Effects of Dual-Frequency Ultrasound-Assisted Thawing Technology on Thawing Rate, Quality Properties and Microstructure of Large Yellow Croaker (Pseudosciaena crocea)

This research evaluated the effects of dual-frequency ultrasound-assisted thawing (UAT) on the thawing time, physicochemical quality, water-holding capacity (WHC), microstructure, and moisture migration and distribution of large yellow croaker. Water thawing (WT), refrigerated thawing (RT), and UAT (single-frequency: 28 kHz (SUAT-28), single-frequency: 40 kHz (SUAT-40), dual-frequency: 28 kHz and 40 kHz (DUAT-28/40)) were used in the current research. Among them, the DUAT-28/40 treatment had the shortest thawing time, and ultrasound significantly improved the thawing rate. It also retained a better performance from the samples, such as color, texture, water-holding capacity and water distribution, and inhibited disruption of the microstructure. In addition, a quality property analysis showed that the pH, total volatile basic nitrogen (TVB-N), and K value were the most desirable under the DUAT-28/40 treatment, as well as this being best for the flavor of the samples. Therefore, DUAT-28/40 treatment could be a possible thawing method because it improves the thawing rate and maintains the quality properties of large yellow croaker.

Thawing rate and heating temperature effects on immunoglobulin A and lysozyme activity in human milk

BackgroundThe rate of infants receiving frozen HM is increasing, allowing critically ill preterm infants and infants with working mothers to benefit from the advantages of their mother's milk. The effects of thawing and warming on secretory immunoglobulin A (SIgA) and lysozyme activity in frozen human milk (HM) should be investigated to identify optimal methods for preserving immune factors in frozen HM.MethodsForty mothers that delivered full-term infants provided milk that was frozen and stored at -18°C two months before analyses. We compared the methods involving placing the container in a 4°C refrigerator overnight (slow thawing, ST) and placing it in a container of warm water (rapid thawing, RT). Additionally, we investigated the effect of warming temperature using room temperature (25°C) and physiological temperature (37°C). SIgA concentrations and lysozyme activities in the milk samples were determined by ELISA kits and fluorometric lysozyme activity assay kits, respectively. Data were analyzed by paired t-tests.ResultsSIgA concentrations and lysozyme activity were reduced by 16.5-52.1% and 16.8-39.3% in frozen HM compared to fresh HM, respectively. Significantly higher SIgA concentrations were maintained with slow thawing and warming at 37°C than with rapid thawing and warming at 25°C (p <0.001). Greater lysozyme activity was retained at 25°C with slow thawing than with rapid thawing (p <0.001) and more was preserved at 25°C than at 37°C with slow thawing (p <0.01).ConclusionsThawing HM overnight in the refrigerator before warming has the potential to preserve SIgA levels and lysozyme activity better than thawing immediately after removal from the freezer. Broader temperatures ranges should be analyzed to determine the temperature that minimizes HM SIgA and lysozyme activity losses.Trial registrationNot applicable

Physicochemical properties of frozen tuna fish as affected by immersion ohmic thawing and conventional thawing

One of the key points in the frozen food processing is thawing with minimal damage to the quality. Since the commonly used methods for thawing of foods are slow and reduce the quality of the product, application of an efficient method seems necessary. In this research, thawing of tuna fish was performed by immersion ohmic method. Thawing rate roles a vital key in the quality and significantly increased by ohmic ([Formula: see text], the mean of ohmic group) in comparison with conventional thawing ([Formula: see text], the mean of conventional group) methods. Immersion ohmic thawing increased rate of thawing about 5 times. Parameters important in quality such as T-VBN, protein solubility, thawing evaporation loss, pH, thawing loss and press juice were measured. Group analyses showed significant difference between ohmic and conventional treatment in protein solubility, thawing evaporation and thawing loss (p < 0.05).

Methods for Measuring Frost Tolerance of Conifers: A Systematic Map

Frost tolerance is the ability of plants to withstand freezing temperatures without unrecoverable damage. Measuring frost tolerance involves various steps, each of which will vary depending on the objectives of the study. This systematic map takes an overall view of the literature that uses frost tolerance measuring techniques in gymnosperms, focusing mainly on conifers. Many different techniques have been used for testing, and there has been little change in methodology since 2000. The gold standard remains the field observation study, which, due to its cost, is frequently substituted by other techniques. Closed enclosure freezing tests (all non-field freezing tests) are done using various types of equipment for inducing artificial freezing. An examination of the literature indicates that several factors have to be controlled in order to measure frost tolerance in a manner similar to observation in a field study. Equipment that allows controlling the freezing rate, frost exposure time and thawing rate would obtain results closer to field studies. Other important factors in study design are the number of test temperatures used, the range of temperatures selected and the decrements between the temperatures, which should be selected based on expected frost tolerance of the tissue and species.

