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P R E S E N T E R :

ROSEBELLA L MALOMFT- ISCOF GRADUATE STUDIES

TIWI BAROTAC NUEVO

PRESENTED TO:ROSITA BRAGANZA PHD

PROFESSOR

FT 302 ADVANCES IN EVALUATION AND QUALITY

CONTROL OF FISHERY PRODUCT

Measuring Food Quality with

Instrument



Measuring Food Quality withInstrument

According to the standard ISO 8402 Quality is"thetotality of features and characteristics of a productor service that bear on its ability to satisfy stated or

implied needs" .



Measuring Food QualityInstrumental Method

Physical Test

Physical methods involve the measurement of

fish !"

te#tureelectrical roerties.

These methods are rarely used $ecause they are eithernot sufficiently relia$le



Measuring Food QualityInstrumental Method

Physical Test• pH and Eh

. %easurements are carried out &ith a !'meter

Measuring Texture

Te#ture is an e#tremely imortant roerty of fish muscle" &hether ra&or coo(ed. )ish muscle may $ecome tough as a result of fro*en storage orsoft and mushy as a result of autolytic degradation.

Instron %odel T% e+uied &ith a ,ramer shear cell &ith 4 cutting $lades. This method correlated &ell &ith data o$tained from a trained

te#ture anel. Electrical Properties

the - Torrymeter /ason and ichards" 135. !o&ever" theinstrument is not a$le to measure +uality or freshness of a single fish"




Chemical methods

rely on the measurement of meta$olite/s5 roduced during fish storage ordistri$ution to o$tain a +uantitative fish inde#.

%ost &idely used chemical test

Total volatile bases (TVB5" ' measures the content of trimethylamine /T%A5 6 dimethylamine 6 ammonia 6other $asic nitrogenous comounds associated &ith seafood soilage.

Other tests target the searate measurement of T%A" 7%A ,nucleotide catabolites (known as the %K-value) or bioenic amines

contents (!5. The , or freshness inde# gives an indication of fish freshness during the early stages after

cature"

T%A" T9: or :A gives this indication at later stages &hen the $acterial soilage starts.

7%A is used to measure the +uality of fro*en fish.

o#idative rancidity is measured $y evaluating the ero#ide value /P95 during the early stages

or the thio$ar$ituric acid'related su$stances /T:A'S5 during later stages.




Biochemical and chemical methods

The aeal of $iochemical and chemical methods forthe evaluation of seafood +uality is related to the

a$ility to set +uantitative standards. $iochemical; chemical methods may $est $e used in

resolving issues regarding roducts of marginal+uality. "

$iochemical;chemical indicators have $een used torelace more time consuming micro$iologicalmethods.



Measuring Food Quality with Instrument

#icrobioloical e$amination

evaluating hygienic +uality of fish" includingtemerature a$use" and the ossi$le resence ofathogenic microorganisms in the fish.

%easurement

total late count /TP<5" soilage $acteria" and variousathogenic $acteria. time consuming" costly and re+uire technical s(ills.

ne& raid methods are $eing develoed and mar(eted. $ased on immunological reactions /=>ISA" monoclonalanti$odies5 or genetic engineering /P<" 7?A'ro$es5.

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Amines - Total Volatile Basic Amines

Total volatile $asic amines /T9:5 is one of the most &idely usedmeasurements of seafood +uality.

measurement of trimethylamine /roduced $y soilage $acteria5

" dimethylamine /roduced $y autolytic en*ymes during fro*enstorage5" ammonia /roduced $y the deamination of amino'acidsand nucleotide cata$olites5 and other volatile $asic nitrogenouscomounds associated &ith seafood soilage.

useful for the measurement of +uality in cehaloods such ass+uid />e:lanc and -ill" 1845" industrial fish for meal and silage/!aaland and ?@aa" 1885" and crustaceans /9ync(e" 1305.

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Ammonia

' Ammonia is formed $y the $acterial degradation;deamination ofroteins"

' etides and amino' acids.

' also roduced in the autolytic $rea(do&n of adenosine monohoshate

/A%P"5.

2 convenient methods use of the en*yme glutamate dehydrogenase"

?A7! and alha'(etoglutarate.

Test (its for ammonia $ased on glutamate dehydrogenase are no& availa$lefrom Sigma /St. >ouis" %issouri" SA5 and :oehringer %annheim/%annheim" -ermany5. A third tye of ammonia test (it is availa$le in theform of a test stri /%erc(" 7armstadt" -ermany5

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Trimethylainine (TMA)

Trimethylamine is a ungent volatile amine often associated &iththe tyical fishy odour of soiling seafood.

