Radiofrequency pasteurization process for inactivation of Salmonella spp. and Enterococcus faecium NRRL B-2354 on ground black pepper.

Salmonella persistence in ground black pepper has caused several foodborne outbreaks and created public concern about the safety of low water activity (aw) foods. In this study, radiofrequency (RF) processing was evaluated for pasteurization of ground black pepper. Stability and homogeneity tests were done for both Salmonella spp. and E. faecium during moisture equilibration before RF heating to evaluate the inoculation method. Moisture content of samples were conditioned such that the final moisture content after RF heating reached the optimal storage moisture. RF heating was shown to provide more than 5.98 log CFU/g reduction for Salmonella spp. and the reduction of 3.89 log CFU/g for E. faecium with a 130 s of treatment time. The higher thermal resistance of E. faecium indicated its suitability as surrogate for Salmonella spp. during RF heating of ground black pepper. Piperine, total phenolics, volatile compounds, and antioxidant activity were assessed as quality parameters for ground black pepper. The results demonstrated that the RF processing provided effective inactivation of Salmonella spp. with insignificant (p > 0.05) quality deterioration.

Radio-Frequency Processing for Inactivation of Salmonella enterica and Enterococcus faecium NRRL B-2354 in Black Peppercorn.

Several Salmonella outbreaks linked to black pepper call for effective inactivation processes, because current decontamination methods result in quality deterioration. Radio-frequency (RF) heating provides a rapid heating rate and volumetric heating, resulting in a shorter come-up time. This allows for choosing a high-temperature and short-time combination to achieve the desired inactivation with minimal quality deterioration. The objectives of this study were to evaluate RF heating for inactivation of Salmonella enterica and Enterococcus faecium in black peppercorn and evaluate quality changes of RF-treated black peppercorn. Black peppercorns were inoculated with a five-strain cocktail of Salmonella or E. faecium to attain initial population levels of 6.8 and 7.3 log CFU/g, respectively, and were then adjusted to a moisture content of 12.7% (wet basis) and a water activity of 0.60 at room temperature. A stability test was performed to quantify the microbial reduction during inoculation and equilibration before RF heating inactivation. During RF heating, the cold spot was determined to be at the center on the top surface of the treated sample. In addition to inoculating the entire sample, an inoculated packed sample was placed at the cold spot of the tray. An RF heating time of 2.5 min provided a 5.31- and 5.26-log CFU/g reduction in the entire sample contained in the tray for Salmonella and E. faecium, respectively. Color parameters (L*, a*, b*), piperine content, total phenolics, scavenging activity, and most of the volatile compounds of 2.5-min RF-treated samples were not significantly different from those of the control samples. These data suggest that RF heating is a promising thermal inactivation treatment for Salmonella without significant quality deterioration, and E. faecium seems to be a suitable surrogate for Salmonella to validate the efficacy of RF heating of black peppercorn.

Biofuel production by liquefaction of kenaf (Hibiscus cannabinus L.) biomass.

In this study, kenaf biomass, its dried hydrolysate residue (solid residue left after removing water from hydrolysate) and non-hydrolyzed kenaf residue (solid residue left after hydrolysis process) were liquefied at various temperatures. Hydrolysis of biomass was performed in subcritical water condition. The oil+gas yield of biomass materials increased as the temperature increased from 250 to 300°C. Increasing temperature to 350°C resulted in decreases in oil+gas contents for all biomass feeds studied. On the other hand, preasphaltene+asphaltene (PA+A) and char yields significantly decreased with increasing the process temperature. The use of carbon or activated carbon supported Ru catalyst in the process significantly decreased char and PA+A formations. Oils produced from liquefaction of kenaf, dried kenaf hydrolysate and non-hydrolyzed kenaf residue consist of fuel related components such as aromatic hydrocarbons, benzene and benzene derivative compounds, indane and trans/cis-decalin.

