Apparently they can be shelled and boiled and then vacuum sealed.
Found this on the net in about two seconds. Just search preserving chestnuts.
You can easily preserve chestnuts through the winter, after removing them from their green prickly husks make sure they are perfectly dry then place them in a wooden box or barrel between layers of dry fine sand much like the method used to preserve carrots. Once full store the box in a cool dry place. If still in their shells fresh chestnuts will keep in the salad drawer of the fridge for up to a month. Cooked chestnuts can be frozen whole or pureed and used in many recipes, try adding whole chestnuts to dishes like braised Pork or use them pureed to make delicious tasting stuffing's. Chestnuts can also be dried and ground up into a flour and used for making pastas, pancakes or used in baking.
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