Higher Activity Values Research Articles

Evaluation of the in vitro biological activity of protein hydrolysates of the edible red alga, Palmaria palmata (dulse) harvested from the Gaspe coast and cultivated in tanks

The in vitro antioxidant activity and angiotensin-converting enzyme (ACE) inhibition potential of protein extracts of Palmaria palmata (dulse) red seaweed from the Gaspe coast (QC, Canada) were investigated. The effects of the algae geographical origin and cultivation conditions were also studied. The highest activity values were displayed by <10 kDa protein fraction hydrolyzed by chymotrypsin (HF) at concentrations as low as 0.1 to 5 mg mL−1. Algae harvested in Pabos (QC, Canada) were more biologically active than algae from Newport (QC, Canada), demonstrating, respectively, 67.74 ± 3.9 % and 49.10 ± 10.9 % ACE inhibition at a concentration of 5 mg mL−1. Algae collected in Newport, cultivated in tanks with or without nutrients (NC+, NC−), scored higher biological activity than algae grown in Newport (N) waters. The <10 kDa HF obtained from the algae batch NC+ demonstrated, through an oxygen radical absorbance capacity assay, the highest antioxidant value: 440.73 ± 43.21 μmol trolox equivalents g−1 at 0.4 mg mL−1. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with database searches, protein precursors such as protein ribulose-1,5-biphosphate carboxylase/oxygenase (RuBiSCo) enzyme, allophycocyanins and phycocyanins, were identified in <10 kDa HF (P, N, NC−, NC+). Results show that protein hydrolysates from P. palmata demonstrate a high potential as healthy and functional ingredients and identified proteins could be targeted for crop improvement.

An exploratory study on the influence of orange juice on gut microbiota using a dynamic colonic model

The aim of this research was to evaluate the influence of fresh orange juice (FOJ) and pasteurized orange juice (POJ) on gut microbiota using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) in a long-term experiment. SHIME® vessels were used to investigate orange juice fermentation throughout the colon and to assess changes in microbial composition and fermentation metabolites (short-chain fatty acids, or — SCFA, and ammonium). Antioxidant activity of the SHIME® vessels and juice was also evaluated. The FOJ increased (p≤0.05) Lactobacillus spp., Enterococcus spp., Bifidobacterium spp., and Clostridium spp. and reduced (p≤0.05) enterobacteria. The POJ increased (p≤0.05) Lactobacillus spp. and reduced (p≤0.05) enterobacteria. The PCR-DGGE analysis showed a reduction in total bacteria population richness values. The FOJ and POJ increased (p≤0.05) butyric, acetic, and propionic acid concentrations, whereas ammonium production was reduced. High values of antioxidant activity were observed as a result of the FOJ and POJ treatments. Principal component analysis indicated that both POJ and FOJ juices had a positive influence on gut microbiota. The FOJ and POJ were found to exhibit selective prebiotic activity, particularly in terms of gut microbiota. This finding is in agreement with increases in both SCFAs and commensal bacteria, as well as with decreases in ammonium levels, though total bacteria richness values were reduced.

Catalysts based on large size-controlled Pd nanoparticles for aqueous-phase hydrodechlorination

This work is aimed at evaluating the catalytic performance of Pd/C catalysts based on size-controlled nanoparticles (mean size 10–50nm). Carbon black was used as support and the catalysts were tested in the aqueous phase hydrodechlorination of 4-chlorophenol. The Pd precursor was reduced with a methanol/water (10%vol.) mixture in the presence of PVP (PVP/Pd molar ratio 5–35) as capping agent. The performances of unsupported Pd–PVP colloidal nanoparticle and the catalysts prepared by impregnation of them on the carbon black (ex-situ synthesis), reduction of the precursor in the presence of that support (in-situ synthesis) and wetness impregnation were compared. The ex-situ preparation with less content of PVP (PVP/Pd molar ratio of 5) boosted the activity of the Pd–PVP nanoparticles from 16.8 to 167mmolgPd−1min−1 showing the role of the support in enhancing the catalytic performance. The in-situ synthesis with less content of PVP (PVP/Pd molar ratio of 5) resulted in catalysts with lower activity than that prepared by ex-situ synthesis, although they exhibited higher ability to hydrogenate phenol to cyclohexanone and cyclohexanol, which can be related to the morphology of the nanoparticles synthesized. Regardless of the type of synthesis, as PVP dose in synthesis increased, activity and selectivity to hydrogenation products decreased. High activity values were obtained (20–167mmolgPd−1min−1) taking into account the high mean size of the Pd nanoparticles in the catalysts.

