Denaturation Temperature Research Articles

Semi-rational design in simultaneous improvement of thermostability and activity of β-1,3-glucanase from Alkalihalobacillus clausii KSM[sbnd]K16

Endo-β-1,3-glucanase (β-1,3-GA) is a key enzyme capable of acting on the β-1,3-glycosidic bond of β-1,3-glucan, resulting in the production of β-1,3-gluco-oligosaccharides with higher water solubility. Higher temperatures are beneficial for curdlan hydrolysis; however, low enzymatic activity and thermal stability limit their applicability. In this study, a mutant library of Endo-β-1,3-glucanase (AC-GA) derived from Alkalihalobacillus clausii KSM-K16 was constructed by a semi-rational design using amino-acid-based multiple sequence alignment and protein structure-based computer-aided engineering. The best combination mutant (S52T/M120L) was screened through ordered recombination mutations, which showed a 24.88 % increase in specific enzyme activity over the wild-type. The melting temperature (Tm) value, an enzyme protein denaturation temperature, was raised to 82.99 °C from 78.60 of the wild type. In comparison, the Km for hydrolysis of curdlan by S52T/M120L was reduced by 12.1 %, while the kcat was increased by 59.39 %, thus leading to a higher catalytic efficiency (kcat/Km, 227.73 vs 125.46 mL·s−1·mg−1). Molecular dynamics (MD) simulations showed that mutations resulted in a reduction in the overall flexibility of the enzyme, an increase in rigidity, and a more stable structure. An increase in the hydrophobic network at the entrance of the substrate increases the accessibility of the substrate to the enzyme, resulting in increased enzyme activity. High-efficiency mutants have potential industrial applications in the enzymatic preparation of β-1,3-gluco-oligosaccharides.

OPTIMIZATION OF DENATURATION TEMPERATURE AND TIME USING REAL-TIME PCR METHOD IN HEPATITIS B TEST

Background: The hepatitis B test can be conducted using the real-time PCR method. In chronic cases, the test is performed by detecting one of the Hepatitis B Virus (HBV) specific genes, HBcAg. The real-time PCR method requires optimization to obtain optimal results. Purpose: This research aims to determine the optimal temperature and time for denaturation in the hepatitis B test using the real-time PCR method. Method: The research method used was a quasi-experiment involving variations in temperature (94 °C, 95 °C, and 96 °C) and time (10 seconds, 15 seconds, and 20 seconds) for denaturation. Data processing resulted in static group comparisons based on 27 primary data from the Cycle Threshold (CT) value. Result: Variations in temperature conditions, specifically at 94 °C, 95 °C, and 96 °C, combined with a denaturation time of 10 seconds, yielded the mean CT values of 26.495, 26.355, and 26.003, respectively. When the temperature conditions were maintained at 94 °C, 95 °C, and 96 °C, with a denaturation time of 15 seconds, yielded the mean CT values of 25.962, 25.641, and 25.396. Similarly, under temperature conditions of 94 °C, 95 °C, and 96 °C with a denaturation time of 20 seconds, yielded the mean CT values of 26.544, 26.505, and 25.830 were obtained. Conclusion: Optimal results in this study are obtained through the acquisition of the smallest CT value, namely at temperature conditions of 96 °C and 15 seconds.

The effect of ultrasound-assisted freezing, metal plate assisted freezing and conventional freezing on the quality characteristics of beef samples

In this study, the effects of household refrigerator freezing (control group), ultrasound-assisted freezing at different power levels (40 %, 70 %, and 100 %) and metal plate assisted freezing on the quality characteristics of beef samples were investigated. While the freezing time decreased for the fillet samples with ultrasound-assisted freezing (40 % and 70 %, respectively) and for all samples with metal plate assisted freezing, the weight loss and cooking loss values generally decreased compared to control samples. The total color values of the ultrasound-assisted frozen samples were higher than those of the control samples, while the metal plate assisted frozen samples were lower than those of the control samples. The TBARS values were found to be lower in both methods compared to control samples. The hardness values of control samples were generally lower than the samples subjected to both methods after or before cooking. The protein denaturation temperatures of the metal plate-assisted frozen samples were generally higher than others. As a result, ultrasound and metal plate assisted freezing processes preserved the quality characteristics of beef and had significant effects on several quality characteristics of beef. The application of ultrasound at 40 % provides a significant advantage in terms of quality characteristics. The effects of conduction heat transfer with metal plate-assisted freezing processes also provides the positive impact on the freezing of beef samples. Thus, the use of innovative technologies during the freezing of food in household refrigerators were evaluated within the study which brings new idea to integrate them in the production of household refrigerators.

