Aqueous and enzymatic extraction processes for the production of food-grade proteins and industrial oil from dehulled yellow mustard flour

Aqueous extraction is an emerging alternative to hexane-based oilseed extraction since it eliminates the dangers associated with processing, and allows the simultaneous recovery of high-quality protein products and vegetable oils. Five different successive non-enzymatic and enzymatic aqueous extraction processes (AEPs/EAEPs) were developed for dehulled yellow mustard flour with the aim of producing food-grade protein and yellow mustard oil for industrial applications. The oil released in these processes was tied up in oil-in-water emulsions that must be destabilized to recover free oil prior to industrial utilization. This study endeavored to ascertain the extraction parameters that increase oil and protein extraction yields and reduce emulsion stability during successive AEPs/EAEPs for dehulled yellow mustard flour. The remarkable stability of the emulsions was due to the presence of protein emulsifiers of high molecular weight along with the mixed phospholipid–oleosin layer. pH adjustment for emulsion destabilization was relatively inefficient; therefore, enzymatic demulsification treatments with different proteases and phospholipases were evaluated for their ability to release free oil by hydrolyzing the targeted emulsifiers. Although protease treatments with Protex 6 L at a concentration of 2.5 wt.% were effective in recovering over 91% of the oil in the emulsions, phospholipase treatments did not modify the free oil recovery from the emulsions. The results indicated that the enzymatic aqueous extraction of dehulled yellow mustard flour did not offer sufficient improvement in usable protein recovery to warrant the extra effort and cost.     

Nb/HUSY as a highly active catalyst for the direct transformation of fructose to methyl lactate

One-pot conversion of biomass-based carbohydrates to methyl lactate (MLA), a versatile platform chemical for the production of food additives as well as the starting material of pharmaceutical industry, is an attractive green process. In this study, the Nb/HUSY catalysts with highly catalytic performance are successfully synthesized and used for the production of MLA from fructose. Remarkably, when using 2%Nb/HUSY as catalyst, the highest MLA yield of 56.1% is obtained with complete conversion of fructose under optimal conditions (140 °C for 6 h). The introduction of niobium into HUSY enhances the Lewis acid properties, which facilitates the stepwise process, involving the retro-aldol condensation and dehydration reactions. The as-prepared catalysts have shown promising potential for conversion of fructose to MLA and effectively inhibited the formation of by-products. More importantly, the catalyst exhibits superior stability and could be reused for at least four cycles.     

Experimental study on the formation of ultrafine particulate matters (PMs) during pulverized coal (PC) char combustion in O2/N2 and O2/CO2 atmospheres

Under the force of increasingly strict emission standard of particulate matters (PMs) and serious haze in China, further understanding of the formation of ultrafine PMs during coal combustion is crucial. In this work, the formation characteristics of ultrafine PMs during pulverized coal (PC) char combustion in O₂/N₂ and O₂/CO₂ atmospheres were investigated through a high-temperature drop tube furnace (DTF) with a two-stage dilution sampling system and a 14-stage electrical low pressure impactor (ELPI+). Results showed that in both number-based and mass-based particle size distribution (PSD) the peaks of ultrafine PMs located nearby 0.2 μm under all experimental atmospheres including O₂21%/N₂79%, O₂21%/CO₂79%, O₂27%/CO₂73% and O₂33%/CO₂67% (O21N79, O21C79, O27C73 and O33C67). And the peak values increased with the increase of O₂ concentration in O₂/CO₂ atmospheres because of the high char combustion temperature at elevated O₂ level. However, the mass and number concentration of ultrafine PMs in O₂/CO₂ atmospheres reduced significantly compared with these in O₂/N₂ atmosphere. When O21N79 atmosphere switched to O21C79, O27C73, O33C67 atmosphere, the mass concentration of ultrafine PMs reduced by 80.90%, 76.58% and 14.31%, and the number concentration reduced by 74.16%, 63.17% and 10.50%, respectively. Furthermore, the total mass of the ultrafine PMs was determined by the mass of the ultrafine PMs with larger particle size, whereas the total number of ultrafine PMs was determined by the number of the ultrafine PMs with smaller particle size. In this work, the ultrafine PMs with the aerodynamic size smaller than 0.3 μm were collected on the 1st to 7th impactor surfaces of the ELPI+. Among the ultrafine PMs, the particles on the 7th impactor (PMs with the superior limit of ultrafine PMs size) accounted for more than 94.8% of the total ultrafine PMs by mass, but less than 2.3% of the total ultrafine PMs by number; The particles deposited on the 1st impactor (PMs with the detectable minimum size of ultrafine PMs) accounted for more than 79.6% of the total ultrafine PMs by number, but less than 0.4% of the total ultrafine PMs by mass. In addition, PM_0.1 which accounted for 96% of the total number of the ultrafine PMs was analyzed for chemical composition by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Results showed that the prominent components of PM_0.1 were Ca, Na, and Si in both O₂/N₂ and O₂/CO₂ atmospheres. However, compared with O₂/N₂ atmosphere, Na, Si, Al, and Fe were more enriched in PM_0.1 in O₂/CO₂ atmospheres.     

