至90.6 ℃,粘度降低,表明玉米淀粉热糊稳定性和冷糊稳定性增强,糊凝沉性降低;测定分析淀粉分子量可知,淀粉颗粒内部分子链发生了断裂、降解。     

小麦氧化-酯化淀粉的制备及其性质的研究

以醋酸酐为酯化剂,对小麦氧化淀粉进行酯化,研究酯化程度与反应条件的关系,测定粘度性质和结构特征.研究表明,反应体系pH、醋酸酐用量和氧化淀粉氧化程度的影响比较大.淀粉经氧化-酯化复合变性后,颗粒受到了更大程度的破坏,存在明显的酯羰基;复合变性后的淀粉更易糊化,糊的粘度有所降低,稳定性更好.     

绿豆淀粉糊粘度性质的研究

用Viscograph-E型Brabender粘度计测定了绿豆淀粉糊在不同浓度、pH、糖、盐、明矾、硼砂条件下Brabender粘度曲线的变化情况,研究了其粘度性质及影响因素,为进一步了解绿豆淀粉的特性及开发其应用,提供淀粉科学方面的理论依据。     

抗性淀粉热性质分析[Ⅰ]

采用热失重法(TG)和差示扫描量热分析技术(DSC)对松谷Fibersol2抗性淀粉进行热性质分析。TG曲线显示该抗性淀粉在293.85℃开始分解,312.37℃分解速度最快,330.89℃是分解的最终温度。DSC吸热曲线显示,样品在24.36℃左右开始出现吸热峰,相变高峰温度约在98.54℃(相变焓179.1J/g),另外在204.23℃和225.48℃出现两个小的吸热峰,表明样品以支链晶体结构为主。     

芋头淀粉的研究

本文研究了芋头淀粉的性质，实验采用高分辨分析透射电子显微镜JEM2010拍摄了芋头淀粉颗粒的形态；用D／max2550V型X射线衍射仪测定了X-光衍射图样及结晶结构；用高效液相色谱仪测定了芋头淀粉及其直、支链淀粉的重均聚合度、数均聚合度、分子量分布及分散度等，并与大米淀粉进行了比较。在淀粉的应用中，糊的性质至关重要，实验采用德国Branbender连续粘度计，通过测定芋头淀粉在不同浓度、pH及蔗糖添加量下的粘度曲线，研究了不同条件对糊粘度的影响。为指导芋头淀粉生产、开发和应用提供理论基础。     

柠檬酸脱镉对糙米粉结构及理化性质的影响

在前期柠檬酸脱除糙米粉中镉的研究基础上,为进一步了解柠檬酸脱镉对糙米粉品质的影响,采用扫描电镜、X射线衍射仪、傅里叶变换红外光谱仪、差示扫描量热仪、快速黏度分析仪对柠檬酸脱镉前后糙米粉的结构及理化性质进行了测定。结果显示,酸处理糙米粉的直链淀粉含量显著低于原糙米粉;酸处理糙米粉的表面变得粗糙,小颗粒淀粉数目增多,但未改变其晶体类型,也未产生新的化学键或基团;酸处理糙米粉的糊化开始温度、峰值温度、终止温度均显著降低,但吸热焓增大;酸处理糙米粉的最高黏度、崩解值显著增大,最低黏度、最终黏度、回生值、糊化温度显著降低。结果表明,柠檬酸脱镉后糙米粉的结构未发生显著变化,但品质有所提高。     

抗性淀粉糊化规律的研究

采用差示扫描量热分析技术(DSC)对原淀粉及各抗性淀粉样品的糊化温度及糊化热效应进行了测试和研究。DSC吸热曲线显示,经处理过的样品晶体完全不同于原淀粉晶体。抗性淀粉的吸热曲线除了在85℃左右出现一个小峰外,在125℃左右又开始出现吸热峰,相变高峰温度约在155℃。随着样品中抗性淀粉含量的升高,曲线中第二吸热峰的相变焓逐渐升高,相变高峰温度也遵循同样的规律。     

酸湿热处理对米粉性质的影响研究

本文在实验室条件下采用酸湿热处理米粉样品,测定处理前后米粉的化学组成变化、颗粒形貌、结晶性质、红外图谱、热力学性质、糊化性质和消化特性。研究表明,经过酸湿热处理后的米粉蛋白质含量减少较多,其它的粗脂肪、还原糖变化不大。显微结构分析得出米粉保持原有的团粒结构,但偏光十字稍微变得模糊,颗粒的有序结构遭到一定破坏,少数淀粉脐点处出现凹坑。红外图谱变化不大,结晶度变小。处理后米粉的起糊温度升高,糊的峰值粘度降低,吸收焓减小。酸湿热处理可以一定程度下提高米粉中慢速消化淀粉(SDS)的含量。     