Effect of support materials on supported platinum catalyst prepared using a supercritical fluid deposition technique and their catalytic performance for hydrogen-rich gas production from lignocellulosic biomass.

A number of supported Pt catalysts have been prepared by supercritical carbon dioxide deposition technique using various supports. The reduction of Pt precursor to metal performed by heat treatment under nitrogen flow. The prepared catalysts were evaluated for gasification of wheat straw biomass hydrolysates and glucose solution for hydrogen-rich gas production. The activities of the catalysts were highly affected by distribution, amount and particle sizes of platinum on the support. In general carbon-based supported Pt catalysts exhibited better catalytic activity compared to other supports to be used. Compared to biomass hydrolysate feed, gasification of glucose always resulted in higher volume of gas mixture, however, hydrogen selectivity was decreased in all catalyst except multi-walled carbon nanotube. The deposition of Pt particles inner side of that support makes the large organic substrates inaccessible to reach and react with those metal particles.

Effect of the solvent type and temperature on phytosterol contents and compositions of wheat straw, bran, and germ extracts.

Wheat fractions, such as bran, germ, and straw, are rich in a number of health beneficial bioactive compounds. However, they have not been exploited to their full capacity for value-added product development. This study examines the potential of recovering phytosterol (PS)-enriched extracts from wheat germ, bran, and straw. The main objective of the study was to evaluate the effect of solvent type and temperature on PS content and composition in straw, bran, and germ extracts. Petroleum ether, chloroform, n-hexane, and ethanol were used as solvents. A pressurized solvent extraction system was used for extraction of wheat fractions. Germ extracts had the highest total PS content followed by straw and bran extracts. Beta-sitosterol, campesterol, and stigmasterol were the main PSs in all of the extracts. Ethanol extraction resulted in the lowest total PS recovery from germ. Solvent type had a significant effect on PS composition in straw extracts. beta-Sitosterol was the most abundant PS in straw hexane extracts (74% of total PS). Petroleum ether, chloroform, and ethanol extracted more stigmasterol than beta-sitosterol from straw. This study demonstrated that the solvent type and temperature had significant effects on both PS content and composition of extracts collected from wheat fractions. Because of the complex nature of the agricultural materials, solvent selection and process optimization need to be based on experimental data. Pressurized solvent extraction is a useful technique to screen complex biological materials for their composition and to determine processing conditions to be optimized.

Biocatalysis of linoleic acid to conjugated linoleic acid.

CLA refers to a group of geometrical and positional isomers of linoleic acid (LA) with conjugated double bonds. CLA has been reported to have diverse health benefits and biological properties. Traditional organic synthesis is highly capital-intensive and results in an isomeric mixture of CLA isomers. Biotechnology presents new alternatives to traditional lipid manufacturing methods. The objective of this study was to examine the effect of protein isolation procedures on linoleate isomerase (LAI) recovery from microbial cells and biocatalysis of LA to CLA. Protein isolation experiments were carried out using Lactobacillus acidophilus L1 and two strains of Lactobacillus reuteri (ATCC 23272 and ATCC 55739). Under the same assay conditions, ATCC 55739 had the highest LAI activity among the microbial cultures examined in this study. Efficiency of cell lysis methods, which included various combinations of lysozyme and mutanolysin treatments in combination with sonication and osmotic rupture of cells with liquid nitrogen, was very low. Although treatment of cell material with a detergent (octylthioglucoyranoside) freed a significant amount of LAI activity into the solution, it was not sufficient to recover all the LAI activity from the residual cells. Crude LAI preparations produced mainly the cis-9,trans-11 CLA isomer. Time and substrate/protein ratio had a significant effect on biocatalysis of LA to CLA. It appears that the mechanism and kinetics of enzymatic conversion of LA to CLA are quite complex and requires further research using pure LAI preparations.

Degradation of 17beta-estradiol and bisphenol A in aqueous medium by using ozone and ozone/UV techniques.

