丁二酸酐酯化改性糯米淀粉的研究

目的 为了提高糯米淀粉的粘度，以达到标签胶的要求。方法 对糯米淀粉进行丁二酸酐酯化改性，通过单因素试验及响应面优化确定出最佳酯化条件，测定其理化性质，并对其进行结构表征。结果 丁二酸酐酯化改性糯米淀粉的最优工艺条件：丁二酸酐添加量（丁二酸酐占淀粉干基的质量百分比）为10.3%，酯化温度为41.5℃，酯化时间为2.0 h,pH为9.0，在此条件下制得的糯米淀粉胶的粘度较高，可达到61.6 Pa·s，且溶解性与溶胀度均有不同程度的提高。电镜与热力学性质分析表明，酯化后淀粉颗粒结晶结构受到破坏，表面粗糙，出现凹陷与裂缝。结论 经过丁二酸酐酯化后，糯米淀粉胶的粘度得到提高。     

Rethinking the Citric Acid Cycle: Connecting Pyruvate Carboxylase and Citrate Synthase to the Flow of Energy and Material

In 1937, Sir H. A Krebs first published the Citric Acid Cycle, a unidirectional cycle with carboxylic acids. The original concept of the Citric Acid Cycle from Krebs’ 1953 Nobel Prize lecture illustrates the unidirectional degradation of lactic acid to water, carbon dioxide and hydrogen. Here, we add the heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex, connecting the original Citric Acid Cycle to the flow of energy and material. The heart lactate dehydrogenase•proton-linked monocarboxylate transporter 1 complex catalyses the first reaction of the Citric Acid Cycle, the oxidation of lactate to pyruvate, and thus secures the provision of pyruvic acid. In addition, we modify Krebs’ original concept by feeding the cycle with oxaloacetic acid. Our concept enables the integration of anabolic processes and allows adaption of the organism to recover ATP faster.     

辛烯基琥珀酸淀粉酯对人造奶油物化特性的影响

目的 研究超微细化辛烯基琥珀酸淀粉酯(octenyl succinic anhydride modified starch, OSAS)对人造奶油物化特性的影响。方法 对超微细化OSAS糊透明度、糊凝沉性、OSAS人造奶油流变特性、热特性进行检测。结果 随着取代度(degree of substitution, DS)的增加, OSAS糊透明度增加, 糊凝沉性增加; 随着OSAS添加量的增加, 人造奶油的弹性模量(G'')、黏性模量(G'')降低。搅打频率与G''、G''的关系可采用指数模型描述, 快速搅打有利于形成网络结构紧密的质地。结论 超微细化OSAS的添加可以改善人造奶油的质地口感, 降低脂质融化温度, 提高冰凉感, 有利于提高人造奶油的综合品质。     

Impact of octenyl succinylated pearl millet (Pennisetum typhoides) starch addition as fat replacer on the rheological,textural and sensory characteristics of reduced‐fat yoghurt

The current study evaluated the impact of octenyl succinic anhydride (OSA)‐esterified pearl millet (Pennisetum typhoides) starch as a fat replacer (0.5, 1.0, 1.5 and 2.0%) on various characteristics of reduced‐fat yoghurt (1.5% fat). Firmness, flow point, storage and loss modulus increased with increasing levels of the OSA starch. The Herschel–Bulkley model was best fit for elucidating their pseudoplastic behaviour. Syneresis decreased considerably, whereas sensory acceptability improved with increasing OSA starch level. Owing to this reduced syneresis, improved structural strength and sensory acceptability, OSA‐esterified pearl millet starch functions as a fat replacer in reduced‐fat yoghurt.     

聚异丁烯及其衍生物的结构分析与性能评价

聚异丁烯马来酸酐（PIBSA）作为制备无灰分散剂的中间产物，其结构和性质直接决定了后续胺化反应的成败。采用傅里叶变换红外光谱(FTIR)和核磁共振波谱(1H-NMR)分析两种催化工艺 (BF3和AlCl3催化法)制备的不同活性的聚异丁烯和不同烃化工艺（氯化法和热合成法）制备的PIBSA的结构，探讨PIBSA的合成反应机理，对比分析了两种PIBSA进一步胺化制备的无灰分散剂的低温油泥分散性、高温清净性以及烟炱分散性能。结果表明：采用两种工艺制备PIBSA时，由于聚异丁烯的结构及反应原理不同，合成产物PIBSA的结构差异较大；热合成法PIBSA的末端以接枝的单五元环酸酐结构为主，氯化法PIBSA的末端主要以邻苯二甲酸酐结构为主，两种不同结构对无灰分散剂的性能产生较大影响。氯化法PIBSA制备的无灰分散剂DL和热合成法PIBSA制备的无灰分散剂DR的低温油泥分散性相当，DL的高温清净性优于DR，而烟炱分散性略差于DR     

辛烯基琥珀酸淀粉酯的醇相法制备及其理化性质

以木薯淀粉为原料，在醇水相中进行预处理，在醇相中进行预处理淀粉与辛烯基琥珀酸酐（OSA）的酯化反应，制备了不同取代度的OSAS，研究了淀粉乳浓度、反应温度、反应pH、OSA用量及反应时间对产物取代度（DS）和反应效率（RE）的影响，并通过正交实验优化制备工艺，得出醇相法制备辛烯基琥珀酸淀粉酯（OSAS）的最佳工艺条件为反应时间4 h，反应温度为35 ℃，OSA用量为30%，pH为8.5，淀粉乳浓度为35%，此时产物DS为0.0889，RE为38.47%。以原木薯淀粉为原料，在该条件下制备的酯化淀粉DS为0.0323，RE为13.98%，表明该预处理能显著提高RE。FT-IR分析表明淀粉分子上成功引入辛烯基琥珀酸基团；XRD测试表明原木薯淀粉经过预处理后结晶度由21.48%下降至8.61%，A型结晶结构部分转化成V型，酯化反应首先发生在淀粉的表面及无定形区，其次进攻淀粉内部及结晶区进而导致结晶度有所下降；淀粉经酯化改性后，糊液粘度、抗凝沉性和透明度明显提高。     

