超声冻融-复合酶解制备小麦多孔淀粉及其吸附特性

针对传统方法制备的小麦多孔淀粉吸附性较差的问题,以小麦淀粉为原料,对比研究超声冻融、复合酶（α-淀粉酶和糖化酶）处理以及超声冻融-复合酶水解淀粉的理化性质和吸附性能。结果表明,小麦淀粉为A型淀粉,超声冻融、复合酶解和超声冻融-复合酶解均未改变小麦淀粉的晶型,经超声冻融处理的淀粉表面被侵蚀,复合酶水解可形成少量孔洞的多孔淀粉,此2种处理均可显著降低淀粉相对结晶度,分别为30.97%和25.53%,显著降低淀粉双螺旋分子的有序性。超声冻融结合复合酶水解制得多孔淀粉的比表面积和总孔体积最大,分别为1.648 6 m2/g和4.294×10-3 cm3/g,淀粉相对结晶度较低（21.73%）、双螺旋结构的有序性达到最低,从而具有最大的膨胀力、吸油率和吸水率,分别为17.38 g/g,81.84%和120.28%。研究为小麦多孔淀粉的制备提供参考。     

高粱多孔淀粉制备工艺的优化及理化性质研究

以高粱淀粉为原料,优化高粱多孔淀粉的制备工艺并对多孔淀粉的理化性质进行了研究。结果表明:高粱多孔淀粉最佳酶解工艺条件为酶配比1∶5(g/g)、底物浓度25%、酶添加量3%、酶解时间10 h、酶解温度50℃、pH4.6,在该条件下制得的多孔淀粉的吸油率为132.04%,比容积为2.39 g/cm~3、溶解率为3.97%、膨胀率为13.80%、透光率为11.89%,较原淀粉分别提高了92.81%、21.31%、69.65%、38.41%、7.2%;扫描电子显微镜(SEM)显示多孔淀粉颗粒完整,表面形成类似蜂窝状孔洞,孔径大小及孔深适中,淀粉内部形成中空结构,成孔效果较好。     

脉冲电场协同酶解提高多孔淀粉制备效率及吸油率

以蜡质玉米淀粉为原料,采用脉冲电场(PEF)协同酶解制备多孔淀粉,探究其对多孔淀粉制备效率及吸油率的影响。结果表明:通过PEF改性后,淀粉水解率达到24.28%时所需的酶解时间缩短一半;在相同加酶量的条件下,通过PEF改性后,淀粉水解率为23.11%,较原淀粉显著提高,表明通过PEF改性可降低加酶量;在酶解6 h和加酶量为0.8×10~(-2) mL/g淀粉干基的条件下,经PEF改性协同酶解制备的多孔淀粉水解率为23.11%、吸油率为145.11%、比表面积为1.25 m~2/g,总孔容为4.31 cm~2/g×10~(-3),原淀粉酶解制备的多孔淀粉上述指标分别为18.38%、119.47%、1.16 m~2/g,4.15 cm~2/g×10~(-3),表明通过PEF改性提高酶解淀粉的水解率、吸油率、比表面积和总孔容。扫描电镜结果显示,PEF改性可使淀粉表面产生凹槽状结构;激光共聚焦显微镜观察显示,PEF改性提高了淀粉颗粒对淀粉酶的敏感性;热力学性质测试结果显示,PEF改性多孔淀粉的焓值低于原淀粉,表明PEF改性破坏了淀粉颗粒内部分致密的结晶区。本项研究揭示了PEF改性对淀粉颗粒及其酶解制备多孔淀粉的构效关系,为高效制备多孔淀粉提供了一个新思路,并拓展了PEF可应用的领域。     

酶法、酸法制备碎米多孔淀粉工艺研究及其比较

以碎米为原料,分别采用酶法、酸法制备多孔淀粉,通过单因素和正交试验,得到两种方法制备碎米多孔淀粉的最佳工艺条件,酶法制备碎米多孔淀粉最佳工艺条件为液料比4:1(mL/g)、加酶量23.0U/g、pH7.0、酶解温度60℃、酶解时间7h;酸法制备碎米多孔淀粉最佳工艺条件为液料比4:1(mL/g)、盐酸浓度0.4mol/L、酸解温度35℃、酸解时间6h。经比较酶法比酸法制得的多孔淀粉吸油率高13.3%。运用扫描电子显微镜对多孔淀粉的颗粒形态进行比较,结果表明酶法比酸法制得的多孔淀粉出孔率高、孔径大、孔穴深。     

