INTRODUCTION+TO+FOOD+ANALYSIS.ppt

food analysis

1. INTRODUCTION TO
FOOD ANALYSIS
Food Analysis

2. Trends and Demands
Consumer
Demand of high quality, safe and
nutritious foods.
Nutrition labeling is used as a guidance
to choose food.

3. Food industry
To produce high quality food in order to
meet consumer demand
Who will be responsible?
FOOD QUALITY DEPARTMENT

4. Government Regulations and
International Standards and Policies
Nutrition labeling regulations, GMP and
HACCP

5. Reasons For Analyzing Foods
Done by:
Food Manufacturers
Ingredients Suppliers
Analytical Laboratory Services
Government Laboratory
University Research Laboratories

6. A. Government Regulations
To maintain the quality
To ensure the food industry provides
consumers with wholesome and safe foods
To inform consumers about the nutritional
composition of foods
To enable fair competition amongst food
companies
To eliminate economic fraud

7. B.Standards-MandatoryStandards
FoodRegulations:specifytypeand
amountofcertainfood.
Examples:Margarinemustcontain>80%
fat.Thosehavelessthan80%,arecalled
aslowfatspread.

8. 2. Standards of Quality.
Standardsofqualityhavebeendefinedfor
certainfoods(e.g.,cannedfruitsand
vegetables)tosetminimumrequirementson
thecolor,tenderness,massandfreedom
fromdefects.

9. 3. Standards of Fill-of-Container.
These standards state how full a container
must be to avoid consumer deception, as well
as specifying how the degree of fill is
measured.
Example: canned food

10. C. Standards-Voluntary Standards
Eggs have grade A to C
Meat can be graded as “prime”, “choice”,
“standard” and etc
Manufacturersopttodothisbecause
superiorgradeproductscanbesoldfora
higherprice.

11. D.NutritionalLabeling
Nutritionallabelsstatethetotalcalorificvalue
ofthefood,aswellastotalfat,saturatedfat,
cholesterol,sodium,carbohydrateandetc.
Consumerscouldmakeinformedchoices
abouttheirdiet.
Examples:transfatinfatsandoilscontaining
foods.

12. E. Authenticity/ genuine
The price of certain foods is dictated by the
quality of the ingredients that they contain.
Forexample,apacketofpremiumcoffee
mayclaimthatthecoffeebeansarefrom
Columbia

13. F.FoodInspectionandGrading
To ensure that they meet the appropriate
laws and regulations.
The most important criteria for this type of
test are often the accuracy of the
measurements and the use of an official
method.

14. G.FoodSafety
Analyzefoodstoensurethattheyaresafe.
Afoodmaybeconsideredtobeunsafe
becauseitcontainsfoodhazards.
Foodmanufacturersmustensurethatthese
harmfulsubstancesarenotpresent,orthat
theyareeffectivelyeliminatedbeforethe
foodisconsumed.

15. H.Qualitycontrol
Characterizationofrawmaterials.
Monitoringoffoodpropertiesduring
processing
Characterizationoffinalproduct
HazardAnalysisandCriticalControlPoint
(HACCP)

16. I.CharacterizationofRawMaterials.
Incomingrawmaterials:toensurethatthey
meetcertainminimumstandardsofquality
Ultimateobjective:tomaintainthequalityof
thefinalproduct

17. J.Monitoringoffoodpropertiesduring
processing.
Toimprovetheoverallqualityofafood
Toreducetheamountofmaterialandtime
wasted.
analyticaltechniques-rapidlymeasuring
thepropertiesoffoodson-line,without
havingtoremoveasamplefromthe
process.

18. K. Characterization of final product
Toensurethatitmeetstheappropriatelegal
andlabelingrequirements,thatitissafe,and
thatitisofhighquality.Itisalsoimportant
toensurethatitretainsitsdesirable
propertiesuptothetimewhenitis
consumed.

19. Properties to be Analyzed
A. Composition
Determines its safety, nutrition,
physicochemical properties, quality attributes
and sensory characteristics.

20. B.Structure
Changesintexturalproperties
Example:icecreamduringtransportation

21. The structure of a food can be examined at
a number of different levels:
Molecularstructure(1–100nm).
Theoverallphysicochemicalpropertiesofa
fooddependonthetypeofmolecules
present

22. Microscopicstructure(10nm–100mm).
Themicroscopicstructureofafoodcanbe
observedbymicroscopy
Consistsofregionsinamaterialwherethe
moleculesassociatetoformdiscretephases,
e.g.,emulsiondroplets,fatcrystals,protein
aggregatesandsmallaircells.

23. Macroscopicstructure(>100mm).Thisis
thestructurethatcanbeobservedbythe
nakedeye,e.g.,sugargranules,largeair
cells,chocolatechips.
Thedifferentlevelsofstructurecontributeto
theoverallpropertiesoffoods,suchastexture,
appearance,stabilityandtaste.

