Nonthermal Processing of Food

8/19/2019 Nonthermal Processing of Food

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NONTHERMAL PROCESSING OFFOOD


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• Traditional thermal processingmethods via heating and cooking aretraditionally used in the food industryto inactivate pathogenic and spoilagemicroorganisms.

• This increases the shelf life of food

and maintains food safety.


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Why Nonthermal?

Disa!anta"e o# Thermal $ro%ess

• since heat treatment can adversely aect food'savor, taste, appearance, and nutrient content,less destructive food preservation methods arenow being sought.

A!anta"e o# Non thermal $ro%essin"

• Simple – vise versa of thermal processing

• preserve food without reducing the uality of food,

• !euire shorter treatment times

• "se less energy, they appear to be moreeconomical.


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#ood preservative

$. %hemical and &odied (tmosphere)ackaging

*. %hemical preservative


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%hemical preservative

Sodium +enoate

Sorbate

)roprionates

Sulfur -ioide

/itrates and /itrites+0(1+0T

Salt

Sugar

Spices and 2ssential 3ils

#lavoring (gents#atty acids

4atic and (cetic (cid

+acteriocins and (ntibiotics


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%hemical and &odied )reservation

• &() – &odied (tmosphere)ackaging

• %arbon dioide

• 5acuum )ackaging

• 2uilibrium &odied (tmosphere

•%ontrolled (tmosphere )ackaging


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#ood (dditives

• 6hy do we use additives more nowthan we did in the past7

The public has come to epect foodfrom farmers, processors, truckersand retailers to be wholesome andfree from microbes, toins, pesticides

and drug residues


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6holesome 8 #ood

• 0igh in nutritional value

• 9ood taste

•4ong shelf life

• Safe

• Sensory pleasing


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%onditions that aect 6holesome

• Temperature

• sanitation

• storage

• )ackaging

• age

• )reservation techniues


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-enition

• #ood (dditives are any substancesthat become part of a food product.

• #ood (dditives can be intentional orunintentional.

:nternational #ood additives act as

• 2nrichment – restore lost nutrients tofood

• #ortication – increase nutritionalvalue of food


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"n8international food (dditives act

as

• :nsecticides

• #ungicides

•0erbicides

• )lant 9rowth !egulators

• 0ormones and (ntibiotics


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#unctions1)urposes

• )rolong shelf life

• %hange1preserve color

• 2nhance avor

• :mprove nutritional value

• %ompensate for vitamin and mineraldeciencies

• &aintain freshness• )revent spoiling

• #acilitate food processing


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-elaney %lause, $;


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:mproper "ses

• To disguise faulty or inferior products

• To deceive consumers

•

To destroy nutritional value• To produce eects that can otherwise

be achieved safely


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+enit•

!educe food spoilage• &aintain nutrient uality

• 4ower food costs

• !educe occurrence of disease

!isk•%ancer, birth defects, allergies,

and health problems can result.3ilis soluble in body fat.• The cost of food production

increases for farmers.


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Types of (dditives

• (ntioidants8)revent fats and oils fromspoiling

• %oloring (gents8:mprove color of processed

foods• 2mulsiers1Stabiliers 8 )revent mied foods

from separating

• )reservatives 8 )revent the growth of

spoilage organisms

• Sweeteners1#lavor 2nhancers 8 +ring out thetaste of foods


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%ontent

)reservatives

#lavouring (gents

%olouring (gents

2mulsiers, Stabiliers and Thickeners

/utrients

(ntioidants

0armful 2ects of #ood(dditives

&onitoring of "se of #ood(dditives


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)reservatives

#lavouring (gents

%olouring (gents

2mulsiers,Stabiliers and Thickeners

/utrients

(ntioidants0armful 2ects of#ood (dditives

&onitoring of "se of

#ood (dditives

)reservatives

• /itrates

• Sulphur -ioideand Sulphates C:5D

• +enoic (cid and+enoates

• Sorbic (cid and

Sorbates• )ropanoic (cid and

)ropanoates


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#lavouring (gents

• Spices• &onosodium

9lutamate• 2sters• Saccharin• (rticial #lavouring• %ommon food

#lavouring• Improve the flavour

of the food

)reservatives

#lavouring (gents

%olouring (gents


/utrients



#ood (dditives


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%olouring (gents

• /atural %olourings

• Synthetic%olourings

• Make the food lookmore attractive

)reservatives

#lavouring (gents

%olouring (gents


/utrients



#ood (dditives


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2mulsiers, Stabiliers and Thickeners

