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this shows what are the important tools in measuring food quality
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7/17/2019 Measuring Food Quality With Instrument
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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
7/17/2019 Measuring Food Quality With Instrument
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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" .
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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
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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$le to measure +uality or freshness of a single fish"
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Measuring Food Quality withInstrument
Chemical methods
rely on the measurement of meta$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.
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Measuring Food Quality withInstrument
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.
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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.
i d li i h
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Measuring Food Quality withInstrument
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.
M i F d Q li i h
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Measuring Food Quality withInstrument
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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Measuring Food Quality withInstrument
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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Measuring Food Quality withInstrument
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 $een sho&n to accumulate slo&ly in sterilefish tissue. .
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Measuring Food Quality withInstrument
Analyte(s) Principle Advantages Disadvantages Reference
Hxenzymes (xanthineoxidase, X0) immobilizedon a test strip
rapidsimple to use outsidethe lab
semi -quantitativeonlycapable of measurin Hx(later staes of spoilae)
!ahns et al. ("#$%)
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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Measuring Food Quality withInstrument
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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Measuring Food Quality withInstrument
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
$y sectrohotometric methods" giving the ero#ide value /P95 as millie+uivalents /m=+5 ero#ide er 1(g of fat e#tracted from the fish.
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Measuring Food Quality withInstrument
Microbiological methods
evaluate the ossi$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 $e analy*ed.
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Measuring Food Quality withInstrument
Total counts
Total Aero$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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