Longer Aging Periods Research Articles

Entry pathways determined the effects of MPs on sludge anaerobic digestion system: The views of methane production and antibiotic resistance genes fates

Sludge is one of the primary reservoirs of microplastics (MPs), and the effects of MPs on subsequent sludge treatment raised attention. Given the entry pathways, MPs would exhibit different properties, but the entry pathway-dependent effect of MPs on sludge treatment performance and the fates of antibiotic resistance genes (ARGs), another high-risk emerging contaminant, were seldom documented. Herein, MPs with two predominant entry pathways, including wastewater-derived (WW-derived) and anaerobic digestion-introduced (AD-introduced), were used to investigate the effects on AD performance and ARGs abundances. The results indicated that WW-derived MPs, namely the MPs accumulated in sludge during the wastewater treatment process, exhibited significant inhibition on methane production by 22.8%–71.6%, while the AD-introduced MPs, being introduced in the sludge AD process, slightly increased the methane yield by 4.7%–17.1%. Meanwhile, MPs were responsible for promoting transmission of target ARGs, and polyethylene terephthalate MPs (PET-MPs) showed a greater promotion effect (0.0154–0.0936) than polyamide MPs (PA-MPs) (0.0013–0.0724). Compared to size, entry pathways and types played more vital roles on MPs influences. Investigation on mechanisms based on microbial community structure revealed characteristics (aging degree and types) of MPs determined the differences of AD performance and ARGs fates. WW-derived MPs with longer aging period and higher aging degree would release toxics and decrease the activities of microorganisms, resulting in the negative impact on AD performance. However, AD-introduced MPs with short aging period exhibited marginal impacts on AD performance. Furthermore, the co-occurrent network analysis suggested that the variations of potential host bacteria induced by MPs with different types and aging degree attributed to the dissemination of ARGs. Distinctively from most previous studies, the MPs with different sizes did not show remarkable effects on AD performance and ARGs fates. Our findings benefited the understanding of realistic environmental behavior and effect of MPs with different sources.

Long-term aged fibrous polypropylene microplastics promotes nitrous oxide, carbon dioxide, and methane emissions from a coastal wetland soil

Microplastics (MPs) has been suggested that it can greatly affect soil greenhouse gases (GHGs) emissions via altering soil physical, chemical, and biological properties. However, the difference in GHGs emissions, especially for those from coastal wetland soils, between varied aged MPs was rarely explored and the underlying mechanisms of GHGs emissions affected by the aged MPs were poorly understood. Therefore, the implications of fibrous polypropylene MPs (FPP-MPs) exposure on N2O, CO2, and CH4 emissions were examined by a 60-day soil incubation experiment. Compared with the control, the additions of un-aged FPP-MPs with both two rates (0.2 and 2 %) and aged FPP-MPs with a low rate (0.2 %) showed an insignificant effect on N2O emission, while the aged FPP-MPs added with a high rate (2 %) resulted in a remarkably increase in N2O emission, especially for those of the 30-day-aged FPP-MPs. A significant increase in CO2 emission was only observed in the 30-day-aged FPP-MPs treatments, compared with the control, and a higher addition rate produced a higher increase of CO2 emission. Regarding CH4 emission, it was significantly increased by adding aged FPP-MPs, and a longer aging period or/and a higher addition rate generated a higher degree of promotion of CH4 emission. However, compared with the CO2 emission, the quantity of CH4 emission was extremely low. These increased GHGs emissions can be ascribed to the improvements in soil physical structure and other chemical properties (e.g., pH and contents of soil organic matter and dissolved organic carbon) and enhancements in the abundances of denitrification- and carbon mineralization-related microorganisms. Overall, our results highlight the risk of elevated GHGs emissions from the soil polluted with 30-day-aged FPP-MPs, which should not be ignored as long-term aged FPP-MPs continue to increase in coastal wetland soils.

