Prolongation Of Storage Time Research Articles

The Morphology, Effects of Temperature and Photoperiod on Pseudopupal Diapause and Low Temperature Storage of Epicauta impressicornis (Coleoptera: Meloidae)

The gross morphology of each phase of the hypermetamorphic development of Epicauta impressicornis Pic (Coleoptera: Meloidae) was observed. The effects of temperature and photoperiod on pseudopupal (5th instar larva) diapause and low temperature storage on eggs and pseudopupae were determined. Low temperatures had a dominant effect on diapause incidence, regardless of the photoperiod. Pseudopupae stored at temperatures lower than 18 °C entered diapause, but completed their development without entering diapause at 21, 24, and 27 °C. The critical temperature for inducing diapause was between 16 °C and 16.5 °C, regardless of the photoperiod. The viability of low temperature storage of eggs and pseudopupae decreased with prolongation of storage time. The optimal storage condition for both eggs and pseudopupae was 4 °C for 30 days. Our results will provide a theoretical basis for additional studies on the biological characteristics of E. impressicornis and will also function as a prerequisite basic reference for the artificial large-scale rearing of E. impressicornis.

Fertilization by short-term stored sperm alters DNA methylation patterns at single-base resolution in common carp (Cyprinus carpio) embryos

Sperm after short-term storage in vitro is widely used for artificial fertilization in aquaculture. It has been shown that short-term storage affects sperm motility characteristics, resulting in diminished fertility. However, the detrimental effects of short-term sperm storage on embryos development have remained unexplored in single-base methylome resolution. The main aim of the present study was to investigate DNA methylation in the offspring of common carp (Cyprinus carpio) derived from short-term stored sperm. Sperm were stored in artificial seminal plasma on ice (0–2 °C) for 0, 3 and 6 days in vitro, fertilization was performed using oocytes from a single female, and embryos were collected at the mid-blastula stage. In the DNA methylation study, DNA from both sperm and embryos was extracted and analysed using liquid chromatography with tandem mass spectrometry (LC–MS/MS). Concurrently, DNA methylation levels of embryos in single base were evaluated through whole genome bisulfite sequencing (WGBS). Sperm storage showed negative effects on sperm motility, viability, and DNA integrity, but had no effect on global DNA methylation of spermatozoa and resulting embryos. Results from the WGBS showed that methylation of 3313 differentially methylated regions (DMRs)-target genes was affected in the embryos fertilized with the 6-day-stored sperm, and the identified DMRs were mainly involved in cell adhesion, calcium, mitogen-activated protein kinase and adrenergic signalling, melanogenesis, metabolism and RNA transport. Such results suggest that prolongation of storage time may have certain impacts on embryonic development. These initial results provide valuable information for future consideration of the DNA methylome in embryos generated from short-term stored sperm, which are used for genetic management of broodstock in aquaculture.

The Optimal Storage Condition and Storage Time of Umbilical Cord Blood from Collection to Preparation

To explore the optimal storage condition and time of umbilical cord blood from collection to preparation. Collect cord blood samples from 30 healthy newborns, with each new born's umbilical cord blood was divided into two parts on average. One part was stored in cold storage (4 ℃) and the other was stored at room temperature (20-24 ℃). Samples were taken at 24, 36, 48, 60 and 72 h, respectively, total nucleated cells (TNC) count and TNC viability was analyzed. Flow cytometry was used to detect the ratio of viable CD34+ cells to viable CD45+ cells and viability of CD34+ cells, and colony-forming unit-granulocyte-macrophage (CFU-GM) count was performed by hematopoietic progenitor cell colony culture. The change trend of each index over time was observed, and the differences in each index was compared between cold storage and room temperature storage under the same storage time. The TNC count (r 4 ℃=-0.9588， r 20-24 ℃=-0.9790), TNC viability (r 4 ℃=-0.9941， r 20-24 ℃=-0.9970), CD34+ cells viability (r 4 ℃=-0.9932， r 20-24 ℃=-0.9828) of cord blood stored in cold storage (4 ℃) and room temperature storage (20-24 ℃) showed a consistent downward trend with the prolongation of storage time. The percentage of viable CD34+ cells (r 4 ℃=0.9169， r 20-24 ℃=0.7470) and CFU-GM count (r 4 ℃=-0.2537， r 20-24 ℃=-0.8098) did not show consistent trends. When the storage time was the same, the TNC count, TNC viability, CD34+ cells viability and CFU-GM count of cord blood stored in cold storage were higher than those stored at room temperature. Under the same storage time (24, 36, 48, 60 or 72 h), TNC viability in room temperature storage was significantly lower than that in cold storage (P <0.001), but TNC count, percentage of viable CD34+ cells and CFU-GM count were not significantly different between room temperature storage and cold storage. When stored at room temperature for 24 h and 36 h, the viability of CD34+ cells was significantly lower than that in cold storage (P <0.001, P <0.01), when the storage time for 48, 60 and 72 h, there was no significant difference in the CD34+ cells viability between room temperature storage and cold storage. It is recommended that cord blood be stored in cold storage (4 ℃) from collection to preparation, and processed as soon as possible.

