Frozen Period Research Articles

OPTIMALIZACE PROCESU MRAŽENÍ VEPŘOVÉHO A HOVĚZÍHO MASA PRO VÝROBU FERMENTOVANÉHO "MÉTSKÉHO SALÁMU"

In this work, the level of microbial contamination of pork and beef meat for processing of heat-untreated fermented meat products was monitored. In company providing samples for this work, meat was kept frozen for period of 6 days (144 hours), which was not effective due to the financialy expensive frozing storages. The relationship between meat freezing period and number of selected technological as well as hygienical significant microorganisms was monitored, with the aim to optimize frozing period to keep microbial quality of meat and meat products. Microbiological analysis of meat samples was performed before freezing of meat and after 48, 72, 96, 120 and 144 hours of freezing. Furthermore, the analysis was carried out after 7 and 21 days of meat products storing period. Total number of microorganisms, total number of psychrotrophic microorganisms, yeast and fungi, co­li­forms, bacteria of the genus Enterococcus and bacteria of the family Enterobacteriaceae were detected. As from results, sufficient period for meat freezing was 72 hours. After this period total count of microorganisms as well as bacteria of the family Enterobacteriaceae, coliforms bacteria and bacteria of the genus Enterococcus reached the level, which at next freezing was not influenced. Number of psychrotrophic microorganisms were growing by next prolonging of freezing period, above 72 hours. Numbers of yeast and moulds became almost unchanged during the whole freezing period.

Effect of freezing on protein denaturation and gelling capacity of jumbo squid (Dosidicus gigas) mantle muscle

The effect of freezing storage on protein denaturation and gelling capacity of jumbo squid muscle was evaluated. Squid mantle muscle samples were evaluated in both, ground (G) and whole presentations (W), and in a control consisting of ground muscle (C). G and W samples were submitted to two freezing storage periods (−20 °C), 1 day (GF-1, WF-1) and 30 d (GF-30, WF-30). Proximate composition, pH, surface hydrophobicity (SoANS) and differential scanning calorimetry (DSC) were evaluated. Additionally folding test, texture profile analysis and water holding capacity were monitored in gels prepared with the different samples. The quality of gels was not affected by any treatment. Neither freezing, grinding or storage period had a significant effect on the above parameters, suggesting that functional properties of the squid mantle muscle are highly stable. DSC did not reveal any denaturation, also adducing high stability of muscle proteins. SoANS revealed that freezing, grinding and time, had an effect on protein properties; however, these influences were apparently not significantly enough to have a further effect on the gel quality. Finally, gelling capacity of muscle was not affected by any factor. Considering these results, squid muscle may be considered as a useful resource either fresh or frozen.

Statistical correlation between meteorological and rockfall databases

Abstract. Rockfalls are a major and essentially unpredictable sources of danger, particularly along transportation routes (roads and railways). Thus, the assessment of their probability of occurrence is a major challenge for risk management. From a qualitative perspective, it is known that rockfalls occur mainly during periods of rain, snowmelt, or freeze–thaw. Nevertheless, from a quantitative perspective, these generally assumed correlations between rockfalls and their possible meteorological triggering events are often difficult to identify because (i) rockfalls are too rare for the use of classical statistical analysis techniques and (ii) not all intensities of triggering factors have the same probability. In this study, we propose a new approach for investigating the correlation of rockfalls with rain, freezing periods, and strong temperature variations. This approach is tested on three French rockfall databases, the first of which exhibits a high frequency of rockfalls (approximately 950 events over 11 years), whereas the other two databases are more typical (approximately 140 events over 11 years). These databases come from (1) national highway RN1 on Réunion, (2) a railway in Burgundy, and (3) a railway in Auvergne. Whereas a basic correlation analysis is only able to highlight an already obvious correlation in the case of the "rich" database, the newly suggested method appears to detect correlations even in the "poor" databases. Indeed, the use of this method confirms the positive correlation between rainfall and rockfalls in the Réunion database. This method highlights a correlation between cumulative rainfall and rockfalls in Burgundy, and it detects a correlation between the daily minimum temperature and rockfalls in the Auvergne database. This new approach is easy to use and also serves to determine the conditional probability of rockfall according to a given meteorological factor. The approach will help to optimize risk management in the studied areas based on their meteorological conditions.