Survey of trichothecene mycotoxins in grains and animal feed in Croatia by thin layer chromatography

Trichothecene mycotoxins are common contaminants of cereal grains and animal feed worldwide. The toxins are toxic to both human and animals. The objectives of this study were to determine the occurrence of trichothecenes in grains and animal feed in Croatia. Total of 465 samples were collected during the seven-year period (1998–2004) from manufactures and small holders farm storage facilities. The samples were analyzed by thin layer chromatography, which proved to be fast, reliable and inexpensive method. T-2 toxin, diacetoxyscirpenol and deoxynivalenol were detected in 16.8%, 27.6% and 41.2%, respectively. The amount of toxins ranged between 0.05 and 3.4 mg/kg. The majority of animal feed samples was poultry feed. Only small number of it contained T-2 toxin and diacetoxyscirpenol levels greater than the Croatian regulatory levels for poultry feed. Positive samples were in correlation with evidenced clinical symptoms of toxicosis in poultry. Since trichothecenes are frequently isolated from animal feed and grains in Croatia, they could have significant economic and safety implications in animal production.     

The properties of pellets from mixing bamboo and rice straw

Rice straw pellets are the main type of biomass solid fuel and have great potential as a bioenergy resource of the future in China. But it also showed important problems because of its high content of ashes and its low gross calorific value, reducing the possibility to be used in domestic heating. It was certified that mixing different types of biomass materials was helpful to improve the properties of pellets. To improve properties of rice straw pellets and investigate the effect of mixing bamboo and rice straw on the pellet properties, some properties of pellets, manufactured using different mixing ratio of bamboo and rice straw particles, were determined in this research. It can be concluded from this research that physical properties of all pellets meet the requirements of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified except for bulk density of pellets, manufactured using mixing ratio (≤3:2) of bamboo and rice straw. The inorganic ash and gross calorific value of rice straw pellets cannot meet the requirement of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified (8.0%) and the minimum requirement for making commercial pellets of DIN 51731 (>17,500 J/g). Both properties are improved through mixing bamboo particles and rice straw particles. It is significant that inorganic ash content and gross calorific value of pellets, manufactured using mixing ratio (≥3:2) of bamboo and rice straw, were lower than 8.0% and higher than 17,500 J/g, respectively. This also shows that mixing different biomass materials is an effective way to optimize properties of biomass solid fuel. All pellets after improvement are proposed as biomass solid fuel and have the potential to be developed as commercial pellets on an industrial scale in China.     

Porous structure and morphology of granular chars from flash and conventional pyrolysis of grape seeds

This work studies the influence of the operating conditions used in the pyrolysis of grape seeds on the morphology and textural properties of the chars resulting. Flash and conventional (283 K min⁻¹ heating rate) pyrolysis have been used within a wide range of temperature (300–1000 °C). The effect of a pretreatment for oil extraction has also been studied. The porous structure of the chars was characterized by adsorption of N₂ at 77 K, Ar at 77 K and 87 K, and CO₂ at 273 K and mercury intrusion porosimetry. The morphology was analyzed by scanning electron microscopy. All the materials prepared revealed an essentially microporous structure, with a poor or even negligible contribution of mesopores. Increasing pyrolysis temperature led to higher specific surface areas and lower pore size. The highest specific surface area values occurred within 700–800 °C, reaching up to 500 m² g⁻¹ with pore sizes in the 0.4–1.1 nm range. No significant morphological changes were observed upon carbonization so that the resulting chars were granular materials of similar size than the starting grape seeds. The hollow core structure of the chars, with most of the material allocated at the periphery of the granules can help to overcome the mass transfer limitations of most common (solid or massive) granular activated carbons. The chars showed a good mechanical strength during attrition tests. These chars can be potential candidates for the preparation of granular carbons molecular sieve or activated carbons raw materials.     

Absorption of nitrogen monoxide in aqueous solutions containing sulfite and transition-metal chelates such as Fe (II)-EDTA,Fe (II)-NTA,Co (II)-Trien and Co (II)-Treten

For wet denitrification processes nitrogen monoxide is the crucial component owing to its low water solubility. By addition of transition-metal complexes, able to form nitrosyls, the effective NO concentration in the liquid phase is enhanced. Kinetic (reaction orders and rate constants) as well as thermodynamic (stability constants) data for nitrosylation have been established. It has been found that Fe(II)-EDTA and Fe(II)-NTA react very fast to form stable NO complexes and are widely pH independent. The formation of Fe(III)-EDTA nitrosyl is found to be rapid, but the large deviation in the measured data prevents reliable evaluation. While the equilibrium constants of the Co(II)-trien and Co(II)-tetren nitrosyls are largely pH independent, the rate of formation is influenced markedly by pH. Each nitrosyl shows individual behavior towards sulfite. Fe(II)-EDTA and Fe(III)-EDTA exhibit the highest absorption capacities. The CO(II) polyamines convert the absorbed NO mainly to gaseous N₂O rather than to liquid-phase products.     