Fermented products of India and its implication: A review

The diversity of Indian fermented food and its significance as a potential source of lactic acid bacteria (LAB). Fermented foods in India are categorized based upon their base material. Fermented foods such as Dahi, Idli, Dosa, Gundruk, Sinki etc. As India’s population increases, lactic acid fermentation is expected to become an important role in preserving fresh vegetables, fruits, and other food items for feeding people. Among the food items, milk, fruits and vegetables are easily perishable due to their high water activity and nutritive values. These are more critical in our country which favors the growth of spoilage causing microorganisms. Lactic acid fermentation increases shelf life of fruits and vegetables and also enhances several beneficial properties, including an increase in nutritive value and flavors, reducing cooking time, and reduces toxicity. As a whole, the traditional fermented milk, fruits and vegetables not only serve as food supplements but also attribute towards health benefits. The objective of this review is to describe important fermented products of India and their significance.

Assessment of Radioactive Concentrations in the Egyptian Natural Gas Grid and Their Relevant Impacts

The radioactivity concentrations of 226Ra, 232Th and 40K in thirty samples representing the technically Naturally Occurring Radioactive Materials (NORM) in the Egyptian natural gas were investigated. The investigations were performed using a gamma ray spectroscopy technique. The obtained data were used to establish a data base for NORM concentrations during the different processing stages of natural gas and to estimate the associated radiation health hazard impacts. Great concern has been devoted to determine the specific activity of 210Pb as it represents all daughters originating from 222Rn that have relatively short half-lives. The samples were collected from the gas pipeline grid covering different areas in Egypt. Fifteen samples were taken from the gas pipelines, whereas the remaining samples were taken from the upstream facilities before pumping into the grid. The average activity concentrations of 226Ra, 232Th and 40k were found to be 16.2 ± 1.5, 10.50 ± 0.9 and 98.46 ± 6.03 Bq/kg for filter samples respectively. The corresponding average values for scale samples were 37.28 ± 3.1, 45.7 ± 2.6 and 621.79 ± 9.2 Bq/kg. The sludge samples gave average values of 14.97 ± 1.94, 9.99 ± 1.48 and 112.82 ± 5.82 respectively. These values are below the recommended international limits. In contrary, the average values of activity concentrations of waste water were found to be 4.895 ± 0.51, 2.241 ± 0.3 and 31.852 ± 2.31 Bq/kg respectively. The obtained results indicate that 226Ra content is higher than the recommended values for domestic or drinking water. Additionally, high values of the specific activity of 210Pb were found in both deposits and filter samples.

Biochemical characterization of solvent, salt, surfactant and oxidizing agent tolerant proteases from Aspergillus niger produced in different agroindustrial wastes

Abstract Proteases produced by Aspergillus niger LBA 02 under solid state fermentation using different agroindustrial wastes had their enzyme activities tested in the presence of organic solvents, NaCl, surfactants and oxidizing agents. The results showed that according to the fermentation substrate, the microorganism was able to secrete proteases with different biochemical characteristics. When wheat bran was used as the substrate, the proteases showed the highest relative activity in 50% (v/v) petroleum ether, reaching 114.3%, while the proteases produced in soybean meal and cottonseed meal presented 94.7% and 106.1%, respectively. These enzymes also presented high relative activity values in 50% (v/v) chloroform, retaining up to 85% of their initial protease activities after 3 h at 37 °C. When surfactants and oxidizing agents were tested, the proteases produced in soybean meal proved to have remarkable and the highest activity followed by the proteases produced in wheat bran and cottonseed meal. Since the protease produced in wheat bran showed considerable tolerance at high concentrations of NaCl, with relative activity of 61.1% at 15% NaCl (w/v), while the proteases produced in soybean meal and cottonseed meal retained 48.7% and 46.3% of their initial activities, respectively. This work provides an interesting approach about the modulation of biochemical properties of enzymes in response to different substrates, what can be used for obtaining proteases with specific applications.

