Wood Smokes Research Articles

Effects of Potassium Lactate and Acetate on Listeria monocytogenes Inhibition, Physicochemical and Sensory Properties of Smoked Catfish Fillets

The objective of this study was to evaluate the effects of liquid and wood smoking with a potassium lactate (PL) and acetate (PA) combination on the quality and inhibition of L. monocytogenes growth in ready-to-eat (RTE) smoked catfish fillets. Catfish fillets were tumbled with PL and PA, and treated with no smoke (NS), wood smoke (WS), liquid smoke 1 (LS1), and liquid smoke 2 (LS2). Wood smoke with antimicrobials (WSWA) showed greater inhibition (p < 0.05) of L. monocytogenes growth than other treatments with the exception of the LS1 treatment with antimicrobials. Consumers preferred (p < 0.05) smoked catfish fillets treated with WS to LS1 with respect to appearance, odor, flavor, texture, and overall acceptability. In conclusion, the use of PL and PA did not have a negative impact on the quality and sensory properties of smoked catfish fillets but had a synergistic effect with wood smoke constituents that inhibited the growth of L. monocytogenes.

Wood-smoked flavour

Wood-smoked flavour

On time dynamics of the complex refractive index and particle microstructure according to data of spectronephelometer measurements in mixed-composition smokes

The specific features in the dynamics of the complex refractive index (CRI) are studied for three particle fractions during aging of mixed-composition wood smokes, generated due to simultaneous particle emission from two sources in the regimes of pyrolysis and flaming combustion, for two days. The initial stage is characterized by the generation of smoke in which the imaginary part of the particle refractive index χ decreases, on average, by a factor of 600 with the growth of particle size. When smoke is aged for a long time, χ decreases (by a factor of 1.2) for ultrafine black carbon particles, simultaneously increasing for moderately (by a factor of 1.5) and coarsely (by a factor of 4.7) dispersed particles. This suggests that the dynamics of microphysical smoke composition, at all stages of its existence, is mainly determined by the coagulationdriven penetration of black carbon from the nanometer-size range toward the region of larger particle sizes. Numerical experiment showed that the inverse problem during aging of mixed-composition smokes can be solved correctly only using CRI values strictly corresponding to a given time instant. Attempts to solve the inverse problem using some time invariable CRI values lead to a several-fold increase in the discrepancy between the measured and retrieved optical characteristics versus the 6–10% discrepancy for the actual CRI values. Testing of the three-fraction method for solving the inverse problem with the help of modeled aerosol with a known CRI (ethylene glycol) showed that our approach ensured high-accuracy retrieval of the true CRI for the optically active particles in a moderately dispersed size range. Using the three-fraction method decreases the discrepancy, on average, by a factor of two versus the traditional one-fraction method (assuming that particles are homogeneous in the nature).

Techniques in the improvement of consumers taste of Heterotis niloticus

Improvement of the consumers’ taste of Heterotis niloticus was investigated by salting techniques. Table size fish were degutted, cut into uniform sizes, and soaked in salt solutions at concentrations that ranged from 0 - 100 g/l for 6 h. The salted pieces of H. niloticus were allowed to drain for an hour before been subjected to fire wood smoking in a kiln for 48 h. The taste of H. niloticus was greatly improved at 50 g/l salt as reported by all members of a 5-man organoleptic taste panel constituted to determine the taste by consuming fish soaked in different concentration of salt solutions. The improvement of the consumers’ taste of H.niloticus by simple salting methods showed in this study would improve the market value and aquaculture potentials of the species which has been discriminated because of its poor consumers taste, despites its excellent muscle quality. Key words: Heterotis niloticus, taste, salting.

Muscle Quality of Yellowfin Tuna (Thunnus albacares) Steaks After Treatment with Carbon Monoxide Gases and Filtered Wood Smoke

ABSTRACT Treating seafood with carbon monoxide (CO) and various filtered wood smokes (FS) containing carbon monoxide has become a common practice in the industry, particularly for seafood intended for the frozen market. Tuna is one of the most common fish species treated with this process. Various quality improvement claims have been made for these treatments, which require investigation. Yellowfin tuna steaks were subjected to various CO treatments (4% CO, 18% CO and 100% CO) and FS treatment (which contained 18% CO) for 48 h, followed by 30 days of freezing and subsequent cold storage (4°C) after thawing. Muscle quality was evaluated after treatment. The FS, 18% CO and 100% CO treatments led to reductions in formation of secondary lipid oxidation products (TBARS) during freezing and subsequent cold storage, possibly due to increased stability of heme proteins. Textural studies using Instron compression tests on tuna steaks did not indicate significant differences (p > 0.05) between the CO or FS treatments compared with untreated controls. Water-holding studies (expressible moisture and drip loss) also did not show significant differences (p > 0.05) between CO- or FS-treated tuna compared with untreated controls. Freezing and thawing and subsequent cold storage did however lead to significant (p < 0.01) losses of water for all treatments. Muscle protein solubility tests, on the other hand, indicated that FS, 18% CO, and 100% CO-treated tuna steaks had proteins with higher salt solubility compared with untreated controls. This suggests that such treatments may stabilize muscle proteins, which was not apparent from textural and water-holding capacity studies.