球磨对绿豆淀粉结晶结构和糊流变特性的影响

采用偏光显微镜、X-射线衍射等测试方法，研究了绿豆淀粉在机械球磨过程中结晶结构的变化；运用Brookfield旋转粘度计测得不同浓度的淀粉糊在不同温度和剪切速率下的表观粘度，建立了相应的流变模型。结果表明机械球磨使得淀粉结晶结构受到破坏，由多晶态转变成无定形态；经球磨处理的绿豆淀粉糊仍保持假塑性流体特征，但随着球磨程度的增大，糊稠度大大降低，流动性增加，且越来越趋向牛顿流体特征。     

碾轧对绿豆淀粉的机械力化学效应

以绿豆淀粉为原料,通过扫描电镜(SEM)、偏光显微镜(PLM)、激光扫描共聚焦显微镜(CLSM)、X-射线衍射(XRD)、差示扫描量热仪(DSC)、快速黏度分析仪(RVA)等手段研究碾轧处理对淀粉结构和性质影响,探究其相互关系并揭示碾轧对绿豆淀粉机械力化学效应。结果表明,碾轧处理3~6 h时,淀粉无定型区和部分结晶区发生破坏,水溶指数、膨胀度、透光率增大,热焓减小。碾轧处理9 h时,淀粉内部发生重结晶,颗粒表面形成球状凸起,脐点区域直链淀粉聚集导致膨胀度、透光率、峰值黏度下降,水溶指数、热焓值、糊化温度增大。碾轧处理12~24 h时,淀粉的结晶区域发生显著破坏,颗粒严重变形,从而使淀粉水溶指数、透光率增大,膨胀度、热焓值减小。根据机械力化学相关理论推断淀粉颗粒内部依次经过了受力阶段、聚集阶段、团聚阶段。     

Physicochemical Characteristics of Pigeonpea and Mung Bean Starches and Their Noodle Quality

This study compared the properties of pigeonpea and mung bean starches and noodles made from each. No large differences in size and shape of respective starch granules were observed. The degree of syneresis of pigeonpea starch was nearly three times that of mung bean starch. Swelling power of pigeonpea starch was considerably lower at 60°C and 70°C but it did not differ markedly at 80° and 90°C. The Brabender . viscosity patterns of 6% starch pastes of pigeonpea and mung bean indicated no pasting peak during heating to 95°C; neither showed breakdown of the hot paste. Sensory tests indicated that pigeonpea starch of dhal (decorticated dry split cotyledons) was as good for noodle preparation as mung bean dhal starch.     

Physicochemical characterization of mung bean starch

Starch from mung bean (Vigna radiata) was isolated and some of the important characteristics determined. The yield of starch was 31.1% on a whole-seed basis. The shape of the starch granule was oval to round to bean shaped, with granules 7–26 μm in diameter. Scanning electron micrographs revealed the presence of smooth surfaces. The gelatinization temperature range was 58–67–82°C and the enthalpy of gelatinization was 18.5 J/g. The total amylose content was 45.3%, of which 12.1% was complexed by native lipids. The X-ray diffraction pattern was of the ‘C’ type and the X-ray intensities were much stronger than in other legume starches. The starch exhibited a high swelling factor ( 43.6 at 95°C) in water. The viscoamylographic examination of the starch paste (6% w/v) showed the absence of a peak viscosity, a low 95°C viscosity [200 Brabender units (BU)], an increase in consistency ( 140 BU) during the holding cycle at 95°C and a set-back of 220 BU. Native granules were readily hydrolyzed by porcine pancreatic α-amylase (76.4% in 72 h). Retrogradation of mung bean starch (as measured by changes in syneresis, gel strength, enthalpy and X-ray diffraction intensities) appeared to be more severe than in other legume starches.     

不同直链淀粉含量对羟丙基氧化玉米淀粉性质的影响

本文采用蜡质玉米、普通玉米和高直链玉米淀粉为原料,改变有效氯添加量,制备羟丙基氧化淀粉,通过XRD、DSC、Brabender粘度仪等测定手段,研究不同直链淀粉含量对羟丙基氧化淀粉理化性质的影响。实验表明,直链淀粉含量对羟丙基化和氧化程度影响显著,其中直链淀粉含量高有利于羟丙基化,而不利于氧化;X-射线衍射分析发现,改性淀粉没有改变晶型,随氧化程度增加,淀粉分子结晶度下降,直链淀粉含量越高,下降趋势越缓;DSC测试和Brabender粘度分析表明,直链淀粉含量直接影响到羟丙基氧化淀粉糊化特性,糊化温度:高直链普通蜡质,糊粘度:蜡质普通高直链,糊化焓:蜡质普通高直链;通过观察淀粉的偏光特性和颗粒表面形态,发现直链淀粉含量越高,羟丙基氧化淀粉的偏光十字越弱,颗粒越不易破碎。     