Past freeze and thaw cycling in the margin of the El'gygytgyn crater deduced from a 141 m long permafrost record

Abstract. The continuous sediment record from Lake El'gygytgyn in the northeastern Eurasian Arctic spans the last 3.6 Ma and for much of this time permafrost dynamics and lake level changes have likely played a crucial role for sediment delivery to the lake. Changes in the ground-ice hydrochemical composition (δ18O, δD, pH, electrical conductivity, Na+, Mg2+, Ca2+, K+, HCO3-, Cl-, SO4-) of a 141 m long permafrost record from the western crater plain are examined to reconstruct repeated periods of freeze and thaw at the lake edge. Stable water isotope and major ion records of ground ice in the permafrost reflect both a synsedimentary palaeo-precipitation signal preserved in the near-surface permafrost (0.0–9.1 m core depth) and a post-depositional record of thawing and refreezing in deeper layers of the core (9.1–141.0 m core depth). These lake marginal permafrost dynamics were controlled by lake level changes that episodically flooded the surfaces and induced thaw in the underlying frozen ground. During times of lake level fall these layers froze over again. At least three cycles of freeze and thaw are identified and the hydrochemical data point to a vertical and horizontal talik refreezing through time. Past permafrost thaw and freeze may have destabilised the basin slopes of Lake El'gygytgyn and this has probably promoted the release of mass movements from the lake edge to the deeper basin as known from frequently occurring turbidite layers in the lake sediment column.

Dynamics of greenhouse gas formation in relation to freeze/thaw soil depth in a flooded peat marsh of Northeast China

Flooded peat wetlands are an important global carbon pool and are relatively sensitive to frost degeneration due to global climate change. To study the dynamics of greenhouse gas (GHG) formations in the soil of a flooded peat marsh in response to freeze–thaw processes, CO2, CH4 and N2O fluxes and gas concentrations at different soil depths were measured in a flooded peat marsh in Northeast China during a freeze–thaw period (from November 2004 to July 2005). During the freeze period, the gas concentrations underneath the frozen soil increased as the freeze developed until the soil completely froze in the root (15−35 cm) and peat (35−80 cm) layers. The highest gas concentrations accumulated in the gley layer (80−120 cm) when the greatest freeze depth formed. During the thaw period, the gas concentrations increased above the frozen layer (15−60 cm); in contrast, the gas concentrations underneath the frozen layer (60–120 cm) rapidly decreased when the bottom of the frozen layer began to thaw. GHG emissions from the marsh were not correlated with gas concentrations underneath the frozen layer during the freeze period but were significantly correlated with gas concentrations above the frozen layer (15−60 cm) during the thaw period. The study suggested that large changes in GHG formation dynamics occurred underneath the frost in the flooded peat marsh when the frost began to thaw due to gas physical diffusion within the peat layer.

Freezing period strongly impacts the emergence of a global consensus in the voter model

It is well known that human beings do not always change opinions or attitudes, since the duration of interaction with others usually has a significant impact on one's decision-making. Based on this observation, we introduce a freezing period into the voter model, in which the frozen individuals have a weakened opinion switching ability. We unfold the presence of an optimal freezing period, which leads to the fastest consensus, using computation simulations as well as theoretical analysis. We demonstrate that the essence of an accelerated consensus is attributed to the biased random walk of the interface between adjacent opinion clusters. The emergence of an optimal freezing period is robust against the size of the system and the number of distinct opinions. This study is instructive for understanding human collective behavior in other relevant fields.

Evaluation of Fertilizing Ability using Frozen Thawed Sperm in the Longtooth Grouper, Epinephelus bruneus.