Quality assessment of the preparation and storage of leukocyte-depleted pooled platelet concentrates

ABSTRACT Objective: To explore the feasibility of using a disposable platelet storage bag containing a leukocyte filter to prepare leukocyte-depleted pooled platelet concentrates with the buffy coat method. Methods: 150 bags of whole blood samples (400 mL/bag) were stored overnight at 22 ± 2°C, and buffy coats were separated on Day 2, then 5 units of ABO homotypic buffy coat and 1 unit of plasma were pooled into a disposable platelet storage bag containing a leukocyte filter to prepare leukocyte-depleted pooled platelet concentrates and stored in a Platelet Agitator. On Day 2, 4, 5 and 7 after the collection of whole blood, platelet content, pH value, pO2, pCO2, glucose (GLU), ATP, and other quality indicators were measured. Results: The quality indicators of leukocyte-depleted pooled platelet concentrates met the requirements for leukocyte-depleted aphaeresis platelets in the Chinese national standard Quality Requirements for Whole Blood and Blood Components (GB18469-2012). With the prolongation of storage time, MPV and PDW of platelets gradually increased, pH value, bicarbonate, and GLU gradually decreased, LA, LDH, and ATP gradually increased, pO2 slightly increased, pCO2 decreased, and HSR had no significant change. ESC decreased significantly on Day 7, CD62p decreased first and then increased, sP-selectin and GP V increased first and then decreased, but the results on Day 7 were higher than those on Day 2. Conclusion: The quality of leukocyte-depleted pooled platelet concentrates prepared by the buffy coat method using disposable platelet storage bags containing a leukocyte filter was comparable to that of leukocyte-depleted apheresis platelets, and could be used clinically.

Evaluation of Lipidomics Profile of Quinoa Flour and Changes during Storage Based on Ultra Performance Liquid Chromatography Coupled with Quadrupole Exactive Orbitrap Mass Spectrometry.

Although quinoa is nutritious, its high fat content and lipase activity make it easily oxidized during storage. Meanwhile, quinoa's lipid composition and changes during storage are still unknown. Therefore, we stored fresh quinoa flour at low temperature and low humidity (LL), normal temperature and normal humidity (NN), and high temperature and high humidity (HH) conditions for 120 days to assess its oxidative stability and to monitor the changes in lipid composition. Herein, the contents of fatty acids, the peroxide values, the malondialdehyde values, and the lipase activity in quinoa flour during storage are determined to evaluate its oxidation stability. At LL and NN conditions, the contents of fatty acids, the peroxide values, the malondialdehyde values, and the lipase activity changed slowly. They were 3 (LL) and 5 times (NN), 2.7 (LL) and 4.7 times (NN), 1.4 (LL) and 2.3 times (NN), and 1.5 (LL) and 1.6 times (NN) the initial content at storage up to 120 d. However, with the prolongation of storage time under HH conditions, they all increased significantly to 8, 6.6, 3, and 2 times the original content. Moreover, during the storage of quinoa under LL, NN, and HH conditions for 120 days, we continuously monitored the lipid composition of quinoa grains with UPLC-Q-Exactive Orbitrap MS/MS. We identified a total of 14 subclasses of 229 lipids, including 90 significantly different lipid species. PCA and PLS-DA showed that quinoa lipids in HH conditions changed significantly with prolonged storage; among these, the TG and DG classes were the most susceptible to oxidation, which could distinguish fresh quinoa from oxidized quinoa. Simultaneously, we also found that lipase activity has a significant impact on lipid metabolism through correlation analysis, which also indicates that enzyme inactivation treatment can slow down lipid hydrolysis and oxidation during storage. To explore the mechanism of these changes, we also identified twelve important lipid metabolism pathways during quinoa storage. In conclusion, our study advances knowledge of the storage stability and lipid oxidation mechanisms of quinoa and provides a theoretical basis for setting the shelf life of quinoa.