Preparation of mayonnaise with excellent thermal and storage stability from egg yolk-amino acid complex: Rheology, interfacial property, microstructure and lutein delivery

In this paper, egg yolk-amino acid (betaine or proline) complex was prepared at different pasteurization temperatures (68, 72 and 76 °C). Then complexes were applied to stabilized mayonnaise emulsion system. The results demonstrated that liquid egg yolk (LEY) protein structure gradually aggregated, molecular flexibility increased by 5 %, interfacial tension and intermolecular force enhanced remarkably with growth of pasteurization temperature. Compared with LEY, egg yolk-amino acid complex exhibited a more flexible structure with lower interfacial tension and superior molecular wettability. Complexes stabilized mayonnaise emulsion displayed excellent rheological property, homogeneous droplet distribution, smaller average particle size and higher (about 10 °C) thermal denaturation temperature (Td). In terms of thermal stability, oil binding capacity (OBC) of heated betaine mayonnaise (HBM) and heated proline mayonnaise (HPM) was approximately 20 % higher than that of heated control mayonnaise (HCM). Notably, the group of HBM thermal stability was generally excellent. During storage, mayonnaise might be an intermediate unstable state before emulsion breakage. In vitro digestion results illustrated that bioaccessibility of lutein delivered by BM-72 and PM-72 was 48.9 % and 37.0 % higher than CM-72, respectively. The results will provide reference for preparation of mayonnaise by egg yolk-amino acid complex as a carrier to deliver fat-soluble substances to improve bioaccessibility.

Longissimus from Berkshire pigs in a small-scale supply chain have increased oxidative metabolism, tenderness and water-holding capacity, compared with Large White × Landrace pigs in a modern commercial supply chain

Context Selection for leanness in the modern Australian pig has resulted in inconsistent quality, including a lack of pork tenderisation during ageing. Inconsistent quality is potentially a result of differences in supply chain and breed as well as the variation in muscle fibre-type proportion in pork longissimus. Aim The aim was to investigate differences in fibre-type proportion and pork quality between Large White-Landrace pigs in a large supply chain and Berkshire pigs processed in a small supply chain. Methods Pigs (n = 22) from two suppliers with different breeds (Supplier 1, Large White × Landrace, SC1-LWLR, n = 12, modern commercial pigs; Supplier 2, Berkshire, SC2-Berk, n = 10, heritage pigs) were slaughtered and samples from the longissimus were extracted at 3, 24, and 48 h postmortem for enzyme and pH analyses. Longissimus samples were subjected to ageing for either 2 or 16 days postmortem (Day 2, Day 16), assessed for colour, muscle fibre-type proportion (%), muscle fibre diameter (μm), water-holding capacity (purge, % and cook loss, %), Warner–Bratzler peak shear force (WBSF, N), and protein denaturation temperature using differential scanning calorimetry (DSC, peak temperature, °C). Key results SC1-LWLR had higher purge than SC2-Berk (2.85% and 1.83% respectively; standard error of the difference (SED) = 0.33; P = 0.003), higher cook loss on Day 16 (24.63% and 16.79% respectively; SED = 1.62; P = 0.017) and higher WBSF on Day 2 and Day 16 (Day 2, 30.9 N and 26.7 N respectively; Day 16, 28.6 N and 22.0 N respectively; SED = 0.98, interaction P = 0.003). SC1-LWLR had a lower proportion of Type I (10.1% vs 16.0%; SED = 0.51) and Type IIA (14.0% vs 22.0%; SED = 0.77) and a higher proportion of Type IIB (75.9% vs 62.0%; SED = 0.74) (P < 0.001 for all) fibres. SC1-LWLR had lower DSC temperatures for two peaks. SC2-Berk had higher citrate synthase activity (P = 0.003) and glycolytic potential (P < 0.001) than SC1-LWLR. Conclusions SC2-Berk longissimus had improved quality compared with SC1-LWLR pork, most likely owing, in part, to higher proportion of oxidative and intermediate fibres in the Berkshires. However, effects of differences in environmental conditions and/or processing conditions cannot be ruled out. Implications The experiment increased our understanding of how variation in supply chains and muscle fibre-type proportion can impact the production of consistently high-quality pork.