This study examines the effects on fertilization rate (FR), hatching rate (HR), and normal individual rate after artificial fertilization using frozen thawed sperm according to the cryoprotectant (DMSO) concentration and the period of cryopreserved sperm of longtooth grouper, Epinephelus bruneus. Performing artificial fertilization using frozen-thawed sperm, after freezing the sperm at different DMSO concentration of 5.0%, 7.5%, 10.0% respectively, FR were (DMSO 5.0%: 99.5±0.8%, DMSO 7.5%: 99.5±0.7%, and DMSO 10.0%: 99.6±0.6%). The results are not significantly different from the control fresh sperm (100%). HR also (DMSO 5.0%: 96.2±2.3%, DMSO 7.5%: 95.3±3.6%, 10.0%: 96.6±1.8%) were not significantly different in each group. The normal individual rate after hatching using with control fresh sperm (98.4%±0.5) and DMSO concentration level of 5.0% (97.8±0.1%) were not significantly different. However, with 7.5% (97.2±0.6%) and 10.0% DMSO concentrations (95.9±0.2%) are lower than the normal individual rate after hatching observed in the control and 5.0% DMSO. Performing artificial fertilization using frozen-thawed sperm at different frozen period (2 days, 2 years, and 3 years), 10% DMSO FR and HR of 3 years (FR; 66.8±1.8%, HR: 82.0±12.9%) and 2 years (FR; 78.5±14.8%, HR: 79.3±0.6%) cryopreserved sperm were lower than control (FR; 100%, HR: 91.1±3.6%) and 2 days cryopreserved sperm (FR; 99.6±0.6%, HR: 96.6±1.8%). These results suggest suitable DMSO concentration ranges of cryopreservation sperm for E. bruneus is 5 to 10% and with 2 to 3 years cryopreservation period, cryopreservation sperm can be useful for seed production.

Abnormal patterns of theta frequency oscillations during the temporal evolution of freezing of gait in Parkinson’s disease

ObjectiveWe sought to characterize the electrophysiological signature of Freezing of gait in Parkinson’s disease. MethodsWe examined 24 patients with idiopathic Parkinson’s disease and significant freezing of gait as they performed a series of timed up-and-go tasks in their ‘off’ state while electroencephalographic data was collected from four scalp leads. Fast Fourier Transformation was utilized to explore the power spectral density between periods of normal walking and periods of freezing, as well as during the transition between the two states. In addition, Cross Spectrum and Cross Frequency analyses were used to explore the role of impaired temporal and spatial connectivity. ResultsWhen compared to walking, episodes of freezing were associated with a significant increase in theta band power within the central and frontal leads. The transition from normal walking to freezing of gait was also associated with increased theta frequency coupling between the central and frontal leads, along with an increase in cross-frequency coupling in the central lead. ConclusionsEpisodes of freezing of gait in Parkinson’s disease are associated with abnormal oscillatory activity in the brain. SignificanceThese results provide novel insights into the pattern of spatiotemporal dynamics underlying freezing of gait and may provide a potential means for therapeutic prediction and alleviation of freezing episodes in susceptible patients.

Habitat-dependent population recovery in the Dartford Warbler Sylvia undata following a severe winter episode

Capsule After a population crash following a long period of winter freezing and snow blanketing the ground, Dartford Warblers underwent a population recovery, positive in heathlands but non-existent in nearby early-growth forest. Aims To estimate the impact of a severe winter episode on the population size of Dartford Warblers in two habitats, heathland and early-growth forest. Methods We analysed data collected on 124 point counts in three successive years, 1 year before and 2 years after the cold spell. We first estimated trends in detected numbers in the two habitats. Second, we used distance sampling and capture–recapture approaches to estimate global population sizes corrected for detection probability, verifying that the observed trends were not biased by detection probability. Results Warbler populations crashed after the severe winter in 2008–9, while numbers increased in spring 2010 only on heathlands, not in early-growth forests. Variation in detection probability alone could not explain this difference. Conclusion After the severe winter episode, Dartford Warblers showed a short-term population recovery only in heathland.

Mechanism Analysis of Subgrade Frost Heaving in Seasonally Frozen Regions

AbstractTo elucidate the frost heaving mechanism of subgrade, as well as reduce cracking, subsidence, and mudding due to water freezing and thawing in seasonally frozen regions, temperature sensors were embedded in the subgrade in a heavily frozen region to automatically monitor subgrade temperature during freeze periods. A drilling investigation was also conducted to determine the typical disease caused by road frost. Results show that (1) The upper roadbed exhibited a wide cooling range and a high cooling rate. (2) The lower roadbed exhibited a narrow cooling range and a low cooling rate; sufficient moisture transfer and accumulation occurred. The depth of the ice accumulation zone is found in this roadbed. (3) Different ice formations developed on various subgrade soils, and the depth and moisture content of these formations presented some regularity. (4) The mean depth of the ice accumulation zone was 1.08 m to 1.65 m, and the scope of mean moisture content was 14.7% to 23%. The maximum moisture conte...