Changes in fruit texture and cell structure of different pumpkin varieties (lines) during storage

After harvest, the pumpkin fruit has strong respiration and metabolic activities, which easily induce quality deterioration, shortening the storage period and shelf life, which affects the farmers' income. To understand the quality change mechanisms of pumpkins and extend the storage period, the fruit cell wall components, related enzyme activities, and fruit texture of Baimi No. 2, Baimi No. 3, Baimi No. 5, Baimi No. 10 and 2020-X1 pumpkin varieties (lines) were monitored during storage at 18 ± 2 °C after harvest.The pumpkin fruit texture was analyzed via the texture profile analysis (TPA) method, and the cell structure changes in peel and pulp cells were monitored using paraffin sections. The results revealed that the hardness, brittleness, viscosity, and elasticity of the five pumpkin fruits were decreased, while the adhesiveness, cohesion, recovery, and chewiness were first increased before decreasing with the prolongation of storage time. In addition, the protopectin, cellulose, and hemicellulose contents were decreased, while the soluble pectin content was increased. In addition, the polygalacturonase activity was increased, and the β-galactosidase, Cx cellulase, and pectinesterase activities were decreased. The cell wall components and enzymatic activities in Baimi No. 10 had minor changes, implying it is storage resistant. In addition, its peel and pulp cells were small and tightly arranged, with minor cellular changes. The peel cells were nearly square, and the pulp cells nearly round, rendering this variety more storable. Baimi No. 5 pulp cells were large and loosely arranged, with large intercellular spaces, rendering this variety short-lived.

Discrimination of Milk Freshness Based on Synchronous Two-Dimensional Visible/Near-Infrared Correlation Spectroscopy Coupled with Chemometrics.

Milk is one of the preferred beverages in modern healthy diets, and its freshness is of great significance for product sales and applications. By combining the two-dimensional (2D) correlation spectroscopy technique and chemometrics, a new method based on visible/near-infrared (Vis/NIR) spectroscopy was proposed to discriminate the freshness of milk. To clarify the relationship be-tween the freshness of milk and the spectra, the changes in the physicochemical indicators of milk during storage were analyzed as well as the Vis/NIR spectra and the 2D-Vis/NIR correlation spectra. The threshold-value method, linear discriminant analysis (LDA) method, and support vector machine (SVM) method were used to construct the discriminant models of milk freshness, and the parameters of the SVM-based models were optimized by the grid search method and particle swarm optimization algorithm. The results showed that with the prolongation of storage time, the absorbance of the Vis/NIR spectra of milk gradually increased, and the intensity of autocorrelation peaks and cross peaks in synchronous 2D-Vis/NIR spectra also increased significantly. Compared with the SVM-based models using Vis/NIR spectra, the SVM-based model using 2D-Vis/NIR spectra had a >15% higher prediction accuracy. Under the same conditions, the prediction performances of the SVM-based models were better than those of the threshold-value-based or LDA-based models. In addition, the accuracy rate of the SVM-based model using the synchronous 2D-Vis/NIR autocorrelation spectra was >97%. This work indicates that the 2D-Vis/NIR correlation spectra coupled with chemometrics is a great pattern to rapidly discriminate the freshness of milk, which provides technical support for improving the evaluation system of milk quality and maintaining the safety of milk product quality.