复合酶法大黄米多孔淀粉的制备及其微观结构和理化性质

以吸油率为指标,大黄米淀粉为原料,采用复合酶法(α-淀粉酶和糖化酶)制备大黄米多孔淀粉。通过单因素实验与Box-Benhnken响应面试验优化大黄米多孔淀粉制备的工艺参数,并对原淀粉及大黄米多孔淀粉进行结构表征。结果表明,复合酶法制备大黄米多孔淀粉的最优工艺参数是：复合酶添加量1.2%,酶解温度56℃,酶解时间14 h,酶解pH 4.6,复合酶配比1∶4。在此条件下大黄米多孔淀粉的吸油率为(174.00±2.00)%。扫描电镜结果显示,形成多孔淀粉后,淀粉颗粒表面存在不均匀分布的孔洞及圆形凹陷,内部呈中空结构。粒度分布测试结果显示,多孔淀粉粒径均减小,淀粉颗粒分布均一度提高。X-射线衍射分析及傅里叶红外光谱表明,酶的水解作用不会改变大黄米淀粉的A型晶体结构及基本化学结构,相对结晶度和红外吸收峰均明显增加,淀粉颗粒内部有序程度提高。低温氮气吸附结果表明,复合酶酶解作用使大黄米淀粉的比表面积由13.9 m²/g增加至29.42 m²/g,孔径由4.143 nm增加至6.637 nm,孔容由14.81×10^-3cm^3...     

微波辅助制备多孔淀粉的研究

以玉米淀粉为原料酶解制备多孔淀粉,在酶解前、后分别用微波对干淀粉进行处理,以水解率、吸油率、柠檬黄吸附量为指标,探讨了微波功率、微波时间等因素对所得产品成孔情况的影响;并对多孔淀粉颗粒的微观形态、晶体结构和糊化特性进行了分析。结果表明:(1)微波辅助处理制得多孔淀粉的水解率和吸附性较好。酶解前的高功率微波辐射30s使产品的吸油率达到最高,较之普通酶解产品提高了35%,辐射40s使产品的色素吸附量达最高,较普通产品提高了16.5%;酶解后的中功率微波辐射30s使产品的吸油率和色素吸附量较之普通酶解产品分别提高了18%和17%。(2)酶解后微波处理制得的产品成孔性优于酶解前处理,其孔径、孔深及数目较之普通酶解产品有较大改善。微波辅助制备的多孔淀粉基本保持原淀粉的结晶结构,产品结合水的能力和形成凝胶的能力均增强。     

不同酶处理对多孔大米淀粉性能的影响

使用麦芽糖α-淀粉酶（MA）和淀粉葡糖苷酶（AMG）分别处理制备多孔大米淀粉,对其表征特性进行对比分析。通过扫描电镜可知,这两种酶均使淀粉颗粒表面产生蜂窝状多孔结构。经酶处理的大米淀粉颗粒的相对结晶度（25.54%～33.26%）均高于天然淀粉的相对结晶度（23.74%）。MA处理增加了短支链淀粉链的数量,并且随着酶处理时间的延长降低了分子质量。与对照组相比,MA和AMG处理的淀粉颗粒溶胀度、表观直链淀粉含量、峰值黏度、崩解值、最终黏度和回生值均下降。MA处理的淀粉颗粒具有更高的溶解指数（1.46%～2.57%）,AMG处理的淀粉颗粒的溶解指数均小于0.42%。与对照组相比,经酶处理的大米淀粉糊化温度会延迟0.8～6.0℃,焓变增加范围在1.0～3.8 J/g。     

生物酶法制备蜡质玉米淀粉纳米晶及其表征

淀粉纳米晶是从天然淀粉中制得的一种纳米尺寸的聚多糖晶体。本试验通过糖化酶部分酶解蜡质玉米淀粉,并对其进行超声波处理,离心后经真空冷冻干燥得到淀粉纳米晶。采用扫描电子显微镜、激光粒度分布仪、X-射线衍射、傅里叶红外光谱等手段对淀粉纳米晶进行表征。结果表明:淀粉纳米晶颗粒表面粗糙,颗粒之间由于静电引力相互聚集;酶解得到的淀粉纳米晶的粒径集中在100 nm左右,结晶度为75.86%,产率达到27.53%。酶法制备过程对环境无污染,是一种新型的纳米晶绿色制备技术。     