The Influence of Packaging Type and Time of Frozen Storage on Antioxidative Properties of Brussels Sprouts

Food-processing operations have a major influence on the stability of phytochemicals in vegetables and their products apart the preharvest factors. The optimization of food processing and storage factors is very important to reduce the degradation of phytochemicals. The aim of this study was to investigate the influence of packaging type, namely zipper bags (low-density polyethylene) and plastic boxes (oriented polystyrene), on some antioxidative properties of frozen stored Brussels sprouts. In the present study, vegetables were subjected to the process of blanching, freezing and 3-month period of frozen storage and were compared at each stage of the study, the content of dry matter, vitamin C, β-carotene, total polyphenols and antioxidant activity. Studies have shown that vegetables stored in frozen conditions for a period of 3 months, in two types of packaging, were characterized by a similar content of dry matter, vitamin C and β-carotene. Brussels sprouts stored in zipper bags contained a significantly higher content of total polyphenols, and showed a trend to a higher antioxidant activity than those in the plastic boxes. Practical Applications Brussels sprouts belong to the group of vegetables, which are subjected to this process on an industrial scale. The quality of frozen product depends primarily on the initial quality of raw material. A very important step in the process of freezing is blanching. The aim of this study was to investigate changes in vitamin C, β-carotene, total polyphenols contents, as well as antioxidant activity in Brussels sprouts (Brassica oleracea var. Gemmifera), a variety of Ajax F1, as a result of blanching and freezing, and frozen storage for 3 months using two types of packaging, namely zipper bags (low-density polyethylene) and plastic boxes (oriented polystyrene). For the optimal frozen stored of these vegetables, the two kinds of packaging were considered.

艾比湖地区土壤呼吸对季节性冻土厚度变化的响应

As an special process for soils in the regions of high altitude,the freeze-thaw process directly or indirectly influences the physical,chemical and biological properties of soils. Under the background of the global warming,increasing attention has been paid to the effect of soil freezing-thawing alternation on carbon cycles. By measuring the changes of depth of seasonal frozen soil,of soil properties and soil respiration,our main objective was to provide insight into the responses of soil properties and soil respiration to changes in depth of seasonal frozen soil in arid area,and to further elaborate the effect of global warming on seasonal frozen soil and the resulted carbon release. Soil respiration rate( Rs) of Ebinur Lake area was measured from January to April in 2010 in the field using an automated CO 2 efflux system( LI-8100). Meanwhile, temperature( air temperature),atmospheric relative humidity and wind speed were measured 150 cm above the ground. Temperature,atmospheric relative humidity and wind speed were also measured at 10 cm above the ground,with a handheld weather instrument. Soil temperatures were measured at 5 cm,10 cm,15 cm,20 cm and 25 cm below soil surface with two geo-thermometers. The results showed that: during the frozen period,soil temperature is the most important factor determining the depth of frozen soil,while during thawing period,the depth of frozen soil was not influenced by temperature( P0.05). There was significant positive correlation between soil respiration rate and depth of frozen soil during most of the freezing period( R2= 0. 782,P0. 05),this correlation did not apply to the initial stage of freezing period( P0. 05). There was no significant difference in soil respiration rate between the freezing period and the initial stage of freezing period, but soil respiration rate significantly increased with the temperature during thawing period until the soil was unfrozen completely( the changes was 0. 14—0. 37μmol·m-2·s-1),indicating that permafrost melting significantly increased soil carbon emissions. Climate change impact on seasonal frozen soil depth,on the duration of frozen period,will change the seasonal crop production in permafrost regions. The natural vegetation biomass,spatial distribution pattern of vegetation and ranges of natural native plants distribution will also be changed. Even the plant community succession direction and patterns may also be altered by the changes in duration and depth of frozen soil. All those will affect the ecosystem carbon cycling process. The difference in soil respiration rate of different periods was influenced by soil organic content,snow-melt recharging to soil water and other factors,which may have a collectively effect on carbon cycle of the local ecosystem. Our preliminary findings in the current study revealed the impacts of seasonal frozen- thawing process on soil respiration in Ebinur Lake area,and provided theoretical basis for revealing carbon release mechanism during frozen-thawing processes under the background of global warming.