• %arboymethymethylcellulose

• Eanthan 9um

• )ectin

• -etrins

• Sodium (lginate

)reservatives

#lavouring (gents

%olouring (gents


/utrients



#ood (dditives


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/utrients

• 5itamins

• &inerals F :odine

)reservatives

#lavouring (gents

%olouring (gents


/utrients



#ood (dditives


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(ntioidants

• (scorbic (cid and(scorbates

• +0( and +0T

)reservatives

#lavouring (gents

%olouring (gents


/utrients


&onitoring of "se of#ood (dditives


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0armful 2ects of #ood(dditives

• (llergies• 0yperactivity• 4ong8term illnesses• %ontroversy over

+0( and +0T• Side 2ects of &S9• Toicity and )otent

carcinogenic /atureof /itrates C:::D

• Toicity of sulphurdioide

• )otent carcinogenicnature of saccharin

)reservatives

#lavouring (gents

%olouring (gents


/utrients




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&onitoring the "se of #ood(dditives

• +y !esearch

• +y 4egislation

)reservatives

#lavouring (gents

%olouring (gents


/utrients




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(pplication of #ood(dditives

• raises the n&trient !al&e

• prevents %an%er %a&sin" a"ents from forming

• 'lea%hin" a"ents( doughconditioners

• %olo&rin" agents

• em&lsi)ers * sta'ili+ers• as $reser!ati!es F prevent fats

from ran%iity

•to slo, "ro,th of microorganisms


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:ntentional (dditives

• %hemicals that are intentionallyintroduced to foods to aid inprocessing

• to act as preservatives

• or to improve the uality of the food– are called intentional additives

• Their use is strictly regulated bynational and international laws


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• The use of food additives is in eecta food processing method

• because both have the sameobGective – to preserve the foodand1or make it more attractive

• :n many food processing techniues,

the use of additives is an integralpart of the method, as is smoking,heating, and fermenting


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• The purpose of food additives

– To improve or maintain nutritional value

– To enhance uality

– To reduce wastage

– To enhance consumer acceptability

– To improve keeping uality

– To make the food more readily available – To facilitate preparation of the food


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• The use of food additives is in eect afood processing method

• because both have the same obGective

– to preserve the food and1or make itmore attractive

• :n many food processing techniues,

the use of additives is an integral partof the method, as is smoking, heating,and fermenting


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• The purpose of food additives

– To improve or maintain nutritional value

– To enhance uality

– To reduce wastage

– To enhance consumer acceptability

– To improve keeping uality

– To make the food more readily available – To facilitate preparation of the food


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• There are several ways of classifyingintentional food additives

• 3ne such method lists the following three

main types of additives• iD comple substances such as proteins or

starches that are etracted form otherfoods

– #or eampleA the use of caseinate insausages and prepared meats


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• iiD naturally occurring, well8denedchemical compounds such as salt,phosphates, acetic acid, and ascorbic

acid• iiiD substances produced by

synthesis, which may or may not

occur in nature, such as coal tardyes, synthetic +8carotene,antioidants, preservatives, and

emulsiers


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)reservatives

• )reservatives or antimicrobial agents playan important role in todayHs supply of safeand stable foods

•

:ncreasing demand for convenience foodsand reasonably long shelf life of processedfoods make the use of chemical foodpreservatives imperative

• Some of the commonly used preservatives– such as sultes, nitrate, and salt – havebeen used for centuries in processed meatsand wine


