Physicochemical characterisation of corn extrudates prepared with varying levels of beetroot (Beta vulgaris) at different extrusion temperatures

This study examines the effect of beetroot powder (BRP) incorporation (0%, 5%, 10% and 15%) at different extrusion temperatures (125, 150 and 175 °C) on the physicochemical, antioxidant and sensory properties of corn grit (CG) extrudates. BRP showed higher values of total phenolic content (TPC = 9095 μg GAE g^?1) and free radical inhibition (ABTS = 6.5 μm trolox mg^?1 and DPPH = 7.9 μm trolox mg^?1) than CG (1346 μg GAE g^?1, 1.5 μm trolox mg^?1 and 2.2 μm trolox mg^?1, respectively). Pasting viscosity (peak, breakdown and final) decreased, while pasting temperature of CG increased with the level of BRP incorporation. Analyses of the extrudates showed an increase in redness, bulk density, hardness, TPC, free radical inhibition, total dietary fibre (TDF) and a decrease in water absorption index (WAI), water solubility index (WSI), expansion ratio and oil uptake with the increase in the level of BRP incorporation. On the other hand, higher extrusion temperature increased porosity, WAI, WSI, oil uptake but decreased redness, bulk density, hardness and TPC.     

Optimization of parameters for cerium（III） biosorption onto biowaste materials of animal and plant origin using 5-level Box-Behnken design：Equilibrium,kinetic, thermodynamic and regeneration studies

Response surface methodology （RSM） employing 5-level Box-Behnken design was used to optimize the biosorption of cerium（III） onto biowaste materials of animal and plant origin viz. prawn carapace （PC） and corn style （CS）. Various process parameters viz. pH （A：3.0-9.0）, biomass dosage （B：0.05-0.35 g/L）, initial metal concentration （C：50-350 mg/L）, contact time （D：2-6 h） and temperature （E：20-60 ℃ were chosen for optimization. A log transformation was suggested by the Box-Cox plot in the present case. A low p-value of〈0.0001 validated the significance of the model. Maximum Ce（III） uptake of 218.3 mg/g for PC and 180.2 mg/g for CS was noted under optimum conditions. Among the equilibrium isotherms, Freundlich model was found to be the best fitted one suggesting a heterogeneous mode of biosorption on PC whereas Langmuir model showed the best fit suggesting homogeneous mode of cerium biosorption on CS. This was further confirmed by scanning electron microscopy （SEM）. Kinetic studies showed better applicability of pseudo-first order model suggesting physisorption as phenomena underlying the process. Film-diffusion was suggested by the non-linearity of the Boyd plot. Thermodynamic studies showed that the process was endothermic and spontaneous. FTIR analysis confirmed a major involvement of the participation of amide, amines, ketones and primary alcohol groups during Ce（III） biosorption. EDAX analysis confirmed the major participation of carbon group during Ce（III） biosorption. This was the first report on parameter optimization of Ce（III） biosorption onto biowaste materials using 5-level Box-Behnken experimental design which might be helpful for the recovery of Ce（III） from aqueous environment.     

硫酸脲复合肥对玉米生长指标及产量的影响

通过田间试验方式研究硫酸脲复合肥、普通缓释肥、硫基肥、BB肥对玉米生长和产量的影响。结果表明,4种肥料处理均能促进玉米植株茎粗、穗粗和穗行数的增加,特别是硫酸脲复合肥处理,较CK分别增加了3.8%、3.6%和18.2%;而且4种肥料处理对玉米也有不同程度的增产效应,其中硫酸脲复合肥处理增产率最高,为21.09%。     

Characterization of Crude and Partially Purified Lipase from Geotrichum candidum Obtained with Different Nitrogen Sources

Lipases from Geotrichum candidum were produced in two different medium: A = 12 % (w/v) clarified corn steep liquor (CCSL) + 0.6 % (w/v) soybean oil (SO) and B = 3.5 % (w/v) yeast hydrolysate (YH) + 0.7 % (w/v) SO. Lipases were partially purified from both media by hydrophobic interaction chromatography using 3.0 mol L^?1 of NaCl as mobile phase, and they were characterized in the crude and partially purified forms. The recovery of lipase activity from CCSL and YH via HIC were 96 and 94.3 %, and the purification factors were 44.3 and 86.7‐fold, respectively. All evaluated lipases had similar optimum pH (7.0–7.7), but, for the CCSL crude lipase, optimum temperature (47 °C) was 10 °C higher than others lipases evaluated. CCSL crude lipase possessed a higher thermo stability than YH crude lipase, e.g., at 37 °C (pH 7.0) the half‐life of CCSL crude lipase was 19.25 h and at pH 8.0 (30 °C) the half‐life was 48 h, which are five and ten times higher than with YH crude lipase, respectively. On the other hand, the YH crude lipase possessed a higher catalytic constant (k_cat = 2.3 min^?1) but with almost the same catalytic efficiency (K_m/k_cat = 32.12 mg mL min^?1) in relation to CCSL crude lipase. The lipases differ in biocatalytic properties between substrates, suggesting that the two lipases can be employed for different applications.     