Analysis of changes in gel properties during retrogradation of four kinds of sorghum starch

SummaryIn this study, four kinds of sorghum starch gels containing different amylose were taken as the research objects and stored for 28 days. The parameter changes of gel properties during the retrogradation of different varieties of sorghum starches were observed using X‐ray diffraction, Low‐field nuclear magnetic resonance, textural, rheological and anti‐enzymatic hydrolysis capacity studies to construct kinetic models for the retrogradation. The results showed that the degree of retrogradation, crystallinity and anti‐enzymatic hydrolysis capacity of sorghum starch increased with the prolongation of storage time, and the crystal forms of H5 (Hongnuo No. 5 sorghum) and L13 (Longza No.13 sorghum) starch changed from type A to B. Among the four kinds of starch, L13 starch had the highest degree of retrogradation, and H5 starch had the strongest recrystallisation ability. The hardness of L13 retrograded starch gel grew fastest with increasing storage time, while the viscoelasticity of H1 (Hongnuo No.1 sorghum) retrograded starch showed a stable trend. Low‐field nuclear magnetic resonance was used to detect that the L1 (Longmiliang No.1 sorghum) retrograded starch gel had more free water. The crystallisation rate was positively correlated with hardness, resistant starch content and crystallinity and negatively correlated with springiness, gumminess and resilience.

Qualitative and quantitative analysis of Lanmaoa asiatica in different storage years based on FT-NIR combined with chemometrics

With the extension of storage time, the quality of mushroom will decline. In order to ensure food safety, it is very necessary to establish a reliable and rapid prediction model of mushroom storage life. In this study, the changes of nucleosides content in Lanmaoa asiatica were detected by high performance liquid chromatography (HPLC). Qualitative and quantitative analysis of L. asiatica in different storage periods based on Fourier transform near infrared spectroscopy (FT-NIR) and chemometrics. The results showed that with the prolongation of storage time, the chemical substances in mushrooms were decomposed, resulting in an increase in the contents of uridine, adenosine and guanosine. The model was optimized by spectral preprocessing and feature variable extraction, which improves the predictability of the model. Partial least squares discriminant analysis (PLS-DA) could effectively identify samples with different storage years, and its model accuracy was 100%. In the established partial least squares regression (PLSR) prediction model for uridine, guanosine and adenosine, the regression coefficients Rp2 were 0.91, 0.90 and 0.62 respectively, and the RPD values were 3.86, 4.21 and 1.98 respectively. In general, the method has good stability and applicability, and provides an effective and rapid analysis method for food safety and quality evaluation.

Factors Affecting the Preservation of Human Peripheral Blood Mononuclear Cells at 4 ℃

To analyze the preservation effect and related influencing factors of human peripheral blood mononuclear cells under serum-free condition at 4 ℃. Human peripheral blood mononuclear cells were isolated by density gradient centrifugation, and stored at 4 ℃ under different cell concentrations, supplemented with human serum albumin, and glucose. The cell viability, total cell number, viable cell number and cell phenotype were detected during preservation of 72 h. With the prolongation of storage time, the number of human peripheral blood mononuclear cells gradually decreased(r=0.982). Compared with the cell concentration of (5-6)×106 cells/ml, the cell number decreased more slowly when the cell storage concentration was (1-2)×106 cells/ml; Adding human serum albumin and glucose can effectively improve the survival rate of human peripheral blood mononuclear cells, among which 2% human serum albumin has a better preservation effect; Compared with the blank control group, the analysis results of cell subsets showed that the downward trends of NK cells and T cells were significantly slowed after adding albumin and glucose. The cell density of (1-2)×106/ml and 2% human serum albumin are more suitable for the preservation of PBMC, and 5% glucose can improve the preservation effect of human peripheral blood mononuclear cells at 4 ℃.

Non-target metabolomics reveals the changes of small molecular substances in duck breast meat under different preservation time