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)reservatives

• The choice of antimicrobial agent hasto be based on a knowledge of the – antimicrobial spectrum of the

preservative – the chemical and physical properties of

both food and preservative

–the conditions of storage and handling,

– the assurance of a high initial uality ofthe food to be preserved


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+enoic (cid

• +enoic acid occurs naturally in many types of 'erries,plums, prunes, and some spices

• (s an additive, it is used as benoic acid or as benoate

• The latter is used more often because benoic acid issparsely soluble in water, and sodium benoate is more

soluble• The &nisso%iate form on benoic acid is the most

eective antimicrobial agent

– pI a of J.*K optimum p0 range is from -./ to 0.1

– This makes it an eective antimicrobial in high8acid

foods, fruit drinks, cider, carbonated beverages, andpickles

– :t is also used in margarines, salad dressings, soy sauce,and Gams


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)arabens

• )arabens are alkyl esters of p8hydroybenoicacid

• They dier form benoic acid in that they haveantimicrobial a%ti!ity in 'oth a%i anal2aline $H regions

• )arabens are colourless, tasteless, and odorlessCecept the methyl parabenD

• )arabens are more active against mols anyeast than a"ainst 'a%teria3 an morea%ti!e a"ainst "ram4$ositi!e than "ram4ne"ati!e 'a%teria

• They are used in fruitcakes, pastries, and fruitllings


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)arabens

• Methyl an $ro$yl $ara'ens can beused in soft drinks

• Com'inations of several parabens are

often used in applications such as shproducts, avor etracts, and saladdressing


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Sorbic (cid

• Sorbic acid is a straight8chain, trans-trans unsaturated fatty acid, *,J8headienoic acid

• (s an acid, it has a lo, sol&'ility in ,aterat room temp

• The salts3 soi&m3 or $otassi&m aremore sol&'le in ,ater

• Sorbates are stable in the dry formK the areunstable in aueous solutions because they

decompose through oidation• The rate o# o5iation is in%rease at lo,

$H, by increased temp, and by light eposure


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Sorbic (cid

• Sorbic acid and other sorbates are e6e%ti!ea"ainst yeasts an mols

• Sorbate inhibit yeast growth in a variety of foodsincluding ,ine3 #r&it 7&i%e3 rie #r&it3

%otta"e %heese3 meat3 an )sh $ro&%ts• Sorbates are most eective in products o# lo,

$H including salad dressings, tomato products,carbonated beverages, and a variety of other

foods• The eective level of sorbates in foods is in the

range of 1.1/ to 1.81 $er%ent


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Sorbic (cid

• Sorbates are generally used in s,eetene,ines or ,ines that contain residualsugars to prevent refermentation

• (t the levels generally used, sorbates donot a6e%t #oo 9a!or

• 0owever when used at higher levels, theymay be detected by some people as an

&n$leasant 9a!or• Sor'ate %an 'e e"rae 'y %ertain

mi%roor"anisms to $ro&%e o649a!ors


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S&l)tes

• Sultes CS3>D are used as antio5iants to

prevent en+ymati% 'ro,nin", inhibitbacterial growth Cin wineD, bleaching

agent, dough conditioner, to preventmelanosis on shrimp, and in theproduction of some food packaging.

• They are present in the form of sulfur

dioide, sodium sulte, sodiummetabisulte, sodium bisulte.


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Sultes

• S&l#&r io5ie an s&l)tes have longbeen used as preservatives

• Serving both as antimicrobial substance

and as antio5iant• Sulfur dioide is a gas that can be used incompressed form in cylinders – :t is liuid under pressure of >.J atm and can

be inGected directly in liuids – :t can also be used to prepare solutions in icecold water