Pecan (Carya illinoinensis (Wangenh.) K. Koch) nuts as an emerging source of protein: extraction, physicochemical and functional properties.

The increasing demand for sustainable alternatives to traditional protein sources, driven by population growth, underscores the importance of protein in a healthy diet. Pecan (Carya illinoinensis (Wangenh.) K. Koch) nuts are currently underutilized as plant-based proteins but hold great potential in the food industry. However, there is insufficient information available on pecan protein, particularly its protein fractions. This study aimed to explore the physicochemical and functional properties of protein isolate and the main protein fraction glutelin extracted from pecan nuts. The results revealed that glutelin (820.67 ± 69.42 g kg-1) had a higher crude protein content compared to the protein isolate (618.43 ± 27.35 g kg-1), while both proteins exhibited amino acid profiles sufficient for adult requirements. The isoelectric points of protein isolate and glutelin were determined to be pH 4.0 and pH 5.0, respectively. The denaturation temperature of the protein isolate (90.23 °C) was higher than that of glutelin (87.43 °C), indicating a more organized and stable conformation. This is further supported by the fact that the protein isolate had a more stable main secondary structure than glutelin. Both proteins demonstrated improved solubility, emulsifying, and foaming properties at pH levels deviating from their isoelectric points in U-shaped curves. Compared to the protein isolate, glutelin displayed superior water and oil absorption capacity along with enhanced gelling ability. The protein isolate and glutelin from pecan nuts exhibited improved stability and competitive functional properties, respectively. The appropriate utilization of these two proteins will support their potential as natural ingredients in various food systems. © 2024 Society of Chemical Industry.

Comparative study of Maillard reaction and blending between soybean protein isolate and soluble soybean polysaccharide: Physicochemical, structure and functional properties

Soybean protein isolate-soluble soybean polysaccharide (SPI-SSPS) complexes and mixtures with varying SPI/SSPS concentration ratios (1: 1, 2:1, 4:1, 8:1) were prepared by Maillard reaction and blending, respectively, and their physicochemical, structure, and functional properties were compared studied. The physical stability of SPI-SSPS complex, which consisted of CN and CS bonds, was better than that of the SPI/SSPS mixture with electrostatic interactions and hydrogen bonds, and both were superior SPI alone. The complex with SPI/SSPS concentration ratio of 8:1 had the highest grafting degree (33.25 %) and a more ordered structure, making its solubility and emulsifying property lower than the SPI/SSPS mixture; however, the physical and thermal stability of the SPI-SSPS complex was higher than that of the SPI and SPI/SSPS mixture. In particular, the SPI-SSPS complex with a high grafting degree showed a higher thermal denaturation temperature (194.06 °C). This study aimed to provide effective modification methods to utilize soybean processing by-products by modifying soybean protein isolate with soluble soybean polysaccharide.

Unlocking a Key Residue in a Lipase for Efficient Polyethylene Terephthalate (PET) Hydrolysis and Influencing Depolymerization Product Profiles

AbstractPolyethylene terephthalate (PET) pollution is a global challenge. Advancing the bioprospecting of PET‐degrading enzymes through metagenomics and using computational and functional methods to identify key positions influencing the catalytic rate and selectivity are part of the solution. Here, we report PETase activity in the metagenomic lipase LipMRD9, which exhibits peak activity at 30 °C and pH 9.0 and has a denaturation temperature of 42 °C. In addition to acting on long‐chain triglycerides (up to ∼13 units (U)/mg, pH 8.0, 30 °C) and a wide range of 34 other esters (up to ∼228 U/g), LipMRD9 hydrolyses mono(2‐hydroxyethyl) terephthalate (∼57 U/g) and bis(2‐hydroxyethyl) terephthalate (∼131 U/g). It also efficiently deconstructs GoodFellow amorphous submicro‐ and nanosized PET particles (∼984/2238 μM degradation products at 30/40 °C, pH 7.0, 21.5 h) and films (∼112/198 μM degradation products at 30/40 °C, pH 7.0, 7 days). Through molecular modelling and experimental analysis, the active site of LipMRD9 was revealed, identifying a key residue contributing to its PETase activity compared with those of its closest homologues. This residue plays a crucial role in determining the distinct profiles of degradation products from PET hydrolysis and should be studied in other PETases for its influence on the catalytic process.

