芝麻叶中总黄酮的最佳提取工艺研究

该文测定了芝麻叶中总黄酮的含量，并对芝麻叶黄酮的提取工艺进行了研究。重点探讨了采用乙醇提取法和微波处理与乙醇提取相结合的方法提取芝麻叶黄酮类化合物的最佳工艺条件。试验结果表明：芝麻叶中总黄酮的含量为0.98%；乙醇提取法的最适工艺参数是浸提剂乙醇浓度为80%、浸提温度为80℃、料液比为1∶25、浸提时间为2.5 h，如此条件可使黄酮提取率达95.6%；微波处理与乙醇提取相结合的方法的最适工艺参数是微波功率200 W、微波处理时间70s，乙醇浓度为80%、浸提温度为80℃、料液比为1∶25、浸提时间为30 min，这种工艺可使黄酮提取率达95.8%。     

杜仲叶绿原酸和黄酮类化合物提取工艺研究

对杜仲叶中绿原酸和总黄酮的最佳提取工艺进行了研究,结果表明溶剂为60%乙醇;提取时间为2h;提取次数为3次;温度为80℃;料液比为116(W/V).其中浸提温度是首要影响因素,其次是时间和料液比.此工艺所得的杜仲浸膏,得率为31.67%,其中绿原酸含量为8.43%,提取率为90.21%;总黄酮含量为5.49%,提取率为93.32%.     

响应面优化花生叶可溶性蛋白提取工艺及抗氧化活性分析

为确定花生叶可溶性蛋白提取最佳工艺,本试验以花生叶为材料,利用碱溶酸沉法提取花生叶可溶性蛋白,分析浸提pH值、料液比及提取时间对蛋白提取率的影响;在单因素试验的基础上,采用Box-Behnken响应面分析法(RSM)优化花生叶可溶性蛋白提取条件,并对所得蛋白进行抗氧化活性分析。结果表明,各影响因素主次顺序为浸提pH值>提取时间>料液比,最佳提取条件为料液比1∶20(w/v)、提取时间40 min、浸提pH值 9.0,以此条件建立的响应面试验回归模型拟合性好(R²=0.992 7),花生叶可溶性蛋白理论提取率为52.8%,实际提取率为54.2%,纯度为63.8%。花生叶可溶性蛋白具有较强的DPPH自由基、超氧阴离子自由基清除能力,以及较好的还原能力。本研究结果为花生叶的开发利用及花生产业链的延长提供了一定的数据支持。     

早籼米制备大米蛋白和酒精的联产工艺研究

该文以早籼米为原料,采用碱法提取大米蛋白并利用残余淀粉发酵制备酒精。通过研究碱液浓度、提取温度、料液比和时间对大米蛋白提取的影响,确定了提取大米蛋白的较佳工艺条件为：碱液浓度0.05 mol/L、提取温度30℃、料液比1∶4、提取时间2 h。此条件下提取的大米蛋白纯度为94.9%,提取率为52.4%。残余淀粉中添加25%的玉米粉有较好的发酵效果：发酵时间45 h,酒精度为12.78%,残余还原糖为0.13%。     

不同粒色藜麦挤压面条品质特性分析

为了探究不同粒色藜麦挤压面条品质特性的差异及机理,该研究对比分析了不同粒色藜麦粉的基础组分、糊化特性、挤压面条微观结构、蒸煮品质、活性成分及淀粉体外消化特性的差异。结果表明：白藜麦粉中淀粉含量最高,糊化后峰值黏度、最终黏度和回生值也最高。红、黑藜麦粉及挤压面条中的多酚、黄酮含量及抗氧化活性显著高于白藜麦粉和挤压面条。挤压后,淀粉结晶度均下降,白藜麦面条中淀粉的结晶度最高。红（2.25 min）、黑藜麦（2.75 min）面条的蒸煮时间短,但蒸煮品质显著低于白藜麦面条（P < 0.05）。扫描电镜显示白藜麦面条淀粉凝胶网络结构更加连续致密,导致其淀粉水解率和预计升糖指数显著低于红、黑藜麦面条（P < 0.05）。该研究为高品质藜麦面条的生产加工提供理论和技术参考。     