– :t dissolves to form sulfurous acid


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Sultes

• Sulfurous a%i inhi'its mols an'a%teria an to a lesser e5tent yeasts

• #or this reason, S3* can be used to %ontrol

&nesira'le 'a%teria an ,il yeasts in#ermentations without aecting the S3*8

tolerant cultured yeasts

• The undissociated acid is $ LLL times more

active than 0S3>8 for Escherichia coli, $LLto


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Sultes

• The use of S3* is not permitted in foods that

contain signicant uantities o# thiamine3'e%a&se this !itamin is estroye 'y SO-

• S3*

are used in

– Wine3 meat $ro&%ts

– Drie #r&its3 rie !e"eta'les

• +ecause S3* is volatile and easily lost to the

atmosphere, the residual levels may be muchlower than the amounts originally applied


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/itrates F /itrites

• C&rin" salts3 ,hi%h $ro&%e the%hara%teristi% %olo&r an 9a!or of productssuch as bacon and ham, have been usedthroughout history

• %uring salts have traditionally contained nitrateand nitrite

– The discovery that nitrite was the activecompound was made in about :;


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:. Nitrites

• /itrite inhibits the bacterial production byinhi'itin" %ertain en+ymes within themicrobe and on its cell membrane.

• /itrite weakens the 'a%terial s$ores,

reducing the like8hood of germination.• /itrite is very reactive and can be directly

to5i% or #orm %ar%ino"eni% /8nitrosocompounds.

• :t can oidie blood o5yhemo"lo'in Cferrous formD to methemoglobin CferricformD.


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• 3yhemoglobin is a good transport foroygen throughout the body, while oygencanHt bind to methemoglobin

unavailable for respiration.• 2cessive nitrite intake can lead to

s&6o%ation.

• The average lethal ose of nitrite isa$$ro5 1. 0 " as sodium nitrite.

• The sub8lethal doses of nitrite may lead toa'normalities in meta'olism o# the

'oy.


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-. Nitrates

• %ommonly found in water and vegetables,especially those grown with high8nitratefertilier.

• :t has lo, rea%ti!ity not to5i%.

• 0owever, nitrate becomes a haard when it is

reduced to nitriteM -ietary nitrates can beconverted to nitrites during digestion.

• %ases of life8threatening methemoglobinemiawhen the patientHs diet contained too many

nitrate so&r%es Ce.g. drinking water andspinachD within a short time span.

• /= o# in"este nitrates in sali!a isre&%e to nitrite 'y 'a%teria.


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/itrates F /itrites

• +oth nitrates and nitrites are thought tohave antimi%ro'ial a%tion

• /itrate is used in the production of 9ouda

cheese to prevent gas formation by butyricacid8forming bacteria

• The action of nitrate in meat curing isconsidered to involve inhi'ition o# to5in

#ormation 'y Clostridium botulinum,an important factor in establishing safety ofcure meat products


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/itrates F /itrites

• The nitrate8nitrite intake from naturalsources is much higher than thatfrom processed foods

• :ts estimated that the nitrate intakefrom – $LL g of processed meat might be


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)henolic (ntioidants

• They are used to $rote%t #ats a"ainsto5iation.

• >&tylate hyro5ytol&ene >HT@ an

'&tylate hyro5yanisole >HA@ arerai%al s%a!en"er.

• They interfere propagation step duringlipid peroidation.

• C&rio&sly3 these antio5iants %ane5hi'it 'oth antit&mori"eni% ant&mori"eni% e6e%ts3 and they are known

to alter enyme activity aecting


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0ydrogen )eroide

• 0ydrogen peroide is a strong oidiing agentand is also useful as a bleaching agent

• The antimicrobial action of of hydrogenperoide is used for the preservation of cheesemilk

• 0ydrogen peroide decomposes slowly intowater and oygen

– This process is accelerated by increased

temp – The presence of catalysts such as

catalase, lacto8peroidase and heavemetals


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0ydrogen )eroide

• :ts antimicrobial action increases withtemp

• 6hen hydrogen peroide is used for

cheese making, the milk is treated withL.L* percent hydrogen peroide followedby catalase to remove hydrogen peroide

• 0ydrogen peroide can be used for

steriliing food processing euipment andfor steriliing packaging material used inaseptic food packaging systems


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Salts

• (n important food additive for prevention of bacterialgrowth, for necessary technical reason, or for avor.