Poultry products are an essential animal source of protein for humans. Many factors could destroy the balance of the poultry production chain and cause an overstock of products, which need to be stored in the frozen storage warehouse for a long time. The long-term frozen storage may affect the quality of meat products. In this study, the changes of small molecular substances were revealed in duck meat during long-term storage using non-targeted metabolomics. The results showed that compared with fresh meat, even if the meat is stored under frozen storage conditions, the number of differential metabolites of frozen storage meat continues to increase with the prolongation of storage time, indicating that the meat composition has changed significantly with the storage time increased. With the increase in storage time, the nitrogen-containing small molecular compounds in duck meat increased (carnosine and anserine, aspartic acid, and tyrosine, 1H-indole-3-acetamide, 2-Hydroxyphenethylamine, 2-Naphylamine, allocystathionine, and O-phosphoethanolamine), the nucleotides decomposition process strengthened (IMP and AMP, GMP and UMP), and the content of organic acid increased (5-hydroxy indole acetic acid, 5-hydroxypentanoic acid and phenylacetate, taurine) and carbohydrate (1-O-sinapoyl-beta-d-glucose, 4-O-beta-d-glucopyranosyl-d-mannose, and alpha-d-glucose). These small molecular substances can be used as biomarkers to detect long-term stored duck meat deterioration. KEGG enrichment analysis showed that protein catabolism, nucleotide catabolism, fat decomposition and oxidation, and carbohydrate decomposition were the main metabolic processes of meat deterioration during the long-term storage of duck meat. In addition, Non-target metabolome technology is a powerful tool to reveal the meat deterioration process during long-term storage systematically. This study provided a reference for optimizing domestic poultry meat storage methods and ensuring food safety.

Changes in quality characteristics of southern bluefin tuna (Thunnus maccoyii) during refrigerated storage and their correlation with color stability

In this paper, we explore the quality characteristics of southern bluefin tuna during refrigerated storage at 4 °C. Moreover, partial least squares is used to understand the correlation between the quality characteristics and color stability of the tuna. The initial myoglobin content (192,533 mg/kg) was significantly higher than that on day 6 (133,760 mg/kg; P < 0.05). The content of total pigments, myoglobin, and a*/b* value (redness) showed a downward trend, whereas metmyoglobin content (MetMb%) showed an upward trend. The value of a*/b* was 0.698 on day 0 and dropped to 0.163 on day 6 with the surface browning evident. Moreover, MetMb% increased from 27.52% to 35.08% over storage period. With the prolongation of storage time, the degree of lipid and protein oxidation in tuna muscle aggravated and so did the browning tendency. A model correlating the changes in quality traits with color stability suggested that thiobarbituric acid reactive substance content was significantly and positively correlated with MetMb% (r = 0.706, P < 0.05) but negatively with a*/b* (r = −0.942, P < 0.01). The current results can provide theoretical basis for developing color protection technology, so as to better promote the development and utilization of bluefin tuna.

Co-Pigmentation of Caffeic Acid and Catechin on Wine Color and the Effect of Ultrasound in Model Wine Solutions.

Wine color is considered an important indicator in judging red wine quality and is also employed to evaluate wine aging. However, wine color can be influenced by many factors. In this paper, it was investigated that the effects of caffeic acid and catechin on wine color and related mechanisms by HPLC and ultraviolet-visible spectroscopy for the wine model solutions containing malvidin-3-O-glucoside. The spectrum changes of the model wine solutions (Mv-glc, Mv-glc + caffeic acid, and Mv-glc + catechin) during 120 days storage were monitored to analyze the influence of co-pigmentation on red wine color. The results indicate that the color properties of red wine could be affected by caffeic acid and catechin to a certain extent. Moreover, caffeic acid had a stronger auxiliary color effect on the malvidin-3-O-glucoside than that of the catechin in the model wine solutions, and the former effect continued to increase with prolongation of storage time. The latter effect (catechin) only had a temporary auxiliary color effect in the beginning, and weakened from red to orange yellow with increased storage time. Furthermore, ultrasound irradiation improved co-pigmentation, resulting in the modification of wine color. All results indicate that the co-pigmentation reaction of wine color could be modified by the addition of caffeic acid and ultrasonic treatment to improve the quality of red wine.