PSIII-A-10 Effect of Grain Type and wet-Aging Time on Lamb Meat

Abstract Visual appearance is critical for the consumer perception of meat quality. Color, as well as juiciness are key factors in determining consumer choice. The objective of this study was to evaluate the effect of grain type and different wet-aging periods on lamb meat. Eighteen castrated Merino x Corriedale lambs (± 40 kg) were randomly assigned to three dietary treatments: 60% corn grain (CG), 60% oats grain (OG) or all fescue hay (Control); diets were isonitrogenous (13% CP). After slaughter, pieces of Longissimus thoracis muscle from each animal were aged during 1, 4, 8 and 16 d. Treatments were arranged as a 3x4 factorial experiment, and color and water-holding variables were measured. No interactions were found (p > 0.05) between type of grain and aging time. Meat from CG showed the highest values for lightness, redness and yellowness (p= 0.0240, 0.0119, 0.0077, respectively), while meat from OG had the lowest values for redness and yellowness. Expressible juice was lowest (p= 0.0307) for Control, intermediate for CG and higher for OG. Meat cooking loss (p= 0.0157) resulted highest for Control, intermediate for OG and lowest for CG. Cooking loss, drip loss (48h) and expressible juice showed differences among aging periods (p= 0.002, 0.0001, 0.0015, respectively); the highest loss was found for 1d-aging, but no differences were detected for the other aging periods. The effect of aging period was greater than type of grain for cooking loss (F: 7.82, 4.48) and expressible juice (F: 5.88, 3.71) respectively. Purge-thaw loss showed no differences for diet type (p > 0.16) or aging period (p > 0.11). A more intense color developed by CG than OG might favor consumer perception of meat quality. Additionally, water-loss seems to be independent of these diets, showing that a longer aging period would be more relevant to get juicier lamb meat.

Adsorption-desorption effect on physical aging in PMMA-silica nanocomposites

Poly(methyl methacrylate) (PMMA)-silica nanocomposite was used to study the adsorption-desorption of polymer chains on the surface of silica nanoparticles. We demonstrate that the adsorption-desorption is a dynamic process with respect to temperature and time. The adsorption condition could be changed after annealing at Tg + 16 °C. Then, the physical aging under confinement was investigated under different adsorption conditions. At relatively high aging temperatures, we reveal a one-step equilibration with reduced enthalpy recovery of nanocomposite compared with neat PMMA. In contrast, the aging rate of composite is decelerated and then accelerated after a long period of aging at a relatively low temperature due to the emergence of two-step equilibration. Furthermore, the material system with a higher adsorption fraction exhibits a stronger confinement effect on aging. We speculate that the transition from one-step to two-step equilibration corresponds to the activation of segmental α′ relaxation in the interfacial region. The adsorbed chains result in restrained segmental α′ and β′ relaxation and low enthalpy recovery at relatively high aging temperatures. At a relatively low temperature, the interfacial α′ relaxation with high released enthalpy comes to the surface after a long aging time, inducing the elevated aging rate.

The effect of heat treatment on pseudoelastic behavior of spark plasma sintered NiTi

Porous NiTi shape memory alloys are considered as artificial bio-materials for possible use in implant applications. Their extraordinary pseudoelastic response under uniaxial loading through phase change needs further analysis. The objective of this work is to show the effect of heat treatment on the pseudoelastic behavior of NiTi SMA produced by spark plasma sintering (SPS). NiTi samples were prepared from pre-alloyed Ti-50.7 at.% Ni powders of 100-150 μm average diameter, and subjected to a wide range of homogenization and/or aging at different temperatures and duration. Transformation characteristics of heat treated samples were obtained from DSC, their phase composition was identified using X-ray diffraction (XRD), and checked with scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Instrumented micro-indentation was carried out to measure the hardness altered by aging. Uniaxial compression tests were performed on heat treated samples, and their pseudoelastic behavior was shown on the stress–strain diagrams; the results showed a variation in pseudoelasticity. In general, Ni concentration of the matrix resulted in partial-pseudoelastic behavior of samples. Homogenization prior to aging improved the pseudoelasticity of the SPSed NiTi. The pseudoelastic response of the samples that have not shown the expected full pseudoelastic behavior was enhanced by applying a considerably long period of homogenization and aging.

