Midrasz do Kapłańska 27:30

8) (Vayikra 12:4) "All that is holy she shall not touch": I might think even (second-) tithe, (which is called "holy" [viz. Vayikra 27:30]); it is, therefore, written (Vayikra 12:4)" and into the sanctuary she shall not come." Just as (entering the sanctuary in a state of tumah) is liable to "taking of the soul" (kareth), so (eating) "holy" (terumah, in a state of tumah) is liable to "taking of the soul" (death at the hands of Heaven, viz. Vayikra 22:9), to exclude the tithe. — But perhaps: Just as one who enters the sanctuary in a state of tumah is liable to kareth, so one who eats "holy" in a state of tumah is liable to kareth, to exclude terumah, (which is liable to death at the hands of Heaven.) It is, therefore, written "All that is holy," to include terumah. — But perhaps: Just as (eating) "holy" involves touching, so (entering) the sanctuary must involve touching (it). Whence is it derived (that he is liable for entering it even) if he does not touch it, (as when he enters in a box)? From "and into the sanctuary she shall not come" (— in any event). "until the fulfillment of the days of her purification": to include a woman who bears a female (in the prohibitions against entering the sanctuary and eating consecrated food).

8) "holy": It is written here "holy," and elsewhere, (in respect to ma'aser [viz. Vayikra 27:30]), "holy." Just as "holy" there requires a one-fifth surcharge (for redemption), and removal (from the house in the fourth and seventh years of the shemitah periods), so, "holy" here requires a one-fifth surcharge and removal.

9) (Vayikra 27:30) ("And all the ma'aser [tithes] of the earth, of the seed of the earth, or the fruit of the tree, it is the L–rd's; it is holy to the L–rd.") "the seed of the earth": to include (the seed of) garlic, onycha, and berries. I might think to include the seed of turnips, radishes, and other garden seeds which are not eaten; it is, therefore, written "of the seed of the earth," and not all of the seed of the earth. "of the fruit of the tree": to include all the fruit of the tree. I might (also) think to include the carobs of Shikmah and Tzalmonah and those of Giridah, (which are of inferior quality); it is, therefore, written "of the fruit of the tree," and not all the fruit of the tree. Whence do we derive the inclusion of vegetables for ma'aser? From "And all the ma'aser." I might think that Scripture is speaking of two tithes (ma'aser rishon and ma'aser sheni); it is, therefore, written "it (is the L–rd's"). What is mentioned there (in the section of ma'aser (Devarim 14:22-23), (namely, ma'aser sheni), is the same as "it" mentioned here. What is missing here is mentioned there.