24. Physicochemical Properties
These properties include:
Optical
Rheological
Stability
Flavor
Usetodetermineperceivedquality,sensory
attributesandbehaviorduringproduction,
storageandconsumption.

25. Optical Properties
Theopticalpropertiesoffoodsaredetermined
bythewaythattheyinteractwith
electromagneticradiationinthevisibleregionof
thespectrum,e.g.,absorption,scattering,
transmissionandreflectionoflight.
Forexample,fullfatmilkhasa“whiter”
appearancethanskimmilkbecauseagreater
fractionofthelightincidentuponthesurfaceof
fullfatmilkisscatteredduetothepresenceof
thefatdroplets.

26. Rheological properties
Studyoftheflowanddeformationofthe
materialsinresponsetosomeappliedforce.
Forexample,margarineshouldbespreadable
whenitcomesoutofarefrigerator,
butitmustnotbesosoftthatitcollapsesunder
itsownweightwhenitisleftonatable.

27. Stability Properties
Isameasureofitsabilitytoresistchangesinits
propertiesovertime.
Thesechangesmaybechemical,physicalorbiological
inorigin.
Chemicalstabilityreferstochemicalorbiochemical
reactions,e.g.,fatrancidityornon-enzymatic
browning.
Physicalstabilityreferstothechangesinthespatial
distributionofthemoleculespresente.g.,droplet
creaminginmilk.
Biologicalstabilityreferstothechangeinthenumber
ofmicroorganismspresent,e.g.,bacterialorfungal
growth.

28. Flavour Properties
Isdeterminedbythewaythatcertainmoleculesinthe
foodinteractwithreceptorsinthemouth(taste)and
nose(smell)ofhumanbeings.
Theperceivedflavorofafoodproductdependsonthe
typeandconcentrationofflavorconstituentswithinit,
thenatureofthefoodmatrix,aswellashowquicklythe
flavormoleculescanmovefromthefoodtothesensors
inthemouthandnose.

29. Types of Samples Analyzed
Why do we need to carry out chemical
analysis?
For quality assurance program
Formulating and developing new products
Evaluating new processes for making food
products
Identifying the source of problems with
unacceptable products

30. Steps in Analysis
A. Select and Prepare Sample
Obtaining a representative sample and
converting the sample to a form than can
be analyzed
Example: To determine TAG composition in
palm olein, you need to dissolve the
sample in aceton.

31. B. Perform the Assay
Assay for each analysis for different
component or characteristic or specific type
of product is unique.
Example: Methods to determine fatty acid
and amino acid are different.

32. C. Calculate and Interpret the Results
Important to make appropriate calculations to
interpret the data correctly.
Example: Calculation of total protein.
Choosing the right factor is important.

33. Choice and Validity of A Method
A. Characteristics of the Method
Must be familiar with the principles
underlying the procedures and the critical
steps
Example: To modify method using HPLC,
one can consider the flow rate, mobile
phase and solvent used.

34. B. Objective of the Method
Example: methods used for rapid on-line
processing measurements may be less
accurate than official methods used for
nutritional labeling purposes

35. C. Consideration of Food Composition and
Characteristics
The accuracy of the method used is affected
by the food matrix.
Example: determination of milk fat using
soxhlet extraction is not suitable as it has
high water content.

36. D. Validity of the Method
Specificity, precision, accuracy and
sensitivity of the method must be
considered.

37. Official Methods
1.AOAC International
Formerly known as the Association of
Official Analytical Chemists)
2.American Association of Cereal Chemists
(AACC)
3.American Oil Chemist’s Society (AOCS)

38. 4. Other Endorsed Methods
Standard Methods for the Examination of
Dairy Products
Standard Methods for the Examination of
Water and Wastewater
Food Chemical Codex

39. Selecting an Appropriate Technique
Important criteria in selecting a technique:
Precision: A measure of the ability to reproduce an
answer between determinations performed by the same
scientist (or group of scientists) using the same equipment
and experimental approach.
Reproducibility: A measure of the ability to reproduce an
answer by scientists using the same experimental
approach but in different laboratories using different
equipment.
Accuracy: A measure of how close one can actually
measure the true value of the parameter being measured.

40. Simplicityofoperation:Ameasureoftheeasewith
whichrelativelyunskilledworkersmaycarryoutthe
analysis.
Cost:Thetotalcostoftheanalysis,includingthe
reagents,instrumentationandsalaryofpersonnel
requiredtocarryitout.
Speed:Thetimeneededtocompletetheanalysisofa
singlesampleorthenumberofsamplesthatcanbe
analyzedinagiventime.
Sensitivity:Ameasureofthelowestconcentrationofa
componentthatcanbedetectedbyagivenprocedure.