Antioxidant and ACE Inhibitory Bioactive Peptides Purified from Egg Yolk Proteins.

Protein by-products from the extraction of lecithin from egg yolk can be converted into value-added products, such as bioactive hydrolysates and peptides that have potential health enhancing antioxidant, and antihypertensive properties. In this study, the antioxidant and angiotensin converting enzyme (ACE) inhibitory activities of peptides isolated and purified from egg yolk protein were investigated. Defatted egg yolk was hydrolyzed using pepsin and pancreatin and sequentially fractionated by ultrafiltration, followed by gel filtration to produce egg yolk gel filtration fractions (EYGF). Of these, two fractions, EYGF-23 and EYGF-33, effectively inhibited the peroxides and thiobarbituric acid reactive substance (TBARS) in an oxidizing linoleic acid model system. The antioxidant mechanism involved superoxide anion and hydroxyl radicals scavenging and ferrous chelation. The presence of hydrophobic amino acids such as tyrosine (Y) and tryptophan (W), in sequences identified by LC-MS as WYGPD (EYGF-23) and KLSDW (EYGF-33), contributed to the antioxidant activity and were not significantly different from the synthetic BHA antioxidant. A third fraction (EYGF-56) was also purified from egg yolk protein by gel filtration and exhibited high ACE inhibitory activity (69%) and IC50 value (3.35 mg/mL). The SDNRNQGY peptide (10 mg/mL) had ACE inhibitory activity, which was not significantly different from that of the positive control captopril (0.5 mg/mL). In addition, YPSPV in (EYGF-33) (10 mg/mL) had higher ACE inhibitory activity compared with captopril. These findings indicated a substantial potential for producing valuable peptides with antioxidant and ACE inhibitory activity from egg yolk.

Comparison of Essential Oils Obtained from Different Extraction Techniques as an Aid in Identifying Aroma Significant Compounds of Nutmeg (Myristica Fragrans)

Distribution of volatile constituents in the essential oil of nutmeg obtained by simultaneous distillation extraction (SDE), high vacuum distillation (HVD) and super critical fluid extraction (SFE) was compared with reduced pressure distillation (RPD) and head space (HS) analysis. HS and RPD volatiles were characterized by a high content of sabinene, followed by α-pinene and β-pinene. Interestingly, unlike the SDE, HVD and SFE oils, distillates from HS and RPD were marked by the absence of phenolic ethers namely myristicin, elemicin and safrole. The HS and RPD volatiles possessed a pleasant nutmeg aroma indicating a significant role of terpenic constituents in contributing to the top aroma note. GC-olfactometry (GC-O) of the oils aided in establishing the role of sabinene, α-pinene and β-pinene in contributing to the distinctive note of the spice. A high odor activity value (OAV) of sabinene and α-pinene established the role of these two constituents in imparting the characteristic nutmeg odor.

Re-Examination of the Particle Size Effect on the ORR for Nafion-Free Ultrathin Uniform Pt/C Catalyst Layers

