Peppermint essential oil (Peo) is an efficient antifungal agent, and 2.0 μL of Peo per milliliter culture medium can completely inhibit the mycelium growth and spore germination of Geotrichum citri-aurantii. In vitro experiments showed that the main functional component in Peo was L-menthol, which could lead to changes in sugar and protein contents, reduce the content of alkaline phosphatase (AKP), and destroy the spore membrane structure, with a significant increase in electrical conductivity. Meanwhile, the content of reactive oxygen (ROS) accumulated sharply, and the enzyme activity changed significantly with the change in the gene expression level. In addition, L-menthol could cause degradation in spore genetic material differently. Furthermore, a total of 1704 differentially expressed genes (DEGs) in G. citri-aurantii after 1.6 μL/mL L-menthol exposure for 2 h were obtained by the transcriptome sequencing. These DEGs were involved in transmembrane transport, carbohydrate transmembrane transport protein activity, and mitogen-activated protein kinase (MAPK) signaling pathway. The protein−protein interaction (PPI) analysis of DEGs yielded 10 highly cross-linked nodes, and these genes were associated with DNA replication and cell cycle. The expression level of the hub gene was confirmed by real-time quantitative PCR (RT-qPCR), with the most significant changes in POL 30 (5.9-fold). Molecular simulation was performed and it was found that the binding site between L-menthol and POL 30 was the 44th ARG residue in POL 30, and it was speculated that L-menthol and POL 30 may be combined by hydrogen bonding interaction. The results of flow cytometry assay showed that L-menthol blocked the replication process in the S-phase of G. citri-aurantii. This study provides new insights into the development and application of Peo in food safety.

The aim of this experiment was to assess the effect of different storage temperatures on the texture quality, phenolic profile, and antioxidant capacity of a grape. Fresh grapes were stored at 4 and 25 °C for nine days and sampled on alternate days. The hardness, total phenolics, total flavanones, total flavanols, total anthocyanin content, antioxidant activity, differential metabolite screening, and key gene expression were evaluated. In addition, four phenolic compounds were screened out as differential metabolites in response to storage temperature by OPLS-DA analysis. The results showed that the fruit firmness was better maintained in low-temperature storage and the storage life was longer than that at 25 °C. During the whole storage process, the contents of phenolics, flavanones, flavanols, and anthocyanins all showed an increasing trend first and then decreased regardless of what temperature. Since the antioxidant capacity of a grape was positively correlated with the contents of total phenols and total flavonoids, the same trend was also shown. However, the grape's phenolic compound content and antioxidant activity were higher at 25 °C than at 4 °C. Furthermore, through qualitative and quantitative analysis of 16 monomeric phenols, this study selected catechin, 1-O-vanilloyl-β-D-glucose, p-coumaric acid 4-glucoside, and resveratrol-3-O-glucoside as the main differentially expressed metabolites at the two temperatures. In conclusion, for a short shelf life or immediate consumption, keeping grapes at room temperature is more beneficial to obtain high antioxidants. However, if the goal is to prolong the storage period of the fruit, keeping the fruit at 4 °C is recommended.