41. Specificity:Ameasureoftheabilitytodetectandquantify
specificcomponentswithinafoodmaterial,eveninthe
presenceofothersimilarcomponents,e.g.,fructoseinthe
presenceofsucroseorglucose.
Safety:Manyreagentsandproceduresusedinfoodanalysis
arepotentiallyhazardouse.g.strongacidsorbases,toxic
chemicalsorflammablematerials.
Destructive/Nondestructive:Insomeanalyticalmethodsthe
sampleisdestroyedduringtheanalysis,whereasinothersit
remainsintact.
On-line/Off-line:Someanalyticalmethodscanbeusedto
measurethepropertiesofafoodduringprocessing,whereas
otherscanonlybeusedafterthesamplehasbeentaken
fromtheproductionline.

42. OfficialApproval:ISO,AOAC,AOCS.
NatureofFoodMatrix:Thecomposition,structureand
physicalpropertiesofthematrixmaterialsurrounding
theanalyteofteninfluencesthetypeofmethodthatcan
beusedtocarryoutananalysis,e.g.,whetherthe
matrixissolidorliquid,transparentoropaque,polaror
non-polar.

43. STEPS IN ANALYSIS
Sample Selection and Sampling
Populations, Samples and Laboratory Samples
Population. The whole of the material whose
properties we are trying to obtain an estimate of is
usually referred to as the “population”.
Sample. Only a fraction of the population is
usually selected for analysis, which is referred to
as the “sample”.The sample may be comprised
of one or more sub-samples selected from
different regions within the population

44. LaboratorySample.Thesamplemaybetoo
largetoconvenientlyanalyzeusinga
laboratoryprocedureandsoonlyafractionof
itisactuallyusedinthefinallaboratory
analysis.Thisfractionisusuallyreferredto
asthe“laboratorysample”.
Theprimaryobjective:Toensurethatthe
propertiesofthelaboratorysampleare
representativeofthepropertiesofthe
population,otherwiseerroneousresultswillbe
obtained.

45. Sampling Plans.
Toensurethattheestimatedvalueobtained
fromthelaboratorysampleisagood
representationofthetruevalueofthe
populationitisnecessarytodevelopa
“samplingplan”.
Forcertainproductsandtypesofpopulations
samplingplanshavealreadybeendeveloped
anddocumentedbyvariousorganizations
whichauthorizeofficialmethods

46. Thechoiceofaparticularsamplingplanis
dependson
thepurposeoftheanalysis
thepropertytobemeasured
thenatureofthetotalpopulationandofthe
individualsamples
thetypeofanalyticaltechniqueusedto
characterizethesamples.

47. Factors to be consideredQuestions
Purpose of inspectionsIs it to accept or reject the lot?
Is it to measure the average quality of the lot?
Is it to determine the variability of the product?
Nature of the productIs it homogenous or heterogeneous?
What is the unit size?
How consistently have past populations met specifications
What is the cost of the material being sampled?
Nature of the test methodIs the test critical or minor?
Will someone become sick or die if the population fail to
pass the test?
Is the test destructive or non destructive
How much does the test cost to complete?
Nature of population
being investigated
Is the lot large but uniform?
Does the lot consist of smaller, easily identifiable sub lots?
What is the distribution of the units within the population

48. Sampling Plans
Attribute sampling
Performedtodecideontheacceptability
ofapopulationbasedonwhetherthe
samplepossessesacertaincharacteristic,
forexample,Clostridiumbotulinum
contaminationincannedfood

49. Variable sampling
Performed to estimate quantitatively the
amount of a substance (e.g., salt) or a
characteristic (e.g., color) on a continuous
scale.
The estimate obtained from the sample is
compared with an acceptable value.

50. Three basic types of sampling plans
Single sampling plans
Allow accept/reject decision to be made by
inspection of one sample of a specific size
Double sampling plans
Require the selections of two sample sets.
However, if the lot is extremely high or low
quality, acceptance or rejection may be
determined after evaluation of the first set of
samples

51. Multiple sampling plans
The amount of sampling depending on the
overall lot quality
Reject low quality lots and accept high quality
lots quickly

52. Purpose of Analysis
Official samples.
Selectedforofficialorlegalrequirementsby
governmentlaboratories.
Rawmaterials.
Forincomingmaterials
Processcontrolsamples.
Toensurethattheprocessisoperatingin
anefficientmanner.

53. Purpose of Analysis
Finishedproducts.
Toensurethatthefoodissafe,meetslegal
andlabelingrequirements,andisofahigh
andconsistentquality.
ResearchandDevelopment.
Fornewormodifiedproducts.

54. Purpose of Analysis
Nature of Sample
To clearly specify the particular property that
is going to be measured, e.g., color, weight,
presence of extraneous matter, fat content or
microbial count.
Requireslesssamplesthanattribute
sampling.