Evaluation of structures affected by Alkali-Silica reaction (ASR) using homogenized modelling of reinforced concrete

The computation of large reinforced concrete structures such as nuclear power plants, dams and bridges requires realistic behaviour laws to be considered for concrete and reinforcements. Regarding the problem of cracking in RC structure, meshing separately concrete and rebars is the classical way to perform a nonlinear finite element analysis. However, when the structures have to be studied at full scale, the explicit meshing of rebars becomes so heavy that the computing time reaches values incompatible with engineering applications. The method proposed in this paper consists of using large finite elements considering reinforcement and concrete as a homogenized material. In comparison to the mesh reinforcement approach, this one limits the number of finite elements and returns to a computation compatible with engineering. The particularity of the proposed model resides in its ability to treat interaction between rebars and concrete affected by the Alkali-Silica Reaction (ASR). The model is able to predict the anisotropic swelling induced by the combination of homogenized rebars and external loadings. An application to a well-documented laboratory test for reinforced concrete beams shows the ability of the model to assess residual strength capacity of the beam after a long period of ageing in a natural environment. A parametric study of the size of the finite elements confirms the possibility of using a coarse mesh without loss of the model’s predictive capability.

Precipitation behavior of P550 steel for non-magnetic drill collars during isothermal aging at 650–900 °C

Precipitation behavior of P550 steel for non-magnetic drill collars was investigated by microstructure characterization as well as thermodynamic calculation. The results demonstrate that the main precipitate formed at 650–900 °C was cellular Cr2N, and its precipitation depended heavily on the aging temperature. The most sensitive precipitation temperature of cellular Cr2N was 750 °C. At 750 °C, the cellular Cr2N exhibited fast-slow precipitation kinetics with the aging time prolonging. The initial precipitation of cellular Cr2N was governed by the short-range intergranular diffusion of Cr. During long-term aging, its growth was controlled by the long-range bulk diffusion of Cr. In addition, cellular Cr2N induced the precipitation of σ phase ahead of the cell after long period of aging. Increasing the nitrogen content resulted in the increment of both the nucleation site and the driving force for the cellular Cr2N, which jointly promoted its precipitation.

Dry-aged and wet-aged beef: effects of aging time and temperature on microbiological profile, physicochemical characteristics, volatile compound profile and weight loss of meat from Nellore cattle (Bos indicus)

Context Dry-aged beef is a value-added product with a unique flavour. The effects of the dry aging process, in terms of chamber temperature and aging time, have not been described previously for Bos indicus meat. Aims This study evaluated the effects of aging conditions (method, temperature, time) on the microbiological, physicochemical, volatile compound profile and weight loss characteristics of dry-aged and wet-aged beef from Nellore cattle (Bos indicus). Methods Beef loins (n = 16) were cut into eight portions and assigned to treatments in a complete block design combining aging method (dry or wet), temperature (2°C or 7°C) and time (21 or 42 days). Key results Samples dry-aged at 7°C had higher (P < 0.05) weight loss than samples dry-aged at 2°C. Although storage temperature did not affect (P > 0.05) the yield of wet-aged samples, Enterobacteriaceae counts increased (P < 0.05) in the samples stored at 7°C compared with 2°C. Aging for 42 days resulted in greater (P < 0.05) process losses (drip + evaporation + trimming) for both aging methods than aging for 21 days. The pH, moisture content and Warner–Bratzler shear force values were not affected (P > 0.05) by aging method, temperature or time. Qualitative analysis indicated that volatile compounds were affected by aging method and time, but not by aging temperature. Conclusions The results indicate that higher temperature and longer aging periods cannot be not recommended for either dry or wet aging, owing to the increase in process losses of dry-aged samples, and growth of Enterobacteriaceae and psychrotrophic bacteria in wet-aged samples. Implications This study highlights the importance of controlling conditions for dry aging to produce a safe product and obtain higher yields. Processing plants or retailers that produce dry-aged or wet-aged meat could use these results to adjust their production systems.

