Chemistry of Food Additives and Preservatives

335 Pages·2012·3.14 MB·English

by  Titus A. M. Msagati(auth.)

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Chemistry of Food Additives
and Preservatives
P1:SFK/UKS P2:SFK
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Chemistry of Food Additives
and Preservatives
Titus A. M. Msagati, B.Sc. (Hons), MSc, Ph.D., CChem, MRSC
DepartmentofAppliedChemistry
UniversityofJohannesburg
RepublicofSouthAfrica
A John Wiley & Sons, Ltd., Publication
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Chemistryoffoodadditivesandpreservatives/TitusA.M.Msagati.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN978-1-118-27414-9(hardcover:alk.paper) 1.Foodadditives. 2.Foodpreservatives.
3.Food–Analysis. 4.Food–Composition. I.Msagati,TitusA.M.
TX553.A3C4552012
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2012009754
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1 2013
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Contents
Preface ix
Introduction x
ListofAbbreviations xiii
1 AntioxidantsandRadicalScavengers 1
1.1 Chemistryoffreeradicalsandantioxidants 1
1.2 Typesofantioxidants 4
1.3 Efficacyofdifferentantioxidants 7
1.4 Actionmechanismsofantioxidants 9
1.5 Structure–activityrelationshipofantioxidants 11
1.6 Factorsaffectingantioxidantactivity 14
1.7 Qualityassessmentofdietaryantioxidants 15
1.8 Howsafearefoodantioxidants? 23
1.9 Summary 25
References 25
Furtherreading 31
2 Emulsifiers 33
2.1 Mechanismsoffoodemulsifiers 33
2.2 Theroleofemulsifiersinfoods 35
2.3 Classificationofemulsifiers 37
2.4 Typesoffoodemulsifiers 38
2.5 Qualityandanalysisoffoodemulsifiers 58
2.6 Foodscontainingemulsifiers 60
References 62
Furtherreading 64
3 Stabilisers,Gums,ThickenersandGellingAgentsasFoodAdditives 67
3.1 Introductiontostabilisers,thickenersandgellingagents 67
3.2 Polysaccharides 68
3.3 Protein-basedfoodstabilisers 77
3.4 Qualitycontroloffoodstabilisersandthickeners 78
3.5 Analyticalmethods 78
References 80
Furtherreading 82
4 Sweeteners 83
4.1 Introductiontosweeteners 83
4.2 Propertiesofsweeteners 84
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vi Contents
4.3 Intensesweetenersinfoods 86
4.4 Bulkfoodsweeteners 92
4.5 Qualityassuranceandqualitycontrol 95
4.6 Analyticalmethods 98
References 98
Furtherreading 100
5 Fragrances,FlavouringAgentsandEnhancers 102
5.1 Introductiontoflavoursandflavouringagents 102
5.2 Classificationoffoodflavourings 103
5.3 Chemistryoffoodflavourings 105
5.4 Qualitycontrolofflavourcompounds 119
5.5 Analyticalmethodsfortheanalysisoffoodflavourings 120
References 121
Furtherreading 124
6 FoodAcidsandAcidityRegulators 125
6.1 Whatarefoodacidsandacidregulators? 125
6.2 Typesoffoodacids 126
6.3 Usesoffoodacids 128
References 129
Furtherreading 130
7 FoodColourandColourRetentionAgents 131
7.1 Whyaddcolourantstofoods? 131
7.2 Classificationoffoodcolourants 131
7.3 Overviewofcolourants 133
7.4 Chemistryoffoodcolourants 143
7.5 Extractionfromnaturalsources 143
7.6 Qualityassuranceoffoodcolourants 144
7.7 Analyticalmethods 145
References 145
8 FlourTreatment/ImprovingAgents 148
8.1 Whatareflourtreatment/improvingagents? 148
8.2 Flourmaturingagents 148
8.3 Flourbleachingagents 151
8.4 Flourprocessingagents 154
References 154
9 AnticakingAgents 155
9.1 Thecakingphenomena 155
9.2 Mechanismsofcaking 156
9.3 Classificationofanticakingagents 159
9.4 Anticakingagentsinuse 159
References 160
Furtherreading 161
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10 Humectants 162
10.1 Humectantsandmoisturecontrol 162
10.2 Classificationofhumectants 162
References 166
11 AntifoamingAgents 167
11.1 Sourcesoffoaminfoodprocessing 167
11.2 Propertiesofantifoamingagents 168
11.3 Mechanismsofantifoamingandfoamdestabilisation 168
11.4 Syntheticdefoamers 168
11.5 Naturaldefoamers 170
References 171
12 MineralsandMineralSalts 172
12.1 Theimportanceofmineralsandmineralsalts 172
12.2 Inorganicmineralsalts 173
12.3 Organicmineralsalts 175
References 176
13 DietarySupplements 177
13.1 Introductiontodietarysupplements 177
13.2 Classificationofvitamins 178
13.3 VitaminA(retinols) 179
13.4 VitaminD(calciferol) 189
13.5 VitaminE 194
13.6 VitaminK 196
13.7 VitaminB 199
13.8 VitaminC(L-ascorbicacid) 210