Spaceborne radar monitoring of soil freezing/thawing processes in the Arctic tundra

In this article, the possibility of measuring the average temperature in the active topsoil of the Arctic tundra from the temperature dependence of the radar backscattering coefficient is theoretically studied. The radar backscattering coefficient is simulated by the small perturbation method at a frequency of 1.26 GHz of radars placed onboard ALOS-2 and SMAP satellites. In simulation, the soil density, surface roughness, and temperature and moisture profiles measured in situ at the biosphere station Franklin Bluffs, Alaska (69°39′ N, 148°43′ W), from August 1, 2000 to July 1, 2001 were used. The soil permittivity was calculated for the generalized temperature-dependent refractive mixing dielectric model for organic rich soil whose sample was taken on the Alaska North Slope (68°38′N, 149°35′W). This model allows the complex dielectric constant of moist thawed and frozen soil to be calculated at temperatures in the range from –30°С to +25°С. It is demonstrated that the radar backscattering coefficient is correlated with the topsoil temperature with the error less than 5.7°С during the entire period of freezing and thawing.

Changes of lipids in insect (Rhynchophorus phoenicis) during cooking and storage

AbstractLipid stability of Rhynchophorus phoenicis (RP) larvae extract (edible oil) was evaluated, including the usual analytical indices and analysis by Fourier transform infrared (FTIR) spectroscopy at different periods of freezing, refrigeration storage conditions and cooking methods. A study of the quality of oil obtained showed that boiling before smoking reduced the acidity of the oil. Boiling, refrigeration for 3 days or more, freezing, sun drying, and electrical drying increased the acidity of the oil. Culinary and dehydration methods significantly increased the peroxide value, especially when boiling preceded dehydration. Cool storage had protective effects on lipid oxidation of RP larvae. Smoking methods produced good quality products.

The Study of Dynamic Changes of Sea Ice in Antarctic Nearly a Decade under the Context of Global Warming

This paper aimed to research the changes in sea-ice extent of the Antarctic region using moderate-resolution imaging spectroradiometer (MODIS) sea ice data. The procedure include: MODIS sea ice data, image layering, information extraction, data synthesis, estimation of sea ice extent. The results showed that: the sea ice has obviously seasonal dynamical changes, and been divided into freezing and melting periods; but the inter-annual variations of sea ice range is not obvious; In summary, the sea ice range displayed decreasing trend in the whole study area, but that showed different tendency in different year and waters area.

Model of the movement of the edge of ice in channel-type reservoirs under freezing conditions

A model of the movement of the edge of ice in channel-type reservoirs during a period of freezing of a water entity is developed. The model is verified in an example of the freezing of the reservoir under design for the Krasnogorsk HPP on the Irtysh River.

MicroRNA Regulation in Extreme Environments: Differential Expression of MicroRNAs in the Intertidal Snail Littorina littorea During Extended Periods of Freezing and Anoxia

Several recent studies of vertebrate adaptation to environmental stress have suggested roles for microRNAs (miRNAs) in regulating global suppression of protein synthesis and/or restructuring protein expression patterns. The present study is the first to characterize stress-responsive alterations in the expression of miRNAs during natural freezing or anoxia exposures in an invertebrate species, the intertidal gastropod Littorina littorea. These snails are exposed to anoxia and freezing conditions as their environment constantly fluctuates on both a tidal and seasonal basis. The expression of selected miRNAs that are known to influence the cell cycle, cellular signaling pathways, carbohydrate metabolism and apoptosis was evaluated using RT-PCR. Compared to controls, significant changes in expression were observed for miR-1a-1, miR-34a and miR-29b in hepatopancreas and for miR-1a-1, miR-34a, miR-133a, miR-125b, miR-29b and miR-2a in foot muscle after freezing exposure at −6°C for 24h (P<0.05). In addition, in response to anoxia stress for 24h, significant changes in expression were also observed for miR-1a-1, miR-210 and miR-29b in hepatopancreas and for miR-1a-1, miR-34a, miR-133a, miR-29b and miR-2a in foot muscle (P<0.05). Moreover, protein expression of Dicer, an enzyme responsible for mature microRNA processing, was increased in foot muscle during freezing and anoxia and in hepatopancreas during freezing. Alterations in expression of these miRNAs in L. littorea tissues may contribute to organismal survival under freezing and anoxia.

