038 How It Works http://www.howitworksdaily.com
SCIENCE
C
uring meat keeps it safe for consumpti
over a prolonged period of time.Using
combination of methods in production,
the qualities of meat are manipulatedtomake
more difficult for microbes to invade. When
these processes were first established,theyhe
the single purpose of preventing the spreadof
disease, especially in populated areas.Howev
w ith the emergence of fridges and freezers,so
of these early methods are simply usedforthe
sakeoftradition,ortoaddtotheflavourusing
salt,herbsandspices.Why do cured meats have
such a long shelf life?
is cured
the Middle Ages
Meatcuringis a methodthathasbeen
usedforcenturies.Foodpreservationin
theMiddleAges,forexample,was
essentialtolife,whetherit was
preservingfruitsinthesummertolast
theharshwinters,orslaughteringand
storingtheiranimalssotheywouldn’t
needtofeedthemoverwinter.
Everyyearbeforewinter,families
wouldpreparea bathtubofsaltwater,
whichtheywouldusetokeepfreshmeat
andfishin.Whencooked,meatwasoften
coatedingelatinetopreserveit,while
porkwasoftensmokedovera fire.
Lookingfurtherback,cavepaintings
discoveredinSicilyfrom40,000BCEgive
usreasontobelievepeopleusedtouse
saltfromseawaterevaporationandash
fromplantstocureearlymeats.Medievalmeatcuringinvolvedhangingmeatin
smokehouseslikethisMethods
Nitrateandnitrite
Long-term
Usingnitratesandnitritesin meatcuringhelpsto
maintainthemeat’sredcolour,whilealsokillingharmful
microbes.However,whennitritesarecookedwiththe
aminoacidsofmeatathightemperatures,theycanform
toxiccompounds.Nitrosamineis a cancer-causing
chemicalthatcanresultfromthisprocess.bacterialenzymesfromworkinganddestroyingDNA,
makingit difficultforbacteriatogrowonsaltymeats.
Thesaltalsoworkstodehydratethemeat,removing
someofthewaterthatbacterianeedtothrive.Fordry
saltcuring,it needstoberubbedintothemeatbyhand.Drying
Long-term
Dehydratingmeatnotonlypreservesit,butalsomakesit
morecompact.If keptin a freezer,itsfreshnesscanbe
maintainedforsixmonths.Oneexampleofdriedmeatis
beefjerky.Jerkyis driedmeatwhere 50 percentofthe
waterhasbeentakenout.Afterbonesandfatare
removed,meatis placedin dryingovensfor 12 hours.Canning
Long-term
Threemainstepsin meatcanningincludefillingthecan,
exhaustionandheattreatment.Whenfilling,around 30
percentofthecanis brine.Airexhaustionremovesallair
andreducestheabilityofaerobicbacteriatoliveinside.
Afterheatingtoaround 90 degreesCelsius,thecansare
sealed.Thisproducesa vacuumwhenthecancools.Brining
Short-term
A concentrationofatleast 20 percentsaltin water
makesa saltbrine.Asthesaltyconcentrationsitsonthe
outsideofthemeat,it drawswateroutof
microorganisms’cells.Thesaltalsoreplacessomeofthe
lostwaterwithinthemeat.Thisensuresthatthesalt
helpspreventthegrowthofbacteriathroughout.Over 200 diseases are
transmitted through food.
The most common bacteria
in beef is E.coli© Getty© Alamy© Getty© Alamy© Alamy© Getty© Getty