Free Calcium Concentration, Calpain-2 Activity, and Final Product Tenderness of Electrically Stimulated Beef

The objective of this study was to evaluate the effect of timing of electrical stimulation on free calcium concentration, calpain-2 activity, Warner-Bratzler shear force (WBSF), and consumer sensory analysis. Twenty-three beef steers were harvested and stimulated (S) using extra-low voltage or not stimulated (NS), at exsanguination and/or 1 h postmortem, resulting in 4 different stimulation treatments: NS-NS, NS-S, S-NS, or S-S. Samples were removed from the longissimus lumborum (LL) and semimembranosus (SM) for free calcium and calpain-2 analysis on days 1, 4, and 14 postmortem. WBSF and sensory analysis steaks were removed on day 4 and frozen (4 d) or aged to 14 d postmortem. Data were analyzed using the mixed model or generalized linear mixed model procedure of SAS (SAS Institute, Inc., Cary, NC), with significance determined at P < 0.05. There was a tendency for an aging-period-by-stimulation-treatment interaction for LL free calcium concentration (P = 0.05), and there was a significant difference between aging periods (P < 0.01). No difference was observed in free calcium concentration in the SM between stimulation treatments (P = 0.44); aging, however, significantly increased SM free calcium concentration (P < 0.01). Stimulation did not impact native calpain-2 activity in the LL (P = 0.71) or SM (P = 0.89). Stimulation treatment did not improve tenderness values for WBSF analysis for the LL (P = 0.69) or SM (P = 0.61) or consumer sensory analysis in the LL (P = 0.56) or SM (P = 0.36). A longer aging period tended to increase calpain-2 activity in the SM (P = 0.08), improve WBSF in the LL (P = 0.09), and significantly improve consumer tenderness scores in the SM (P < 0.01). In conclusion, the timing of electrical stimulation utilized in the current study tended to influence free calcium concentration in the LL but did not influence calpain-2 activity or beef tenderness. Aging, however, improved tenderness.

Astringency subqualities and sensory perception of Tuscan Sangiovese wines

Aim: The Sangiovese grape cultivar is at the basis of the most well-known Italian wines produced in the Tuscany region. However, little is known about the sensory characteristics of Tuscan Sangiovese wines, and the diversity in astringency subqualities has never been investigated. In this study we evaluated the sensory perception of 16 commercial Sangiovese wines belonging to four categories of denomination (Chianti DOCG, CH; Chianti Classico DOCG, CC; Morellino di Scansano DOCG, MS; Toscana IGT, TS), and again after 20 months of bottle aging.Methods and results: A sensory evaluation was made, consisting of the astringency subqualities, taste, odor, and aroma profiles of wines. In addition, chemical analyses were carried out for the base parameters, polyphenols and some volatile compounds. Astringency subqualities varied depending on the percentage of Sangiovese in wines (from 80 % to 100 %). Blended Sangiovese wines were characterized by positive mouthfeel sensations. According to these, the drivers of liking the wines were associated with soft, mouthcoat, and rich subqualities. The Tuscan Sangiovese denominations were differentiated by volatile active compounds, whereas after about two years of bottle aging the astringency subqualities better achieved this task. Moreover, aging also influenced the evolution of wines: CC and CH wines positively evolved, revealing a complex odor profile; MS lost the fruity character; and TS was less involved in sensory modification.&#x0D; Conclusions: For the first time, a detailed evaluation of the astringency subqualities of commercial Sangiovese wines was undertaken. Sangiovese subqualities differed according to the percentage of Sangiovese and denomination. Tuscan denominations were distinguished by peculiar sensory characteristics. In addition, bottle aging significantly influenced the evolution of the sensory perception of Sangiovese wine. In particular, mono-varietal Sangiovese wine needed a long period of aging to soften the astringency characteristics.Significance and impact of the study: Sangiovese wine represents - with its denominations and styles - the best-known and high-quality Italian wine in the world, and its popularity is increasing worldwide. Tuscan Sangiovese wines are often a blend with other red varieties of the region, and these can vary according to the production regulations. This study aimed to improve the knowledge of the sensory characteristics of Sangiovese wines belonging to different denominations and made with different percentages of this grape cultivar. In particular, the astringency subqualities are fundamental to fully appreciating the quality of the red wine during tasting.

Effect of ageing time on consumer preference and sensory description of foal meat.

