Preserving Tomatoes: 5 Methods Compared
When tomatoes ripen faster in August than you can eat them, it's time to preserve them. Five methods – each with its own strengths.
1. Canning as Sugo
Blanch the tomatoes, peel, purée. Adding acid is mandatory: per 1 l jar 2 tbsp + 2 tsp bottled lemon juice (consistent acidity) or a heaped ½ tsp citric acid, per 0.5 l jar 1 tbsp + 1 tsp or a heaped ¼ tsp (National Center for Home Food Preservation, NCHFP: 1 tbsp or ¼ tsp per pint = 0.47 l, 2 tbsp or ½ tsp per quart = 0.95 l – rounded up here because 0.5 l and 1 l jars are slightly larger). Tomatoes are borderline low-acid – without this acid there is a risk of botulism, so do not reduce the amount. Then process in sterilized jars 30 minutes at 100 °C in a water bath. There is no way around the acid: tomatoes sit right at the pH threshold, modern varieties sometimes above it, and at 100 °C low-acid produce does not become spore-free – the rules are in "Safe Canning: Avoiding Botulism". Result: a ready-made sauce base for winter. Shelf life: 1–2 years.
2. Freezing
The fastest method. Dice or purée the tomatoes, freeze in portions. There's texture loss after thawing – suitable only for sauces, not salads.
3. Oven Drying
In the oven at 40–50 °C with the door slightly open, as the BZfE advises, or in a dehydrator at about 60 °C according to the NCHFP. Place halves on parchment paper, cut side up. This takes many hours – only done once no moist spots remain. The flavor becomes extremely concentrated – ideal for antipasti and pasta.
4. Preserving in Oil
Layer dried tomatoes with herbs into olive oil and always keep them fully covered. Store in the fridge and eat them no later than the day after making them (BfR): oil excludes oxygen, and the layer of oil protects against mould, not against botulism. The BfR advises against preserving and storing vegetables in oil altogether.
5. Fermenting
Submerge in a 2% salt brine, let ferment at room temperature for 5–7 days. The result is lacto-fermented, complex, tangy, and very flavorful.
Sources
- National Center for Home Food Preservation (NCHFP), University of Georgia: Tomato Acidification Directions, accessed 4 Oct 2026
- German Federal Institute for Risk Assessment (BfR): Rare but avoidable: questions and answers about botulism, as of 12 Nov 2025, accessed 4 Oct 2026
- German Federal Centre for Nutrition (BZfE): Getrocknete Leckereien, accessed 5 Oct 2026
- National Center for Home Food Preservation (NCHFP), University of Georgia: Food Dehydrators, accessed 5 Oct 2026
The sources support individual statements in this article. The organisations named have neither reviewed nor endorsed it.