The so-called ‘particle size effect’ for the oxygen reduction reaction on platinum based catalysts has been debated since the 1960’s and extensively studied in phosphoric, sulfuric and perchloric acid electrolytes. Most literature report an increase in specific activity (SA) corresponding to an increase in particle size, giving rise to a peak mass activity (MA) at 2­–4 nm,1–4 while some groups have not found evidence supporting the particle size effect.5,6 Researchers have attempted to correlate the particle size effect with the following properties: i) oxide coverage—smaller particles are more oxophilic,7 ii) geometric effect—fraction of terrace/step sites that have different sensitivity to anion adsorption from electrolyte and oxide species,8 iii) surface electronic effects—potential of total zero charge (pztc),4 and, iv) electronic effects—d-band vacancy/position of d-band center.9,10 Nesselberger et al.11 reported a linear dependence of MA for particle sizes >~2 nm that departed from the typical peak observed by others. They attributed the discrepancy to the inconsistent application of iR and background corrections to the raw I-V data in the literature. Our previous studies12,13 have identified several artifacts that can influence the measured ORR activity and observed particle size effect in 0.1 M HClO4 in TF-RDE. They include: i) anion adsorption/blocking by Nafion ionomer incorporated in Pt/C catalyst films (but not for poly-Pt), ii) film thickness and uniformity—O2 diffusion within the catalyst film, iii) ORR activity measurement protocols, and, iv) impurity levels in the electrochemical system. We reported SA and MA for Pt/HSC and Pt/V using Nafion-free ultrathin uniform films fabricated using advanced techniques to be ~2.8x higher than that reported in the literature using conventional methods. The SA (0.9–1.1­ mA/cm2 Pt) for 2–4 nm Pt/C approaches 30–40% the SA of poly-Pt; these high activity values would certainly be expected to alter the particle size effect profile and provided the impetus for this work. We conducted activity measurements for various catalysts having average Pt particle size in the range 2 nm to bulk poly-Pt. Our results indicate a much steeper increase in SA with particle size in the range 2–6 nm followed by a shallow increase for larger particles. We observe a MA peak around 3 nm and a profile that is in agreement with the theoretical model reported by Tritsaris et al.14 who attribute the effect to the proportion of terrace/step sites on particles with varying size. Reference 1. L. J. Bregoli, Electrochim. Acta, 23, 489 (1978). 2. M. Peuckert, T. Yoneda, R. A. Dalla Betta, and M. Boudart, J. Electrochem. Soc., 133, 944 (1986). 3. H. A. Gasteiger, S. S. Kocha, B. Sompalli, and F. T. Wagner, Appl. Catal. B Environ., 56, 9 (2005). 4. K. J. J. Mayrhofer, D. Strmcnik, B. B. Blizanac, V. Stamenkovic, M. Arenz, and N. M. Markovic, Electrochim. Acta, 53, 3181 (2008). 5. J. Bett, J. Lundquist, E. Washington, and P. Stonehart, Electrochim. Acta, 18, 343 (1973). 6. H. Yano, E. Higuchi, H. Uchida, and M. Watanabe, J. Phys. Chem. B, 110, 16544 (2006). 7. Y. Takasu, N. Ohashi, X.-G. Zhang, Y. Murakami, H. Minagawa, S. Sato, and K. Yahikozawa, Electrochim. Acta, 41, 2595 (1996). 8. K. Kinoshita, J. Electrochem. Soc., 137, 845 (1990). 9. S. Mukerjee and J. McBreen, J. Electroanal. Chem., 448, 163 (1998). 10. E. Toyoda, R. Jinnouchi, T. Hatanaka, Y. Morimoto, K. Mitsuhara, A. Visikovskiy, and Y. Kido, J. Phys. Chem. C, 115, 21236 (2011). 11. M. Nesselberger, S. Ashton, J. C. Meier, I. Katsounaros, K. J. J. Mayrhofer, and M. Arenz, J. Am. Chem. Soc., 133, 17428 (2011). 12. S. S. Kocha, J. W. Zack, S. M. Alia, K. C. Neyerlin, and B. S. Pivovar, ECS Trans., 50, 1475 (2012). 13. K. Shinozaki, B. S. Pivovar, and S. S. Kocha, ECS Trans., 58, 15 (2013). 14. G. A. Tritsaris, J. Greeley, J. Rossmeisl, and J. K. Nørskov, Catal. Letters, 141, 909 (2011).

Improving the Thermostability and Activity of a Thermophilic Subtilase by Incorporating Structural Elements of Its Psychrophilic Counterpart.