黑曲霉发酵法制备小红栲多孔淀粉

对黑曲霉发酵法制备小红栲多孔淀粉的工艺进行了研究,并分析了多孔淀粉的形态结构、晶体特征和糊化特性。试验结果表明,在发酵培养基母液体积分数为90%的培养基中,当黑曲霉发酵至第48 h时,加入质量分数为7.0%的原淀粉后继续发酵56 h,由此制得小红栲多孔淀粉。小红栲多孔淀粉的形成过程是:酶作用于淀粉颗粒表面的凹坑形成孔洞,由浅入深,直达颗粒中心,最终形成彼此相连的桥形网状空洞结构,其上分布着孔径1μm左右的孔洞。小红栲原淀粉与多孔淀粉的X-射线衍射图谱由尖峰衍射特征和弥散衍射特征两部分组成,属C-型晶体。多孔淀粉比原淀粉的结晶度、微晶尺寸和吸热焓要大,而微晶间距和糊化温度则小。     

稻米淀粉的理化特性研究Ⅱ稻米直链淀粉和支链淀粉的理化特性

本文研究了稻米淀粉不同级分的理化特性及稻米类型对各级分理化特性的影响。结果表明 :稻米淀粉级分的理化特性有较大差异 ,稻米类型对各级分理化特性有影响。直链淀粉的碘结合力为 19.99～2 0 .31mgI2 /g淀粉 ,支链淀粉为 0 .0 6～ 0 .0 95mgI2 /g淀粉 。直链淀粉的碘兰值为 0 .2 0～ 0 .2 5OD/0 .1g淀粉 ,以籼稻直链淀粉的碘兰值较大 ;支链淀粉碘兰值为 0 .0 3～ 0 .10OD/0 .1g淀粉 。直链淀粉的特性粘度为 5 0～ 15 0mL/g ,以粳稻较大 ;支链淀粉的特性粘度为 5 0 0～ 95 0mL/g ,以糯稻最大 ,籼稻最小。直链淀粉与碘复合物的可见光最大吸收波长为 6 0 0～ 6 2 0nm ,支链淀粉为 5 2 0～ 5 40nm ,品种差异较小。分离纯化后直链淀粉的结晶度为 2 3%～ 2 5 % ,支链淀粉则无晶体结构 ,结晶度的品种差异较小。稻米支链淀粉的分子量为 4 7× 10 6 (籼稻 )～ 2 35× 10 6 (糯稻 ) ,直链淀粉的分子量为 0 .4 4× 10 6 (籼稻 )～ 1.6 2× 10 6 (粳稻 )。     

PFI及超声波预处理对阔叶木溶解浆纤维性能及其黄化过程的影响

本研究对阔叶木溶解浆纤维进行PFI(磨浆)预处理和超声波(破碎)预处理,考察预处理前后对纤维长度和宽度、孔隙结构、表面形貌、纤维素结晶度和Fock反应性能的影响。结果表明,PFI预处理对纤维孔容、比表面积、纤维素结晶度和Fock反应性能影响较小,而超声波预处理(540 W/10 min)后,纤维的孔容由1.0×10-2cm3/g增加至2.2×10-2cm3/g,比表面积由5.358 m2/g增加至9.503 m2/g,纤维素结晶度从82.57%下降至76.38%,Fock反应性能由38.82%增加至49.80%。纤维在黄化试剂体系中的溶解历程主要是"鼓泡式"润胀-溶胀-溶解的过程,随着黄化反应的进行,纤维二重质均长度先下降后上升,二重质均宽度持续增加;细小纤维含量先增加后降低,纤维素结晶度不断降低,纤维素部分溶解;在黄化反应3 h过程中,纤维二重质均宽度由17.6μm增加至34.3μm,纤维素结晶度由76.38%下降至57.53%;纤维的二重质均长度在0~2 h时由0.826 mm下降至0.547 mm,3 h后增加至0.766 mm;细小纤维含量在0~2 h时由1.2%增加至6.2%,3 h后则降低至3.4%。     

Effect of Acid Hydrolysis and Ball Milling on Porous Corn Starch

Porous corn starch from glucoamylase hydrolysis of native corn starch was examined before and after cross-linking, acid hydrolysis and dry ball milling. Cross-linking does not significantly change the crystallinity, water absorption or gelatinisation properties but acid hydrolysis at 60°C increases, proportionately, crystallinity and water absorption capacity and decreases moisture adsorption at humidities less than 80%, in comparison to untreated porous corn starch. Highly crystalline porous starch has a fragile granule structure. Ball milling destroys crystallinity in both normal, porous, and cross-linked or partially hydrolyzed starches. Particle sizes of 1–2m are obtained by milling dry starches for 48 h. Water absorption for milled starches is more than 200% (weight water/weight starch d.b.). Viscosities of these products were significantly reduced at high temperatures. Products formed stable gels in 25–30% dispersions in cold water.     