• The chemical name for salt, sodium chloride, revealsthat sodium is in fact a component of salt. +y weight,salt is composed of JLN sodium and OLN chloride.

3ne teaspoon of salt weighs < grams and containsabout *,>LL mg of sodium.

• +oth sodium and chloride ions are important inphysiological processes, but ecess sodium directlycause hypertension Chigh blood pressureD, a maGor

risk factor for heart disease, stroke and kidneydisease.


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Sodium %hloride

• Salt has the following characteristicsA

– :t produces an osmotic eect

– :t limits oygen solubility

– :t changes p0

– Sodium and chloride ions are toic

– Salt contributes to loss of magnesium

ions• The use of sodium chloride is self8

limiting because of its eect on taste


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+acteriocins 8 /isin

• /isin is an antimicrobial polypeptide produced bysome strains of Lactococcus lactis

• /isin8like substances are widely produces bylactic acid bacteria

• These inhibitory substances are known asbecteriocins

• /isin has been called an antibiotic, but this termis avoided because nisin is not used fortherapeutic purposes in humans or animals

• /isin8producing organisms occur naturally in milk


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• /isin can be used as a processing aidagainst gram8positive organisms

• +ecause its eectiveness decreases as the

bacterial load increases, it is unlikely to beused to cover unhygienic practices

• /isin is a polypeptide with a molecularweight of >


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• :t contains no aromatic amino acidsand is stable to heat

• :t has been used eectively in

preservation of processed cheese

• :t is also used in the heat treatmentof nonacid foods and in etending

the shelf life of sterilied milk


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(cids

• Straight8chain carboylic acids,propionic and sorbic acids, are usedfor their antimicrobial properties

• )ropionic acid is mainly used for itsantifungal properties


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(ntioidants

• Slows down food going o by slowingdown the reaction with oygen

• #ood antioidants in the broadest

sense are all of the substances thathave some eect on preventing orretarding oidative deterioration in

foods


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2mulsiers

• Ieeps ingredients thoroughly mied• 6ith the eception of lecithin, all

emulsiers used in foods are synthetic

• They are characteried as ionic or

nonionic and by their hydrophile1lipophilebalance C04+D

• (ll the synthetic emulsiers arederivatives of fatty acids

• 4ecithin is the commercial name of amiture of phospholipids obtained as abyproduct of the rening of soybean oil

E l i)


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Em&lsi)ers

Oil and water do not mix

Emulsifiers keep them mixed together in mayonnaise.

An emulsifier molecule has two parts.

The hydrophilic head bonds to water molecules.

The hydrophobic tail bonds to the oil molecules.

This prevents oils molecules from oining together.


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+read improvers

• To speed up the aging process ofwheat our, bleaching and maturingagents are used

• +enoyl peroide is a bleachingagent that is freuently used – 3ther compounds – including the oides

of nitrogen, chlorine dioide, nitrosylchloride, and chlorine – are bothbleaching and improving CmaturingDagents


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+read improvers

• :mprovers used to ensure that dough willferment uniformly and vigorously include – 3idiing agentsA )otassium bromate,

potassium iodate, calcium peroide

• There may be small amounts of otherinorganic compounds in bread improvers – :ncluding ammonium chloride, ammonium

sulfate, calcium sulfateQ

• &ost of these bread improvers can only beused in small uantities, becauseecessive amounts reduce uality


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/onnutritive sweeteners

(spartame

• (pproved in $;=$ as articial sweetener.

• :t is *LL times sweeter than sugar and has

the same number of calories per teaspoonful.Stevioside• ( natural sweetener from Stevia rebuadiana

plant.• :t is *LL8>LL times sweeter than sugar and

have no calories.• :t was used as a common sweetener in ?apan

Cherbal teasD during $;=LHs.