The incorporation of the structural elements of thermostable enzymes into their less stable counterparts is generally used to improve enzyme thermostability. However, the process of engineering enzymes with both high thermostability and high activity remains an important challenge. Here, we report that the thermostability and activity of a thermophilic subtilase were simultaneously improved by incorporating structural elements of a psychrophilic subtilase. There were 64 variable regions/residues (VRs) in the alignment of the thermophilic WF146 protease, mesophilic sphericase, and psychrophilic S41. The WF146 protease was subjected to systematic mutagenesis, in which each of its VRs was replaced with those from S41 and sphericase. After successive rounds of combination and screening, we constructed the variant PBL5X with eight amino acid residues from S41. The half-life of PBL5X at 85°C (57.1 min) was approximately 9-fold longer than that of the wild-type (WT) WF146 protease (6.3 min). The substitutions also led to an increase in the apparent thermal denaturation midpoint temperature (Tm) of the enzyme by 5.5°C, as determined by differential scanning calorimetry. Compared to the WT, PBL5X exhibited high caseinolytic activity (25 to 95°C) and high values of Km and kcat (25 to 80°C). Our study may provide a rational basis for developing highly stable and active enzymes, which are highly desired in industrial applications.

Characteristics and Metallurgical Effects of Medium Basicity Refining Slag on Low Melting Temperature Inclusions

Recently, large sized CaO-Al2 O3 inclusions with low melting temperature have been the main reason for lowering mechanical properties of high strength low alloy (HSLA) steel plates. New philosophy, i. e. refining by top slag with relatively low basicity and Al2 O3 content, was proposed to control such kind of inclusions. Firstly, the characteristics of refining slag, such as component activities and sulphide capacity (Cs) of CaO-A12O3-SiO2-MgO slag, were studied through thermodynamic calculation. Then, slag-metal equilibrium experiments were carried out in laboratory to investigate the exact chemical composition of refining slag together with thermodynamic analysis. Finally, industrial trials were done to verify the desulphurization ability and inclusions control in steel refined by the new slag. Thermodynamic calculations indicated that the slags with basicity of 3. 5 and Al2 O3 content of 20% and basicity of 5.0 and A12O3 content of 20% or 25% have high values of CaO activity, sulphide capacity and ratio of MgO activity to Al2 O3 activity. Laboratory equilibrium experiments showed that the slag with basicity of about 4. 5 and Al2 O3 content of about 20% is helpful for increasing the melting temperature of inclusions in steel. After introducing such kind of refining slag in industrial trials, the sulphur content in eight heats of steel is below 20 × 10−6, which meets the requirement of HSLA steel, and most inclusions distribute in relatively high melting zone (±1773 K) of CaO-Al2O3-MgO(-SiO2) quasi-ternary diagram. New philosophy of top refining slag is feasible to control low melting point inclusions of CaO-Al2O3 system in HSLA steel.

Shelf life, physicochemical, microbiological and antioxidant properties of purple cactus pear (Opuntia ficus indica) juice after thermoultrasound treatment

The objective of this study was to evaluate changes in color, betalain content, browning index, viscosity, physical stability, microbiological growth, antioxidant content and antioxidant activity of purple cactus pear juice during storage after thermoultrasonication at 80% amplitude level for 15 and 25min in comparison with pasteurized juice. Thermoultrasound treatment for 25min increased color stability and viscosity compared to treatment for 15min (6.83 and 6.72MPa, respectively), but this last parameter was significantly lower (p<0.05) compared to the control and pasteurized juices (22.47 and 26.32MPa, respectively). Experimental treatment reduced significantly (p<0.05) sediment solids in juices. Total plate counts decreased from the first day of storage exhibiting values of 1.38 and 1.43logCFU/mL, for 15 and 25min treatment, respectively. Compared to the control, both treatments reduced enterobacteria counts (1.54logCFU/mL), and compared to pasteurized juice decreased pectinmethylesterase activity (3.76 and 3.82UPE/mL), maintained high values of ascorbic acid (252.05 and 257.18mg AA/L) and antioxidant activity (by ABTS: 124.8 and 115.6mg VCEAC/100mL; and DPPH: 3114.2 and 2757.1μmol TE/L). During storage thermoultrasonicated juices had a minimum increase in pectinmethylesterase activity (from day 14), and exhibited similar total plate counts to pasteurized juice. An increase of phenolic content was observed after 14days of storage, particularly for treatment at 80%, 25min, and an increase in antioxidant activity (ABTS, DPPH) by the end of storage.

Immobilization of Pseudomonas fluorescens lipase on hydrophobic supports and application in biodiesel synthesis by transesterification of vegetable oils in solvent-free systems.

