Monascus rice (MR) as a well-known functional food, produces various pigments and active compounds, as well as flavor enhancers. The present study aimed to evaluate the effect of Monascus bioaugmentation on the microbial community, flavor quality, and bioactivity of Zhejiang rosy vinegar by inoculating 1% of three single MR from Jinhua (JH), Lishui (LS), and Gutian (GT) during traditional fermentation. In the early solid-state fermentation, Rhizopus was the dominant fungal genera in the three MR groups compared to Hypocerea in the Control, and the relative abundance of Acetobacter, Limosilactobacillus, and Komagataeibacter apparently increased in JH-MR and LS-MR samples during liquid-state fermentation. The addition of MR significantly increased the total acidity and the amount of amino acid nitrogen in the vinegar samples. Among these vinegar samples, the levels of acetic acid, succinic acid, Glu, Ala, Leu, and Cys were significantly higher in the JH-MR group (P < 0.05). A total of 77 volatile flavoring compounds were identified, and their contents of acids and alcohols in the three MR vinegar were slightly higher than in the Control. Spearman correlation analysis displayed that 12 flavor compounds were related to Lactobacillus and Acetobacter, respectively, such as acetoin, octanoic acid and 2-methyl-1-butanol. Additionally, JH-MR vinegar had the higher content of total flavonoid and total polyphenol than other three samples, associated with significant enhancement of antioxidant activity. Compared with Control, JH-MR vinegar presented 73 differential metabolites and contained more bioactive substances, such as ferulic acid, gluconic acid and taurine. Starch and sucrose metabolism, pentose phosphate pathway, valine, leucine and isoleucine biosynthesis and galactose metabolism were the significant differentially enriched pathways. Therefore, Monascus bioaugmentation promoted the saccharification and acetic acid fermentation by stimulating the proliferation and metabolism of Rhizopus and Acetobacter, enhancing the flavor quality and bioactive properties of rosy vinegar.

Food safety and quality are the basis and prerequisite for ensuring the harmonious and stable development of the modern economy and society. At present, foodborne pathogens, veterinary drug residues, genetically modified foods and adulteration cause or may cause food safety hazards. Metabolomics is an emerging technology that can be used to identify and monitor various trace food safety hazard factors by detecting the changes of small-molecule metabolites in organisms caused by exogenous disturbances, which will help to explore the metabolic mechanism. Furthermore, metabolites resulting from the degradation of food hazard factors can be potential biomarkers of food hazards, providing insights into the mechanism of action of foodborne pathogens and setting the stage for food quality and safety control. This review article describes targeted and non-targeted metabolomics, as well as the data acquisition and mathematical statistics methods commonly used for metabolomics. The recent progress in the application of metabolomics in the field of food quality and safety is summarized such as the detection of foodborne pathogens, veterinary drug residues, genetically modified foods, fresh produce quality, and meat adulteration. This review concludes with an outlook on the joint application of multi-omics technologies, which is expected to promote the wider application of metabolomics in the field of food safety and quality.

Pseudomonas, an important spoilage bacterium in animal-derived foods as well as fruits and vegetables in the cold chain, can cause huge economic losses to the food industry. The food spoilage ability of Pseudomonas is closely related to the formation of biofilm, which can enhance the survival and adaptability to the food processing and storage environment of Pseudomonas, causing persistent contamination. However, a systematic review of the biofilm formation of Pseudomonas and its mechanism is still lacking at present. This article describes the contamination status of Pseudomonas in fresh foods, analyzes the biofilm formation and extracellular matrix composition of Pseudomonas, and elucidates the major regulatory factors of the biofilm formation of Pseudomonas such as cyclic diguanylate, quorum sensing system and small RNAs. We believe that this review will provide a theoretical reference for uncovering the mechanism of food spoilage caused by Pseudomona and controlling its biofilm contamination.

Immunochromatographic assay (ICA) has been widely used in various fields for its economy, simplicity, sensitivity and specificity. The application of colloidal gold nanoparticles in ICA has limitations in quantification and interference resistance. Fluorescent nanomaterials have become an important signal label in ICA due to their excellent optical properties. This article briefly describes the preparation and properties of fluorescent nanolabels, such as quantum dots, up-conversion nanoparticles, time-resolved fluorescent microspheres, and persistent luminescence nanoparticles. The focus of this review is the application of fluorescence immunochromatography in the detection and analysis of foodborne pathogens, mycotoxins, pesticides, veterinary drugs, antibiotics, hormones, endocrine disruptors, heavy metals and other food hazards. The combined use of fluorescence immunochromatography with smartphones is also discussed. It is hoped that this review can provide a reference for food safety detection and on-site and real-time monitoring.