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9overnment controlsA

• only certain additives are allowed for use• amounts are controlled F must be noted

on the label

• maimum amounts used are small F mustserve a useful purpose

• are safety tested by the industry F thesetests are monitored by 0ealth )rotection

+ranch of %an.• monitoring usage of additives is ongoing

(merica's favorite food


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(merica s favorite foodadditives

• Sodium ascorbate – (nti8oidant

• &onogylcerides –

• 9um Tragacanth 8 stabilier CsaladdressingsD

• )ropylene glycol 8 emulsier, stabilier,

and thickener• !ed JL 8 -ye

• (cesulfame potassium C(spartameD –articial sweetener


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!2- JL

• 6hen red JL was rst approved by the #-(as a food coloring additive there was somecontroversy as to whether or not it causedtumors and cancer. Those claims havebeen proven to be false but now manyparents, -octors and Teachers arebecoming aware of other concerns

regarding intake of red JL, especially inyoung children.


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6here it is found

Red 40 is used in many food products including kool-

aid, orange and other flavored sodas, cheetos and

dorito chips, strawberry pop-tarts, any candy with redcoloring to it including m&m's, skittles, many chewing

gums, etc.

lso many children's vitamins and pain relievers!cold

medicine have red 40 in the ingredients.


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Iids and !2- JL"hildren are most often the ones who have sensitivityto red 40. Reactions include temper tantrums,

hyperactivity, aggressive behavior, uncontrollable

crying and screaming, kicking, nervousness,

dizziness, inability to concentrate and sit stillamong other findings. #hysically you may get fre$uent

headaches or migraines, upset stomach and feel ill

after ingesting this additive. %ften when Red 40 is

eliminated from the child's diet a remarkable change is

noticed immediately.


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%lasses of (dditives• Antimicrobial agents

• Antioxidants

• Artifcial colors

• Artifcial avors and avorenhancers

• Bleaching agents

• Chelating agents (hich are used to

prevent discolorationand avor changes!

• "utrient additives

•

#hic$ening and stabili%ing agents


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- ;.L$ 88 /on8Thermal )reservation

De)nition

• :nvolves manipulating theproperties of food or its

environment without using heat.• 2amples includeA

– :rradiation

– 3hmic heating

– 3onation

– 0igh pressure processing


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)reservation by

:oniing radiation

: i i ! di ti


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PO

:oniing !adiation

•Exists in form of waves

• Shorter wavelength = greater energy

• Light, radio, microwave, television = long wavelength,low energy cannot alter structure of an atom

• Shorter wavelengths have enough energy to “knock off”

an electron to form a “free radical” but not high enough

to “split” an atom and cause target to become“radioactive”

• nteraction between free radicals and !"# responsible

for “killing effect” of $


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Irraiation

• 2posure of food

to ioniingradiation forpreservation

• :n the ".S.

irradiated foodsare reuired to belabeled.

#ood


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P=

#ood:rradiation

• Exposure of foods to ioni%ing radiation in form of

gamma radiation, &'rays and electron beams to destroy

pathogenic microorganisms

• n use for over () years in European *nion

• *S consumers perceptions of effects of radiation

prevented widespread acceptance of food irradiation

• Limited use allowed since +-. on specific food

products for specific purposes/


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• 4onger wave length, lower freuencywaves Cheat and radioD have less energythan shorter wave length

• higher freuency waves CE and gammaraysD. /ot all electromagnetic C2&Dradiation is ioniing.

• 3nly the high freuency portion of the

electromagnetic spectrum which includes rays an "amma rays is ioni+in".


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%omparison of radiation sensitivity


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%omparison of radiation sensitivityof dierent organisms

1 10 10

2

10

3

10

4

10

5

10

6

10

7

NO ACUTE

EFFECTS

LETHALTO

HUMANS

SPROUTING

INHIBITED

LETHAL TO

INSECTS

STERILIZATION OF MICROORGANISMS

Dose

(rad)

:oniing !adiation


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:oniing !adiation

• 2nergy emitted from a source is generally referred toas radiation. 2amples include heat or light from thesun, microwaves from an oven, E rays from an E8raytube, and gamma rays from radioactive elements

Ioni+in" Raiation• :oniing radiation is radiation with enough energy so

that during an interaction with an atom, it can removetightly bound electrons from the orbit of an atom,causing the atom to become charged or ionied.

