Maaseros 4:1-2

Maasros 4:1

If a person pickles, boils or salts produce while it is still in the field, it must be tithed. If he stores produce underground in order to ripen it, it need not be tithed. If he dips produce in salt or vinegar while still in the field, it need not be tithed. If he bruises olives to extract the sap, they need not be tithed. If he squeezes olives onto his skin (in order to anoint with their oil), they need not be tithed (even though he eats the oil). If he squeezed olives into his hand (and thereby collected the oil), they must be tithed. If one skimmed the refuse of wine into a cooked dish, the wine need not be tithed but if he skimmed it into a pot, it must be tithed because the pot is considered like a small vat.

Maasros 4:2

If children hid figs for Shabbos and they neglected to tithe them, they may not be eaten untithed on Shabbos. If one put a basket of fruit aside for Shabbos, Beis Shammai say it need not be tithed before eating and Beis Hillel say that it must (i.e., the act of designating it for Shabbos renders it liable to tithes). Rabbi Yehuda says that if one gathers a basket of fruit to send to a friend, he may not eat from it untithed (because designating it for a friend has the same effect as designating it for Shabbos).