Effect of tremella polysaccharides on the quality of collagen jelly: insight into the improvement of the gel properties and the antioxidant activity of yak skin gelatin.

BACKGROUND: The present study aimed to investigate the effects of tremella polysaccharides on the gel properties and antioxidant activity of yak skin gelatin with a view to improving the quality of collagen jellies. The preparation of composite gels were performed by yak skin gelatin (66.7 mg mL-1) and tremella polysaccharides with different concentrations (0, 2, 4, 6, 8 mg mL-1), and finally the collagen jelly was prepared by composite gel (yak skin gelatin: 66.7 mg mL-1; tremella polysaccharides:6 mg mL-1) with the best performance. RESULTS: Tremella polysaccharides not only improved the hardness, springiness, gel strength, water holding capacity and melting temperature of yak skin gelatin, but also enhanced the composite gel's scavenging activity against ABTS radicals, DPPH radicals, O2 and OH radicals. The filling of tremella polysaccharides into the gelatin network increased the number of crosslinking sites inside the gel, which resulted in the gel network structure becoming dense and orderly. The gel particles became finer and more uniform, and the thermal stability was improved. Furthermore, the sensory score of commercially available gelatin jelly decreased more rapidly during storage compared to the composite gel jelly. CONCLUSION: The gel properties and antioxidant activity of yak skin gelatin were improved by adding tremella polysaccharides, and then the quality and storage properties of the jelly were improved, which also provided technical reference for the development of functional gel food. © 2024 Society of Chemical Industry.

Characterization of sodium alginate-carrageenan films prepared by adding peanut shell flavonoids as an antioxidant: Application in chilled pork preservation.

This study prepared and characterized sodium alginate and carrageenan (SAC) composite films incorporated with peanut shell flavonoids (PSFs). PSFs compound identification research was implemented. The physicochemical features of PSFs-SAC composite films and their ability to preserve chilled pork in a 4 °C refrigerator were determined. PSFs consist of luteolin, eriodictyol, 5,7-dihydroxychromone, and 8 other components. They significantly improved the mechanical properties, barrier properties, thermal stability, and antioxidant properties of SAC composite films (P < 0.05). PSFs were also responsible for increasing the density of the film structure between the sodium alginate and carrageenan molecules. During storage, compared with the control group, the prepared PSFs-SAC composite films did not allow the total viable count (TVC), pH and total volatile base nitrogen (TVB-N) of the chilled pork to increase rapidly. Further, they were able to inhibit lipid oxidation more effectively (P < 0.05). For these reasons, the use of the PSFs-SAC composite films prolonged shelf life of chilled pork from 6 days to the 12 days. Therefore, PSFs-SAC composite films are expected to be used as bioactive substances in food preservation.

Hydroxypropyl methyl cellulose/soybean protein isolate nanoparticles incorporated broccoli leaf polyphenol to effectively improve the stability of Pickering emulsions.

This study prepared SPI-Pol-HPMC (SPH) nanoparticles from soybean protein isolate (SPI), hydroxypropyl methyl cellulose (HPMC), and broccoli leaf polyphenol (Pol) and used them as a stabilizer for the Pickering emulsion. The SPH (2:1) nanoparticles have the best ability to encapsulate broccoli leaf polyphenols, with uniform particle size distribution, and a more dense and stable structure. The chemical and hydrogen bonding forces between the SPH nanoparticle components were enhanced. Additionally, the 1.5 % SPH nanoparticle-stabilized emulsions exhibited good physical stability, manifesting as small particle droplets with good rheological properties and uniform dispersion. The volume fraction of the emulsified phase of the 1.5 % SPH nanoparticle-stabilized emulsions was the greatest after 21 days of storage. Interestingly, SPH nanoparticles also improved the oxidative stability of the emulsions, as evidenced through their lower peroxide values and thiobarbituric acid active substances. The aforementioned results suggest that SPH nanoparticles may be used as food-grade emulsifiers that stabilize emulsions and inhibit their lipid oxidation.

Rapidly adaptable automated interpretation of point-of-care COVID-19 diagnostics.