• 0ere we are concerned with only one type of radiation,ioniing radiation, which occurs in two forms 8 wavesor particles.

%hanges caused in #oods by


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%hanges caused in #oods by:!

!. Temperature rise" abt. #$% degrees.

#. &hemical changes' Abt. (.(!) of the chemical bonds are affected.

%. *iological effects' +i, biological function of the complex biological material is changed when apenetrating charged particle hits the complex

+ii, radiation induced ioni-ation of the solventsystem results in formation of highly reactive hydrogen andhydroxl radicals.

. *actericidal effects' +i, physical damage caused on the bacterial cell due to the direct hit of aparticle through a cell wall. This may cause alterations in the nucleus"cytoplasm of the cell and the media surrounding the cell"

+ii, gene mutation

th


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others

$. %hanges in proteinsA CiD opening of peptide chains, CiiD polymeriation,CiiiD coagulation, CivD precipitation

*. 2nymesA 4ess sensitive to radiation. %omplete inactivation reuiresabt. < times the dose reuired to destroy microorganisms.

>. 5itamins are sensitive to radiation, destruction similar to heatprocess.

J. %arbohydratesA -epolymeriation and degradation may occur.


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The &a1&in !atio

• )ackaging is appropriate – complete penetration of e8

beam from above andbelow

– relatively even dosage, low&a1&in ratio

•

:mproper packaging Fprocessing 8 too thickM – incomplete penetration of

e8beam

– uneven dosage, high


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Irradiation /nit

())4:%(T:3/ 3# :3/:R:/9 !(-:(T:3/


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#3! -2ST!"%T:3/ 3#&:%!33!9(/:S&S

Two approachesA – )artial or selective destruction Cradiation pasteuriationD

– %omplete destruction Cradiation steriliationD

Raiation Sterili+ation o# #oo

• :f the intent is to produce a sterile food product, certainconditions must be met.

– For ma5imal shel# li#e sta'ility3 not only mi%roor"anisms'&t tiss&e en+ymes sho&l 'e ina%ti!ate

– The #oo sho&l 'e %a$a'le o# $ossessin" a lon"stora"e li#e ,itho&t neein" re#ri"eration.

– En+yme reB&ire a hi"her irraiation osa"e #orina%ti!ation than mi%roor"anisms there#ore3 a s&'sterili+ation thermal treatment may 'e reB&ire tos&$$lement raiation.

– The raiation toleran%e o# a material sho&l 'e%onsiere.

– The material ,ill a%t as a shiel3 ,ill also alter the

())4:%(T:3/ 3# :3/:R:/9 !(-:(T:3/


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#3! -2ST!"%T:3/ 3#&:%!33!9(/:S&S

Raiation Paste&ri+ation o# #oo

• !adiopasteuriation can be etend the shelf lifeof a variety of fresh food products if certainfactors are considered.$. the initial number of microorganisms must be

reasonably low.

*. the irradiated product should be maintained at arefrigeration temperature as low as possible.

>. the packaging must be the proper type

J. recontamination after irradiation must be minimal


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:rradiation and 0eat Treatment of 6hole 2ggs

:rradiation of eggsA


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2ggs and egg products are responsible foran estimated *>L,LLL cases of foodborneillnesses each year, resulting in economiclosses and representing a consistent and

serious obstacle to the well8being ofconsumers

Salmonella and mainly serovar 2nteritidis isthe leading cause of all egg8relatedfoodborne illnesses

:oniing radiation can inactivate Salmonella spp. in shell eggs and egg products.

