On food and cooking the science and lore of the kitchen ( PDFDrive ) 737

dilution. Passion fruits are unusual for their
relatively high acid content, mainly citric —
more than 2% of the pulp weight in purpleskinnedtypes,anddoublethatinmostyellow
ones — and their strong, penetrating aroma,
which appears to be a complex mixture of
fruity and flowery notes (esters, peach-like
lactones, violet-like ionone), and unusual
musky notes (from sulfur compounds like
those in black currants and sauvignon blanc
wines). Passion fruit pulp is used mainly to
make beverages, ices, and sauces, with the
milder purpleP. edulis generally consumed
fresh and the stronger yellowP. edulis var.
flavicarpa processed (an early commercial
applicationwasHawaiianpunch).
Meat-EatingFruits:ThePuzzleofPlant
Proteases
Atfirstglance,itseemsstrangethatfruits
should contain meat-and gelatin-digesting
enzymes,themoleculesthatpreventcooks


from making jellies with those raw fruits.
Of course there are a few carnivorous
plants that trap insects and other small
creatures in digestive juices.And in some
plant parts, similar enzymes probably
provideprotectionagainstattackbyinsects
andlargeranimals,whoseinsidestheycan
irritateorinjure.Butfruitsaremeanttobe
eaten by animals so that the animals will

dispersetheplant’sseeds.Sowhyfillthem
withproteases?
In the cases of papaya, pineapple,
melon, fig, and kiwi, the enzymes may
limit the number of fruits that any one
animal eats: too many and the animal’s
digestive system suffers. Another
intriguingsuggestionisthatinmoderation,
the enzymes actually benefit seeddispersing animals by ridding them of
intestinal parasites. Some tropical peoples
use fig and papaya latex for this purpose,
andit’sknownthattheenzymesdoindeed