Decomposition and complete degradation of two endocrine disrupters, namely 17beta-estradiol (E2) and bisphenol A (BPA) in aqueous medium by using ozone (O3) only and O3/UV advanced oxidation techniques (AOT) has been studied. The efficiency of the O3 systems used were determined based on the initial conversion and complete degradation of the substrates. Within the limits of the O3 dosages used, coupling of UV decreased the O3 consumption by 22.5% in converting the same amount of E2. Also the time to convert the same amount of E2 was considerably decreased. It was observed that there is no significant difference in O3 amount consumed for complete conversion of BPA by O3 and O3/UV systems. However, when O3 dosage decreased the amount of BPA conversion exhibits significant differences between two processes. The intermediate products formed during the oxidation of E2 were determined to be formed by oxidation of aromatic side of E2 with O3/*OH radical.

Policosanol contents and compositions of wheat varieties.

Policosanol (PC) is the common name for a mixture of high molecular weight (20-36 carbon) aliphatic primary alcohols, which are constituents of plant epicuticular waxes. Wheat germ oil has been reported to improve human physical fitness, and this effect is attributed to its high PC, specifically its high octacosanol (OC) content. Although the PC composition of wheat leaves has been studied extensively, information on PC content and composition of wheat grain fractions is scarce. The objective of this study was to examine the PC contents and compositions of wheat grain fractions of 31 varieties grown in Oklahoma. PC compositions of the samples were identified using a gas chromatograph coupled with a mass spectrometer. The PC content of wheat bran was higher than that of the germ, shorts, and flour. The Trego and Intrada varieties had the highest PC content among the 31 wheat varieties studied. Tetracosanol (C24), hexacosanol (C26), and OC (C28) were the major PC components in all varieties. This study showed that wheat varieties grown under identical growing conditions and management differ significantly in PC content and composition.

Comparison of the treatment methods efficiency for decolorization and mineralization of Reactive Black 5 azo dye.

Degradation of Reactive Black 5 (RB5), a well-known non-biodegradable disazo dye, has been studied using UV/TiO2, wet-air oxidation (WAO), electro-Fenton (EF) and UV/electro-Fenton (UV/EF) advanced oxidation processes (AOPs). The efficiency of substrate decolorization and mineralization in each process has been comparatively discussed by decreases in concentration and total organic carbon content of RB5 solutions. The most efficient method on decolorization and mineralization was observed to be WAO process. Mineralization efficiency was observed in the order of WAO>UV/TiO2>UV/EF>EF. Final solutions of AOPs applications after 90 min treatment can be disposed safely to environment. Photocatalytic degradation kinetics of RB5 successfully fitted to Langmuir-Hinshelwood (L-H) kinetics model. The values of second order degradation rate constant (k'') and adsorption constant (K) were determined as 5.085 mg L(-1)min(-1) and 0.112 L mg(-1), respectively.

Comparison of several advanced oxidation processes for the decolorization of Reactive Red 120 azo dye in aqueous solution.

In this study UV/TiO2, electro-Fenton (EF), wet-air oxidation (WAO), and UV/electro-Fenton (UV/EF) advanced oxidation processes (AOPs) have been applied to degrade Reactive Red 120 (RR120) dye in aqueous solution. The most efficient method on decolorization and mineralization of RR120 was observed to be WAO process. Photocatalytic degradation of RR120 by UV/TiO2 have been studied at different pH values. At pH 3 photocatalytic degradation kinetics of RR120 successfully fitted to Langmuir-Hinshelwood (L-H) kinetics model. The values of second order degradation rate (k") constant and adsorption constant (K) were determined as 4.525 mg L(-1) min(-1) and 0.387 L mg(-1), respectively. Decolorization efficiency observed in the order of WAO > UV/TiO2 = UV/EF > EF while WAO > UV/TiO2 > UV/EF > EF order was observed in TOC removal (mineralization). For all AOPs, it was found that degradation products in reaction mixture can be disposed safely to environment after 90 min treatment.