紫外光引发淀粉接枝丙烯腈的溶剂效应

在紫外光引发条件下进行玉米淀粉与丙烯腈的接枝反应，考察了单溶剂、混合溶剂的种类及用量对接枝反应接枝率和接枝效率的影响，得到了光接枝反应过程中溶剂效应的一些规律．     

Fermentation and heat-moisture treatment induced changes on the physicochemical properties of foxtail millet (Setaria italica) flour

This research intends to verify the effect of Lactobacillus paracasei Fn032 fermentation and heat-moisture treatment (HMT) on the physicochemical properties of foxtail millet (Setaria italica) flour. The results obtained showed a significant (P < 0.05) increase in protein content (12.02–20.54%), total starch (15.78–51.01%) and starch fractions after fermentation and HMT. Differential scanning calorimetry (DSC) analysis showed high decomposition temperature (T_d) trend of 180.59 and 189.82 °C after HMT. However, there was significant (P < 0.05) enthalpy (ΔH) decrease. Flour digestion resulted in variation of slow digestible starch (SDS) and resistant starch (RS) count from 6.83 to 18.42% and 7.61 to 22.68% respectively, after fermentation and HTM. Following this observation, it was ascertained that in X-ray diffraction; pasting viscosity and fluorescence spectrophotometry show greater HMT influenced on the flour components. Findings from the scanning electron microscopy (SEM) analysis showed microstructure differences of the flours samples. Fermentation and heat moisture treatment methods present a possible way of changing or improving the physicochemical properties and add nutritional value to foxtail millet meal.     

Starch as ion-based gate dielectric for oxide thin film transistors

Application of nature bio-materials in electronics represents an emerging field of science and technology that began a few years ago. For the dielectric of transistors, the ion-based electric double layer (EDL) gating has becoming the widely accepted theory of charge modulation with hydrated bio-polymer dielectrics. Herein, we report on the use of starch as the ion-based gate dielectric for oxide thin film transistors. Two types of starches, i.e., water-soluble starch and potato starch were studied either with or without the incorporation of glycerol. Important parameters including mechanical strength, surface morphology, specific capacitance and ion conductivity were analyzed in accordance with the molecular structure of starches. The transistor performance was found in close relation with the specific capacitance and ion conductivity of the starch dielectrics. Higher on/off ratio (2.6 × 10⁶) and field mobility (0.83 cm²V⁻¹s⁻¹) were obtained with glycerol incorporated potato starch due to the advantage in capacitance and ion conductivity. Lower ion conductivity of the water-soluble starch on the other hand caused the large current hysteresis, so the current retention property was examined for the potential application as a memory element. Collectively, this work solidifies our knowledge on the material type, EDL gating mechanism and applicability of nature bio-material gated transistors.     

含有植物纤维或玉米淀粉的食品接触产品质量安全风险研究

研究市售的含有植物纤维或玉米淀粉的食品接触产品质量状况并对其安全性进行初步评价。参考标准要求并结合可能存在的质量安全隐患,从傅里叶变换红外(FTIR)材质分析、总迁移量、重金属(以Pb计)、脱色试验、五氯苯酚特定迁移量及砷、镉、铬、铅含量等维度对含有植物纤维或玉米淀粉的食品接触产品进行研究。35批次样品中有2批次塑料主体材质为密胺,2批次塑料主体材质为聚乳酸,31批次塑料主体材质均为聚丙烯;35批次样品的重金属(以Pb计)、脱色试验、五氯苯酚特定迁移量等项目均符合所参照标准的要求;35批次样品均检出至少含2种重金属,有4批次一次性淀粉餐具总迁移量超标。从检验结果可知,市面上销售的含有植物纤维或玉米淀粉的食品接触产品存在总迁移量超标及样品含重金属的情况,说明市场上该类产品确实存在一定的潜在风险。     

Thermophilic hydrogen production from starch wastewater using two-phase sequencing batch fermentation coupled with UASB methanogenic effluent recycling