碱法制备蚕蛹蛋白浸提条件的优化（简报）

该文通过中心组合设计及相应面分析,研究了碱法制备蚕蛹蛋白的浸提条件对蚕蛹蛋白浸提率的影响,得到了蚕蛹蛋白提取率的数学模型。优化了蚕蛹蛋白的浸提的条件,提高了碱法制备蚕蛹蛋白的蛋白提取率。结果表明NaOH浓度和液固比（V/m）对蚕蛹蛋白提取率影响显著（P＜0.05）。蚕蛹蛋白浸提的最佳工艺条件为：NaOH浓度1.03%、液固比（V/m）70︰1、浸提温度50℃、NaCl浓度0.070 mol/L。在此最佳工艺条件下蚕蛹蛋白的实际提取率达78.69%。利用优化工艺条件制备的桑蚕蛹蛋白,其蛋白含量为96.70%,必需氨基酸占总氨基酸含量的47.1%,必需氨基酸与非必需氨基酸的比值为0.9,具有较好的应用价值。     

碱法制备蚕蛹蛋白浸提条件的优化

该文通过中心组合设计及相应面分析.研究了碱法制各蚕蛹蛋白的浸提条件对蚕蛹蛋白浸提率的影响,得到了蚕蛹蛋白提取率的数学模型.优化了蚕蛹蛋白的浸提的条件,提高了碱法制备蚕蛹蚩白的蛋白提取率.结果表明NaOH浓度和液固比(V/m)对蛋蛹蛋白提取率影响显著(P<0.05).蚕蛹蛋白浸提的最佳工艺条件为:NaOH浓度1.03%、液固比(V/m)70:1、没提温度50℃、NaC1浓度0.070moVL.在此最佳工艺条件下蚕蛹蛋白的实际提取率达78.69%.利用优化工艺条件制备的桑蚕蛹蛋白,其蛋白含量为96.70%,必需氨基酸占总氨基酸含量的47.1%,必需氨基酸与非必需氨基酸的比值为0.9,具有较好的应用价值.     

不同淀粉糊化及凝胶特性与粉条品质的关系

为了研究粉条加工过程中原料淀粉的糊化及凝胶特性对粉条品质的影响,该文对绿豆、红薯、马铃薯、大米和玉米等5种原料淀粉的糊化凝胶特性及其粉条品质进行了测定,并对淀粉糊化凝胶特性与淀粉粉条品质之间的关系进行探讨。结果表明:5种淀粉原料所制的粉条中,绿豆粉条的品质是较好,其次就是马铃薯粉条和红薯粉条,大米粉条和玉米粉条的品质较差;淀粉的糊化特性与粉条品质之间具有显著相关性,按显著程度的大小(P值大小)依次是:峰值黏度谷值黏度衰减值回生值、最终黏度;淀粉凝胶的硬度、弹性、黏性和咀嚼性对粉条品质的影响较大,按显著程度的大小(P值大小)依次是:硬度黏性咀嚼性弹性。在粉条加工原料选择及粉条品质改善中可以考虑用谷值黏度、回生值以及淀粉凝胶特性特征值回复性、咀嚼性和黏性作为考核衡量指标。研究结果为粉条生产中原料选择及品质改善提供参考依据。     

平远慈橙皮黄酮类化合物的提取工艺探究

采用超声波辅助乙醇提取橙皮中黄酮类化合物,以硝酸铝显色法测定的黄酮类化合物总量为指标,探究平远慈橙皮黄酮类化合物的提取工艺。运用单因素实验研究溶剂p H、乙醇体积分数、提取温度、提取时间、料液比对黄酮类化合物提取率的影响,通过正交试验进一步优化提取工艺条件。结果表明:平远慈橙皮黄酮类化合物最佳提取工艺为乙醇体积分数50%,温度50℃,料液比1∶50,超声时间50 min。通过最佳工艺验证,此条件下平远慈橙皮黄酮类化合物提取率达到2.10%。该工艺简单可行,有较好的参考价值。     

