Jam making: tips for consistency and food safety

Proper jam preparation and storage are essential for both texture and safety. To ensure correct consistency, the ‘cold plate test’ can be used. By placing a drop of boiling jam on a frozen plate, cooks can observe if the jam sets or flows like water, indicating whether further cooking is required. Ideal gelling typically occurs between 104°C and 105°C.

Regarding food safety, the presence of mold in jam poses risks. While some culinary sources suggest that surface mold can be carefully removed, food safety authorities, such as the Ministère de l’Agriculture, des Pêcheries et de l’Alimentation du Québec (MAPAQ), recommend discarding the entire jar. This is because toxins produced by fungi can penetrate deep into soft foods, even if they are not visible on the surface.

To improve preservation, it is recommended to use sterilized jars, fill them to three-quarters capacity, and invert them overnight to create a vacuum. Once opened, jam is more susceptible to spoilage due to air exposure, moisture, and potential contamination from utensils.