Silver nanoparticles embedded in modified polyallylamine resin as efficient catalysts for alkyne–azide 1,3-dipolar cycloaddition in water

A silver nanoparticle composite based on modified polyallylamine has been synthesized by a simple chemical route and its catalytic activity has been tested for alkyne–azide cycloaddition reaction. This silver nanocomposite shows an excellent catalytic activity at 80 °C for the synthesis of 1,4-disubstituted 1,2,3-triazole by alkyne–azide cycloaddition. The solid silver nanocomposite catalyst was characterized by transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffractometry and thermogravimetric analysis. The developed catalyst is stable in air, easy to prepare and can be recovered easily and reused ten times without a significant decrease in activity.     

Influence of atmospheric pressure plasma jet on the structure of microcrystalline starch with different relative crystallinity

This study demonstrated the effect on microcrystalline starch (MS) with different relative crystallinity (RC) by atmospheric pressure plasma jet (APPJ) treatment for 1, 3, 5 or 7 min. The morphology of MS granules was destroyed according to Scanning electron microscopy (SEM) analysis. APPJ treatment did not change the crystalline type of MS, but obviously decreased the RC of MS. Short-range molecular order of MS was clearly decreased after APPJ treatment though the Fourier transform infrared (FTIR) and Raman spectroscopy. Notably, the effect of APPJ on crystalline and short-range order structure of MS was gradually increased with the increase of RC, which revealed that the crystalline region of MS might be destroyed by APPJ. Furthermore, the pH of MS was decreased while water binding capacity (WBC) and swelling volume (SV) of MS were increased. Therefore, the APPJ treatment could be used as an alternative physical technology for starch modification.     

Logistics cost analysis of rice straw pellets for feasible production capacity and spatial scale in heat utilization systems: A case study in Nanporo town,Hokkaido, Japan

Rice straw is a promising renewable energy source because it is abundantly available in Asia. This study conducted a case study of logistics cost analysis for rice straw pellets by considering all stages in the supply chain to define the main factors affecting the selling price of rice straw pellets: collection (job-commission or employment of part-time workers), transportation, storage (vinyl greenhouses or storage buildings with larger capacity), pelletizing, and delivery to users with biomass boilers. The selling price was found to be strongly dependent on the production capacity because the investment cost for the pellet production facility had a significant effect of economies of scale. A production capacity of larger than 1500 t y⁻¹ is required for rice straw pellets to compete with wood pellets and fossil fuels in the studied Japanese context if the subsidy rate for the investment is 50%, part-time workers conduct the collection, and rice straw is stored in the storage buildings. Our sensitivity analysis also showed an economically feasible spatial scale: for example, rice straw should be collected within a 20 km radius and the users should be within a 38 km radius when the production capacity is 1500 t y⁻¹. In addition, other critical factors related to the collection of rice straw from the paddy fields and transportation of rice straw rolls to storage were identified as planning factors to further reduce the total logistics cost of rice straw pellets.     

Estimating sensory properties of common beans (Phaseolus vulgaris L.) by near infrared spectroscopy

Near infrared spectroscopy (NIRS) has been widely used to determine food chemical composition and to a lesser extent to evaluate sensory properties. Because sample preparation is relatively simple, NIRS is especially useful in situations where many samples must be analysed, such as gene-bank characterization or breeding. We aimed to assess the feasibility of using NIRS to predict aroma, flavour, mealiness, seed-coat perception, seed-coat brightness, and seed-coat roughness in common beans. Spectra of raw, undried cooked and dried cooked common bean seeds of 55 accessions were registered. Partial least squares (PLS) regression equations were developed between spectra absorbance and sensory properties scored by eleven trained panellists. Spectra registered on dried cooked samples generally yielded the best predictions. The relative ability of prediction (RAP) values were greater than 0.8 for flavour and mealiness and between 0.5 and 0.7 for seed-coat roughness and brightness. However, a suitable model to estimate the seed-coat perception was not found. These results make it possible to screen for samples that are close to the target sensory properties and thus substantially reduce the number of panel sessions needed for gene-bank evaluation or breeding.     

Acquisition of amino acids by Lactobacillus delbrueckii subsp. bulgaricus 2038 when grown in the presence of casein

The acquisition of amino acids by Lactobacillus delbrueckii subsp. bulgaricus 2038 (Lb. bulgaricus 2038) when grown in the presence of bovine casein, the major protein in bovine milk, was investigated by examining the expression of genes related to proteolysis and amino acid biosynthesis. To support the growth on bovine casein, Lb. bulgaricus 2038 has to synthesise five kinds of amino acids de novo, as proteolysis from casein does not provide these. The incomplete hydrolysis in combination with amino acids biosynthesis may explain the slow growth of Lb. bulgaricus 2038 in a casein environment. Meanwhile, it was determined that Lb. bulgaricus 2038 uses different intracellular peptidases when grown in casein or whey medium, and initially yields the important amino acid glutamate from the C-terminal or N-terminal end of peptides imported into the cell.     