响应面分析法优化家蚕1-脱氧野尻霉素的稀酸浸提工艺

本文以稀HCl从蚕粉中提取1-脱氧野尻霉素（1-deoxynojirimycin,1-DNJ）,通过单因素试验确定提取影响因素的水平,并采用响应面法研究料液比分数、浸提温度和浸提时间对蚕粉1-DNJ提取工艺的影响。其中1-DNJ含量测定采用9-芴基氯甲酸甲酯（FMOC-Cl）衍生化法,并用反相高效液相色谱对其衍生物进行测定。1-DNJ高效液相色谱检测谱图表明,通过液相色谱荧光可以检测蚕粉来源的1-DNJ。响应面优化实验结果表明,1-DNJ的最佳提取条件为：提取时间3.3h,浸提温度72.9℃,料液比分数为1：282。在此条件下,1-DNJ的理论提取率为0.493%,实际提取率为0.487%,相对误差为1.2%。本研究初步建立了稀酸浸提家蚕1-DNJ的二次多项数学模型,确定其最佳提取工艺条件,为工业化生产提供参考。     

Partial Characterization of Buckwheat (Fagopyrum esculentum) Starch

Laboratory-isolated buckwheat (Fagopyrum esculentum) starch was compared to commercial corn and wheat starches. Buckwheat starch granules (2.9–9.3 μm) were round and polygonal with some holes and pits on the surface. Buckwheat starch had higher amylose content, waterbinding capacity, and peak viscosity, and it had lower intrinsic viscosity when compared with corn and wheat starches. Buckwheat starch also showed restricted swelling power at 85–95°C and lower solubility in water at 55–95°C and was more susceptible to acid and enzymatic attack. Gelatinization temperatures, determined by differential scanning calorimetry, were 61.1–80.1°C for buckwheat starch compared to 64.7–79.2°C and 57.1–73.5°C for corn and wheat starches, respectively. A second endotherm observed at 84.5°C was an amylose-lipid complex attributed to the internal lipids in buckwheat starch, as evidenced by selective extraction. The retrogradation of buckwheat, corn, and wheat starch gels was examined after storage at 25, 4, and -12°C for 1–15 days. In general, buckwheat starch retrogradation was slower than that of corn and wheat starch, but it increased as storage time increased, as did that of the other starch pastes. When the values of the three storage temperatures were averaged for each storage period analyzed, buckwheat starch gels showed a lower percentage of retrogradation than did corn and wheat starch gels. Buckwheat starch also had a lower percentage of water syneresis when stored at 4°C for 3–10 days and had better stability to syneresis after three freeze-thaw cycles at -12 and 25°C.     

Elucidation of Fermentation Effect on Rice Noodles Using Combined Dynamic Viscoelasticity and Thermal Analyses

Natural fermentation of whole polished rice grains (indica) is a traditional processing method widely applied in China and South Asia to improve the texture of rice noodles. To elucidate the effects of fermentation on noodle texture, thermal analysis of rice flour and rheological measurement were performed on a gel made from the rice flour with the same solids concentration as practical noodles. The test method proved useful for monitoring starch granule swelling, gel forming, and retrogradation of rice gels during rice noodle production. Dynamic viscoelasticity in a temperature ramp sweep test showed that starch granules of the fermented sample swelled more and were more resistant to breakdown than those of the nonfermented sample. Differential scanning calorimetry revealed that the gelatinization temperature of fermented rice flour shifted to a lower temperature. The decreased protein content after fermentation also played a role in the modified rheological and thermal properties of fermented rice flour. Both fermented and nonfermented rice flour formed an elastic gel just after heating to the conclusion temperature of gelatinization (T_c). The fermented rice flour gel formed earlier with a well‐formed structure; however, it had slower retrogradation during aging. The result also indicated that the retrogradation of amylopectin impaired the desired texture of rice noodles.     