Evaluation of quality deterioration of dried whole-wheat noodles with extrusion-stabilized bran and germ during storage

The prepared DWWN samples were placed under 60% humidity, at 25 °C, 35 °C, and 45 °C and stored for 300 days, 150 days, and 35 days, respectively. Changes in chemical-physical, volatile compounds and sensory quality of DWWN were monitored during storage. During the whole storage period, the water activity ranged from 0.60 to 0.66, and the free fatty acid showed an overall increasing trend. As the storage temperature increased, the acidity value showed a significant logarithmic increasing trend; the relative content of ketones, esters and pyrazines increased, and the aldehydes decreased. The content of linolenic acid, trans-linoleic acid and palmitoleic acid increased mutationally for a certain period of time, then decreased rapidly and became stable when stored at 35 °C and 45 °C. The freshness decreased, the inherent fresh wheat aroma diminished with the prolongation of storage time, and the higher storage temperature, the worse deterioration within a short time for DWWN. The changes in the relative content of 44 volatile flavor compounds were evaluated through GARS-PLS multivariate statistics, revealing that 10 identified compounds could be related to the loss in wheat aroma or the accumulation of unpleasant flavor. Combined with a correlation analysis of volatile compounds and physicochemical indexes, the quality of DWWN was mainly related to the acidity and free fatty acid, and closely related to the content of palmitoleic acid, linolenic acid and gadoleic acid.

Comprehensive Evaluation of the Accelerated Aging Law of NEPE Propellants

In order to study the accelerated aging law of nitrate ester plasticized polyether (NEPE) propellants, the mechanical properties, weight loss, adhesive network structure fracture, and stability of NEPE propellants during storage were analyzed. The results show that the maximum tensile strength σm shows good change law with the increase of storage time, and the failure of NEPE propellants is mainly strength failure. The content of the stabilizer decreased with the increase of storage time. With the prolongation of storage time, the weight loss ratio increases gradually with good regularity. The decomposition of the components in the propellant leads to the degradation of the polyethylene glycol (PEG) network structure. The thermal decomposition of the nitrate plasticizer in NEPE propellants will occur, and the products will cause the adhesive network structure to decompose and break the chain, leading to the destruction of the matrix structure. The thermal decomposition of the propellant has temperature-increasing rate dependency.

Ram semen preserved at 0°C with soybean lecithin Tris-based extender substituted for egg yolk.

ObjectiveThe present study evaluated the preservation of ram semen at 0°C using soybean lecithin with a Tris-fructose extender.MethodsSemen was collected by artificial vagina ejaculation from six rams with proven fertility. High quality ejaculates were diluted by soybean lecithin (0.25%, 0.5%, 0.75%, 1.0%, 1.25%) using Tris-fructose extender and control (Tris-fructose egg yolk extender), respectively. The ejaculates were diluted to a concentration of 5×108 sperm/mL, followed by cooling to 0°C in 90 min and maintaining the temperature for 12 days. The diluted semen samples were examined and recorded for sperm progressive motility, acrosome integrity at 0, 24, 72, 144, 216, 288 h, respectively. Two hundred and twenty-three ewes were inseminated for 216 h with optimal soybean lecithin concentrated semen or control via trans-cervical insemination.ResultsThe results showed that there were no differences in sperm progressive motility at 0, 24, 72, and 144 h (p>0.05). After 216 h, the sperm progressive motility in the control group and 0.5% concentration groups was significantly higher when compared to 0.25% concentration (p<0.05). The 0.5% concentration group demonstrated the highest survival rate and had no difference with the control group (p>0.05). At 216 h, the sperm progressive motility of all groups was still above 50%. The acrosome integrity of all groups was decreased with prolongation of storage time, but there was no difference at each time point (p>0.05). There was no significant difference in the lambing rate and pregnancy rate between the 0.5% concentration group and the control group (p>0.05).ConclusionThese results suggest that ram sperm is capable of fertilization after preservation at 0°C with 0.5% of soybean lecithin in Tris-based extender substituted for egg yolk and produce normal offspring after insemination.

A simple formula to correct for the effects of storage time and temperature on the insulin concentration.