Screening and identification of a Bacillus amyloliquefaciens strain for aqueous enzymatic extraction of medium-chain triglycerides

A strain with a high yield of neutral proteinase and low yield of lipase, resistance to medium chain fatty acid triglycerides is the key to increasing yield and quality of Cinnamomum camphora seed kernel oil (CCSKO) with aqueous enzymatic extraction technology. A bacterial strain, NCU116 isolated from the waste residue produced in CCSKO production through primary screening with plate and secondary screening with shake-flask fermentation. It was found to be suitable for the extraction of CCSKO or other medium-chain triglycerides by using the extraction technology. Its activity of neutral proteinase was 4536.5 U/mL, and only 0.088 U/mL for lipase production. The strain was identified as Bacillus amyloliquefaciens by morphological, physiological, biochemical and 16S rDNA molecular identification. The extracellular enzymes produced by NCU116 included neutral proteinase, pectinase, glucoamylase, cellulase, amylase and lipase. The neutral proteinase had the maximum activity at 50 °C, but was unstable. Its optimum temperature and pH value were approximately 40 °C and 7.0 respectively. Mn²⁺ was an activator of neutral proteinase. The glucoamylase had the maximum activity at 45 °C, and was activated by Ca²⁺, Zn²⁺, Fe³⁺ and Mn²⁺. Its optimum temperatures and pH value were 45–50 °C and 6.0 respectively. The pectinase had the maximum activity at 40 °C, and was activated by Cu²⁺, Fe²⁺, Mn²⁺ and Ca²⁺. Its optimum temperatures and pH value were 35–40 °C and 7.0 respectively. The cellulase had the maximum activity at 35 °C, and was activated by Ca²⁺ and Mn²⁺. Its optimum temperatures and pH value were 30–40 °C and 7.0 respectively.     

Colorimetric ELISA based on glucose oxidase-regulated the color of acid–base indicator for sensitive detection of aflatoxin B1 in corn samples

This study described a sensitive direct competitive enzyme-linked immunosorbent assay (ELISA) for naked-eye detection of aflatoxin B₁ (AFB₁) by using glucose oxidase (GOx)-regulated bromocresol purple (BCP) color change. GOx was used as an alternative to horseradish peroxidase (HRP) for oxidization of glucose into hydrogen peroxide and gluconic acid. BCP, whose color is significantly sensitive to pH variation, was used as a signal output. Under optimal conditions, the developed method exhibited a considerably high sensitivity for AFB₁ detection with a cutoff limit of 100 pg/mL by the naked eye. The reliability of the developed colorimetric ELISA using naked-eye detection showed no false negative and false positive results among 70 AFB₁ spiked tests. Furthermore, the developed method showed a good linear range of 25–200 pg/mL for AFB₁ quantitative detection with a half-maximal inhibitory concentration at 66.72 pg/mL, which was approximately 10-fold lower than that of conventional HRP-based ELISA (IC₅₀ = 707 pg/mL). The recoveries from four kinds of AFB₁-spiked concentrations in corn extract solutions ranged within 80.56%–108.53%, with a coefficient of variation range of 1.69%–11.86%. These results exhibited good agreement with those of LC–MS/MS method indicating an acceptable accuracy and precision for AFB₁ quantitative detection in actual corn samples. In brief, this study was the first to use a GOx-mediated color change of BCP in immunoassay for naked-eye detection of AFB₁. This study also provided a new method for high-throughput screening detection of other small molecular chemicals using naked eye in resource-constrained countries.     

Different degrees of stone decay on the inner and outer walls of a Cloister

Avila is a city located on the Central Meseta of Spain whose climate follows a continental trend with strong daily fluctuations in temperature, that produce stresses in exposed materials owing to processes of dilation/contraction. Specially in heterogeneous materials such as granite. These stresses lead to microfissures and even surface sand formation (arenization) decay. The different degrees and types of decay observed in exposed and protected materials inside the Cathedral Cloister microenvironment in Avila are largely due to the above phenomena. In the present study, the environmental characteristics at three different points of the Cathedral are analyzed. One outside the building (E) and the other two inside it, at the Southern (I–S) and Northern (I–N) ends of its East gallery. At these points, the fluctuations in relative humidity and temperature were found to be very low, accounting for the lower degree of decay of the stone used to construct the building.