Chemical Characterization of Fine Particle Emissions from the Fireplace Combustion of Wood Types Grown in the Midwestern and Western United States

Results are presented from a series of source tests on the fireplace combustion of 10 wood species found in the Midwestern and Western United States: white oak, sugar maple, black oak, American beech, black cherry, white spruce, quaking aspen, douglas fir, ponderosa pine, and pinyon pine. Fine particle emission factors for total mass, organic, and elemental carbon, ionic species, elemental species including potassium, and over 250 individual organic compounds were determined. The data are intended for use in apportionment studies that utilize particulate organic compounds as specific tracers to identify the sources of ambient fine particles. The cellulose pyrolysis products levoglucosan, mannosan, and galactosan were quantified in each of the wood smokes studied; they act as molecular tracers for cellulose from combustion of all wood types. Differences in the emission rates of syringol- and guaiacol-type phenolic compounds from lignin and of resin acids can be used to distinguish between hardwood and softwood smoke emissions. The triterpenoid, friedelin, known to be present in the bark of white oak, is emitted in significant quantities from white oak combustion, but was not found in the emissions from any other North American wood species. Friedelin can potentially be utilized to trace particulate emissions back to specific geographic regions where white oak is used for firewood. These results, along with previously published data from the other U.S. regions, provide a complete set of emission factors of the prevalent chemical species found in wood smoke throughout the United States.

Organic compounds in biomass smoke from residential wood combustion: Emissions characterization at a continental scale

Wood smoke in the atmosphere often accounts for 20–30% of the ambient fine‐particle concentrations. In communities where wood is burned for home heating, wood smoke can at times contribute the majority of the atmospheric fine‐particle burden. Chemical mass balance receptor models that use organic compounds as tracers can be used to determine the contributions of different emission sources, including wood smoke, to atmospheric fine‐particle samples. In order for organic chemical tracer techniques to be applied to communities across the United States, differences in wood smoke composition that arise from differences in the type of wood burned in various regions must be understood. A continental‐scale accounting of particulate organic compound emissions from residential wood combustion has been constructed which helps to quantify the regional differences in wood smoke composition that exist between different parts of the United States. Data from a series of source tests conducted on 22 North American wood species have been used to assemble a national inventory of emissions for more than 250 individual organic compounds that are released from wood combustion in fireplaces and wood stoves in the United States. The emission rates of important wood smoke markers, such as levoglucosan, certain substituted syringols and guaiacols, and phytosterols vary greatly with wood type and combustor type. These differences at the level of individual wood type and combustion conditions translate into regional differences in the aggregate composition of ambient wood smoke. By weighting the source test results in proportion to the availability of firewood from specific tree species and the quantities of wood burned in each locale, it is possible to investigate systematic differences that exist between wood smokes from different regions of North America. The relative abundance of 10 major wood smoke components averaged over the emissions inventory in different regions of the United States is computed and then used to illustrate the extent to which wood smoke composition differs from region to region in North America.

Occupational Monitoring of Particulate Diesel Exhaust by NIOSH Method 5040

NMAM 5040 is a particulate carbon method based on a thermal-optical analysis technique. The method was evaluated and published as a method for monitoring occupational exposures to particulate diesel exhaust, but it is applicable to particulate carbon aerosols in general, and has been routinely used in both occupational and environmental settings. Both organic and elemental carbon are determined, but EC is a more selective measure of workplace diesel exposure. In previous studies, good agreement between TC results obtained by different methods has been achieved, but the OC-EC results for different methods have been quite variable. Although a reference material is not currently available to test the accuracy of different methods, previous studies indicate that purely thermal methods are subject to positive bias from organic materials that char. Charring and inadequate removal of refractory OC components during the nonoxidative mode (typically 550 degrees C in nitrogen) likely explain the positive bias of thermal methods, as well as the large variability across methods. These interferences may be negligible in some cases (e.g., samples from mines), but they present significant biases in others (e.g., urban air samples, samples containing wood or cigarette smokes). Good interlaboratory agreement was obtained in a round robin comparison between six laboratories that used NMAM 5040, which was not the case with purely thermal methods. Good agreement has also been seen in smaller-scale comparisons conducted for quality assurance purposes. Until a suitable reference material becomes available, such comparisons are recommended as part of a laboratory's QA procedures. At present, five commercial laboratories (4 in the United States and 1 in Canada) perform the 5040 analysis, and over 40 instruments are in use globally for environmental and occupational monitoring.