Production of phage free cheese whey: Design of a tubular laboratory membrane filtration system and assessment of a feasibility study

An interposed “phage filtration” process step is proposed prior to subsequent processing of cheese whey to whey products to reduce fermentation risks due to phage contamination. At laboratory scale, the characteristics of three single tube ceramic membranes on the filtration performance in terms of phage retention, protein transmission and filtrate flux were analysed. From these tested membranes, a 0.1 μm microfiltration membrane was found to be suitable for significant phage reduction (3.4 log units) in cheese whey, simultaneously allowing total protein transmission of 56.2%. The experiments within the designed feasibility study conducted with a pilot plant microfiltration system provided a higher phage retention (4.1 log units) and a significantly increased transmission of major whey proteins (up to 84%) in comparison with the laboratory plant. The results shown in this study can easily be adapted by the dairy industry for better phage control and enhanced process safety.     

Development of an immobilization system for in situ micronutrients release

An immobilization system constituted by coated microcapsules was developed aiming at immobilizing probiotic bacteria capable of producing folate and release it in a sustained manner into the intestine. Despite no probiotic folate-producers have been immobilized so far, the system has been developed with this goal and this work reports its stability and ability to release folate under gastro-intestinal conditions.Microcapsules were made of alginate with three consecutive coatings of poly-l-lysine, sodium alginate and chitosan. Turbidity experiments showed a strong electrostatic interaction between these polymers. Fourier transform infrared spectroscopy (FTIR) and confocal analysis showed the stability of the coating materials when applied on the microcapsules, even after they were immersed in solutions simulating conditions in the stomach and small intestine (i.e. pH 2, 60 min and pH 7.2, 120 min, respectively). Coated microcapsules have an average diameter size ranged from 20 and 40 μm, and swelled upon exposure to a neutral medium, without dissolution as showed by microscopy analyses. Release experiments proved the ability of the coated microcapsules to release folic acid, at different rates, depending on the applied coating. Release experiments showed that the first coating (Ɛ-PLL) is characterized by Fickian diffusion as the main release mechanism of folic acid. Fickian rate constant (k_F) decreased with the number of consequent coatings, reflecting the decrease of predominance of Fick's behavior. Results showed that the developed coated microcapsules have suitable characteristics for encapsulation of folic acid aiming in situ release in the intestine.     

Biohydrogen by Rhodobacter sphaeroides during photo-fermentation: Mixed vs. sole carbon sources enhance bacterial growth and H2 production

Mixed carbon sources fermentation by bacteria is a promising approach for biohydrogen (H₂) production biotechnology. In the present study, growth and Н₂ production by purple bacteria Rhodobacter sphaeroides MDC6521 during mixed carbon sources (succinate + acetate, succinate + malate, and malate + acetate) photo-fermentation was investigated. The growth rate of bacteria in mixed carbon sources containing medium was of ∼0.33 h⁻¹ which was considerably higher (1.3–1.7-fold) compared with sole carbon substrate containing one. Moreover, the H₂ production during photo-fermentation of succinate and acetate mixture was of ∼6.5 mmol H₂ g⁻¹ (dry weight of biomass) and significantly more (∼2–3-fold) than that with appropriate sole sources and higher (1.5-fold) than that with succinate and malate mixture. Probably, supplementation of the mixed carbon sources into bacterial culture alters the mode of metabolism, resulting in enhanced H₂ production, thus they can be preferable compared to the sole carbon source. The changed F_OF₁-ATPase activity of membrane vesicles suggested its important role in the increase of Н₂ production efficiency. The results showed that mixed carbon sources provide more H₂ than the sole carbon substrates and succinate with acetate mixture is better than succinate with malate.     

Facial synthesis of dandelion-like g-C3N4/Ag with high performance of photocatalytic hydrogen production

Nowadays, energy shortage is one of the major problems in the world. Photocatalytic hydrogen production is a new type of energy technology with good application prospect. As a new type of photocatalytic semiconductor material, g-C₃N₄ has attracted much attention as a photocatalyst. By ultrasonic treatment of a mixed solution of g-C₃N₄ and bovine serum albumin, followed by adding a certain amount of silver nitrate solution and then directly hydrothermal treatment, a special dandelion-like g-C₃N₄/Ag (D-g-C₃N₄/Ag) was prepared. The scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction, Fourier transform infrared, fluorescence and physicochemical adsorption methods were used to characterize the morphology and structure of D-g-C₃N₄/Ag. In addition, the photocatalytic H₂ production of D-g-C₃N₄/Ag with different Ag loadings or in different sacrificial agents and different pH conditions were investigated. The results indicated that when triethanolamine was used as sacrificial agent, photocatalytic hydrogen efficiency was the best, and the rate of photocatalytic hydrogen production reached 862 μmol g⁻¹ h^{− 1} as the Ag loading was 4%.