Separating Tithes from Pineapple

I bought a pineapple from a non-Jew on the way north (with leaves, locally grown). Do I need to separate tithes with a blessing, and how is it done?

Hello Rabbi,

There is a doubt regarding the separation, whether it is grown by a non-Jew or purchased from a Jew, therefore it should be separated without a blessing.

I will arrange for you the steps of separation and the text according to the instructions of our teacher, the Gaon, Rabbi Ovadia Fried, shlita:

Steps of separation:

A: Remove slightly more than one percent of all the fruits and vegetables.
B: In this year, when separating the second tithe, a coin should be designated for redeeming the second tithe.
C: Recitation of the blessing and the text of separation, as follows.

Text of separation (for this year):

Initially, the long text should be recited, which is:
 'The more than one out of a hundred that is here, is a large terumah on its northern side, 

that one out of a hundred that is here and nine more parts like it on the northern side of the fruits, is the first tithe.

That one out of a hundred that is here which I made the first tithe is made terumat maaser.

And the second tithe on the south of the fruits..
Then he shall redeem the second tithe on the coin he prepared, and say in these words: 'All the second tithe that is here, it and its fifth are redeemed on a prutah and a quarter on the coin I designated for redeeming the second tithe'. If it does not have the value of a prutah, it shall be redeemed, it and its fifth, according to its value on the coin I designated for redeeming the second tithe.
After reciting the blessing and the text, one should take the percent and more that was separated from the fruit initially, and throw it in the trash wrapped in a bag. And destroy the coin when possible by making it unusable [such as bending it with two pliers], 

Shulchan Aruch Yoreh De'ah 331