玉米多孔淀粉颗粒结构及性质的研究

多孔淀粉是生淀粉酶在低于淀粉糊化温度下水解各种淀粉形成的一种中空的变性淀粉。作为一种高效、无毒、安全的新型有机吸附剂被广泛用于食品、医药、农业、化妆品、造纸等行业。本文探讨原淀粉被生淀粉酶水解后颗粒结构和性质的变化,为多孔淀粉工业化生产和拓宽其应用范围提供一定的理论依据。采用比表面积分析仪、扫描电镜、X射线衍射分析和差热分析等测试方法对酶解前后的玉米淀粉颗粒进行结构和性能分析。通过BET法测定的多孔淀粉的比表面积、比孔容大小均比原淀粉增大,淀粉颗粒表面呈蜂窝状,孔密度均一,结晶度提高,糊化温度范围变窄,但是吸热焓无显著变化。原淀粉通过生淀粉酶在低于淀粉糊化温度下水解得到的多孔淀粉缓释载体,其颗粒结构及性质均发生了变化。     

Granule Size and Distribution of Raw and Germinated Oat Starch in Solid State and Ethanol Solution

The morphology and granular properties of oat starch during germination were investigated by scanning electron microscopy and X-ray powder diffractometer. The granule size distribution of oat starch was studied in various concentrations in ethanol using a laser particle-size analyzer. The starch granule shape before germination remained almost the same after germination, as shown by low-magnification (×1000) scanning electron microscopy. However, surface fissures at high-magnification (×5000) were found on the sample at the end of germination. After soaking, the relative crystallinity of the samples significantly reduced, by following increased and then decreased, reaching a maximum crystallinity of 16% at the end of germination. In various ethanol concentrations, the size of starch granules produced in different germination phase slightly varied, but this difference was not easy to detect in the scanning electron microscope ×1000 images. Overall, the particle size of oat starch generally decreased and the specific surface area increased significantly during oat germination.     

Isolation and partial characterization of Mexican taro (Colocasia esculenta L.) starch

Taro starch was isolated from Mexican variety and its morphological, physicochemical, and molecular characteristics were evaluated. Yield starch (in dry basis) was 81%, and this starch had low AM content (2.5%). Taro starch granules showed a mixture of shapes with sizes between 1 and 5 µm. Taro starch presented an A‐type XRD pattern with a crystallinity level of 38.26%. Solubility and water retention capacity did not change in the temperature range of 50–70°C and thereafter they increased as temperature increased too. Taro starch showed high peak viscosity due to its high AP content. The peak temperature of gelatinization of taro starch was 80.6°C with an enthalpy value of 10.6 J/g, with low retrogradation rate due to its low AM content. Weight‐average molar mass (Mw) and gyration radius (Rz) of taro starch were 1.21 ± 0.8 × 10⁹ g/mol and 424 ± 70 nm, respectively. Taro tuber could be an alternative for starch isolation with functional and physicochemical characteristics for food and non‐food applications.     

不同米淀粉精细结构对其回生特性的影响

选用4种不同的淀粉,通过考察回生特性,探究相对分子质量、链长分布、短程有序性、相对结晶度及半结晶层状结构等精细结构影响回生特性的机理。结果表明：与糯米淀粉和粳米淀粉相比,小米淀粉和黑米淀粉回生值、硬度和热焓值较大,糯米淀粉储藏前后硬度和回生后的热焓值均较小,具有较好的抗回生特性。研究发现,这是由于小米淀粉和黑米淀粉的直链质量分数较高(小米淀粉15.55%、黑米淀粉11.22%),支链淀粉峰M_w较大(小米淀粉M_w=2.12×10⁷ g/mol、黑米淀粉M_w=2.25×10⁷ g/mol)、半结晶层厚(小米淀粉d=6.978 4 nm、黑米淀粉d=6.698 6 nm),且中长链占比大(小米淀粉B1链占比40.91%),易形成稳定的双螺旋结构,具有更高的表面有序度(小米淀粉0.76、黑米淀粉0.70),回生后2种淀粉分子重排更有序稳定。     