挤压体系中可得然胶对小麦淀粉回生特性和冻融稳定性的影响

小麦淀粉的回生现象和较差的冻融稳定性是限制面制品加工的重要原因。为探索一种有效抑制小麦淀粉回生及改善其冻融稳定性的方法,该文研究了挤压体系中不同质量分数的可得然胶对小麦淀粉回生特性和冻融稳定性的影响,利用差示扫描量热仪、X-射线衍射和傅里叶红外光谱等技术表征了可得然胶-小麦淀粉复合物的分子结构,并结合化学试剂处理、质构仪和扫描电镜探讨了可得然胶与小麦淀粉的结合机制。结果表明：随着可得然胶浓度的增加,可得然胶-小麦淀粉复合物的回生值和析水率先降低后增加;与挤压小麦淀粉相比,添加质量分数0.6%的可得然胶能够显著提高小麦淀粉的糊化温度,并降低小麦淀粉的相对结晶度、短程有序性和碘结合力,抑制了直链淀粉的重结晶;挤压体系中可得然胶与小麦淀粉主要通过氢键和弱的静电相互作用结合,使小麦淀粉的结构更加致密,从而抑制小麦淀粉的回生并改善其冻融稳定性,该研究可为开发抗回生和低析水率的挤压小麦淀粉基食品提供参考。     

Thermal Properties of Corn Starch Extraction Intermediates by Differential Scanning Calorimetry

Thermal properties of corn starch extraction intermediates from four types of corn were studied using differential scanning calorimetry. Starch at four different stages of extraction, including a standard single-kernel starch isolation procedure and three starch extraction intermediates, was isolated from mature corn kernels of B73 and Oh43 inbreds and the mutants of waxy (wx) and amylose extender (ae) in an Oh43 background. Differences in thermal properties and moisture and protein contents of starch from the extraction stages were statistically analyzed. Most thermal properties (gelatinization and retrogradation onset temperatures, gelatinization and retrogradation ranges, gelatinization and retrogradation peak temperatures, gelatinization and retrogradation enthalpies, peak height index, and percentage of retrogradation) of starches extracted at stage 3 intermediate (a procedure that did not include a final washing step) were similar to those of starch extracted by the standard single-kernel isolation procedure. Values for gelatinization peak temperature, gelatinization enthalpy, and peak height index were different between the standard and the stage 3 intermediate. The values obtained from starches extracted at stage 3, however, were consistent and predictable, suggesting that this extraction intermediate might be used in screening programs in which many starch samples are evaluated. By using the stage 3 extraction, samples could be evaluated in three rather than four days and the procedure saved ≈0.5 hr of labor time. The other two starch extraction intermediates, which excluded filtering and washing or filtering, washing, and steeping, produced starch with thermal properties generally significantly different from starch extracted by the standard single-kernel isolation procedure.     

气流粉碎对玉米淀粉结构及理化性质的影响

为研究气流粉碎对玉米淀粉结构及理化性质的影响,该文以普通玉米淀粉为原料,通过流化床气流粉碎处理,采用扫描电子显微镜、偏光显微镜、粒度分析仪、X-射线衍射仪、红外光谱仪、差示扫描量热仪、快速黏度分析仪等分析手段研究经微细化处理前后玉米淀粉颗粒形貌、晶体结构、热力学特性、糊化特性、溶解度和膨胀度、冻融稳定性、持水能力等结构及性质的变化。结果表明,微细化处理后,淀粉颗粒形变的不规则,粒径明显减小,中位径(D50)由14.37μm减小到5.25μm,偏光十字减少,相对结晶度由33.43%降低至15.46%,淀粉颗粒结晶结构被破坏,由多晶态向无定形态转变,粉碎过程淀粉无新的基团产生;热焓值、糊化温度均降低,热糊稳定性好;溶解度、膨胀度均升高,持水能力增加,冻融稳定性好,产生较好的热糊稳定性和冷糊力学稳定性,该研究为玉米淀粉的深度加工与应用提供了理论依据及技术支撑。     

Effect of polysaccharides on the gelatinization properties of cornstarch dispersions