The influence of the volume fraction of meat in dumplings on their cooking time

Based on the studied literature, the aim was to investigate the influence of the volume fraction of meat in meat dumplings (pelmeni) and the number of dumplings on their cooking time, as well as to analyze the physico-mathematical and technical aspects to be taken into account (or not) within the framework of the planned experiment. To achieve this goal, the following tasks were set: to conduct experimental studies, to describe the assumptions that need to be accepted when performing the study and to conduct theoretical studies (numerical experiments, using the finite element method). When conducting experiments, dumplings of well-known brands, the names of which were conventionally labeled as “SK”, “SZ”, “RE”, “TS”, were chosen as objects of research. The need to study the dumplings of well-known brands is justified by both consumer interest and a smaller variability of product parameters, which increases the reproducibility of the results of the study. As assumptions adopted in real experiments, the authors emphasize the following ones: distilled water is used in cooking, the volume of a dumpling does not change during cooking, the biochemical composition of the filling can be neglected. As a result of the theoretical analysis, the following assumptions were made: the study of dumpling cooking does not take into account the resistance forces, i. e., turbulent and convective flows, as well as thermo-elastic effects; the time of dumpling floating to the surface is negligibly small; "approximation of initial values" — geometric, physico-chemical parameters of the dumpling do not change during cooking. Cooking time of 1, 5, 10 dumplings of known brands was obtained on the basis of numerical experiments. Using real experiments, the time from immersion of the dumplings in water to their floating to the surface was investigated. As a result of numerical experiments it has been found that the time of heating the center of the dumpling of known brands to the temperature of protein denaturation differs from the time of floating to the surface by about 360 seconds. Consequently, after floating to the surface, the dumplings of known brands need about six more minutes of cooking time until they are fully cooked.

Effect of Shikimic Acid on Oxidation of Myofibrillar Protein of Duck Meat During Heat Treatment.

The myofibrillar protein (MP) of duck meat is prone to excessive oxidation during thermal processing, resulting in a decline in its overall quality. In this paper, the effect of shikimic acid on the oxidative structure of duck muscle fibrin was studied. The findings showed that, at a mass ratio of 1:50,000 (g/g) between shikimic acid and MP, the carbonyl content of MP was reduced by 74.20%, while the sulfhydryl content was increased by 73.56%. MP demonstrated the highest denaturation temperature, whereas its thermal absorption was the lowest. The percentage of α-helixes and β-sheets increased by 16.72% and 24.74%, respectively, while the percentage of irregular structures decreased by 56.23%. In addition, the surface hydrophobicity index of MP exhibited a significant decrease (p < 0.05), while there was a significant increase in its free radical-scavenging ability (p < 0.05). Molecular fluorescence spectrum analysis showed that shikimic acid could bind to MP, altering the internal environment of MP and enhancing its thermal stability. FTIR analysis showed that shikimic acid could enhance the distribution of protein particle sizes by reducing irregular structures, the proportion of β-rotation, and the degree of protein aggregation. It is hoped that this research can offer scientific support for improving meat processing technology.

Investigating binding mechanism between coconut globulin and tannic acid mediated by atmospheric cold plasma: Protein structure and stability

Physical methods present promising avenues for inducing covalent modifications of proteins by polyphenols, circumventing the safety and sustainability issues associated with traditional approaches. This study sought to enhance the physicochemical properties of coconut globulin (CG) by facilitating covalent cross-linking with tannic acid (TA) through atmospheric cold plasma (ACP). The ACP treatment effectively transitioned the interaction between CG and TA from non-covalent to covalent in a voltage-dependent manner at pH 6.0, resulting in structural modifications of CG. The treatment with TA enhanced the spherical structure of CG, with a reduction in particle size from 474 to 384 nm. This size reduction was further amplified by the exposure of charged groups induced by ACP treatment. Consequently, the solubility, surface hydrophobicity, and viscosity of ACP-treated CG-TA increased, leading to an elevated denaturation temperature and enhanced physical stability. These results suggest a viable approach to improving the suboptimal physicochemical properties of plant proteins.

