Types of food based on its perishability

Types of food based on its perishability

1. OBT554
UNIT 1
Types of Food Based on its
Perishability
Dr K.Geetha
Associate Professor,
Dept of Biotechnology,
KamarajCollege of
Engg& Tech, Madurai

2. INTRODUCTION
Somefoodshavelongershelflifethanothers.
Perishabilityreferstothequicknesswithwhicha
foodgetsspoilt.
Foodscanbeclassifiedintothreegroupsdepending
onhowlongtheycanbekeptwithoutanytreatment.

3. Classification
Foods are classified into three groups based on ease of their
spoilage.
Relatively stable or non-perishable foods:Foods
that do not spoil unless handled carefully. E.g. grains,
flour, sugar, pulses etc.
Protectable or semi-perishable foods:Foods those
remain unspoiled for a fairly long period if properly
handled and stored. E.g. potatoes, apples, onions etc.
Perishable foods:Foods that spoil readily unless
special preservative methods are used. E.g. milk, eggs,
meat, fish, poultry, most fruits and vegetables.

4. PerishableFoods
PF can be kept at room temperature for only few hours or
1 or 2 days before spoiling.
For example-milk and milk products, meat, fish, poultry,
fruits, leafy vegetables and cooked food.
These foods keep well under refrigeration at household
as well as commercial level.
In general, the most perishable foods contain a high level
of protein or have moisture and carbohydrates in them.
Special methods are used to preserve such foods.
The rate of spoilage varies with the temperature,
moisture and or dryness of the environment.

6. Storage of Perishable Foods
Fleshfoodslikemeat,chickenandfishneedtobekeptfrozen
at-60°Cinadeepfreezeforlongtermstorage.
Eggsarebestkeptinacoolplaceorinabasketinanairy
roomrefrigerator.
Milkinboiledformcanbekeptatroomtemperaturefor6to
12hoursduringwinters.Insidearefrigeratormilkcanlast3
to4daysorevenmoreinclosedcontainer.
Thekeepingqualityofavegetabledependsuponitsnature.
Leafyvegetableswiltanddeterioratewithinminutesof
buyingunlesstheyarekeptwrappedinadampclothor
insideaplasticbagintherefrigeratorwhereintheylastfor
morethanadayortwo.

7. Storage of Perishable Foods
Allothervegetableskeepwellinacoolplacewithrelatively
highhumidityinabasketcoveredwithadampcloth.
Vegetablesmustbekeptinplasticbagstopreventdryingby
evaporation,ifstoredinarefrigerator.
Donotwashfruitsbeforestoringastheyspoilfaster.
Remember notto,refrigeratebananas,pineapples,
papayasandavocadoes,asthesefruitsundergoundesirable
changesintextureandflavouratrefrigeratortemperature.
Mostotherfruitskeepwell,whenrefrigerated.

9. Semi –PerishableFoods
SPFcanbestoredforacoupleofweeksorevenamonthor
twowithoutanydetectablesignsofspoilage.
Temperatureandhumidityoftheenvironmentagainaffects
theshelfstabilityofsuchfoods.
Properhandlingandstoragecanresultinfairlylongstorage
withoutspoilage.
Examplesareallcerealandpulseproductslikewheat
flour,semolina,vermicelli,brokenwheat,Bengalgramflour,
andsomefruitsandvegetableslikecitrusfruits,aonla,
apples,pumpkin,rootsandtubers,yams,potatoes,onions,
garlicetc.

11. Storage of Semi-Perishable Foods
Processedcerealproductsdevelopanoff-flavourorare
infestedbyinsectsveryeasilyifnottakencare.
Theyshouldbesievedandcleanedofallsuchcontamination,
exposedtothesunforafewhours,allowedtocoolandthen
storedintightlycoveredbottlesorothercontainers.
Especiallyonionsandpotatoesshouldbestoredinacool,dry
andairyplacetopreventthemfromdevelopingmouldsor
growingshoots.
Theyarebesthungupfromtheceilinginawireorplastic-
meshbasket,orkeptinmeshcontainerswhichpermitair
circulation.

12. Storage of Semi-Perishable Foods
Nutsbecomerancidandgetinfestedwithinsects
veryeasily,therefore,theyshouldbeboughtinlarge
quantitiesonlywhenstoragespaceisavailable.
Fruitslikeapples,orangesandsemi-ripemangoesdo
lastforafewweeksandshouldbeputinabasket
linedandcoveredwithpapertopreventthemfrom
dryingup.Theyneedacoolenvironmenttolastlong.

13. Non-PerishableFoods
NPFwillkeepformonthsoryearswithoutspoiling
unlesshandledandstoredcarelessly.
Examplesofsuchfoodsareallpreservedfood
products(canned,dried,pickledetc.),whole
cereal,pulseandmilletgrains,oilseeds,
nuts,fatsandoils,honey,sugar,jaggery,salt,
somespicesandessence.

15. Storage of Non-Perishable Foods
NutsFoodshouldbecarefullycleanedi.e.freefromgravel,husk
andotherforeignmatteretc.anddriedthoroughlyinthesun/
drierbeforestorage.
Storageoffoodsshouldbedoneincleancontainerswithtight-
fittinglids.Containerscanbemadeoftin,aluminum,plasticor
glass.Claypotsorgunnybagsmayalsousedincaseoflarge
quantities.
Adry,coolanddarkareashouldbechosenforstorageofnon-
perishablefoods.

16. Theperishabilityoffooddictatestoaconsiderableextentthe
preservationtechniquesthatareusedtokeepthatfoodingoodquality.
Incaseofnon-perishablefoods,preservationtechniquesarededicated
tokeepingoutinsects,rodentsandotherpestsandkeepingthefoods
drytopreventitfrombecomingmoldy.
Perishableandsemi-perishablefoodsdependagreatdealonthe
technologiesofrefrigeration,drying,freezing,canningandtheuseof
chemicalpreservativestogiveshelfstability.
Thesetreatmentscanmakesuchfoodcommoditieskeepformany
monthsoryearsiftheyareperformedproperly.

17. THANK YOU