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BACKGROUND: Morden advanced analytical tools offer valuable information into the understanding of molecular mechanism of traditional food processing. Chopping temperature is well‐known to affect the surimi gel quality of silver carp, but the detailed molecular mechanism is not very clear. In this study, a gel‐based proteomics was performed on the extracted surimi proteins under different chopping temperatures (0, 5, 10, and 25 °C) along with other physicochemical characterization of surimi proteins and gels. RESULTS: With increased chopping temperature, protein extractability (in 3% sodium chloride) generally decreased, while the extracted protein generally exhibited larger surface hydrophobicity, reduced intrinsic fluorescence intensity, lower sulfhydryl content. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) profile of extracted protein showed a clear difference at 25 °C when compared with the other three temperatures, and more protein fragmentation occurred. Proteomic analysis of selected bands indicated that major myofibrillar proteins react differently with chopping temperatures, especially at 25 °C. The selected bands contained a variety of other proteins or their fragments, including adenosine triphosphate (ATP) synthase, glyceraldehyde‐3‐phosphate dehydrogenase, glucose‐6‐phosphate isomerase, heat shock protein, parvalbumin, collagen, and so forth. For the surimi gel, water‐holding capacity and gel strength generally decreased with increased chopping temperature. CONCLUSION: Our results suggested that chopping at 0–10 °C is acceptable for the production of silver carp surimi in terms of gel strength and water‐holding capacity. However, a chopping temperature near 0 °C led to less protein oxidation and denaturation. The inferior gel quality at 25 °C is linked to a decreased concentration of extracted protein and degradation of major myofibrillar protein, the latter is likely crosslinked with sarcoplasmic proteins. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The diurnal temperature range (DTR) has significantly decreased in many land areas as a consequence of global warming. The DTR spatial distribution and future projections of spatiotemporal variations in the case of global warming levels at 1.5 and 2.0°C under the RCP4.5 emission scenario was investigated using datasets from the Climatic Research Unit (CRU‐TS v.3.24.01) and the Coupled Model Intercomparison Project Phase 5 (CMIP5) in the Mongolian Plateau. And the main factors influencing DTR spatiotemporal variations were also evaluated using the Geo‐detector model at different time scales. The results showed that variations of the DTR significant decrease in snow‐winter dry‐warm summer climate region are higher than in other climate regions in spatial scale. As a result of the increasing rates of Tmin, which was more than double that of Tmax, the DTR decreased significantly on a temporal scale. In climate projections, the DTR was lower at global warming of 2.0°C (2037–2056) than 1.5°C (2017–2036). Precipitation was determined to be the predominant factor underlying the annual and seasonal (spring, summer, and autumn) DTR changes. Total cloud cover was the main factor in winter. Soil moisture was the key factor for the spatial variations in DTR in the warm and dry seasons. This study enhances the understanding of climate change in the Mongolian Plateau and provides a strong reference for other DTR variation studies in similar climates. [ABSTRACT FROM AUTHOR]

Over the recent decades,protein oxidation in muscle foods has gained increasing research interests as it is known that protein oxidation can affect eating quality and nutritional value of meat and aquatic products. Protein oxidation occurs during freezing/thawing and frozen storage of muscle foods, leading to irreversible physicochemical changes and impaired quality traits. Controlling oxidative damage to muscle foods during such technological processes requires a deeper understanding of the mechanisms of freezing‐induced protein oxidation. This review focus on key physicochemical factors in freezing/thawing and frozen storage of muscle foods, such as formation of ice crystals, freeze concentrating and macromolecular crowding effect, instability of proteins at the ice–water interface, freezer burn, lipid oxidation, and so on. Possible relationships between these physicochemical factors and protein oxidation are thoroughly discussed. In addition, the occurrence of protein oxidation, the impact on eating quality and nutrition, and controlling methods are also briefly reviewed. This review will shed light on the complicated mechanism of protein oxidation in frozen muscle foods. [ABSTRACT FROM AUTHOR]

