Rennet is essential for cheese production, containing milk-clotting enzymes derived from animal, plant, or microbial sources. Accurate labelling of rennet’s biological origin is essential to respect consumer dietary choices, while microbial contamination may pose food safety risks. We developed an integrated strategy combining qPCR, metagenomics, culture-based methods, whole-genome sequencing, and mass spectrometry to verify the biological origin and microbial safety of 27 commercial products labelled as being of animal (n = 11), plant (n = 3), or microbial (n = 13) origin. DNA matching the labelled production organism was detected in most products, although DNA belonging to other known rennet-producing organisms was also found in several products, including one plant-labelled product containing animal DNA. Additionally, viable B. cereus s.l. was detected in some animal rennet products. To evaluate the potential food safety impact of B. cereus s.l. contamination, rennet products were used to produce cheeses, analysed for B. cereus s.l. growth and cereulide. Bacterial growth and measurable cereulide levels were observed in one cheese, confirming potential food safety risks. To the best of our knowledge, this study provides the first integrated assessment of commercial rennet combining both conventional methods and (meta)genomics, demonstrating the potential of these approaches to identify authenticity issues and microbial safety risks.
This study used metagenomics, untargeted metabolomics, and flavoromics to investigate the effects of the indigenous strain Lactiplantibacillus plantarum ST as a starter on the microbial community and metabolite profiles during the fermentation of De’ang pickled tea. The results showed that after ST inoculation, the microbial interaction network and the relative abundance of rare taxa in the pickled tea changed, accompanied by enrichment of genes related to amino acid metabolism pathways. Metabolomics showed that after ST inoculation, amino acids and their derivatives increased, while the volatile metabolite profile changed, with increases in compounds with pleasant fruity and floral notes and decreases in compounds related to musty and waxy odors. Metabolic pathway prediction further suggested that these metabolic changes may be related to the increased relative abundance of rare taxa such as Sphingomonas sp. and Chryseobacterium camelliae. Overall, L. plantarum ST may shape the metabolic and flavor characteristics during De’ang pickled tea fermentation by affecting the microbial community structure and functional potential. These findings provide a theoretical basis for using indigenous L. plantarum as a starter to regulate quality formation in De’ang pickled tea.
Methods integrating isothermal amplification with the CRISPR/Cas12a system have gained significant attention due to their sensitivity and specificity. Herein, a gelatin-assisted recombinase polymerase amplification (RPA)-CRISPR/Cas12a tandem (GARC) assay was developed to detect Listeria monocytogenes. The GARC assay design exploited temperature-responsive gelatin to physically encapsulate CRISPR/Cas12a reagents, maintaining them in a gelled state during RPA incubation at 37 °C. This spatial separation prevents premature interaction between RPA and CRISPR components, while the gelatin at an appropriate concentration enhances fluorescence signal intensity, facilitating visual readout. The optimized GARC assay achieved a limit of detection (LOD) of 10 ag/μL for the hlyA gene, representing 104 and 107 fold improvements over paraffin-based one-pot RPA-CRISPR (100 fg/μL) and conventional PCR methods (100 pg/μL), respectively. Notably, the assay detected 8 CFU/mL of L. monocytogenes and 1.03 × 10−5 ng/μL of genomic DNA, with favorable sensitivity (5/5) and specificity (16/16). Practical applicability was demonstrated through the successful detection of L. monocytogenes in salmon samples after 7-h enrichment at 20 CFU/25 g. This work introduces a versatile, visually interpretable platform with potential for food safety testing.
Mouthfeel, encompassing the tactile, thermal, and chemesthetic sensations experienced during eating and drinking, is a crucial dimension of flavour perception. This review includes insights from sensory science, neurophysiology, biophysics, molecular biology, and food technology to provide a mechanistic perspective on mouthfeel and its relevance to nutrition and product development. We discuss how integrating this perspective with food design may enable better strategies to promote healthier and more satisfying diets.
Polygonatum cyrtonema Hua is a crucial medicinal and edible plant whose antioxidant activity is primarily attributed to its phenolic constituents. Evaluating samples from five geographical origins revealed that the Fuzhou (FZ) ecotype exhibited the strongest antioxidant capacity, significantly correlating with total phenolic content (TPC). Integrated metabolomics and co-expression network analyses identified 32 key polyphenols (flavonoids, lignans, and phenolic acids) as central contributors to this antioxidant capacity. Furthermore, network pharmacology and molecular docking predicted that 10 key polyphenols stably interact with core oxidative damage-related proteins, including prostaglandin-endoperoxide synthase 2 (PTGS2), matrix metallopeptidase 9 (MMP9), and epidermal growth factor receptor (EGFR). Transcriptomic profiling highlighted the enrichment of phenylpropanoid and flavonoid biosynthesis pathways across origins. Integrative analysis identified 14 structural genes driving polyphenol biosynthesis, with RT-qPCR confirming the upregulation of 4-coumarate: CoA ligase (4CL), Chalcone synthase (CHS), Shikimic acid/Quinic acid hydroxycinnamoyl transferase (HCT), and Dirigent protein (DIR) in the FZ samples. Ultimately, this study elucidates the gene-metabolite basis of geographical variations in P. cyrtonema antioxidant capacity, providing valuable pharmacological insights and genetic resources for breeding superior, high-polyphenol cultivars.
