Hi michihenning, sorry for late reply. IKEA did reply me in a very diplomatic way that what I did should be safe, however they do not recommend to go above the defined specification. (I’d post the reply, but I asked in italian).
I’d have answered the same thing in their shoes. I keep using these as other firends of mine are doing, quite confidently at least till 65C.
For yogurt I use glass jars. I am looking for reusable silicone bags for other things. I am wondering if the large bag from stasher was big enough for a 1.5-2kg roast.
Why didnt i think of it!! Thanks. After reading about leakage with IKEA ISTAD bag, i ended using a big mason jar…to cook Jap Cahshu…with lots of liquid. Lets see the verdict.