挤压改性绿豆粉对小麦粉加工及其面条品质特性的影响

研究了添加挤压改性绿豆粉对挤压改性绿豆-小麦混合粉粉质特性、面团流变特性和所制备面条品质的影响。首先采用双螺杆挤压机处理绿豆粉,随后将挤压改性绿豆粉以不同添加量(10%~60%)添至小麦粉中,制备面条。然后采用粉质拉伸仪、RVA黏度仪、流变和质构仪对混合粉的粉特性、面团流变性能以及面条的质构特性进行分析。结果表明,随着挤压改性绿豆粉添加量的增加,绿豆-小麦混合粉面团的形成时间、稳定时间、粉质质量指数急剧下降,混合粉的粉质特性明显降低,且与小麦粉相比,混合粉的起始糊化温度、峰值黏度、谷值黏度、最终黏度、崩解值及回生值呈明显的下降趋势;随着挤压改性绿豆粉添加量的增加,混合粉面团的G'和G″降低,面团的网络结构受到破坏;对于挤压改性绿豆-小麦混合面条,随着挤压改性绿豆粉添加量的增加(<40%时),其干物质吸水率和损失率有所提高,蒸煮面条的硬度、弹性、胶粘性、咀嚼性和回复性有所降低,综合感官评分降低,当挤压改性绿豆粉添加量≤ 20%时,整体可接受度接近小麦面条。最后分析三者之间的相关性发现,挤压改性绿豆粉的添加量、挤压改性绿豆-小麦混合粉的粉质特性、黏度特性与其制作面条的品质有明显的相关性。综上所述,挤压改性绿豆粉的添加改变了小麦面团的特性和面条的品质,其添加量不宜超过20%。     

Comparative Studies on Physico-Chemical Properties of Starches from Jackfruit Seed and Mung Bean

The physico-chemical properties of starch from jackfruit seed and mung bean were investigated. Jackfruit seed starch had much higher resistant starch content (26.99%) than that of mung bean starch (4.04%). Furthermore, jackfruit seed starch had a higher gelatinization temperature (T_o) that required more gelatinization energy (ΔH) compared to mung bean starch. However, mung bean starch had higher amylose content and its granules were much larger than that of jackfruit seed starch. Mung bean starch had the highest peak viscosity, breakdown, and setback whereas jackfruit seed starch had the highest pasting temperature. Amylopectin chain length of mung bean starch contained higher proportion of short chains (degrees of polymerization 6–12) but lower proportion of very long chains (degrees of polymerization > 37 ) comparing with jackfruit seed starch. The X-ray diffraction patterns showed both starches to be Type-A crystallinity. In addition, both starch gels showed higher the storage modulus (G′) than the loss modulus (G?) designating as rubber like material. However, mung bean starch gel exhibited higher G’ and less tan δ than that of jackfruit seed starch indicating much stronger of gel structure.     

低取代度乙酰化绿豆淀粉的性质

以绿豆淀粉为原料,冰醋酸为乙酰化剂,制备低取代度的乙酰化绿豆淀粉。对乙酰化绿豆淀粉的膨润力、溶解度、凝沉性、透明度、黏性、质构特性等进行研究。结果表明：与原淀粉相比,经过乙酰化处理的绿豆淀粉透明度、膨润力、溶解度均比原淀粉有所增加,糊化温度降低,谷值黏度、末值黏度有所升高,而峰值黏度、衰减值则降低,绿豆淀粉乙酰化后凝胶特性也有所改善。     

Characterization of Red Bean (Phaseolus radiatus var. Aurea) Starch and Its Noodle Quality

Red bean (Phaseolus radiatus var. aurea) starch was isolated by a wet-milling process and steeping in 0.1% sodium hydroxide which gave the best starch purity. Physical properties of the starch including granule sizes, gelatinization temperature range, iodine affinity, X-ray diffractogram, swelling and solubility pattern, Brabender amylogram, gel strength and degree of syneresis, were examined. Starch noodles were prepared from red bean starch and compared with those from mung bean. Noodle quality was exmained by solid loss during cooking, tensile strength and organoleptic tests. The results indicated that red bean starch noodles gave fairly good quality, although not as good as mung bean starch noodles.