Exploring the binding mechanism and functional properties of lactoferrin-berberine complex: Based on multispectral analysis, molecular docking, and dynamics simulations

Denaturation and/or aggregation of proteins under adverse environmental conditions can greatly impair their bioactivity and functional properties. Based on this, this study aims to improve the functional properties of lactoferrin by complexing with berberine and investigate the mechanism using multispectral techniques, molecular docking and dynamics simulations. The results showed that berberine bound to lactoferrin through hydrogen bonding and van der Waals forces and altered its conformation, surface hydrophobicity, amino acid microenvironment, and secondary structure. Molecular docking and dynamics simulations further revealed that berberine inhibited the drastic changes in the lactoferrin structure, contributing to the complex stability. Consequently, the denaturation temperature and degradation temperature (224 °C to 230 °C) and the tolerance to extreme pH, high temperature, and ions of the lactoferrin-berberine complex were improved. This study systematically revealed the mechanism of berberine to improve the functional properties of lactoferrin, contributing to the development and application of novel functional ingredients.

Novel cell spheroid culture method using Medaka dried fish powder

Highly biocompatible microcarriers are culture materials designed to enhance the efficiency of cell spheroid culture. Typically, collagen or specially processed plastic materials serve as these microcarriers. In the context of cultured-cell-based food production, however, both collagen and plastic materials present challenges regarding their cost-effectiveness and edibility. A notable issue with collagen, especially when derived from fish scales, is its low denaturation temperature, making it unsuitable for use with mammalian cells unless cross-linked. To address this issue, our research pivoted towards utilizing dried fish, a rich source of proteins including collagen. For this study, Medaka fish were selected. The fish were dried, ground into fine particles, and then impregnated with ethanol to create dried fish powder (DFP). Its efficacy was then evaluated as a microcarrier in spheroid cultures. The results revealed that DFP supports the adhesion and proliferation of various cell types, including human epidermal cells, human malignant melanoma cells, mouse fibroblasts, mouse endothelial cells and fish fibroblasts. Furthermore, Western blot analysis was used to verify the expression of mitogen-activated protein kinase-related proteins in both human epidermal cells and mouse fibroblasts cultured with DFP. This fish-derived powdered microcarrier offers a cost-effective production method requiring only a few steps. Its affordability and high performance as a carrier position it as a potentially revolutionary material for use in biological research and food production science.

Ultrasound-assisted preparation of zein particles: Insight into the effects and mechanisms of thermal factors

The research on the application of ultrasound in food processing has been increasing in recent years. In particular, using ice-bath temperature-controlled ultrasound (IBU) to minimize the effects of thermal aspects has been the main focus. However, this approach does not maximize the utilization of energy. Therefore, this study aims to compare the effect of non-temperature-controlled ultrasound (NTU) and temperature-controlled ultrasound (TU), with IBU on the structure and properties of zein. To further explore the role and mechanism of thermal effects in ultrasound processes. Firstly, particle size, zeta potential, hydrophobicity, and thermal stability of zein nanoparticles prepared using various ultrasound-assisted methods were characterized. Compared to the particle size in the IBU group, the NTU group consistently had smaller particles under the same power conditions (e.g., 197 nm versus 176 nm at U1). The particle size in the TU group changes depending on the temperature (e.g., from native 225 nm down to 185 nm). As for the denaturation temperatures, the NTU group (88.9 °C) was significantly higher than that of the IBU (75.76 °C) and TU groups (e.g., 76.9 °C at treatment temperatures of 30 °C). In all, IBU reduces the thermal stability, while NTU treatment enhances it. Furthermore, UV, fluorescence, and CD spectra results indicate that both NTU and TU groups significantly reduce the α-helix structure by unfolding and exposing more internal hydrophobic groups of zein than the IBU group. These results indicate that the effects of ultrasound on zein are closely related to the heating source during the ultrasonic process. IBU could be utilized to maximize the reduction of denaturation levels, but NTU may exhibit superior performance such as protein modification, reducing particle size, or enhancing stability in industrial production.

