A nanny accidentally used an air fryer, which is fleishig, to cook fish sticks. The fish sticks are Tablet K-D, and there is a food warning label about milk on the package. There is no milk in the ingredients, but in the “contains less than 2% of the following” ingredients listing, “whey” is included. What is the status of air fryer?
Let’s first assume that the fish sticks were on aluminum foil or in a pan. There is a debate if whey is milk mide’orayta or only miderabanan. See Shulchan Arukh YD 87:6, 8. I also assume that a “D” reflects the fact that there is a milk product in the food, not whether it is technically bateil or not. So, if whey was definitely derabanan, you could argue that it is a safeik derabanan, because it might be that the whey is already bateil, but that is not possible, since some say it is de’orayta. We might say that this is a safeik sefeika, maybe whey is derabanan, and then it is safeik derabanan lekulah, and even if it is de’orayta, it might actually be bateil.
Either way this is a moot point. Even those who are lenient to say we don’t have to be concerned with zei’ah in modern ovens because of the their size and ventilation, would not hold so in our case becuase of the small size of the air fryer. Nonetheless, since fish sticks are a solid, everyone would agree that zei’ah is not a concern.
If the fish sticks were place directly into the air fryer the standard approach would be to say that if the fryer floor was not used in the last 24 hours, then it is now dairy with eino ben yomo meat absorbed in it and you can only use it for pareve. You can continue to use it for both minim, assuming nothing liquidy, if you use tin foil underneath. If the air fryer was ben yomo meat when she made the fish sticks, then it is indeed treif, and would have to be kashered.
However, as I noted, there is a safeik sefeika here, and I think it can be relied on once it is eino ben yomo from the use of the fish sticks.
Also, if a Jew had tasted the fish sticks and did not detect a dairy taste, then we can assume that the dairy was bateil, since we may rely on te’imat Yisrael in a bedieved case. Hence the air fryer would be fine.
I would like to clarify that this is in no way an endorsement of Tablet K. As I wrote in a previous post, Tablet K relies on the position that cheese does not require Jewish supervision, a position that is rejected by the standard Orthodox community. I also cannot attest to the general level of supervision they provide. The questioner clearly relies on Tablet K and wanted to know the impact on the air fryer. I am not addressing the general reliability of Tablet K, which I find to be problematic.