If you follow the custom of the Benei Sefard and follow the Psakim of Shulchan Aruch may add some more potatoes to do Bitul, to nullify the Terumah in one hundred times, but this won’t work for Bnei Ashkenaz.
Explanation:
The Mishna Terumot 6:7 writes: R Eliezer said Terumah is nullified in one hundred and one times. R’ Yehoshua said One hundred and a bit. This bit has no specific amount. R’ Yossi ben Meshulam said it needs a Kav more than one hundred times which is another sixth.
The Tannaim argue in how much Terumah is nullified. Either 101 times, or 100 and bit, or 100 and a kav. The Rambam (Hilchot terumait3:1)rules like R’ Eliezer that one needs 101 times of the Terumah. Since Terumah and Terumat maser is a little more than one hundredth of the whole amount there is not enough of the fruit to nullify the Terumah. The question can you add more to nullify the Terumah?
The Mishna in Terumot 5:9 writes: A Saah of Terumah which fell into ls than one hundred times and then some more Chullin fell in. If it happened accidentally it is permitted, if it was on purpose it is forbidden.
The Mishna is saying that if there was not enough fruit besides the Terumah to nullify and more fruit fell in accidentally then it will nullify, on purpose it won’t since it is forbidden to nullify prohibited food on purpose. If it is nullified then on just has to take out the amount of the Terumah and give it to a Kohen.
However the Gemara in Beitzah (4b)writes that we are not allowed to nullify by something prohibited from the Torah but a Rabbinically prohibited food you may nullify it.
So rules the Shulchan Aruch in Yod 99:5: We are not allowed to nullify a prohibited food item even if Issur fell into Heter we are not allowed to add to the Heter to nullify it. If he did , then if it was accidental, it’s permitted to eat but if it was on purpose is forbidden for the one who owns it even if someone else didn’t, but is permitted to other people. IN 99:6 he adds: Rabbinically prohibited food we are not allowed to mix it with heter to eat it, and if one did, it is still forbidden, but if it fell into heter you are allowed to add heter to make enough of a shiur to nullify it. The Rema adds : Some say there is no difference between a Issur from the Torah or from the Rabbanan, and this is our custom.
There is an argument between the Shulchan Aruch and the Rema when Issur Derabbanan falls into heter accidentality can one add more to nullify, according to the Shulchan Aruch it is fine and the Rema says it is forbidden. He Rema understood the Gemara in Beitzah where it says it is permitted is discussing wood which is forbidden to burn in an oven and it got mixed with other wood , there it is permitted to add on more wood since the Issur will get destroyed as you sue but an Issur which just nullified snot permitted.
Is Terumah nowadays form potatoes from the Torah or Rabbinic?
The Rambam (Terumot 2:1)writes: Any produce which is guarded while growing is obligated Terumah and is a Mitzvah to separate the first bit to the Kohen as it says ,”Reishit Degnacha (grain) Tiroshcha (wine) Veyitzharecha (Oil) …Titen lo (give him). Just as grain wine and oil are human food and someone owns them anything else like that is obligated in Terumah.
The Kesef Mishna explains the Rambam: It seems he says that anything is obligated from the Torah which meet these criteria of the grain wine and oil.
Therefore according to the Rambam any fruit would be in the Torah category of separating Terumah.
The Raavad however argues (Maasrot 1:9) and Tosfot (Beitzah 4b) who says that only grain, wine and oil are from the Torah and everything else is Rabbinic.
Vegetables everyone agrees that vegetables are only Rabbinic. Even the Rambam writes in Terumot 2:6:Vegetables even though they are human food, they are obligated in Maasrot only from the Rabbis sin it says ‘Tevuah- grains and similar things , but vegetables are not similar. So too by Terumah it says Degancha etc. and anything else which fulfils the criteria but not vegetables. Therefore according the Shulchan Aruch you may add extra to nullify by vegetables. However, according to the Rema, though, you are not allowed to.
