On Food and Cooking

the center and progresses outward, and causes
a manyfold increase in carotenoid pigments
and aroma molecules, as well as a marked
softening. Softening causes the apparent
sweetness to increase even though the actual
sugar content doesn’t change (the sugars are
more readily released from the softened
tissue). A ripe papaya is a low-acid fruit with
a delicate, flowery aroma thanks to terpenes,
and a touch of cabbage-like pungency due to
the surprising presence of isothiocyanates (p.
321). These compounds are especially
concentrated in the seeds, which can be dried
and used as a mildly mustardy seasoning.
Unripe, crisp green papaya is made into
salads and pickles. The green fruit contains
vessels of milky latex rich in the protein-
digesting enzyme papain, which is found in
some meat tenderizers. Papain levels drop
during ripening, but can still cause texture and
taste problems like those caused by the
pineapple enzyme bromelain (p. 384).