淀粉改性酚醛胶粘剂的研究

介绍了以淀粉部分代替甲醛与苯酚反应制备淀粉改性酚表粘剂的工艺，并对该胶粘剂的性能进行了测试，讲座了各种因素驿改笥胶粘剂性能的影响，用淀粉改性酚醛胶粘剂代替酚醛胶粘剂，可以降低成本和毒性，改善生产和施工环境养活环境污染。     

Factors affecting the action of α-amylase on wheat starch: Effects of water availability. An enzymic and structural study

In seeking an explanation for biochemical factors that influence the postprandial glycaemic response of starch-containing foods, a study was made of the action of pancreatic α-amylase on wheat starch. Samples containing different amounts of water were processed at 100 °C before use as substrates for amylase. Structural information on the starch samples was obtained by polarised light microscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD), in parallel with the enzyme studies. The catalytic efficiency of α-amylase was relatively low until the water content reached 30%, whereupon it rose sharply. Surprisingly, the K_m value was higher for samples processed at 20–30% water than at 12% water, suggesting that access of the substrate to α-amylase was less favourable at 20–30% compared with 12% water. K_m values fell at higher water levels, indicating greater availability of starch to amylase, presumably as a consequence of increased disorder of starch structure. Using DSC, XRD and microscopy, the anomaly in kinetic behaviour of 20–30% water samples was shown to be due to annealing of starch during processing (heating at 100 °C). The enzyme kinetic data proved to be a sensitive probe of changes in starch structure.     

Hydrophobic corn starch thermoplastic films produced by plasma treatment

Polymer coating technology is currently an important field in science as it can lead to final products with enhanced characteristics characterized by desired bulk and surface properties. Low power plasmas can induce the polymerization of a precursor gas on the substrate surface as well as introduce functional groups under specific plasma conditions. In the present work, we studied the possibility of reducing water sensitivity of corn starch films by sulfur hexafluoride (SF₆) plasma treatment. Confocal laser microscopy as well as atomic force microscopy was used to observe the main surface modifications and results indicated starch cross-linking. Fluoride was incorporated to the surface and the relationship between fluoride and sulfur incorporation to the surface was very much dependent on plasma power. Results indicate that fluoride could be preferentially incorporated on polymeric surfaces at −100 V self-bias and the overall surface morphology determined the measured contact angle. The dynamic behavior of surface contact angle was observed to be very much dependent on the treatment time and force–distance curves were used to further characterize the chemical surface modifications locally. Optimized treatment conditions led to water contact angles up to 130°. Even after being in contact with water for 10 min, surfaces remained hydrophobic, presenting contact angles over 100°.     

Characterisation of blends between poly(ε-caprolactone) and polysaccharides for tissue engineering applications

In this work, bioartificial binary blends between poly(ε-caprolactone) (PCL) and a polysaccharide (chitosan (CS) or starch (S)) with different contents of the natural polymer (5–30 wt.%) were produced. Melt-mixing and double-precipitation were the methods used for the obtainment of PCL/S and PCL/CS blends, respectively. Tubular scaffolds were produced from bioartificial blends by melt-extrusion. Physico-chemical characterisation was performed by differential scanning calorimetry analysis (DSC), thermogravimetry (TGA), scanning electron microscopy (SEM), infrared analysis (FTIR-ATR and micro-ATR mapping), atomic force microscopy (AFM) and stress–strain tests. Blends were not miscible, phase-separated systems, showing a homogeneous composition and morphology only at low polysaccharide content (≤ 10 wt.%). The biocompatibility of bioartificial guides was investigated by culturing NIH-3T3 mouse fibroblasts. Cells response showed the following order: PCL/S > PCL > PCL/CS. For each blend type, biocompatibility increased with decreasing the polysaccharide content. In vitro cell tests using S5Y5 neuroblastoma cells, carried out on the most biocompatible blends, assessed their absence of cytotoxicity towards these model cells of the nervous tissue. Results showed that blends with a low chitosan or starch content (≤ 10 wt.%) are promising for the regeneration of tissues requiring tubular scaffolds, such as the peripheral nerves.     

Approaches to improve compatibility of starch filled polymer system: A review

When hydrophilic starch is incorporated into synthetic polymers, the resulting products are weakened, especially blending with hydrophobic polymers. Many researchers have been undertaking various approaches to improve compatibility of starch and synthetic polymers. However, no ultimate and comprehensive approach can be determined. This paper aims to investigate and discuss the improvement approaches which have been recently developed by researchers. Also, the extents of improvement are summarized as well. In order to simplify this review, synthetic polymers are categorized into polar and non-polar types. Low density polyethylene was studied as non-polar type polymer, while polyvinyl alcohol was studied to represent as polar type polymer. Both types of synthetic polymers were blended with starches and their results were reported well by researchers. All findings are very informative and further encourage research for other starch filled polymer systems as well. In short, appropriate modifications to starch filled polymer system would induce polarity of the materials and subsequently create harmonious intermolecular interactions among blending components for better product properties.     

化学改性法增抗的影响因素及工艺的研究

本文以藕淀粉为原料，对化学改性法增抗的影响因素及工艺进行了研究，采用单因素实验和L9（33）正交实验，研究了pH值调节剂、酸解温度、时间对抗性淀粉（Resistant Starch，RS）含量百分率的影响。结果表明：pH值调节剂是影响RS含量的主要因素；最佳增抗工艺参数：pH值调节剂柠檬酸、时间4h、温度100℃。     

抗酶解淀粉的研究进展及其在食品工业中的应用

抗酶解淀粉是一种新型的碳水化合物，笔者对抗酶解淀粉的分类、形成及其在食品工业上的应用进行了综述。     

Impact of thermostable amylases during bread making on wheat bread crumb structure and texture

Thermostable amylases [Bacillus subtilis α-amylase (BSuA) and B. stearothermophilus maltogenic amylase (BStA)] with different modes of action and impacts on firming properties were added during straight-dough bread making. BSuA continuously degraded the starch fraction during bread making. Its action resulted in larger gas cells than in control bread, but did not change initial firmness. In contrast to BSuA, BStA mainly degraded starch at the end of the baking phase and during bread cooling, which caused little if any impact on bread crumb texture. However, it led to higher initial firmness readings than for the control breads. Neither BSuA nor BStA were inactivated during bread making. The results evidence that starch properties have a large impact on bread crumb structure and initial firmness and are highly influenced by the mode of action of the enzyme.