On food and cooking the science and lore of the kitchen ( PDFDrive ) 1522
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enzyme digests the gelatin molecules and
liquifies the jelly. But canned pineapple has
been heated enough to denature the enzyme,
andmakesafirmgelatinjelly.
There’sacomplication,though.The
reactivityofmostchemicalsincreaseswith
increasingtemperature.Theruleofthumbis
thatreactivitydoubleswitheachriseof
20ºF/10ºC.Thesametendencygoesfor
enzymes,uptoarangeinwhichtheybeginto
denature,becomelesseffective,andfinally
becomecompletelyinactive.Thismeansthat
cookinggivesenzymesachancetodotheir
damagemoreandmorequicklyasthe
temperaturerises,andonlystopsthemonce
theyreachtheirdenaturationtemperature.In
general,thebestruleistoheatfoodsas
rapidlyaspossible,therebyminimizingthe
periodduringwhichtheenzymesareattheir
optimumtemperatures,andtogetthemallthe
waytotheboilingpoint.Conversely,
desirableenzymeaction—meattenderizing,
forexample—canbemaximizedbyslow,
gradualheatingtodenaturingtemperatures.