Comparison of Commercial Collagen and Marine Collagen: Efficiency and Effects on the Formation of EDC/NHS-Crosslinked Membranes

AbstractThis study investigates the extraction and characterisation of collagen derived from fish skin and scales, the collagens obtained were used to produce membranes which were subsequently cross-linked by EDC/NHS. A comprehensive investigation of their microstructure, composition, mechanical properties, swelling, degradation, thermal properties and a 24 h cell viability test was carried out. The results showed that the yields of collagen from skin and fish scales were 25.14 ± 2.90 and 29.26 ± 2.53%, respectively. Mechanical stress tests showed that membranes made from fish skin collagen and commercial collagen had comparable load-bearing capacities before failure. The Young’s modulus of the membranes was 9.45 MPa ± 1.77 for commercial collagen, 5.76 MPa ± 0.74 for fish skin collagen and 2.43 MPa ± 0.78 for fish scale collagen, this similarity was maintained in degradation tests and at denaturation temperature (75 °C).These results demonstrate the viability of collagen derived from marine by-products as an effective and efficient alternative for biomedical and tissue engineering applications.

Covalent interaction of ovalbumin with proanthocyanidins improves its thermal stability and antioxidant and emulsifying activity.

The structure of proanthocyanidins (PC) contains a large number of active phenolic hydroxyl groups, which makes it have strong antioxidant capacity. This study investigated the structural and functional properties of ovalbumin (OVA) modified by its interaction with PC. It was found that on increasing the concentration ratio of PC to OVA from 10:1 to 40:1, the free amino and total sulfhydryl contents of OVA decreased from 470.59 ± 38.77 and 29.81 ± 0.31 nmol mg-1 to 96.61 ± 4.55 and 21.22 ± 0.78 nmol mg-1, respectively, and the free sulfhydryl content increased from 7.65 ± 0.41 to 9.48 ± 0.58 nmol mg-1. These results indicated that CN and CS bonds were formed and PC was covalently linked with OVA. The PC content in the OVA-PC conjugates increased from 281.93 ± 12.92 to 828.81 ± 46.09 nmol mg-1 on increasing the concentration ratio of PC to OVA from 10:1 to 40:1. The contents of α-helix and β-turn of OVA decreased, and the contents of β-sheet and random coil increased, confirmed by circular dichroism. The tertiary structure of OVA was also altered according to the results of fluorescence and ultraviolet absorption spectra. The surface hydrophobicity of OVA-PC conjugates decreased with increasing bound polyphenol content. The conjugation of OVA to PC significantly improved its emulsification and antioxidant activity and denaturation temperature. This study may provide valuable information for improving OVA's functional properties and its PC conjugates for applications in the food industry. © 2024 Society of Chemical Industry.

Properties of Skin Collagen from Southern Catfish (Silurus meridionalis) Fed with Raw and Cooked Food.

The southern catfish (Silurus meridionalis) is an economically important carnivorous freshwater fish in China. In this study, we compared the properties of skin collagen from southern catfish fed with raw food (RF) and cooked food (CF). The skin collagen yield in the RF group (8.66 ± 0.11%) was significantly higher than that of the CF group (8.00 ± 0.27%). SDS-PAGE, circular dichroism spectroscopy, and FTIR analyses revealed that the collagen extracted from southern catfish skin in both groups was type I collagen, with a unique triple helix structure and high purity. The thermal denaturation temperature of collagen in the RF group (35.20 ± 0.11 °C) was significantly higher than that of the CF group (34.51 ± 0.25 °C). The DPPH free radical scavenging rates were 68.30 ± 2.41% in the RF collagen and 61.78 ± 3.91% in the CF collagen, which was higher than that found in most fish collagen. Both the RF and CF groups had high ability to form fibrils in vitro. Under the same conditions, the CF group exhibited faster fibril formation and a thicker fibril diameter (p < 0.05). In addition, the RF group exhibited significantly higher expression of col1a1 compared to the CF group. These results indicated that feeding southern catfish raw food contributed to collagen production, and the collagen from these fish may have potential in biomaterial applications.