A consumer test (n = 120) was performed in Vitoria-Gasteiz (northern Spain) in order to study the effect of ageing time (0, 7, 14 and 21 days) on the sensory quality of Hispano-Bretón foal meat. Steaks (Longissimus thoracis et lumborum) were wet aged and evaluated in-mouth and visually. In both cases, acceptability was scored using a hedonic scale, and sensory drivers related to ageing were characterised by applying check-all-that-apply method in meat. For both, in-mouth and visual acceptability, meat aged for 7 days obtained higher scores than non-aged meat, whereas longer ageing periods did not improve consumer acceptability. Check-all-that-apply method showed to be able to discriminate among samples, both in-mouth and visually. Results revealed that texture related attributes were the most discriminant ones in the in-mouth evaluation, being non-aged meat related to 'dry', 'high residue', 'tough' and 'chewy' terms, whereas aged meat was associated to 'juicy', 'tender' and 'easily dissolving' terms. Visually, consumers perceived that, after 14 days of ageing, meat colour changed to 'brownish'. Under present study conditions, the establishment of a period of 7 days of ageing would be recommended.

Survey on assistive technologies for people with Dementia

Today, in developed societies, life expectancy is noticeably increasing due to improved healthcare systems and medical advances. Along with a longer aging period, falling birth rates, and other concomitant social factors, the age distribution is evidencing a shift towards the demographic expansion of older population stages. Epidemiological studies about this demographic aging distribution of the world population indicate that older adults are experiencing a variety of age-related problems, including Dementia. Dementia is overwhelming and frightening for both loved persons who live with Dementia, and also their caregivers. The number of people living with Dementia in societies is now rising at an unprecedented rate. Neither decisive treatment, nor effective medicines have been introduced to help society cope with such age associated pathologies. However, one promising alternative to this emerging crisis has been the adoption of Assistive Technologies (AT). Therefore, for this study, a systematic literature review is conducted to provide an overview about recent findings in this field of study and also address some available technologies that have potential application for Dementia sufferers. This work makes a report on existing technologies in the field, thus becoming a survey on existing supportive technologies for People with Dementia (PwD). The findings of this work provide an insight into the types and percentages of suggested technologies for each classification that aim to be useful for those researching the field or who want to know state of the art in this presently relevant domain. Concluding points and discussion are presented subsequently.

Control of Laves Precipitation in a FeCrAl-based Alloy Through Severe Thermomechanical Processing.

In recent years, the development of nuclear grade FeCrAl-based alloys with enhanced accident tolerance has been carried out for light water reactor (LWR) fuel cladding to serve as a substitute for zirconium-based alloys. To achieve excellent microstructure stability and mechanical properties, the control of precipitation particles is critical for application of FeCrAl-based alloys. In this paper, the effect of thermomechanical processing on the microstructure and precipitation behavior of hot-rolled FeCrAl alloy plates was examined. After hot rolling, the FeCrAl alloy plates had typical deformation textures. The rolling direction (RD) orientation gradually rotated from <100> to <110> along with increasing reduction. Shear bands and cell structures were formed in the matrix, and the former acted as preferable nucleation sites for crystallization. Improved deformation helped to produce strain-induced precipitation. The plate with 83% reduction had the most homogeneous and finest precipitation particles. Identification results by TEM indicated that the Laves precipitation was of the Fe2Nb-type crystal structure type, with impurities including Mo, Cr, and Si. The plate with uniform Laves particles displayed favorable heat stability after a long period of aging at 800 °C. The microstructure evolution of the aged sample was also observed. The deformation microstructure and the strain-induced precipitation mechanism of FeCrAl alloys are discussed.

