Shuhong Ye

Sulfur fumigation, as a highly effective method for preservation and appearance enhancement, has been widely applied in fruits, vegetables, and food products. However, excessive sulfur fumigation can pose safety risks. Currently, there is limited research on the bound sulfites produced by sulfur fumigation, and no consensus has been reached regarding their structure and toxicity. Using ultra-performance liquid chromatography–quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS), a total of 34 compounds were identified in 12 lily bulb samples subjected to different sulfur fumigation durations. These derivatives were all hypothesized to form via nucleophilic addition to carbon–carbon double bonds. Based on multivariate statistical analysis, 9 characteristic markers were established to rapidly differentiate between non-fumigated (NF) and sulfur-fumigated (SF) samples. The practicality of this strategy was validated using 18 commercial batches. Molecular docking simulations predicted that the modifications might enhance toxicity toward liver injury-related targets, both by altering the spatial conformation of the compounds and because the sulfonic acid group itself serves as an ideal hydrogen-bond acceptor. Overall, mild fumigation led to a gradual accumulation of free sulfur dioxide in lily bulbs, increased the total content of phenolic components and antioxidant capacity, and did not generate excessive bound sulfur dioxide. However, with further extension of fumigation time, the content of sulfur-containing derivatives rose rapidly, accompanied by a noticeable decline in antioxidant activity. This study elucidates the sulfur-driven chemical transformation mechanisms in lily bulbs and establishes a targeted methodology for the quality control and safety assessment of processed herbal products.

Conjugated linoleic acid (CLA) is a highly value added active lipid that could be utilized as a functional food ingredient. This study introduces an innovative, low-energy biocatalytic approach utilizing lactic acid bacteria (LAB) to enhance CLA production in a sustainable manner. A synergistic coculture of Lactobacillus acidophilus (La) and Lactobacillus plantarum (Lp) was developed, wherein La's rapid acidification (pH < 5.5) effectively activated Lp's linoleate isomerase (LAI). Notably, a food-grade ethanol-based permeabilization method—a non-invasive and environmentally friendly processing technique—was applied to modify cell membranes (confirmed via SEM), thereby facilitating efficient uptake and intracellular conversion of linoleic acid (LA) by LAI, resulting in both cis → trans and Δ12 → Δ11 isomerization. The coculture of La : Lp in MRS media containing 500 µg mL⁻¹ LA exhibited a CLA conversion of 41.3%. When permeabilized cells were used in skim milk—an underutilized dairy byproduct—the CLA yield increased to 220.7 µg mL⁻¹ (44.1% conversion), demonstrating the potential for direct integration into dairy fermentation processes. This research establishes ethanol permeabilization as a promising tool in circular bioengineering, enabling energy-efficient CLA production (<50 °C, no toxic reagents) with minimal process waste, offering new opportunities for the production of CLA-enhanced milk products.

Bacillus amyloliquefaciens is a well-recognized biocontrol agent and plant growth promoter. This study characterized the endophytic B. amyloliquefaciens LJ1, isolated from Nanguo pear fruit, through whole-genome sequencing and functional analyses. The B. amyloliquefaciens LJ1 genome (3,947,365 bp, 46.48% GC content) encodes 3757 protein-coding sequences. Genomic analysis revealed diverse carbohydrate-active enzymes (CAZymes) and 12 secondary metabolite biosynthetic gene clusters, including those potentially producing surfactin, fengycin, bacillibactin, and bacilysin. Safety assessments, including hemolysis, indole production, biogenic amine production, and a 21 day mice-feeding trial, indicated no adverse effects, suggesting B. amyloliquefaciens LJ1 is non-pathogenic. In vitro assays demonstrated significant inhibitory activity against Penicillium expansum, a major post-harvest pathogen, by suppressing spore germination and germ-tube elongation. These results suggest that B. amyloliquefaciens LJ1 possesses significant biocontrol potential and could be a promising agent for sustainable disease management in Nanguo pear and potentially other crops.