Mulberry perishes easily due to its high water content and thin skin. It is important to extend the shelf life of mulberry by proper processing methods. In the present study, the influence of three drying techniques, including hot air drying (HAD), vacuum drying (VD), and vacuum freeze-drying (VFD) on the quality maintenance of mulberry was comprehensively evaluated. Bioactive compounds, antioxidant activity, and the sensory and volatile flavor compounds of mulberry have been researched. The results showed that VFD treatment maintained the highest anthocyanins (6.99 mg/g), total flavones (3.18 mg/g), and soluble sugars (2.94 mg/g), and exhibited the best DPPH· (81.2%) and ABTS⁺· (79.9%) scavenging ability. Mulberry also presented the lowest hardness and the greatest brittleness after VFD. Additionally, VFD maintained the optimal color and presented the best sensory attributes. Furthermore, 30, 20, and 32 kinds of volatile flavor compounds were detected in HAD, VD, and VFD, respectively, among which aldehydes, esters, and ketones were the most abundant compounds. This study indicated the potential application value of VFD for the drying of fruit and vegetable foodstuffs.

Mulberry Jiaosu, derived from natural fermentation using fresh mulberry fruit as a raw material, refers to an edible product containing specific bioactive substances. However, the dynamic changes in the bioactive substances of organic acids, amino acids and polyphenols as well as the species and function of microorganisms in mulberry Jiaosu are still not clear. Herein, the whole fermentation process of mulberry Jiaosu was comprehensively researched by analyzing the microbial community structure and bioactive substances. The results showed that the change in physicochemical parameters mainly happened within 30 days of fermentation. The total organic acids and total polyphenols presented upward trends. Total amino acids were partly consumed during the fermentation. A total of 173 fungal genera and 295 bacterial genera were detected in mulberry Jiaosu, mainly including Torulaspora, Zygosaccharomyces and Lactobacillus, whose abundance can be influenced by changes in the fermentation environment. During the fermentation of mulberry Jiaosu, 8 organic acids, 17 amino acids and 9 polyphenols were observed, which could be regulated by the metabolism of microorganisms. Zygosaccharomyces exhibited positive correlations with the majority of the organic acids, amino acids and polyphenols, presenting a great influence on the formation of bioactive substances. Compared with fungi, bacteria contributed more to the synthesis of organic acids, free amino acids and polyphenols. This study revealed the bioactive substances and microbial diversity during the fermentation of mulberry Jiaosu, which are findings that will contribute to the precise regulation of the fermentation process and improvement of the product quality.

Here, a highly sensitive and selective electrochemical sensor for dopamine (DA) determination in pork was developed. This sensor was fabricated using iron-based nanocomposites (Fe@(C-S-N)) to modify a glassy carbon electrode (GCE) substrate. The Fe@(C-S-N) nanocomposites were synthesized through a facile low-temperature chemical precipitation approach by adopting ferrous sulfate and melamine as raw materials, with their structural and compositional properties thoroughly investigated using multiple analytical techniques, including X-ray diffraction (XRD), electron microscopy (EM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectra (EDS). Cyclic voltammetry (CV), chronocoulometry (CC), and differential pulse voltammetry (DPV) were adopted to investigate the electrochemical performance of the fabricated Fe@(C-S-N)/GCE sensor. Notably, the sensor demonstrated a linear response range from 0.05 to 100 μM with a minimal limit of detection (LOD) of 46 nM. Lastly, the fabrication sensor was used to determine DA in pork samples, showing an acceptable recovery of over 96.89%. Thus, the proposed sensor could offer an effective method for determining DA in pork.

Monitoring dopamine (DA) in pork can provide useful information for assessing meat freshness and quality deterioration. In this work, an Fe@N-S-O-C nanocomposite was fabricated as an electrode modifier for DA determination. The Fe@N-S-O-C nanocomposite was synthesized via precipitation followed by calcination using melamine and ferrous sulfate as precursors. The crystal structure, surface chemical composition, and morphology were characterized by XRD, XPS, SEM, and TEM. The Fe@N-S-O-C-modified glassy carbon electrode (Fe@N-S-O-C/GCE) was then evaluated for its electrocatalytic performance toward DA. Under the optimized conditions (pH 6.0), the sensor showed linear responses to DA over 1–65 and 65–220 μM. The sensitivities for these two ranges were 4.357 and 1.685 μA μM⁻¹ cm⁻², respectively, with an LOD of 40 nM. In addition, the Fe@N-S-O-C/GCE showed excellent reproducibility, good repeatability, and strong anti-interference capability against common coexisting substances. After 30 days of storage, 82.74% of the initial current response was retained by the same electrode. Practical applicability of the sensor was verified in pork samples, with recoveries of 95.97–106.73%. These results demonstrate that the Fe@N-S-O-C/GCE sensor offers a reliable and effective platform for DA detection in complex food matrices.

Mianning ham is a traditional dry-cured ham from southwestern China, but the coordinated relationships among quality changes, microbial succession, and nonvolatile metabolite remodeling during long-term ripening remain poorly understood. Therefore, samples of Mianning ham aged for one, two, three, and four years were comparatively analyzed. High-throughput sequencing was used to characterize microbial community composition, and untargeted metabolomics was applied to analyze differential metabolite changes and their associations with dominant microorganisms. The results showed that the physicochemical and sensory characteristics of Mianning ham exhibited stage-dependent changes during ripening, with moisture content and pH generally decreasing, while color, texture, and mature flavor characteristics gradually developed. Multivariate statistical analysis identified 99 differential metabolites, which were mainly involved in peptide accumulation, amino acid metabolism, and nitrogen-containing compound transformation. The bacterial communities were mainly composed of Bacillota and Pseudomonadota, while Ascomycota was the predominant fungal phylum. Distinct successional patterns of dominant microbial taxa were observed at different ripening stages. Furthermore, microorganism–metabolite correlation analysis revealed distinct association patterns between internal and surface samples of the ham. Internal microbial communities were mainly associated with nucleotide-related metabolism- and umami-related characteristics, whereas surface microbial communities were more closely associated with the transformation of protein-derived nitrogen-containing compounds and the accumulation of flavor precursors. This study provides insights into the quality formation patterns of Mianning ham during ripening and offers a theoretical basis for ripening-stage evaluation and quality regulation.

This study evaluated how a lemon essential oil–rutin–chitosan coating (CS-LEO/NE-R), prepared from a 5:95 (v/v) lemon essential oil/rutin-containing nanoemulsion and a chitosan solution containing 1.5% chitosan, 1% acetic acid, and 5% glycerol, combined with controlled freezing-point storage preserves seasoned white snakehead fillets. Compared with controlled freezing-point storage alone, the combined treatment significantly inhibited oxidation, volatile nitrogen accumulation, texture softening, and microbial growth. On Day 10, the coating group recorded a total viable count of 4.98 log CFU/g, which was below the national limit (5 log CFU/g), whereas the control group went beyond this limit by Day 7. This extended the microbiological and physicochemical acceptability period by approximately 3 days under the present experimental conditions. Untargeted metabolomics revealed 2267 metabolites, and the differentially abundant ones mainly comprised amino acids, heterocyclic compounds, aldehydes, ketones, and esters. KEGG enrichment suggested that changes in linoleic acid metabolism, terpenoid related annotations, the actin cytoskeleton, and the phospholipase D signaling pathway were associated with delayed quality deterioration. This work provides a theoretical basis for the composite biopreservation of aquatic products.