Evaluation of the one-step Lumicyano™ used in the visualisation of fingermarks on fabrics

This study consisted of three parts to evaluate the performance of Lumicyano™ on a variety of fabrics. One part assessed the impact of dye percentage (8%, 9% and 10%) on visualisation of fingermark detail and luminescent brightness in split grab marks. A 9% dye produced the highest quality detail of grab impressions with least interference from background fluorescence. The second part investigated the optimal relative humidity (RH, 75–84%) for certain fabric types using Lumicyano on split, six-series depletion fingermarks. It was concluded that the recommended RH of 80% remained the ideal cyanoacrylate fuming environment. The final and third part of this study determined the impact of sequential addition of Basic Yellow 40 (BY40) on Lumicyano compared to traditional cyanoacrylate (CA) followed with BY40 application. Results from this study demonstrated that Lumicyano on its own developed fingermarks with superior quality to Lumicyano with sequential addition of BY40 or traditional cyanoacrylate followed by BY40. Inclusion of more fabrics, donors and longer ageing periods should be explored in future studies to determine what frameworks are best for certain types of fabrics.

Water absorption measurements on WPCs: Assessment of size and direction dependencies in order to design fast and accurate quality control tests

Abstract Wood-plastic composites (WPCs) are water-sensitive materials. Standards describe water absorption protocols on composites to obtain results after a long period of aging. From an industrial point of view, it is necessary to obtain the same information (i.e. equilibrium water content and absorption kinetics) over a short time. In this paper, we propose a new immersion aging protocol based on cubes taken from a reference WPC. This new methodology was validated by varying several test parameters (temperature, sample size, etc.) and applying it to other WPCs. Cubic samples were found to diverge from a Fickian behavior after a certain time of aging because of swelling and cracking that creates another characteristic pore scale and an increase of diffusion coefficient. Compared to the same formulation of cubic samples, the plate samples usually used for water absorption didn't crack. Fick's law approximation was used to determine the diffusion coefficient on plate materials. The coefficients measured in the three directions of WPC decks and a 3D model enabled us to recalculate the apparent coefficient of cubic samples for short-term absorption. Comparison of diffusion coefficients for short and long-term absorption showed the water concentration dependence of composites. Long-term diffusion coefficients and swelling stress coefficients were used in the pseudo-Fickian model to predict the water absorption behavior for composites undergoing water concentration dependence.

1D N-type SnO2 nanofibers coexisted with P-type Co3O4 cubes for highly selective acetone sensor

1D n-type SnO2 nanofibers coexisted with p-type Co3O4 particles were synthesized by electrospinning with subsequent hydro-thermal process. The morphology and composition of Co3O4/SnO2 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). XRD patterns showed that the synthesized Co3O4/SnO2 were assigned to cubic Co3O4 and tetragonal rutile structure of SnO2 without any other impurity peaks. A possible growth mechanism was proposed to describe the formation of hierarchical SnO2 nanofibers coexisted with Co3O4 cubes. The Co3O4/SnO2 compound exhibited a relatively highly selective response to acetone and stable acetone sensing performance after a long period of aging. The Co3O4/SnO2 compound had a p-type response. It may be ascribed to the high coverage of p-type Co3O4 on n-type SnO2. The excellent acetone sensing properties of Co3O4/SnO2 nanostructures may be attributed to p-n junctions between Co3O4 and SnO2 nanograins as well as the unique coexistence structure of nanofibers and cubes.

Study on Microcosmic Characteristics of Gussasphalt after Superheat Aging based on FTIR Technology

Gussasphalt concrete has many excellent characteristics, such as good impermeability, strength, elasticity and so on. In recent years, it has been widely used in large and medium bridges, especially in steel deck pavement. But different from ordinary mixture, gussasphalt needs to undergo long period of high temperature aging during mixing and transportation. In order to reveal the microscopic mechanism of superheat aging of gussasphalt, fourier transform infra-red spectroscopy (FTIR) is mainly used in this paper. The changes of functional groups of gussasphalt before and after aging were analyzed from the microscopic point of view. The results show that there is no new absorption peak of lake asphalt when it is added to the matrix asphalt, the asphalt is mainly physically modified by lake asphalt, and the aging degree of gussasphalt can be quantitatively characterized by carbonyl coefficient.