玉米秸秆热解特性及动力学分析

以玉米秸秆为原料, 利用热重分析法研究其热解的特性及动力学。根据TG和DTG曲线, 研究玉米秸秆的热解特性, 采用Flynn-Wall-Ozawa(FWO)和Kissinger-Akahira-Sunose(KAS)两种等转化率法计算玉米秸秆热解的活化能, 并结合主曲线法和Coats-Redfern(C-R)法探讨了玉米秸秆热解遵循的机理方程。研究结果表明: 玉米秸秆热解过程可分为干燥脱水、过渡、主热解和炭化4个阶段, 随着热解升温速率增大, TG和DTG曲线向高温侧偏移; 利用FWO和KAS法计算得到的表观活化能分别为181.7和181.5 kJ/mol; 利用主曲线法和C-R法求解出玉米秸秆热解的机理方程遵循Avrami-Erofeev方程, 当α=0.1~0.5时, n=3, f(α)=1/3(1-α)[-ln(1-α)]^-2; 当α=0.5~0.7时, n=2, f(α)=1/2(1-α)[-ln(1-α)]^-1。     

Spray Drying of Green Corn Pulp

Maize (Zea mays) is a cereal grown in Brazil, and its availability is limited to the harvest season. An alternative processing route is based on the production of green corn powder, which has a longer shelf-life and increased versatility. This study aimed to evaluate the influence of drying conditions on the physical characteristics, size, and morphology of green corn powder. Drying experiments were performed on a spray dryer according to a central composite rotational design to evaluate inlet air temperature, feed flow rate, and pulp concentration. The yield of dried pulp corn had an average value of 36.19%. The following mean values for the physical properties of the powder were measured: solubility of 94.37 g/100 g, wettability of 128.05 seconds, moisture content of 1.97%, water activity of 0.13, density of 0.79 g/mL, and a particle diameter of 31.02 µm. The powder was also yellow with less intensity, and the particle surface was smooth at higher temperatures and had a tendency to form agglomerates. The estimated optimal conditions for spray drying were 48% (w/w) pulp concentration, 172°C inlet air temperature, and feed flow rate of 0.56 L/h.     

氧化法玉米淀粉胶的制备和改性及其在内墙涂料中的应用

面临石油危机和环境恶化的双重威胁,作为石油替代品,天然高分子的开发利用又一次成为高分子材料研究领域的热点之一。本文以双氧水为氧化剂,硫酸亚铁为催化剂,将玉米淀粉氧化变性后,和苯乙烯及丙烯酸酯单体接枝共聚,获得改性玉米淀粉胶,并以其作为基料,复配得到改性玉米淀粉胶内墙涂料,明显改善了涂料的贮存稳定性和涂膜的附着力、流平性、耐水性、抗飞溅性等性能,是一种环境友好、成本低廉的内墙涂料。     

玉米浆对VB_(12)发酵的影响

玉米浆质量和添加浓度对VB12发酵有很大的影响,为了选取最优玉米浆作为培养基氮源,本实验比较了3个生产厂家和5个不同浓度的玉米浆。结果表明:厂家Ⅲ的玉米浆为最优玉米浆,最适浓度为3.7%。     

玉米须水提物的抗氧化及降尿酸活性

采用超声技术辅助提取玉米须水溶性成分,测定玉米须水提物的DPPH·、·OH清除能力和还原力等抗氧化作用,并通过小鼠实验,分析小鼠体质量、血清尿酸（Serum Uric Acid,SUA）、小鼠肾脏病理学观察,研究玉米须水提物对高尿酸血症小鼠的降尿酸作用。实验结果显示,玉米须水提物（C3组）具有显著的DPPH·（90.75%）、·OH清除能力（86.29%）和还原力（P<0.05）,表明玉米须水提物具有巨大的抗氧化潜力。通过连续4周灌胃玉米须水提物,高尿酸血症小鼠体质量得到改善、SUA水平降低以及肾脏组织状态转好,其中玉米须水提物高剂量组（High Corn Silk Water Extract Group,HCS）小鼠SUA水平显著降低至726.26μmol/L(P<0.05),脏器指数改善（0.60%）,肾脏组织改善情况明显。因此,玉米须水提物具有较好的抗氧化和降尿酸活性,具有开发成为预防氧化损伤、高尿酸血症食品的市场潜力。     

流化床气流超微粉碎不同操作参数对玉米淀粉粒度的影响

目的 研究流化床气流超微粉碎不同操作参数对玉米淀粉颗粒粒度的影响。方法 以玉米淀粉为原料,通过流化床气流粉碎处理,考察原料不同含水量、不同粉碎气体压力、分级轮转速、持料量等参数条件下气流粉碎处理对淀粉颗粒粒径、粒度分布、比表面积、粉体密度及流动性的影响。结果 不同操作参数对淀粉颗粒粒度影响显著,在原料含水量6.18%,气体压力0.8 MPa、持料量1.0 kg、分级转速3600 r/min操作参数条件下获得微细化玉米淀粉粒径最小,中粒径D50为5.22μm,淀粉粒径大小显著降低,微细化玉米淀粉的粒度分布较窄且均匀,颗粒比表面积较原淀粉增大1.8倍,为0.65m²/g,颗粒球形度较好;粉碎降低了淀粉粉体密度,最佳条件下淀粉松装密度和振实密度分别为0.48 g/cm³和0.70 g/cm³,粉体流动性变差。结论 该研究为玉米淀粉资源的加工与应用提供了理论依据与技术支持。