The cooked food used for an eiruv tavshilin does not necessarily need to be cooked. Smoked, roasted or pickled food is also acceptable. The food should be completely cooked; if it is only partially cooked and edible only under pressing circumstances, some poskim hold that it is unacceptable. Some foods are prepared when hot water is poured onto them. These foods may be used for the eiruv when prepared in that fashion. Some poskim consider a pasteurized food to be cooked for this halacha. According to this opinion, commercial cheeses may be used for the eiruv tavshilin.
[שו"ע תקכז, ה, ומשנ"ב יג ו־יז; ביאורים ומוספים דרשו, 21 ,23 ו־24]