Characteristics of pores in native and hydrolyzed starch granules

Low‐temperature nitrogen adsorption and mercury porosimetry were applied for analyzing effect of α‐amylolysis upon the porosity of granules of native corn, wheat, rice, and potato starches. Specific surface area (S_BET), porosity, pore size distribution, total pore area, and mean pore radius were determined for native and digested granules. It was found that native starch granules are macroporous materials with a small participation of mesopores. In the case of native starches, the highest value of S_BET was obtained for rice starch (1.27 m²/g) and the lowest – for potato starch (0.14 m²/g). Pore size distribution curves obtained by nitrogen adsorption showed peaks in the range of diameters 2–3 nm (for all starches) and 100–200 nm (for corn and rice starches). After 60 min of enzyme action, surface area of all starches doubled in comparison to native ones. Arising of the new pores was also noted. The results of mercury porosimetry measurements showed that rice starch had the highest total area of pores and porosity but the lowest mean pore radius among all native starches. The pore size distribution curves for all starches exhibited solely one peak corresponding to the dominant group of pores of the radii in the range 0.5–8 µm, dependent on the starch source. There were also much smaller peaks situated within the range of 3–30 µm. After α‐amylolysis of corn and rice starches, the average radius of the dominant group of pores diminished. No substantial changes in the pore radii could be noted for potato starch.     

湿热处理对大米淀粉多层次结构及消化特性的影响

为了明晰湿热处理前后大米淀粉多层次结构与消化性能之间的关系,本研究采用体外模拟法测定湿热处理前后大米淀粉的消化性能,并通过小角X射线散射（SAXS）、X射线衍射（XRD）和凝胶渗透色谱-多角度激光光散射（GPC-MALS）等现代分析技术考察湿热处理前后大米淀粉不同层次结构的变化。研究表明,湿热处理可引起大米淀粉半结晶片层的有序化程度下降,降低其结晶程度和分子量;同时,伴随着淀粉颗粒内部层状、结晶及分子链结构的破坏,淀粉-脂质复合物的形成及Mw >2×107 g/mol的高分子量片段的降低和Mw<5×106 g/mol的低分子量片段比例的增加（0%增至21.3%）有利于大米淀粉慢消化和抗消化性能的提高,而当Mw<5×106 g/mol比例增至32.1%时,可能由于低分子量片段较多,反而阻碍了慢消化和抗消化性能的提高。研究结果为湿热处理加工技术调控淀粉及淀粉质食品的消化性能提供了理论支撑和基础数据。     

Response Surface Methodology for the Optimization and Characterization of Cassava Starch‐graft‐Poly(acrylamide)

Response surface methodology (RSM) was employed for the synthesis of cassava starch‐graft‐poly(acrylamide) using ceric ammonium nitrate as free radical initiator. Concentration of acrylamide, concentration of ceric ammonium nitrate, reaction temperature and duration of reaction were optimized using a 4‐factor 3‐level Box‐Behnken design. The dependent variables were percentage grafting (%G) and grafting efficiency (GE). Second order polynomial relationships were obtained for %G and GE, which explained the main, quadratic and interaction effects of factors. The highest%G and GE obtained were 174.8% and 90.7%, respectively. The optimum values of parameters predicted through RSM were 20 g acrylamide/10 g dry starch, 3.3 g/L ceric ammonium nitrate, 180 min reaction duration and 45ºC temperature with a %G of 190.0. For GE, the predicted levels of factors for the optimum value of 90.8% were 17.5 g acrylamide/10 g dry starch, 4.1 g/L ceric ammonium nitrate, 180 min reaction duration and 55ºC temperature. The graft reaction was confirmed by FTIR analysis, where the absorption bands corresponding to the C=O stretching and N‐H bending of the –CONH₂ group were observed. Scanning electron microscopic studies on grafted starches revealed that the granular structure of the starch was affected by the reaction. X‐ray diffraction analysis showed that the crystallinity of starch was decreased as a result of grafting and the reduction was higher for the grafted starches with higher percentage grafting.