Summary: To study the effects of freezing temperature on muscle proteins, shrimp (Metapenaeus ensis) were frozen stored at either −18 or −60 °C up to 90 and 210 days. Shrimp frozen at −18 °C had higher thawing and compression loss and poor myofibril water‐holding capacity compared with those frozen at −60 °C. In terms of protein characteristics, shrimp frozen at −18 °C had higher levels of carbonyls and reduced sulphhydryls. Moreover, the shrimp frozen at −18 °C had higher surface hydrophobicity and reduced Ca2+‐ATPase activity, indicating increased protein denaturation. Proteomics revealed that seventy‐five proteins were classified as differentially abundant proteins (DAPs) following freezing. There were sixty‐four DAPs in the F18‐CON comparison group (shrimp frozen at −18 °C vs. control) and thirty‐two DAPs in the F60‐CON comparison group (shrimp frozen at −60 °C vs. control), suggesting that freezing at −18 °C results in more DAPs than freezing at −60 °C. A comparison between F18 and F60 revealed that ribosomal proteins (L44, L7a) and heat shock protein 21 were downregulated in F18. These results increase our understanding of the variable quality associated with shrimp frozen at different temperatures. [ABSTRACT FROM AUTHOR]

Summary: In order to evaluate the effect of steam addition during meat roasting, beef sirloin steaks were cooked at five humidities (0%, 25%, 50%, 75% and 100%) under 230 °C to a centre temperature of 71 °C. With increased humidity, heating rate generally increased and the cooked steak gradually lost the typical roasted appearance. Thiobarbituric acid‐reactive substances (TBARS) values generally increased, while carbonyl groups were not affected. Increased humidity promoted the formation of volatile aldehydes and alcohols, while pyrazines decreased significantly from 0% to 25% humidity. Steam‐assisted roasting inhibited the formation of heterocyclic aromatic amines (HAAs; except for IQ and Norharman). However, further increase in humidity (larger than 25%) did not have additional inhibition effect. Based on the results, it is recommended to roast beef with steam addition to reduce toxic HAAs, but the humidity should be kept at a relatively low level to maintain a typical roasted appearance and flavour profile. [ABSTRACT FROM AUTHOR]

Heat waves (HWs) are one of the current topics of scientific research in the context of global warming, as they can have a disastrous impact on both environment and society. Therefore, detailed studies of variations of HWs that assess variability on spatiotemporal scales are becoming increasingly necessary. The main objective of this study is to detect and analyse variation in HWs and potential climate drivers across China based on Köppen climate classifications. Daily observation data (maximum and minimum temperature) from 1961 to 2016 were used in the study to define HWs based on excess heat factors (EHFs). Linear trend analysis, Bayesian change‐point analysis, cross‐wavelet transform method, and Pearson correlation analysis method were adopted to identify the trends, variability and resonance periodicity of EHFs in sub‐regional, and the possible links between EHFs and large‐scale climate patterns, respectively. Results show that there was an overall significantly increasing trend of EHFs over six climatic zones except for HWM in the Polar tundra (ET). The spatiotemporal characteristics of EHFs in mainland China vary considerably. The spatial patterns of the mean annual EHFs are similar to their change trend. The spatial pattern of the number of individual HWs, the number of days that contribute to HWs, and the length of the longest HW in arid (BB), semi‐arid (BS) and cold semi‐humid (DW) areas of study is the west exceeding the east; temperate humid (CF) is contrary to that, with the south exceeding the north in temperate semi‐humid (CW) and ET. In addition, the mean temperature of all heatwaves (HWM) and the peak daily value in the hottest HW appeared in parts of northern DW, CF and BS. Change point first occurs in the northern and then in the southern region across mainland China, excepting HWM. A dominant positive correlation was found for Multivariate ENSO Index (MEI) and Arctic Oscillation Index (AOI) with EHFs, while a dominant negative correlation was detected for Pacific Decadal Oscillation (PDO) and the North Atlantic Oscillation (NAO) across China. A common significant 2–4 year periodical oscillation was detected in the EHFs series at the nationwide scale. Strengthening anti‐cyclone circulation in the Mongolian Plateau, and weakening monsoon flow and speed have contributed to the changes in EHFs across China. [ABSTRACT FROM AUTHOR]

To understand the quality changes in Songpu mirror carp {Cyprinus carpio) fillets during chilled storage, sensory score, total aerobic counts (TAC), total volatile basic nitrogen (TVB-N) and electrical conductivity (EC) of the fillets stored at 270, 273, 276, 282 and 288 K were investigated. Furthermore, both Arrhenius model and log-logistic model were established to predict the quality changes. The high regression coefficients (R2 > 0.90) represented the acceptability of both Arrhenius model and log-logistic model. Relative errors between predicted values and observed values were all within ±5% for models based on EC, within ± 25% for models based on TAC and TVB-N (except the TVB-N value on 9th and 15th day). The relative errors of sensory score were all within ±35% in the first 9 days. It is concluded that both Arrhenius model and log-logistic model based on EC, TAC or TVB-N can be applied in modelling quality changes in Songpu mirror carp fillets during storage within 270-288 K. [ABSTRACT FROM AUTHOR]