The normal vacuum bags aren’t suitable to reach high temperatures. For all the cooking and heating needs you can use the special cooking vacuum bags Besser Vacuum, that can reach 115°C and are suitable for the cooking in the microwave, with vapour and in bain-marie.
It’s very important to be sure that the bags that are beign used are suitable for the heating and that you are respecting the recommended temperature limits; otherwise there may be the risk that some substances contained in the bag migrate into the food.