Konjac glucomannan (KG, neutral), carboxymethylcellulose (CMC, negatively charged), and chitosan (positively charged) were added to cornstarch dispersions to study the effect of polysaccharide-starch interactions on starch gelatinization properties. Pasting and retrogradation properties were measured with a rheometer and DSC. Swelling properties of the starch granules were determined by solubility index, swelling power, and particle size distribution. Depending on the nature of the different polysaccharides, viscosities of cornstarch dispersions were affected differently. The particle size distributions were not influenced by the addition of any of the polysaccharides. Swelling results showed that the KG and CMC molecules interacted with the released or partly released amylose in the cornstarch dispersions. This was correlated with the short-term retrogradation of the starch pastes being retarded by the additions of KG and CMC. However, the chitosan molecules appeared not to associate with the amylose, so the retrogradation of the chitosan-cornstarch dispersions was not retarded.     

Characteristics of Starch from Eight Quinoa Lines

Starches ranging in amylose content from 3 to 20% from eight quinoa (Chenopodium quinoa Willd.) lines were characterized with respect to thermal, retrogradation, and pasting properties; swelling and solubility behavior; freeze‐thaw stability; water‐binding capacity; shear stability; and granule size and morphology. The starches differed in gelatinization onset temperatures, peak temperatures, and retrogradation tendencies; these characteristics were positively correlated with amylose content. No variation in gelatinization enthalpy was observed. With the exception of pasting temperature, large variations in pasting characteristics were found among starches and were correlated with amylose content. Swelling, solubility, freeze‐thaw stability, and water‐binding capacity also differed among starches and were correlated with amylose content. Granule morphology and size were similar for all starches. The wide variation in amylose content and physicochemical characteristics of quinoa starches suggests applications in a variety of food and nonfood products.     

Functional Properties of Cross-Linked and Hydroxypropylated Waxy Hull-less Barley Starches

Waxy hull-less barley (HB) starches containing 0 or 5% amylose were cross-linked with phosphorus oxychloride and the cross-linked starches were hydroxypropylated with propylene oxide. For comparison, waxy corn and potato starches were similarly modified. For all starches, cross-linking inhibited granule swelling and prevented swollen granules from disintegration, resulting in dramatic improvement in pasting properties and tolerance to cooking shear and autoclaving. Cross-linked waxy HB starches were more tolerant to cold storage and cooking shear than cross-linked waxy corn starch. Hydroxypropylation of the cross-linked starches reduced granule crystallinity and gelatinization temperature, and improved granule swelling, paste clarity, and freeze-thaw stability. The double-modified waxy HB starches showed higher cold tolerance than similarly modified waxy corn and potato starches, as judged by freeze-thaw stability and clarity after cold storage. These results indicated that the cross-linked and double-modified waxy HB starches together may have a wide range of food applications. This study indicated that the behavior of granule swelling and disintegration of swollen granules played an important role in governing paste viscosity, clarity, and freeze-thaw stability of waxy HB starches.     

Pressure-temperature phase transition diagram for wheat starch

Wheat starch suspensions in water (5% dry matter) were subjected to various pressures (0.1-600 MPa) and temperatures (-20 to 96 degrees C) for 15 min. The gelatinization rate was measured after treatment by using microscopic measurements of the loss of birefringence of the granules. This method was previously calibrated by differential scanning calorimetry. Curves of isogelatinization were found to be quite similar to a pressure-temperature (P-T) diagram of unfolding proteins. Results were first analyzed by considering the thermodynamic aspects related to the dT/dP curve shifts. On the basis of equations already shown for proteins, the P-T gelatinization diagram of wheat starch would show different kinds of thermal contributions, suggesting endothermic, athermic, or exothermic melting reactions. Second, as a practical consequence, these previous P-T areas corresponded to specific gelatinization conditions as confirmed by hydration evaluation measured by starch swelling index. Depending on the pressure-temperature conditions, gelatinization would involve hydration. Lowering the pressure and temperature resulted in a complete gelatinization with less hydration in comparison with a thermal treatment at atmospheric pressure. A hydration model based on an energetic approach was proposed.