Bamboo biochar-catalytic degradation of lignin under microwave heating

Abstract

Lignin biochar-catalytic depolymerization using biochar Fe-600, Fe-800, Ni-600, Ni-800 catalysts under microwave-heating (180?°C for 30?min) was explored in an ethanol/formic acid (1:1) media. Non-catalyst depolymerization was also studied and compared with the biochar-catalysts results. Characteristics of the bio-char catalysts were analyze by BET, XRD, and FT-IR. GPC, FT-IR, and MALDI-TOF MS spectrometry were also used to characterize the depolymerization products. The experimental results showed that the S_BET, V_t, and V_mec and average pore diameter of the biochars are considerably dependent on the preparation temperature and type of cation (Ni²⁺ or Fe³⁺). The maximum yield of bio-oil product was obtained as 85?wt% with the addition of biochar Ni-600 and the total amount of oligomers or monomers with a molecular weight of 164 to 446 reaches 80.4%.     

Monitoring unit root and multiple structural changes: An information criterion approach

An information criterion-based model selection method is proposed for monitoring unit root and multiple structural changes. In this method, a battery of possible models is considered by changing the integration order (I(0) or I(1)) and the combinations of change points. Next, the best model is selected from among alternative models via a modified Bayesian information criterion (BIC). Accordingly, on the basis of the selected model, the process that generates the observed time series is determined. The BIC is modified in order to adjust the frequency count of incorrectly selecting stationary models via the conventional BIC. The simulation results of monitoring unit root and structural change suggest that the proposed method outperforms the conventional hypothesis testing method in terms of detection accuracy and detection speed. Furthermore, the empirical results suggest that the proposed method exhibits better performances with regard to detection stability and forecastability.     

Improving the economics of biodiesel production through the use of low value lipids as feedstocks: vegetable oil soapstock

Semirefined and refined vegetable oils are the predominant feedstocks for the production of biodiesel. However, their relatively high costs render the resulting fuels unable to compete with petroleum-derived fuel. We have investigated the production of fatty acid methyl esters (FAME; biodiesel) from soapstock (SS), a byproduct of edible oil refining that is substantially less expensive than edible-grade refined oils. Multiple approaches were taken in search of a route to the production of fatty acid methyl esters from soybean soapstock. The most effective method involved the complete saponification of the soapstock followed by acidulation using methods similar to those presently employed in industry. This resulted in an acid oil with a free fatty acid (FFA) content greater than 90%. These fatty acids were efficiently converted to methyl esters by acid-catalyzed esterification. The fatty acid composition of the resulting ester product reflected that of soy soapstock and was largely similar to that of soybean oil. Following a simple washing protocol, this preparation met the established specifications for biodiesel of the American Society for Testing and Materials. Engine emissions and performance during operation on soy soapstock biodiesel were comparable to those on biodiesel from soy oil. An economic analysis suggested that the production cost of soapstock biodiesel would be approximately US$ 0.41/l, a 25% reduction relative to the estimated cost of biodiesel produced from soy oil.     

The effect of high hydrostatic pressure on the microbiological quality and physical–chemical characteristics of Pumpkin (Cucurbita maxima Duch.) during refrigerated storage