BACKGROUND: Point-of-care diagnostic devices, such as lateral-flow assays, are becoming widely used by the public. However, efforts to ensure correct assay operation and result interpretation rely on hardware that cannot be easily scaled or image processing approaches requiring large training datasets, necessitating large numbers of tests and expert labeling with validated specimens for every new test kit format. METHODS: We developed a software architecture called AutoAdapt POC that integrates automated membrane extraction, self-supervised learning, and few-shot learning to automate the interpretation of POC diagnostic tests using smartphone cameras in a scalable manner. A base model pre-trained on a single LFA kit is adapted to five different COVID-19 tests (three antigen, two antibody) using just 20 labeled images. RESULTS: Here we show AutoAdapt POC to yield 99% to 100% accuracy over 726 tests (350 positive, 376 negative). In a COVID-19 drive-through study with 74 untrained users self-testing, 98% found image collection easy, and the rapidly adapted models achieved classification accuracies of 100% on both COVID-19 antigen and antibody test kits. Compared with traditional visual interpretation on 105 test kit results, the algorithm correctly identified 100% of images; without a false negative as interpreted by experts. Finally, compared to a traditional convolutional neural network trained on an HIV test kit, the algorithm showed high accuracy while requiring only 1/50th of the training images. CONCLUSIONS: The study demonstrates how rapid domain adaptation in machine learning can provide quality assurance, linkage to care, and public health tracking for untrained users across diverse POC diagnostic tests.

It can be difficult to correctly interpret the results of rapid diagnostic tests that give a visual readout, such as COVID rapid tests. We developed a computational algorithm to interpret rapid test results using an image taken by a smartphone camera. This algorithm can easily be adapted for use on results from different test kits. The algorithm was accurate at interpreting results obtained by members of the public using various COVID rapid tests and diagnostic tests with similar outputs used for other infections. The use of this algorithm should enable accurate interpretation of rapid diagnostic tests by members of the public and hence enable improved medical care.

Production and identification of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from discarded cowhide collagen.

The present study focused on the effects of different preparation conditions on the activity and peptide sequence identification of DPP-IV inhibitory peptides based on discarded cowhide collagen and its regulation mechanism. The highest DPP-IV inhibitory activity (IC50 of 3.04 ± 0.13 mg/mL) was obtained by the combination of double enzymatic hydrolysis (papain and compound protease) and optimized IL-US (ultrasound-assisted ionic liquids) pretreatment. The optimal pretreatment condition for ultrasonic power, ultrasonic time, ionic liquid/collagen ratio, and collagen concentration were 389 W, 25 min, 0.7, and 0.3 %, respectively. IL-US pretreatment induced the exposure of active sites and hydrophobic amino acids of collagen peptide, promoted the partial transformation of ß-sheet to ß-turn, and enhanced the stability of gastrointestinal digestion. Seven new peptides with DPP-IV inhibitory ability were identified. Importantly, further molecular docking showed that five peptides (GPVG, FGPGP, APGGAP, GPPGPT, and GPVGPPG) were proposed to be antidiabetic peptides from cowhide collagens.

Changes in chilled beef packaged in starch film containing sea buckthorn pomace extract and quality changes in the film during super-chilled storage.

This study aimed to evaluate the effects of super-chilled storage (-1.3 °C) combined with starch film packaging containing different contents of sea buckthorn pomace extract (SSF, 0, 1, 2, and 3%, w/w) on the quality of chilled beef. The release kinetics, microstructure, and mechanical properties of the film were also measured to investigate its suitability for super-chilled storage. The results of the meat quality assessment showed that the L*, a*, and sensory evaluation values of the SSF-3% samples were significantly higher (P < 0.05), and the pH, b*, thiobarbituric acid reactive substance (TBARS), total volatile basic nitrogen (TVB-N), and total viable count (TCA) were significantly lower (P < 0.05) than the SSF-0%. The release of SBP from the SSF film was controlled by diffusion. Furthermore, SSF-3% was found to have a compact microstructure and good mechanical properties at the end of the super-chilled storage. The results demonstrated that SSF is an effective packaging material for beef at super-chilling temperatures.

Effects of lysosomal iron involvement in the mechanism of mitochondrial apoptosis on postmortem muscle protein degradation.

