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1、Microorganismsnodoubtoutnumberotherlivingentitiesonthisplanetandcanbefoundexistingactivelyorpassivelywhereverlivingorganismsoccur.Whiletheenergyforonthisplanetiscapturedbygreenplantsinthephotosyntheticprocess,microorganismsaregenerallyresponsibleforthefinaldecompositionofthephotosyntheticproducts.An
2、imalsplayaminorroleinthecycle. Inasmuchasbacteria,yeastsandmoldsaretobefoundthroughouttheenvironmentofman,itistobeanticipatedthatthesemicroorganismsareindirectcompetitionwithotherlivingentitiesfortheenergyforlife.Whenevertheconditionsofnutrientsandenvironmentarefavorableformicrobialactivity,itwillb
3、efound. Manmustcompetewithallotherlivingentitiesonearth.Inordertoretainfoodsuppliesforhimself,hemustinterferewithnaturalprocesses.Throughhisstudy,andasafruitofhiscuriosity,manhasevolvedanumberofcontrolsystems.Oneisthepreservationoffoodbycontrolling,yetencouraging,thegrowthofmicroorganisms.Undersuc
4、hacondition,manmayemploymicroorganismstocreateunfavorableconditionsforothermicrobes,yetretaininthefoodstuffsthenutrientsdesired. Whilemicroorganismswerenotidentifiedastheimportantagentsinfoodspoilageuntilacenturyago,winemaking,breadbaking,cheesemakingandsaltingoffoodshavebeenpracticedformorethanfo
5、urthousandyears.Forallthoseyearsmankindpracticedfoodpreservationusingunknown,invisible,active,livingorganisms.Whilefoodpreservationsystemingeneralinhibitsthegrowthofmicroorganisms,allsuchorganismsarenotdetrimental.Infactsomearecommonlyutilizedinfoodpreservation.Theproductionofsubstantialamountsofaci
6、dbycertainorganismscreatesunfavorableconditionsforothers.Toreviewtermsforamoment,respirationisthatprocesswherebycarbohydratesareconvertedaerobicallyintocarbondioxideandwaterwiththereleaseoflargeamountsofenergy.Fermentationisaprocessofanaerobic,orpartiallyanaerobic,oxidationofcarbohydrates.Putrefacti
7、onistheanaerobicdegradationofproteinaceousmaterials.Sodiumchlorideisusefulinafermentationprocessoffoodsbylimitingthegrowthofputrefactiveorganismsandbyinhibitingthegrowthoflargenumbersofotherorganisms.