Pumpkins were processed at high hydrostatic pressure (HHP) ranging from 350 to 550 MPa for 0.5 min to 30 min. Two different nonlinear mathematical models were compared to fit the inactivation kinetics. The second model consistently produced better fits to the inactivation data than the first model (Weibull model). According to the inactivation of microorganisms, pumpkin was subjected to 450 MPa/15 min and 550 MPa/10 min. The microbiological and physicochemical changes in pumpkin subjected to (HHP) and thermal-treated (854 °C/5 min) were compared during 4 °C storage. The total plate counts (TPC) treated with thermal processing, 450 MPa/15 min and 550 MPa/10 min were 5.12, 4.02 and 1.71 log₁₀ CFU/g, respectively on the 60th day. The growth of microorganisms caused the increase in ΔE, decrease in hardness in other treatments. Treatment of 550 MPa for 10 min had little effect on color during storage. There were no significant changes in the L^⁎, a^⁎ and b^⁎ values (p > 0.05). The hardness of pumpkin treated with 550 MPa/10 min decreased by 32.28% after 60 days. A greater retention of the original color, Vc and antioxidant capacity and increased total phenols were observed in 550 MPa/10 min-treated samples immediately after processing. During storage, color changed, Vc content, total phenols and the antioxidant activity were decreased. While the soluble solids content (SSC), sugars and pH value of pumpkin with HHP or thermal treatment did not show significant change immediately during 60-day storage. Based on these results, working at 550 MPa for 10 min ensures physicochemical and high standard of sanitation parameters in pumpkin.Industrial relevancePumpkin (Cucurbita maxima Duch.) is one of the popular vegetables, and fresh-cut pumpkin requires strict processing treatment and storage conditions to protect its quality. HHP is one promising novel non-thermal technique and is likely to replace thermal processes. A better knowledge of effects of storage temperature on the quality of HHP-treated pumpkin and its storage time prediction through microbiological quality and physical–chemical characteristics analysis of these changes is necessary. The available data would provide technical support for commercial application of the HHP technique in fresh-cut pumpkin processing.     

Rapid detection method for aflatoxin B1 in soybean sauce based on fluorescent microspheres probe

Soybean sauce, a Chinese traditional and daily condiment, is often contaminated by aflatoxin B₁. An extract-free immunochromatographic assay was proposed based on fluorescent microspheres probe for the' detection of aflatoxin B₁ in soybean sauce. The probe was prepared by coupling fluorescent microspheres with anti-aflatoxin B₁ antibody by the 1-ethyl-3(3-dimethylaminopropyl) carbodiimides hydrochloride-mediated method. The background from the soybean sauce sample on strip was eliminated because of the optical property of the probe. The sample without extracting procedure was directly detected by diluting with 10% methanol solution. The visible detection limit for the qualitative analysis of aflatoxin B₁ in the proposed method was 2.5 μg/L, which was lower than the maximum level of 5 μg/L set by the Chinese government. The results were well agreed with those obtained by liquid chromatography-mass spectrometry (LC-MS). The method showed satisfactory characteristics, such as rapid detection, easy operation, and high sensitivity, and can thus be applied for the large-scale and on-site screening of soybean sauce contaminated with aflatoxin B₁. To our knowledge, this report is the first one on the qualitative detection of aflatoxin B₁ in dark colored food samples directly by fluorescent microspheres probe-based immunochromatography.     

Influence of ultrasonic treatment on the structure and emulsifying properties of peanut protein isolate

Effects of ultrasonic treatment on emulsifying properties and structure of peanut protein isolate (PPI) were evaluated by analysis of particle size distribution, protein surface hydrophobicity, SDS-PAGE, circular dichroism spectra and environmental scanning electron microscopy. The emulsifying properties of the PPI were found to be improved by ultrasonic treatment. The mean particle size decreased from 474.7 nm to 255.8 nm while the molecular weight remained unaffected. The results of intrinsic fluorescence spectroscopy and surface hydrophobicity indicated that ultrasonic treatment induced tertiary structural changes of the proteins in PPI. Emulsifying activity index and emulsion stability index were found to be correlated fairly well with surface hydrophobicity (H₀) (r = 0.712 and r = 0.668, respectively).     

The effects of oil,egg and salt content on some physical properties of canned moinmoin

Samples of canned moinmoin were prepared containing different quantities of oil, egg and salt. A uniaxial compression test was carried out on these samples using an Instron UTM. Three measurements were taken from the force-deformation traces, i.e. rupture force (F_R), deformation to rupture (D_R) and stress at yield point (Y_S). Variations in the oil content significantly influenced the values of F_R and D_R obtained. Variations in egg content influenced the values of F_R and Y_S. The salt content had no significant influence on the three measurements. The conclusions were that an increase in oil content softened the moinmoin whereas an increase in egg content resulted in a firmer product.