Decadal variability of soil CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;, NO, N&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O, and CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt; fluxes at the Höglwald Forest, Germany

Abstract. Besides agricultural soils, temperate forest soils have been identified as significant sources of or sinks for important atmospheric trace gases (N2O, NO, CH4, and CO2). Although the number of studies for this ecosystem type increased more than tenfold during the last decade, studies covering an entire year and spanning more than 1–2 years remained scarce. This study reports the results of continuous measurements of soil-atmosphere C- and N-gas exchange with high temporal resolution carried out since 1994 at the Höglwald Forest spruce site, an experimental field station in Southern Germany. Annual soil N2O, NO and CO2 emissions and CH4 uptake (1994–2010) varied in a range of 0.2–3.0 kg N2O-N ha−1yr−1, 6.4–11.4 kg NO-N ha−1yr−1, 7.0–9.2 t CO2-C ha−1yr−1, and 0.9–3.5 kg CH4-C ha−1yr−1, respectively. The observed high fluxes of N-trace gases are most likely a consequence of high rates of atmospheric nitrogen deposition (&gt;20 kg N ha−1yr−1) of NH3 and NOx to our site. For N2O, cumulative annual emissions were ≥ 0.8 kg N2O-N ha−1yr−1 in years with freeze-thaw events (5 out 14 of years). This shows that long-term, multi-year measurements are needed to obtain reliable estimates of N2O fluxes for a given ecosystem. Cumulative values of soil respiratory CO2 fluxes tended to be highest in years with prolonged freezing periods, i.e. years with below average annual mean soil temperatures and high N2O emissions (e.g. the years 1996 and 2006). Furthermore, based on our unique database on trace gas fluxes we analyzed if soil temperature, soil moisture measurements can be used to approximate trace gas fluxes at daily, weekly, monthly, or annual scale. Our analysis shows that simple-to-measure environmental drivers such as soil temperature or soil moisture are suitable to approximate fluxes of NO and CO2 at weekly and monthly resolution reasonably well (accounting for up to 59 % of the variance). However, for CH4 we so far failed to find meaningful correlations, and also for N2O the predictive power is rather low. This is most likely due to the complexity of involved processes and counteracting effects of soil moisture and temperature, specifically with regard to N2O production and consumption by denitrification and microbial community dynamics. At monthly scale, including information on gross primary production (CO2, NO), and N deposition (N2O), increased significantly the explanatory power of the obtained empirical regressions (CO2: r2 =0.8; NO: r2 = 0.67; N2O, all data: r2 = 0.5; N2O, with exclusion of freeze-thaw periods: r2 = 0.65).

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Management Insights

Soil moisture control over autumn season methane flux, Arctic Coastal Plain of Alaska

Abstract. Accurate estimates of annual budgets of methane (CH4) efflux in arctic regions are severely constrained by the paucity of non-summer measurements. Moreover, the incomplete understanding of the ecosystem-level sensitivity of CH4 emissions to changes in tundra moisture makes prediction of future CH4 release from the Arctic extremely difficult. This study addresses some of these research gaps by presenting an analysis of eddy covariance and chamber measurements of CH4 efflux and supporting environmental variables during the autumn season and associated beginning of soil freeze-up at our large-scale water manipulation site near Barrow, Alaska (the Biocomplexity Experiment). We found that the autumn season CH4 emission is significant (accounting for 21–25% of the average growing season emission), and that this emission is mostly controlled by the fraction of inundated landscape, atmospheric turbulence, and the decline in unfrozen water during the period of soil freezing. Drainage decreased autumn CH4 emission by a factor of 2.4 compared to our flooded treatment. Flooding slowed the soil freezing process which has implications for extending elevated CH4 emissions longer into the winter season.