十一烯酸/马来酸酐共聚物的制备与表征

以十一烯酸(UA)和马来酸酐(MAH)为原料，偶氮二异丁腈(AIBN)为引发剂，通过沉淀聚合的方法制备了十一烯酸/马来酸酐共聚物(UMA)，研究了单体配比、引发剂用量及反应温度对共聚反应的影响，通过FT-IR、¹³C NMR、DSC分析和酸酐质量分数的测定对共聚物进行了表征。FT-IR和¹³C NMR结果表明：在实验条件下，十一烯酸(UA)与马来酸酐(MAH)发生了共聚反应。当反应温度为75 ℃、AIBN用量为0.75%时，随着MAH用量的增加，共聚物相对分子质量减小，得率和酸酐质量分数呈现先增大后略有减小的趋势，当UA与MAH的物质的量之比为40:60时共聚物的得率及酸酐质量分数均达到最大值，分别为61.78%和20.05%，与DSC曲线中玻璃化转变温度(T_g)的变化趋势基本一致，即当n(UA):n(MAH)为40:60，T_g达到最大值71.98 ℃。提高引发剂用量和反应温度有利于共聚反应的进行，但相对分子质量有所下降，因此可根据所需聚合物的性质来选择合适的反应条件。     

Effects of sulfonation on bis-styrylbiphenyl fluorescent whitening agents for polypropylene

Three derivatives of bis-styrybiphenyl with different degrees of sulfonation to be used as fluorescent whitening agents (FWAs) were synthesized. Studies on their spectroscopic properties were performed using a combination of computational methods. Whitening effects of FWAs and the improved thermal stability of polypropylene (PP) were investigated. The morphology of plastic samples was examined by scanning electronic microscopy (SEM). In order to improve the compatibility between FWA and PP, PP grafted with maleic anhydride (MAH) was applied as compatibilizer. The optical properties were further clarified by the results of frontier molecular orbital modeling, which show that the presence of sulfonic sodium group leads to a red shift of maximum UV absorption wavelength and a low HOMO–LUMO energy band gap. It is observed that the addition of 0.010 wt % of the sulfonated FWA would result in the expected whitening effect as well as improved PP thermal stability, while at or above 0.015 wt %, such effects worsen sharply owing to phase separation. Furthermore, the use of MAH-grafted PP as compatibilizer results in improvement of phase behavior and thermal stability. The study provides new insights into the effect of FWA structure on the properties of PP that are related to the whitening of the material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47635.     

Inverse emulsion polymerization of triple monomers of acrylamide,maleic anhydride,and styrene to achieve highly hydrophilic–hydrophobic modified polyacrylamide

The purpose of this study was the production of copolymers and terpolymers with highly hydrophilic–hydrophobic properties, using inexpensive and available monomers as potential enhancing oil recovery (EOR) and water production control agents for high-temperature and high-salinity (HTHS) oil reservoirs. For this purpose, several copolymers and terpolymers with different molar percentage of acrylamide/styrene, acrylamide/maleic anhydride, and acrylamide/styrene/maleic anhydride were synthesized by the inverse emulsion polymerization technique. The presence of hydrophobic styrene and hydrophilic maleic anhydride monomers in the copolymer and terpolymer structure, provided some unique properties compared to polyacrylamide, was confirmed by several analyses including HNMR, elemental analysis, FTIR, SEM, TGA, and DSC. Simulating HTHS oil reservoir condition under high salinity, temperature, and shear rate, the rheological studies suggested unlike traditional EOR agents such as polyacrylamide, the viscosity of the copolymer, and terpolymer aqueous solutions showed a considerable increase after a critical polymer concentration and less reduction with the salt increment at both ambient and elevated temperatures. Furthermore, the swelling ratio of the insoluble terpolymers measured versus the time and temperature in salt water increased with the maleic anhydride mole fraction, decreased with the salt concentration, and showed a maximum value at around 57 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47753.     

辛烯基琥珀酸酐复合超声改性提高鸡蛋全蛋液热稳定性

全蛋液在64.5℃及以上温度下加热会出现热变性凝固的现象,影响其在食品加工中的应用。采用预热、超声与辛烯基琥珀酸酐(octenyl succinic anhydride,OSA)修饰相结合的技术手段制备改性全蛋液,以聚合物分散性指数(polymer dispersity index,PDI)、粒径、浊度、流变性质、溶解性和差示扫描量热分析为评价指标,探讨不同OSA添加量下鸡蛋全蛋液热稳定性的变化规律。结果发现:在添加10%OSA时,全蛋液的表观黏度、G’与G’’均最小,表明此时蛋白质之间聚集体达到最小化;PDI和平均粒径的减小、浊度的降低、溶解性的提高,都会使全蛋液的热稳定性得到改善;同时采用差示扫描量热仪测定改性后的全蛋液,发现在OSA添加量为10%时,热变性温度达到95.91℃,改善了鸡蛋全蛋液的热稳定性,为全蛋液进一步深加工以及灭菌提供了有效的方法。