Retail Display Properties and Consumer Perception of Extended Aged Beef Topically Treated with Ascorbic Acid and Rosemary Extract

Extended aging increases browning and decreases redness in fresh beef. The goal of this study was to test an already proven combination of antioxidants (0.05% ascorbic acid + 0.1% rosemary extract) using a method that could be applied at the retail level to simply and effectively extend the shelf-life of extended aged beef. The specific objective was to analyze the effect of topical application of ascorbic acid and rosemary extract on color, lipid oxidation, microbial growth, and sensory perception of beef longissimus lumborum (LL; n = 12) and semimembranosus (SM; n = 12) muscles wet aged at 0°C for 14, 28, and 42 (extended aging period) days. After aging, steaks were cut, sprayed with 2 mL of a 0.05% ascorbic acid + 0.1% rosemary extract solution (treated) or untreated (control), and subjected to retail display. Antioxidant treated LL steaks had greater (P &lt; 0.05) L* (lightness) values, but lower (P &lt; 0.05) a* (redness) and b* (yellowness) values than control steaks. Furthermore, antioxidant treatment decreased (P &lt; 0.05) browning on d 4 of retail display compared to control steaks. Consumers scored antioxidant treated SM steaks as less tender on d 28, more juicy on d 14 but less juicy on d 18 and 42. Antioxidant treatment did not affect lipid oxidation, microbial growth, or sensory flavor scores. As expected, longer aging periods resulted in less color stability of LL and SM steaks. Although the antioxidant treatment resulted in measurable subjective color improvements, these improvements are likely not detectable by the consumer.

Utilization of the Crust from Dry-aged Beef to Enhance Flavor of Beef Patties.

The crust that inevitably forms on dry-aged beef is usually trimmed and discarded before sale. The aim of this study was to explore methods for utilizing this crust in processed meat products. Four sirloins were dry-aged for 28 d at 4℃ (75% relative humidity). The crust obtained from the surface of the sirloins after completion of dry aging was lyophilized. Patties were prepared without added crust (control) or with 5% w/w crust, aerobically packaged, and stored at 4℃ for 7 d. Electronic nose analysis indicated that the volatile profile differed significantly between the patties with and without crust. Compared to the control patties, patties containing crust had higher flavor, tenderness, juiciness, and acceptability scores in a sensory panel evaluation (all p<0.05). In addition, patties with crust were less hard, gummy, and chewy than the control patties after 3 and 7 d of storage (all p<0.05). The number of total aerobic bacteria was higher in raw patties with crust than in the control patties during the storage (p<0.05). However, no pathogens were detected. 2-Thiobarbituric acid reactive substance values of patties containing crust were significantly lower than those of control patties after 2 and 6 d of storage (both p<0.05). Thus, crust from dry-aged beef can enhance the flavor by providing beefy and palatable flavor without a long period of dry aging.

Dynamic Oxidative Potential of Atmospheric Organic Aerosol under Ambient Sunlight.

The atmospheric process dynamically changes the chemical compositions of organic aerosol (OA), thereby complicating the interpretation of its health effects. In this study, the dynamic evolution of the oxidative potential of various OA was studied, including wood combustion particles and secondary organic aerosols (SOA) generated from different hydrocarbons (i.e., gasoline, toluene, isoprene, and α-pinene). The oxidative potential of OA at different aging stages was subsequently measured by the dithiothreitol consumption (DTTm, mass normalized). We hypothesized that DTT consumptions by OA were modulated by catalytic particulate oxidizers (e.g., quinones), noncatalytic particulate oxidizers (e.g., organic hydroperoxides and peroxyacyl nitrates) and electron-deficient alkenes. The results of this study showed that the oxidative potential of OA decreased after an extended period of aging due to the decomposition of particulate oxidizers and electron-deficient alkenes. Quinones (GC-MS data) partially attributed to the DTTm of fresh wood smoke particles but rapidly dropped with aging. In biogenic SOA, organic hydroperoxides (4-nitrophenyl boronic acid assay) exclusively accounted for DTTm and decreased with aging. The DTTm of aromatic SOA, mainly comprising organic hydroperoxides and electron-deficient alkenes (FTIR data), was shortly elevated during the early atmospheric process; however, it showed a noticeable decrease (32-75%) for a long period of aging. We concluded that fresh or moderately aged OA are more reactive to a sulfhydryl group than highly aged OA.