Tomato paste preservation: 5 methods to prevent white mold

To prevent white mold from forming on homemade or store-bought tomato paste, five key preservation methods have been identified.

First, sterilization is critical; jars and lids should be boiled in water for at least 10 minutes and dried thoroughly with paper towels rather than cloth to avoid microscopic water droplets. For long-term storage, hot filling is recommended: filling jars while the paste is boiling, leaving a finger's width of space, sealing tightly, and immediately turning the jar upside down to create a vacuum.

Once a jar has been opened, an olive oil layer acts as an oxygen barrier. The surface should be leveled with a spoon and covered with 1-2 tablespoons of olive oil to prevent air contact. Additionally, using unrefined coarse rock salt instead of iodized table salt helps maintain structure and prevents spoilage. Finally, maintaining hygiene by using dry spoons and keeping the jar edges clean is essential for preventing contamination.