Chemical characterzation of fine particle emissions from the fireplace combustion of woods grown in the Southern United States.

The fireplace combustion of wood is a significant and largely unregulated source of fine particle pollution in the United States. Source apportionment techniques that use particulate organic compounds as tracers have been successful in determining the contribution of wood smoke to ambient fine particle levels in specific areas in California. To apply these techniques to the rest of the United States, the differences in emissions profiles between different wood smoke sources and fuel types should be resolved. To this end, a series of fireplace source tests was conducted on six fuel wood species found in the Southern United States to determine fine particulate emission factors for total mass, ionic and elemental species, elemental and organic carbon, and over 250 individual organic compounds. The wood species tested, chosen for their high abundance and availability in the Southern U.S. region, were yellow poplar, white ash, sweetgum, mockernut hickory, loblolly pine, and slash pine. The differences in the emissions of compounds such as substituted phenols and resin acids help to distinguish between the smoke from hardwood and softwood combustion. Levoglucosan, a cellulose pyrolysis product which may serve as a tracer for wood smoke in general, was quantified in the emissions from all the wood species burned. The furofuran lignan, yangambin, which was emitted in significant quantities from yellow poplar combustion and not detected in any of the other North American wood smokes, is a potential species-specific molecular tracer which may be useful in qualitatively identifying particulate emissions from a specific geographical area where yellow poplar is being burned.

Development of an integrated quality assurance system for the traditional Sardinella sp. and anchovy fish smoking industry in Ghana

The physical, chemical, microbiological, sensory and toxicological quality implications of all the operations involved in handling, processing and storage of traditional smoked sardinella sp. and anchovy production in Ghana were evaluated. The results were used to assess the potential hazards in the traditional smoked fish production chain and to identify critical control points for the development of an integrated quality assurance system. A wide range of quality characteristics was observed for products from different processing sites due to lack of a standardized technique. Potential safety and spoilage hazards identified include contamination of raw, processed, and stored fish with pathogenic bacteria, spoilage microorganisms, biogenic amines, insect infestation, as well as possible excessive deposition of wood smoke chemicals. Spoilage microorganisms and insect infestation, however, were found to constitute a high risk in terms of product loss, but low severity of the hazard. Critical control points identified include raw fish quality and handling from landing to processing site, time and temperature controls during handling and processing, fuel wood type, smoking rate and duration, storage conditions and general hygiene and sanitation procedures. Critical limits have been established for each processing and storage step to ensure that microbiological, chemical and sensory quality characteristics are satisfied. An effective monitoring procedure has been suggested.

Changes in the nasal mucosa of furniture workers. A pilot study.

The present study was carried out in order to evaluate whether precancerous lesions could be detected in the nasal mucosa of furniture workers. Histological examination of nasal biopsies from 113 workers (103 active and 10 retired) and 54 referents was performed. The histological sections were evaluated blindly according to a numerical classification scale, and the results were compared, by means of multiple regression analysis, to age, type and duration of exposure to wood dust, smoking habits, nasal allergy, and rhinoscopic findings. Nasal stenosis and mechanical wood preparation were significantly related to the histological findings by the partial correlation coefficients. Fourteen cases (12%) of dysplasia were found among the furniture workers, preferentially among those performing mechanical wood preparation, and among the referents there was one (2%). The evaluation of the importance of exposure to dust of individual types of wood was not possible. Nasal epithelial dysplasia should probably be interpreted as a preneoplastic lesion and may be of significance in the pathogenesis of nasal adenocarcinoma. Standard nasal biopsies appear to be valuable in identifying groups of persons with an increased incidence of nasal carcinoma.

Propagation of Laser Beams in Scattering Media

Experimental investigations have been undertaken of some aspects of the propagation of helium-neon gas laser radiation at lambda = 0.63 micro for different scattering media (artificial water fogs, wood smokes, model media). It has been shown that the attenuation coefficients practically coincide when coherent and incoherent radiation is scattered. The applicability limits of Bouguer-Beer's law for describing the attenuation of radiation in scattering media are investigated and the intensity of multiple forward-scattered light for different geometrical parameters of the source and radiation receiver are measured. The applicability of single scattering theory formulas for describing forward-scattered light intensity are discussed.

Deposition of unipolar charged aerosol particles by mutual repulsion

A simple theory of the deposition of unipolar charged aerosols by their mutual repulsion is developed. The application of this theory enables the average radius and the average charge of the particles to be determined from measurements of the mass of smoke deposited on metal surfaces and the charge given up by the particles. This new method offers a means of determining the rate of coagulation of unipolar charged aerosols. Experiments with wood smokes indicate that the simple theory of deposition is correct. The calculated average radius of the wood smoke particles examined compares favourably with that determined from measurement of the optical density and mass concentration of the smoke. The charge determined by the new method is consistent with that calculated on the basis of corona charging theory.