ObjectiveTo investigate the influence of storage time and temperature on plasma insulin levels and to establish a correction formula.MethodsVenous blood samples were taken from 20 volunteers and processed as follows: whole blood samples, centrifuged samples, and separated plasma samples were stored at 4°C or 25°C. Insulin levels were determined by direct chemiluminescence at 0, 0.5, 1, 2, 4, and 8 hours. According to the correlation between the insulin concentration ratio and storage time, correction formulas for the insulin concentration were established. To verify the test, the venous blood samples of another 33 volunteers were processed in the same way. The insulin levels of the samples were corrected after 3, 6, 12, and 24 hours and compared with the value at 0 hours to verify the feasibility of the corrected formula.ResultsWith the prolongation of storage time, the insulin levels of the whole blood samples at 4°C or 25°C and of the centrifuged samples at 25°C decreased gradually (P < .001), and the insulin level correction formulas were C correction = C determination/0.991e−0.069 x, C correction = C determination/1.048e−0.126 x, and C correction = C determination/[−0.068ln(x) + 0.9242]. There was no significant difference between the corrected insulin results and the original results at any time within 12 hours (P > .05).ConclusionsThe insulin levels of the whole blood samples at 4°C or 25°C and of the plasma samples at 25°C gradually decreased with storage time. The effect of storage time on the insulin level can be reduced with the correction formulas.

Study on the effect of storage time on the quality of mutton of different brands by low-field nuclear magnetic resonance

Based on low-field magnetic resonance technology, the quality of Hainan Dong goat meat was studied at the molecular level. With the prolongation of storage time, the pH value of Hainan Dong goat meat showed an overall upward trend, and the T22 peak and T23 peak of transverse relaxation gradually shifted to the left. As the storage time prolonged, the transverse relaxation times of the peaks of samples T22 and T23 showed a decreasing trend. The T22 peak area of the water that is not easy to flow in the sample gradually decreases, while the peak area of the free water T23 gradually increases. The non-flowable water in Hainan East Goat meat was converted into free water. At the same time, the correlation between the transverse relaxation time and the pH value of the mutton quality index was analyzed, and the relationship between the quality of the mutton and the change of storage time was obtained. Finally, this paper compares Hainan Dong goat meat and Guangxi goat meat. The results show that the value of the hard-to-flow water T22 of Hainan Dong goat meat is small and the meat quality is tender. This provides data support for Hainan Dong goat meat to become the brand of lamb.

Postmortem changes in the freshness and volatile compounds of grass carp (Ctenopharyngodon idella)

Although grass carp is an important freshwater fish in the food industry, little is known about the changes that occur in its volatile components and its degree of freshness postmortem. These changes were, therefore, investigated in this study. including total volatile basic nitrogen (TVB-N), total viable counts (TVC), thiobarbituric acid-reactive (TBA) substances and lipase activity of the dorsal muscle of grass carp stored at 4 °C for postmortem up to 8 days. Volatile components were simultaneously quantified assessed using gas chromatography–mass spectrometry (GC–MS). Sensory assessment (SA) and electronic nose assessments were also performed. Results indicated that the level of TVB-N, TVC and TBA increased with storage time increase, reaching 16.92 mg/100 g, 5.37 log 10 CFU/g and 0.72 mg/100 g at 144 h, respectively. Lipase activity peaked on the first day of storage, and then began to decrease rapidly afterwards, reaching its minimum (34.76 ± 8.90 U/g prot) on the eighth day, suggesting the decrease in the freshness. While the SA had exceeded the acceptable limit by the sixth day. The number of volatile compounds increased with the prolongation of storage time. Relative olfactory activity value (ROAV) analysis showed that 9, 8, 8, 12, 12 and 9 predominant components were identified at 0 h, 24 h, 48 h, 96 h, 144 h and 192 h, respectively. The findings suggest that grass carp should be consumed within 6 days when stored at 4 °C, with the optimal edible time being 4 to 8 h after death.

Oxidation characterization of M2 powders exposed under humid atmosphere for a long time

Atomized M2 powders were stored in an atmosphere of 80% relative humidity for a long time. The oxidation characteristics of atomized alloy powders were analyzed. The results show that the oxygen content of the powders have an increasing trend with the prolongation of storage time under humid atmosphere. The oxygen content of 150-300 mesh coarse powder has a gentle change, and the oxygen content will be reduced to near the original level after drying. The oxygen content of -300 mesh fine powders has a little growth in a short time, but it increases rapidly as time goes on after one week, and increases from 415 ppm to 1098 ppm after four weeks of storage, and the oxygen content of fine powders after drying remained unchanged. Particle size has a great influence on the oxidation characteristics of powders. The smaller the particle size, the greater the oxygen content of the powder. The type of adsorption of oxygen element from coarse powder to fine powder changes from physical adsorption to chemical adsorption.