The aim of this study was to evaluate the performance of thermophilic hydrogenesis coupled with mesophilic methanogenesis in which the effluent was recycled to the hydrogen reactor for starch wastewater treatment. With this system, the hydrogen production rate and yield were 3.45 ± 0.25 L H₂/(L·d) and 5.79 ± 0.41 mmol H₂/g COD_added respectively, and thus higher than the values of the control group without methanogenic effluent recycling. In addition, relatively higher contents of acetate and butyrate were obtained in the hydrogen reactor with recirculation. The methane reactors were operated with the effluent from the hydrogen reactor, and methane yield was stabilized at 0.21–0.23 L/g COD_removal in both. Analysis of the microbial communities further showed that methanogenic effluent recirculation enriched microbial communities in the hydrogen reactor. Two species of bacteria effective in hydrogenesis, Thermoanaerobacterium thermosaccharolyticum and Clostridium thermosaccharolyticum, dominated during hydrogen production, whereas archaea belonging to Euryarchaeota were detected and cultured in the methane reactor. The recycled effluent supplied alkaline substrates for the hydrogen producing bacteria. Alkali balance calculations showed that the amount of added alkali was reduced by 88%. This amount, required for hydrogen production from starch wastewater, was contributed by alkali in the methanogenic effluent, (2225 ± 140 mg CaCO₃/L), resulting in lower operational costs.     

DMA thermal analysis of different parts of potato tuber

Dynamic mechanical analysis (DMA) was applied to three potato tissues (‘cortex’, ‘pith’, and ‘side’ surface) of two cultivars (more waxy ‘Nicola’ and more mealy ‘Saturna’) in temperature scans in the range 30–90 °C and constant air humidity of 90%. The obtained scans indicate peaks in both storage and loss module of elasticity (SM and LM, respectively) at temperatures higher than 70 °C – so called ‘starch’ peak (SP) – as was observed previously. The peak value increase with increasing potato dry matter (DM) content, below DM content approximately 14% no SP is observed (‘Nicola pith’). Slope analysis of the basic parameters: SM, LM, and loss tangent (LT) was performed and further characteristic points on the temperature plots were found: (i) in temperature range A (30–40 °C) maximum of SM and LM and minimum of LT, (ii) in temperature range B (40–50 °C) minimum of SM and LM slopes corresponding to point of inflection on SM-T and LM-T plots, (iii) at about 50 °C, big peak in LT in side tissue only, (iv) at about 70 °C just prior the ‘starch’ peak, big peak in LT that is more marked in ‘pith’; this peak denoted as ‘I’ influenced the ‘starch’ peak ‘II’. It was found that both cultivar and part of the tuber influences the DMA temperature plots.     

Creation of reduced fat foods: Influence of calcium-induced droplet aggregation on microstructure and rheology of mixed food dispersions

The impact of calcium-induced fat droplet aggregation on the microstructure and physicochemical properties of model mixed colloidal dispersions was investigated. These systems consisted of 2 wt% whey protein-coated fat droplets and 4 wt% modified starch granules heated to induce starch swelling (pH 7). Optical and confocal microscopy showed that the fat droplets were dispersed within the interstitial region between the swollen starch granules. The structural organisation of the fat droplets within these interstitial regions could be modulated by controlling the calcium concentration: (i) at a low calcium concentration the droplets were evenly distributed; (ii) at an intermediate calcium concentration they formed a layer around the starch granules; (iii) at a high calcium concentration they formed a network of aggregated droplets. Paste-like materials were produced when the fat droplets formed a three-dimensional network in the interstitial region. The properties of fat droplet–starch granule suspensions can be modulated by altering the electrostatic interactions to alter microstructure.     

The influence of macromolecular architecture on the critical aggregation concentration of large amphiphilic starch derivatives

A range of hyperbranched emulsifiers were prepared by reaction between starch and 2-octen-1-yl succinic anhydride (OSA, commonly used in the food industry), under slightly basic conditions in water, leading to starches bearing hydrophobic OSA groups randomly distributed along the chains. By using different starch backbones and varying the amount of OSA during the synthesis, amphiphilic OSA-modified starches were obtained that formed aggregates in water and having controlled structural parameters. These parameters were characterized using ¹H NMR, multiple-angle laser light scattering and size-exclusion chromatography. The critical aggregation concentration (CAC) was measured for samples with different levels of OSA modification, of macromolecular size and degree of starch branching. Increasing the dispersity in macromolecular size and/or degree of OSA substitution noticeably decreased the CAC. The results are interpreted in terms of the branching structure and conformation of the modified starches: all findings can be understood in terms of the various influences of molecular size, composition and flexibility. The structural factors affecting the CAC of large hyperbranched surfactants are found to be similar to those seen with smaller and simpler branched synthetic surfactants.