This study investigated the effect of lysosomal iron involvement in the mechanism of mitochondrial apoptosis on bovine muscle protein degradation during postmortem aging. Six crossbred cattle were studied to evaluate intracellular reactive oxygen species (ROS), antioxidant enzyme activity, lysosomal membrane stability, mitochondrial dysfunction-induced apoptosis, desmin and troponin-T degradation in both control and iron chelator desferrioxamine (DFO) groups. Results showed that lysosomal iron induced ROS accumulation and lysosomal membrane destabilization by decreasing the antioxidant enzyme activity (P < 0.05). Subsequently, lysosomal dysfunction mediated by iron increased mitochondrial membrane permeability and decreased mitochondrial membrane potential, thereby enhancing Bid and cytochrome c release and caspase-9/-3 activation (P < 0.05). Ultimately, lysosomal iron mediated lysosomal-mitochondrial apoptosis increased the postmortem bovine muscle desmin and troponin-T degradation (P < 0.05). The results indicated that lysosomal iron contributes to postmortem meat tenderization through the lysosomal-mitochondrial dysfunction-induced apoptosis pathway.

Carbon monoxide packaging shows the same color improvement for dark cutting beef as high oxygen packaging.

In this study, carbon monoxide (CO) modified atmosphere packaging (MAP) was used to increase redness (a*) and lightness (L*) values of dark cutting beef (ultimate pH (pHu)≥6.10), compared to normal pHu beef and intermediate pHu beef (pH: 5.40-5.79; pH: 5.80-6.09, respectively) during 20 d chilled storage. Compared with HiOx-MAP, CO-MAP exhibited similar color improvement effects (increased L*, a*, b* values) for all pHu beef groupings. The metmyoglobin (MetMb) content was lower under CO-MAP than that of HiOx-MAP in normal pHu beef, but opposite effects were observed in dark, high pH beef. This result could not be explained by MetMb reducing ability (MRA) and lipid oxidation, as both parameters were higher in CO-MAP beef than either normal or high pHu beef, compared with HiOx-MAP. In conclusion, CO-MAP was effective to maintain the cherry red color for dark cutting beef, but the color improvement mechanisms might be different with HiOx packaging methods.

Study on the apoptosis mediated by cytochrome c and factors that affect the activation of bovine longissimus muscle during postmortem aging.

This study investigates whether bovine longissimus muscle cell apoptosis occurs during postmortem aging and whether apoptosis is dependent on the mitochondria pathway. This study also determines the apoptosis process mediated by cytochrome c after its release from mitochondria and the factors that affect the activation processes. Results indicate that apoptotic nuclei were detected at 12 h postmortem. Cytochrome c release from the mitochondria to the cytoplasm activated the caspase-9 and caspase-3 at early postmortem aging and the activation of caspase-9 occurs before the activation of caspase-3. The pH level decreased during the first 48 h postmortem, whereas the mitochondria membrane permeability increased from 6 to 12 h. Results demonstrate that an apoptosis process of bovine muscle occurred during postmortem aging. Apoptosis was dependent on the mitochondria pathway and occurred at early postmortem aging. Increased mitochondria membrane permeability and low pH are necessary conditions for the release of cytochrome c during postmortem aging.

Effect of suspension method on meat quality and ultra-structure of Chinese Yellow Cattle under 12-18°C pre-rigor temperature controlled chilling.

This study was conducted to evaluate the effects of suspension method under 12-18 °C pre-rigor temperature controlled chilling on quality traits and ultra-structure of Chinese Yellow Cattle M. Longissimus lumborum (LL). After slaughter, the right sides of carcasses were hung by the Achilles tendon (SA), while the left sides were hung from the pelvic bone (SP). Both sides went through the 12-18 °C pre-rigor muscle temperature controlled chilling. LL muscles were aged for 1, 7 or 14 days and then evaluated for quality traits and ultra-structure. SP had no significant effect on myofibril fragmentation index, but significantly decreased the purge loss during aging and the Warner-Bratzler shear force values after aging for 1 day. Electron microscopy and sarcomere length examination of LL showed that SP resulted in extended I-bands and sarcomere length. To conclude, applying SP under 12-18 °C pre-rigor temperature controlled chilling is a potential method for the Chinese beef industry to improve tenderness especially after 1 day of aging.