Abstract: A food contained in a can is heated by a reaction of quicklime with water in an envelope adjacent to that containing the food. According to the invention, in addition to overburnt quicklime, there is used an amount of quicklime having a high or medium reactivity comprised between about 6% and 75% by weight with respect to the total weight of lime. It is also known to use, for the same purpose, quicklime having a low reactivity called "overburnt quicklime", i.e. quicklime having a reactivity with water which has been reduced by calcination at a temperature of more than about 1150.degree. C. The use of such an overburnt lime is necessary. Due to its moderate reaction it allows to obtain a good heat transmission during a long period, to avoid projections of lime milk as well as a loss of heat by emission of water vapor.

Abstract: This invention relates to a device for heating food contained in a sealed container, such as a tin, can or carton, without use of external heat.The device comprises at least one sealed container surrounded by an envelope forming an annular chamber containing quicklime and water separated by a wall which can be easily pierced or torn, so as to allow a contact of the water with the quicklime, said annular chamber containing quicklime the reactivity of which has been previously reduced, as well as an amount of water which is larger than the amount necessary for the hydration reaction of the quicklime. The reactivity of the quicklime has been reduced by calcination at a temperature of more than about 900.degree. C. and preferably comprised between about 1100 and 1400.degree. C. according to the desired reactivity degree. The amount of water contained in the annular chamber surrounding the sealed container is comprised between about 0.75 and 3 parts by weight for 1 part by weight of quicklime.