Its resence in soiling fish is due to the $acterial reduction of

trimethylamine o#ide /T%AO5 &hich is naturally resent in theliving tissue of many marine fish secies

. This henomenon is no& thought to $e due to the resence ofsmall num$ers of secific soilage $acteria &hich do not al&aysreresent a large roortion of the total $acterial flora"

. One of these secific soilage organisms" Photobactetium phosphoreum, generates aro#imately 10 ' 100 fold the amount ofT%A than that roduced from the more commonly'(no&n secificsoiler" hewanella putrefaciens /7algaard" 15 /in ress5.

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Nucleotide ata!olites

en*ymes involved in the $rea(do&n of adenosine

triphosphate (ATP) to inosine monophosphate (IMP) are

believed in most cases to be autolyticthe co!"#$%o o& IMP 'o %o$%" (Io) *+

'," ,.o/*',%" (R/) *#" +" 'o$.o%1*" *c'"#%*

!# has $een sho&n to accumulate slo&ly in sterilefish tissue. .

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Analyte(s) Principle Advantages Disadvantages Reference

Hxenzymes (xanthineoxidase, X0) immobilizedon a test strip

rapidsimple to use outsidethe lab

semi -quantitativeonlycapable of measurin Hx(later staes of spoilae)

!ahns et al. ("#$%)

Hx, &no test strip, 'ith immobilizedenzymes

rapidsimple to use outsidethe lab

semi -quantitativepoor

reproducibilitylimited to Hx and &no (laterstaes spoilae)

hira et al. ("#%)

&*+, &no, Hxenzyme-coated oxyenelectrode

rapidaccuratemore complicated andtime consumin than teststrip technoloy

arube et al. ("#)

-indexcoupled enzyme assay./-"0" reshness *eter.

rapidresults comparable toH+12

must purchase enzymesand reaentscost 3

commercially availablefrom 4rienta lectric, 5iiza6aitama 789, !apan

-indexenzyme-coated oxyenelectrode .*icrofresh.

rapidresults comparable toH+12

cost 3

commercially availablefrom +easus&nstruments, :incourt,45, 2anada

Table 8.3 ish reshness ;estin <sin nzyme ;echnoloy

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Ethanol =thanol has $een used as an o$@ective indicator for seafood +uality although

as common as the analysis of T%A.

derived from car$ohydrates via anaero$ic fermentation /glycolysis5

deamination and decar$o#ylation of amino'acids such as alanine"

it is a common meta$olite of a variety of $acteria.

It has $een used to o$@ectively measure the +uality of a variety of fish including canned tuna /Iida etal&, 181 a" 181$B >er(e and !uc(" 1335" canned salmon /<rosgrove" 138' !olling&orth and Throm"1825, ra& tuna /!uman and ,hayat" 1815" redfish" olloc(" flounder and cod /,elleher and Call" 18D5.

simlest and erhas most relia$le means of measuring

use of the commercial en*yme test (its availa$le from :oehringer %annheim /-erman5 or 7iagnostic

<hemicals /<harlotteto&n" P.=.I." <anada5

One advantageit is heat'sta$le /although volatile5

used to assess the +uality of canned fish roducts.

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Measurements o" oxidati#e rancidity

' highly unsaturated fatty acids found in fish liids

' very susceti$le to o#idation

rimary o#idation roducts are the liidhydroperoxides. These comounds can $e detected $ychemical methods"

hydroero#ides may $e determined $y titrimetricor

$y sectrohotometric methods" giving the ero#ide value /P95 as millie+uivalents /m=+5 ero#ide er 1(g of fat e#tracted from the fish.

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Microbiological methods

evaluate the ossi$le resence of $acteria or organisms of u$lichealth significance and

to give an imression of the hygienic +uality of the fish including

temerature a$use and hygiene during handling and rocessing.

Traditional $acteriological e#aminations are la$orious" time'consuming" costly and re+uire s(ill in e#ecution and

interretation of the results. 9arious raid micro$iological methods have $een develoedduring the last decade and some of these automated roceduresmay $e of use &hen large num$ers of samles are to $e analy*ed.

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Total counts

Total Aero$ic <ount /TA<5 ;Standard Plate <ount/SP<5.

the total num$er of $acteria that are caa$le offorming visi$le colonies on a culture media at a giventemerature.



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