This work describes the preparation of biocatalysts for ethanolysis of soybean and babassu oils in solvent-free systems. Polystyrene, Amberlite (XAD-7HP), and octyl-silica were tested as supports for the immobilization of Pseudomonas fluorescens lipase (PFL). The use of octyl-silica resulted in a biocatalyst with high values of hydrolytic activity (650.0±15.5IU/g), immobilization yield (91.3±0.3%), and recovered activity (82.1±1.5%). PFL immobilized on octyl-silica was around 12-fold more stable than soluble PFL, at 45°C and pH 8.0, in the presence of ethanol at 36% (v/v). The biocatalyst provided high vegetable oil transesterification yields of around 97.5% after 24h of reaction using babassu oil and around 80% after 48h of reaction using soybean oil. The PFL-octyl-silica biocatalyst retained around 90% of its initial activity after five cycles of transesterification of soybean oil. Octyl-silica is a promising support that can be used to immobilize PFL for subsequent application in biodiesel synthesis.

Isolation and Screening of Filamentous Fungi Producing Extracellular Lipase with Potential in Biodiesel Production

Nineteen fungal strains were isolated from a chicken slaughterhouse effluent and within those, only one showed high values of lipolytic activity in submerged cultures. This fungus was identified as Trametes hirsuta. The crude extract was immobilized in chitosan/clay beads, with an immobilization yield of 80.9%. The analyses of the crude extract and the immobilized derivative at different temperatures, pH (s), solvents, metallic ions and storage showed that the immobilization process increased the enzyme life span. Ethyl esters were obtained in solvent free systems using chicken viscera oil and the enzyme crude extract. For effective comparison, a reaction using viscera oil and commercial lipase Novozym 435 was carried out. The result revealed 35% and 28% esters conversion in the reactions containing chicken viscera oil, using Novozym 435 and the crude extract respectively. The extract was also used in a reaction with soybean oil, traditionally used as starting substrate for biodiesel production.

Aroma of Wheat Bread Crumb

Bread aroma is an important parameter for bread quality and this review aims to provide an overview of aroma compounds identified in bread crumb and how these compounds are formed. More than 150 volatile compounds were identified in bread crumb and they mainly originate from the fermentative activity of yeast, from oxidation of flour lipids and to a lower extend from Maillard reactions. Of those volatile compounds, 45 compounds can be characterized as aroma compounds, as they most likely can be sensed when the bread is eaten due to high odor activity values and flavor dilution factors. The influence of ingredients and mixing conditions on bread aroma has only been scarcely investigated. The fermentation conditions; yeast level and strain as well as fermentation temperature and time were found to significantly influence the aroma of bread crumb. Yeast level and strain mainly influence formation of compounds directly related to the fermentative activity of yeast, while fermentation temperature and time also influence formation of compounds from oxidation of flour lipids.

Evaluation of the Key Odorants in Volatile Oils from Tubers of Apios americana Medikus.

This study was investigated the chemical composition of volatile oils and aroma evaluation from the tubers of Apios americana Medikus. Theses volatile oils were obtained by the hydrodistillation (HD) and the solvent-assisted flavor evaporation (SAFE) methods. These oils were analyzed by Gas chromatography (GC), GC-mass spectrometry (GC-MS), GC-olfactometry (GC-O), aroma extract dilution analysis (AEDA) and odor activity values (OAV) for the first time. The major compounds in the HD oil were palmitic acid (36.5%), linoleic acid (10.5%) and nonadecanol (5.7%). Meanwhile, in the SAFE oil, the major compounds were 4-hydroxy-4-methyl-2-pentanone (34.2%), hexanal (11.0%) and hexanol (7.9%). Through aroma evaluation, 20 (HD) and 14 (SAFE) aroma-active compounds were identified by GC-O. As a result, the most intense aroma-active compounds in both extraction methods were 1-octen-3-ol and hexanal, both of which showed high odor activity values (OAV).

Changes in the profile of volatiles of canned coconut milk during storage.