55. Purpose of Analysis
Nature of Population
Needtodefinethenatureofthesample
population.Someoftheimportantpointsto
considerarelistedbelow:
Apopulationmaybeeitherfiniteorinfinite.
Afinitepopulationisonethathasa
definitesize,e.g.,atruckloadofapples,a
tankerfullofmilk,oravatfullofoil.

56. Aninfinitepopulationisonethathasno
definitesize,e.g.,aconveyorbeltthat
operatescontinuously,fromwhichfoods
areselectedperiodically.
Tofacilitatethedevelopmentofasampling
planitisusuallyconvenienttodividean
"infinite"populationintoanumberoffinite
populations,e.g.,alltheproducts
producedbyoneshiftofworkers,orallthe
samplesproducedinoneday.

57. Apopulationmaybeeithercontinuousor
compartmentalized.
Acontinuouspopulationisoneinwhich
thereisnophysicalseparationbetween
thedifferentpartsofthesample,e.g.,
liquidmilkoroilstoredinatanker.
Acompartmentalizedpopulationisone
thatissplitintoanumberofseparatesub-
units,e.g.,boxesofpotatochipsina
truck,orbottlesoftomatoketchupmoving
alongaconveyorbelt.

58. Apopulationmaybeeitherhomogenousor
heterogeneous.
Ahomogeneouspopulationisoneinwhich
thepropertiesoftheindividualsamplesare
thesameateverylocationwithinthematerial
(e.g.atankerofwellstirredliquidoil)
Aheterogeneouspopulationisoneinwhich
thepropertiesoftheindividualsamplesvary
withlocation(e.g.atruckfullofpotatoes,
someofwhicharebad).

59. Nature of Test Procedure
Thenatureoftheprocedureusedtoanalyze
thefoodmayalsodeterminethechoiceofa
particularsamplingplan,e.g.,thespeed,
precision,accuracyandcostperanalysis,or
whetherthetechniqueisdestructiveornon-
destructive.

60. Developing a Sampling Plan
Samplesize
Dependsonthe:
expectedvariationsinpropertieswithina
population
theseriousnessoftheoutcomeifabad
sampleisnotdetected
thecostofanalysis
thetypeofanalyticaltechniqueused

61. Statisticaltechniques:todesignasampling
plantoobtainanaccuraterepresentationof
thepopulation.
Sequentialsampling:sub-samplesselected
fromthepopulationareexamined
sequentiallyuntiltheresultsaresufficiently
definitefromastatisticalviewpoint.For
example,sub-samplesareanalyzeduntilthe
ratioofgoodonestobadonesfallswithin
somestatisticallypredefinedvaluethat
enablesonetoconfidentlyrejectoraccept
thepopulation.

62. Sample location.
In homogeneous populations it does not
matter where the sample is taken from
because all the sub-samples have the same
properties.
In heterogeneous populations the location
from which the sub-samples are selected is
extremely important.

63. In random sampling
The sub-samples are chosen randomly
from any location within the material being
tested.
Avoid human bias and facilitates the
application of statistics.

64. In systematic sampling
the samples are drawn systematically with
location or time, e.g., every 10th box in a
truck may be analyzed, or a sample may
be chosen from a conveyor belt every 1
minute.
Easy to implement, but it is important to
be sure that there is not a correlation
between the sampling rate and the sub-
sample properties.

65. Injudgmentsampling
Basedonjudgmentandexperienceofthe
analyst.
e.g.,nearthedoorsofawarehousewhere
thetemperaturecontrolisnotsogood.
Notusuallyagoodrepresentationofthe
population.

66. Sample collection
Bymanualormechanicalsamplingdevices
Riskassociatedwithsampling
The consumer risk
Describe the probability of accepting a
poor quality population (< 5% probability
are accepted)
The vendor risk
The probability of rejecting an acceptable
product. (5-10% probability are accepted)

67. Sources of Analysis Information
Internet
Analyticalmethodsdevelopedbyother
scientistsareoftenreportedinscientific
journals,e.g.,
JournalofFoodScience
JournalofAgricultureandFoodChemistry
JournaloftheAmericanOilChemists
Society

68. Instrument/EquipmentSuppliers
Manycompaniesthatmanufactureequipment
andreagentsusedtoanalyzefoodsadvertise
theirproductsinscientificjournals,trade
journals,tradedirectories,andtheInternet.

69. Internet
Anexcellentsource
Thisinformationcanbeaccessedusing
appropriatelyselectedkeywordsinan
Internetsearchengine.

70. Tabulated of Official Methods of Analysis
Association of the Official Analytical Chemists
(AOAC)
American Oil Chemists Society (AOCS).
American Association of Cereal Chemists
(AACC)