4D-Quantification of alpine permafrost degradation in a bedrock ridge using multiple inversion schemes and deformation measurements

&lt;p&gt;Warming of permafrost in steep rock walls decreases their mechanical stability and could triggers rockfalls and rockslides. However, the direct link between climate change and permafrost degradation is seldom quantified with precise monitoring techniques and long-term time series. Where boreholes are not possible, laboratory-calibrated Electrical Resistivity Tomography (ERT) is presumably the most accurate quantitative permafrost monitoring technique providing a sensitive record for frozen vs. unfrozen bedrock. Recently, 4D inversions allow also quantification of frozen bedrock extension and of its changes with time (Scandroglio et al., in review).&lt;/p&gt;&lt;p&gt;In this study we (i) evaluate the influence of the inversion parameters on the volumes and (ii) connect the volumetric changes with measured mechanical consequences.&lt;/p&gt;&lt;p&gt;The ERT time-serie was recorded between 2006 and 2019 in steep bedrock at the permafrost affected Steint&amp;#228;lli Ridge (3100 m asl). Accurately positioned 205 drilled-in steel electrodes in 5 parallel lines across the rock ridge have been repeatedly measured with similar hardware and are compared to laboratory temperature-resistivity (T&amp;#8211;&amp;#961;) calibration of water-saturated samples from the field. Inversions were conducted using the open-source software BERT for the first time with the aim of estimating permafrost volumetric changes over a decade.&lt;/p&gt;&lt;p&gt;(i) Here we present a sensitivity analysis of the outcomes by testing various plausible inversion set-ups. Results are computed with different input data filters, data error model, regularization parameter (&amp;#955;), model roughness reweighting and time-lapse constraints. The model with the largest permafrost degradation was obtained without any time-lapse constraints, whereas constraining each model with the prior measurement results in the smallest degradation. Important changes are also connected to the data error estimation, while other setting seems to have less influence on the frozen volume. All inversions confirmed a drastic permafrost degradation in the last 13 years with an average reduction of 3.900&amp;#177;600&amp;#160;m&lt;sup&gt;3&lt;/sup&gt; (60&amp;#177;10% of the starting volume), well in agreement with the measured air temperatures increase.&lt;/p&gt;&lt;p&gt;(ii) Average bedrock thawing rate of ~300 m&lt;sup&gt;3&lt;/sup&gt;/a is expected to significantly influence the stability of the ridge. Resistivity changes are especially evident on the south-west exposed side and in the core of the ridge and are here connected to deformations measured with tape extensometer, in order to precisely estimate the mechanical consequences of bedrock warming.&lt;/p&gt;&lt;p&gt;In summary, the strong degradation of permafrost in the last decade it&amp;#8217;s here confirmed since inversion settings only have minor influence on volume quantification. Internal thermal dynamics need correlation with measured external deformation for a correct interpretation of stability consequences. These results are a fundamental benchmark for evaluating mountain permafrost degradation in relation to climate change and demonstrate the key role of temperature-calibrated 4D ERT.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Reference:&lt;/p&gt;&lt;p&gt;Scandroglio, R. et al. (in review) &amp;#8216;4D-Quantification of alpine permafrost degradation in steep rock walls using a laboratory-calibrated ERT approach&amp;#8217;, &lt;em&gt;Near Surface Geophysics&lt;/em&gt;.&lt;/p&gt;

Characterization of an optical signature of the DOM of the coastal permafrost in the Mackenzie delta, by PARAFAC analysis

&lt;p&gt;&lt;span&gt;&lt;span&gt;Global warming increases the thawing rate of the permafrost in high northern latitudes. The Arctic soil organic carbon accounts for over 50% of global soil carbon which is roughly twice the amount present in the atmosphere. An increasing amount of the newly mobilized old organic carbon, and its associated compounds, originating from permafrost thaw, is expected to be delivered to the Arctic Ocean by rivers and groundwater discharges all along the Arctic coastline. Absorbance and fluorescence spectroscopy can be used to identify a specific optical signature of permafrost-derived solutes with the objective of studying their transport and transformation to coastal waters. &lt;/span&gt;&lt;/span&gt;&lt;span&gt;Emission-excitation spectra (EEMs) from three sampling sites along the coastal area of the delta were assessed and parallel factor analysis (PARAFAC) was used to identify three different components characterizing the origin and the nature of the organic carbon present in various types of samples (massive ice, groundwater, seawater and water samples on top/bottom of slumps). This study suggests that the carbon originating from the thawing of the permafrost could indeed be traced along the coastal area of the Delta. &lt;/span&gt;&lt;/p&gt;

Cryopreservation: The secret of modern preservation of brewer’s yeasts – minireview

The aim of the long-term preservation of cells, tissues and organs is to maintain their cellular structures and biological functions for as long as possible. Cryopreservation is a process where biological material is stored and preserved at very low temperatures. However, freezing and thawing processes can cause irreversible cell damage, which is related to formation of ice crystals, osmotic stress, accumulation of reactive forms of oxygen, etc. Therefore the cell viability depends mainly on the freezing rate, the composition of the cryoprotective medium as well as on the thawing rate. Using a suitable cryoprotective medium can increase the viability rate of the yeasts after “revitalization“. Appropriate pre-cultivation before freezing also plays an important role. These facts show that cell freezing and thawing processes must be controlled to avoid cell damage.