The alteration of the profile of volatiles of canned coconut milk was monitored during storage at ambient temperature. Canned coconut milk was thermally processed (121 °C for 5 min), and then stored at ambient temperature (32 to 35 °C) for 6 mo. Volatile compounds were assessed monthly using direct solvent extraction (diethyl ether), followed by high-vacuum distillation and gas chromatography-mass spectrometry analysis. Six groups of compounds consisting of alcohols, aldehydes, ketones, acids, esters, lactones, and others were identified. Two stages of major changes in profile of volatiles were observed. The 1st occurred after 2 mo as indicated by a high abundance of alcohols, acids, and lactones. The 2nd was observed after 5 mo and corresponded to a large increase in lactones, short-chain free fatty acids, 3-methyl-2(5H)-furanone, and phenol. Acetic and butyric acids observed after 5 mo could contribute to the potential of off-odor development in the product as indicated by their high odor activity values. Lactones increased approximately 10-fold. Identification of 3-methyl-2(5H)-furanone indicated that Maillard reaction had occurred in conjunction with the development of a coconut, toffee-like, and caramel odor.

Caracterización bioquímica de AmiJ33, una amilasa de Bacillus amyloliquefaciens aislada de suelos cultivados con caña de azúcar en la región del Papaloapan

La amilasa (E.C. 3.2.1.1) de Bacillus amyloliquefaciens JJC33M (AmiJ33) fue producida por fermentación sumergida. Se probó el efecto de peptona, extracto de levadura, Ca+2 y glicina en la producción de AmiJ33. El extracto de levadura y Ca+2 tuvieron un efecto positivo sobre la síntesis de AmiJ33. La enzima fue recuperada mediante precipitación a saturación al 60% con (NH4)2SO4. El peso molecular aproximado de la enzima purificada fue de 50 kDa. Así mismo, se evaluó el efecto del pH y la temperatura sobre la actividad enzimática, concluyendo que los valores más altos de actividad se observaron a pH 6.0 y 80°C, respectivamente. En condiciones ligeramente ácidas (pH 4.0 y 5.0), AmiJ33 mantuvo el 72% de su actividad. AmiJ33 fue estable por 3 h a 40°C, y por 30 min a 45 y 50°C, conservando el 88 y 82% de actividad residual. A 60°C, la actividad disminuyó 40%. La actividad de AmiJ33 se incrementó 50.27% con b-mercaptoetanol, no fue inhibida por EDTA y se inhibió totalmente con SDS

Cobalt(II) and Manganese(II) Complexes of Novel Schiff Bases, Synthesis, Charcterization, and Thermal, Antimicrobial, Electronic, and Catalytic Features

Carbazoles containing two new Schiff bases (Z,Z)-N,N′-bis[(9-ethyl-9H-carbazole-3-yl)methylene]propane-1,3 diamine (L1) and (Z,Z)-N,N′-bis[(9-ethyl-9H-carbazole-3-yl)methylene]-2,2-dimethylpropane-1,3-diamine (L2) and their Co(II) and Mn(II) complexes were synthesized and characterized using various spectroscopic methods and thermal analysis, which gave high thermal stability results for the ligands and their cobalt complexes. The title compounds were examined for their antimicrobial and antifungal activities, which resulted in high activity values for the ligands and their manganese complexes. Oxidation reactions carried out on styrene and cyclohexene revealed that the complex compounds were the most effective catalysts for styrene oxidation, giving good selectivities than those of cyclohexene oxidation. Electronic features of the synthesized compounds were also reported within this work.

Nanoceria: factors affecting its pro- and anti-oxidant properties

Nanoceria redox properties are affected by particle size, particle shape, surface chemistry, and other factors, such as additives that coat the surface, local pH, and ligands that can participate in redox reactions. Each CeO2 crystal facet has a different chemistry, surface energy, and surface reactivity. Unlike nanoceria's industrial catalytic applications, biological and environment exposures are characterized by high water activity values and relatively high oxygen activity values. Electrochemical data show that oxygen levels, pH, and redox species affect its phase equilibria for solution and dissolution. However, not much is known about how the many and varied redox ligands in environmental and biological systems might affect nanoceria's redox behaviour, the effects of coated surfaces on redox rates and mechanisms, and whether the ceria solid phase undergoes dissolution at physiologically relevant pH and oxygen levels. Research that could answer these questions would improve our understanding of the links between nanoceria's redox performance and its morphology and environmental conditions in the local milieu.