Effects of phytic acid from soybean meal on Maillard reaction and antioxidant properties of products

This study used glycine (Gly), glucose (Glu), and soybean meal phytic acid (PA) as raw materials to investigate the effect of different PA addition amounts on the Gly-Glu Maillard reaction system and the antioxidant capacity of the products through rheological properties, particle size, chromatography, and other methods. The results showed that with the addition of PA, the apparent viscosity and average particle size of the system decreased, the thermal denaturation temperature increased, the product concentration decreased, the color became brighter, and the antioxidant performance was enhanced. This indicates that PA reacts with Gly and Glu to form PA - Gly and PA - Glu complexes, respectively, and hinders the Maillard reaction. This work demonstrates the potential application value of soybean meal PA in controlling the Maillard reaction.

Effect of thermal treatment and secondary bonds on the storage stability of ready-to-eat sea cucumbers

Ready-to-eat sea cucumbers (RSC) are highly sensitive to quality deterioration during storage at room temperature. The study investigated the anti-deterioration effects of high-pressure steam sterilization (HPSS) and high-temperature boiling (HTB) on RSC, as well as the impact of secondary bonds on HTB-treated RSC. The results indicated that there were no significant changes in the secondary structure following thermal treatment. Compared to day 0, the maximum thermal denaturation temperature of collagen in the control (CT) group decreased by 24.49℃, while decreases in the HPSS and HTB groups were 8.53℃ and 9.8℃, respectively. This confirmed that the stabilization of RSC could be enhanced through HPSS and HTB treatment during storage. When hydrogen bonds are destroyed, the texture properties of HTB-treated RSC significantly decrease, with hardness values dropping to 3.65±0.514 N and 2.41±0.615 N, springiness to 7.52±1.342 mm and 7.69±0.066 mm, and chewiness to 19.7±1.211 mj and 16.6±1.837 mj, respectively. Furthermore, the degradation of collagen fibers due to the breaking of hydrogen bonds prior to storage was more pronounced. These findings indicate that hydrogen bonds play a crucial role in maintaining the storage stability of RSC. These results offer a theoretical foundation and technical assistance for the processing and storage of RSC.

Exploring somatic mutations in POLE and POLD1: Their role in colorectal cancer pathogenesis and potential therapeutic strategies

Colorectal cancer (CRC) is one of the major causes of morbidity and mortality worldwide, resulting from the accumulation of genetic and epigenetic alterations in several oncogenes and tumor suppressor genes. Recent studies have identified germline and somatic mutations in the exonuclease domain regions of both epsilon polymerase (POLE) and delta polymerase (POLD1) genes in CRCs. We sought to examine the mutation of these genes in a series of sporadic CRCs. To do this, we extracted DNA from 100 primary CRC samples and 40 corresponding normal tissue samples, which had been previously characterized for clinicopathological and molecular features. We employed a combination of quick-multiplex consensus (QMC)-polymerase chain reaction (PCR) and co-amplification at lower denaturation temperature (COLD)-PCR, followed by high-resolution melting (HRM) analysis and Sanger sequencing, to investigate the exonuclease domain regions of POLE and POLD1 genes for somatic mutations that may potentially alter the proofreading activities of these genes. In silico predictions of the functional significance of the identified genetic alterations were performed using the protein variation effect analyzer, sorting intolerant from tolerant, and PON-P2 algorithms. We identified a total of eight new and non-recurrent somatic variants in the endonuclease domains of POLE and two in POLD1. Nine out of ten variants caused amino acid substitutions, whereas one resulted in a stop codon. Although no significant associations or correlations were found between the POLE/POLD1 mutations and the clinicopathological or molecular features of the CRC cases, most of the POLE/POLD1-mutated cases were microsatellite stable (90%) and aneuploid (80%). Furthermore, in silico analyses showed that nine of the ten variants would likely cause some adverse effect on protein function. Ten somatic variants with predicted proofreading activity-altering effects have been identified in the endonuclease domains of POLE and POLD1 in CRC using a combination of QMC-PCR, COLD-PCR, HRM analyses, and Sanger sequencing.