:rradiation of eggsAbackground

:. (lvare

Shell e""s

"S #-( (pproves :rradiation of Shell 2ggs ≤ > L k9y C*$


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8 "S #-( (pproves :rradiation of Shell 2ggs ≤ >.L k9y C*$%#! )art $P;, vol. O


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The dose of radiation received by the food is measured

observing changes in optical density of certain materials+cobalt glass" plastic strips attached to the container offood,

0ood irradiation using limited fre1uency gamma photons andlow energy electrons yields foods with no dangerous level of

radioactivity" provided that the neutron flux is controlled"since these tend to induce radioactivity.


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Ohmi% Heatin"

• #ood is subGected

to an alternatingcurrent owbetween twoelectrodes.


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O+onation

• 6ater treatmentprocess used todestroymicroorganisms byoone, a gasproduced by

eposure of oygenmolecules to highelectric voltage


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Hi"h Press&re Pro%essin"

• )reservation

method whereliuid and solidfoods are subGectedto pressures of

J


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+alanching !eal )urpose


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+alanching – !eal )urpose

• +lanching is a cooking process wherein the foodsubstance, usually a vegetable or fruit, isplunged into boiling water, removed after a brief,timed interval, and nally plunged into iced

water or placed under cold running waterCshockedD to halt the cooking process.

• The meaning of blanching is Bto whitenB, but thisis not always the purpose of blanching in

cooking. #ood is blanched to soften it, or topartly or fully cook it, or to remove a strong tasteCfor eample of bacon, cabbage, or onionsD


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•+lanching may simply mean boiling in water for an etended periodto remove unpleasant avours such as tannins

•:t is recommended that protein8rich salads to be eaten cold Ce.g.,tuna, turkey, ham, shrimp, lobster, and chickenD are prepared byimmersing these protein foods in boiling water for >L secondsfollowed by fast chilling.

•:n addition celery, Bwhich is almost always a component of thesesalads ... should be treated so as to minimie its bacterial content.

•:n the case of #rench fries, blanching often refers to pre8cooking the#rench fries in oil at a lower temperature prior to nishing them at a

higher temperature. The advantage is that the blanching step cooksthe otato. The second ste at the hi her tem erature cris s the


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Salami


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Salami

• Salami are cured in warm, humid conditions to encourage growth of thebacteria involved in the fermentation process. Sugars Cusually detroseDare added as a food source for the bacteria during the curing process,although it tends not to be added to horse meat because of the latter'snaturally high levels of glycogen.

• 4actic acid is produced by the bacteria as a waste product, lowering the

p0 and coagulating and lowering the water8holding capacity of the meat. The acid produced by the bacteria makes the meat an inhospitableenvironment for other, pathogenic bacteria and imparts a tangy avorthat distinguishes salami from machine8dried pork. The avor of a salamirelies Gust as much on how these bacteria are cultivated as it does onuality and variety of other ingredients. 3riginally, the bacteria wereintroduced into the meat miture with wine, which contains other typesof benecial bacteriaK now, starter cultures are used. The whole processtakes about >O weeks, although some age it more for additional taste,and some can cut it down to about *J weeks for a sweeter taste.


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A%ti!e Pa%2a"in"


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Active packaging can be used to improve the safety or quality

of food.Examples

•2rapping in plastic film keeps out oxygen and water whichkeeps the food crisp

•3ome packaging removes water to stop food inside going off

Antioxidants are added to some foods or packaging to stop themreacting with oxygen.

Some of the emerging technologies


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• 0igh pressure processing

• )ulsed electric eld processing

• 3smotic dehydration

• 0igh intensity pulsed light technology

• ( thermal membrane processing

• "ltrasound technology

• :rradiation technology• /ew chemical and biochemical hurdle technology

• !adio8freuency

• 3hmic heating

• %ombined microwave and vacuum drying

• 5acuum cooling of food

• "ltrasonic freeing

• 0igh pressure freeing

• "se of anti8freeing proteins

#uture


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#uture

• Since the goal of food preservation is toprovide the food industry with products thatare

$. microbiologically safe

*. consumer8acceptable

>. economically priced

•. /onthermal technology may be the preservation method of choice in the future.


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Thank youfor your attention4

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Nonthermal Processing of Food

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