On food and cooking the science and lore of the kitchen ( PDFDrive ) 1521
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biologicalcatalysts:thatis,theyincreasethe
rateofspecificchemicalreactionsthat
otherwisewouldoccuronlyveryslowly,ifat
all.Enzymesthuscausechemicalchange.
Someenzymesbuildmoleculesup,ormodify
them;somebreakmoleculesdown.Human
digestiveenzymes,forexample,break
proteinsintoindividualaminoacids,and
starchintoindividualglucoseunits.Asinge
enzymemoleculecancatalyzeasmanyasa
millionreactionspersecond.
Enzymesmattertothecookbecausefoods
containenzymesthatoncedidimportantwork
fortheplantoranimalwhenitwasalive,but
thatcannowharmthefoodbychangingits
color,texture,taste,ornutritiousness.
Enzymeshelpturngreenchlorophyllin
vegetablesdullolive,causecutfruitstoturn
brownandoxidizetheirvitaminC,andturn
fishfleshmushy.Andbacterialspoilageis
largelyamatterofbacterialenzymesbreaking
thefooddownforthebacteria’sownuse.
Withafewexceptions—thetenderizingof
meatbyitsowninternalenzymes,thefirming
ofsomevegetablesbeforefurthercooking,
andfermentationsingeneral—thecook
wantstopreventenzymaticactivityinfood.
Storingfoodsatlowtemperaturesdelays
spoilageinpartbecauseitslowsthegrowthof
spoilagemicrobes,butalsobecauseitslows
theactivityofthefood’sownenzymes.
CookingAcceleratesEnzymeActionBefore
Stopping It Because the activity of an
enzyme depends on its structure, any change
inthatstructurewilldestroyitseffectiveness.
So cooking foods sufficiently will denature
andinactivateanyenzymestheymaycontain.
One vivid example of this principle is the
behavior of raw and cooked pineapple in
gelatin. Pineapples and certain other fruits
contain an enzyme that breaks proteins down
into small fragments. If raw pineapple is
combined with gelatin to make a jelly, the