13.9 Conclusions 212
References 213
14 GlazingAgents 218
14.1 Introductiontoglazingagents 218
14.2 Mineralhydrocarbonglazes 218
14.3 ChemistryofMHCs 220
14.4 Conclusion 222
References 223
15 Preservatives 224
15.1 Preservatives:Past,presentandfuture 224
15.2 Naturalfoodpreservatives 226
15.3 Traditionalfoodpreservationmethods 231
15.4 Artificialpreservativeagents 232
15.5 Modernfoodpreservationtechniques 235
15.6 Safetyconcernsoffoodpreservatives 237
15.7 Analyticalmethodsforthedeterminationofpreservativeresidues 238
15.8 Conclusions 238
References 238
Furtherreading 243
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viii Contents
16 NutraceuticalsandFunctionalFoods 244
16.1 Whatarenutraceuticals? 244
16.2 Classificationofnutraceuticals 245
16.3 Mechanismsofaction 246
16.4 Conclusion 253
References 254
Furtherreading 257
17 NutritionalGenomics:NutrigeneticsandNutrigenomics 258
17.1 Nutritionandgeneexpression 258
17.2 Nutrigeneticareasofapplication 260
17.3 Analyticalmethodsfornutrigeneticalfoodfunctions 268
17.4 Conclusion 270
References 270
18 ProbioticFoodsandDietarySupplements 274
18.1 Microbialgutfloraactivity 274
18.2 Probioticsandnutrition 275
18.3 Probioticsandhealth 275
18.4 Safetyandstabilityofprobiotics 277
18.5 Suitabledietarycarriersforprobiotics 278
18.6 Assessmentofprobioticsinfoodstuffsandsupplements 279
18.7 Conclusions 280
References 281
19 Prebiotics 285
19.1 Prebioticsandhealth 285
19.2 Factorsthatinfluencetheactivityandeffectivenessofprebiotics 286
19.3 Typesofoligosaccharides 286
19.4 Qualityassessmentofprebiotics 289
19.5 Conclusions 290
References 290
20 Synbiotics 291
20.1 Synbioticfoodsandhealth 291
20.2 Healthbenefitsofsynbiotics 292
20.3 Mechanismofactionofsynbiotics 293
20.4 Thefutureofsynboticfoods 294
References 294
21 MicroencapsulationandBioencapsulation 295
21.1 Introductiontomicroencapsulationandbioencapsulation 295
21.2 Commonlyusedfood-grademicrocapsules 297
21.3 Methodsoffoodmicroencapsulation 303
21.4 Microencapsulationforfoodcolourants 307
21.5 Bioencapsulationforprobiotics 309
21.6 Conclusions 310
References 310
GeneralConclusions 314
Index 315
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Preface
Theincorporationofadditivesinfoodpreparationshasbeeninpracticesincetimeimmemo-
rial. Additives are used to perform various functions, for example, to impart or enhance
flavour(taste)whereitisnotsharpenoughtomeetconsumer’sdemand,togivefoodstuffsa
desiredcolour(look/appearance)ortoincreasetheshelflifeofthefood(preservativerole).
Someadditivesperformasessentialelementsornutritioussupplementstocaterforthediet
deficiencies of specific groups of people; without such additives these individuals would
sufferfromsomespecificnutrientdeficiencysyndromeormalnutrition.
The tendency to incorporate additives in food products has increased lately, with the
adventofmanynewtypesofadditivesonthemarket.Knowledgeregardingfoodadditives,
how they are prepared, their compositions and how they work has become very important
tothoseinthefoodindustryandresearchandacademicinstitutions.Thisbookistherefore
intendedtoaddressalltheseaspectsoffoodadditives,andisexpectedtobeofinteresttoall
stakeholdersinacademiaandresearch.
Thebookcoversthechemistryofselectedfoodadditivessuchastheirchemicalnature,the
wayinwhichtheyareincorporatedinfoodsandthetechnologyinvolvedintheirpreparations
andprocessingsteps.Thebookalsocoversthemechanismsormodesofactionfortheactive
ingredientsineachtypeandclassoffoodadditiveandpreservative;theirphysico-chemical
characteristicswhichgivethemspecialqualitiestobeusedinfoodprocessing;parameters
usedasindicatorsforthequalityassuranceoftheproducts;structure-activityrelationships;
andtheirsafetytoconsumers.
Therehasrecentlybeenconcern aboutthepossibletoxicityofsomefoodadditives and
foodprocesses.Thishasledtoeitheratotalbanofsomeadditivesormaximumlimitshave
beensetandstrictruleshavebeenenforcedtosafeguardthehealthofconsumer.Thisaspect
hasalsobeendealtwithinthisbook,andthereportedtoxicadditivesarediscussedaswellas
theanalyticalmethodstodeterminethesafetyofvariousfoodadditives.Standardmethods
forcontrol,monitoringandqualityassurancecertificationforfoodadditiveshavebeensetin
placebyvariousregulatorybodiessuchastheEuropeanUnion(EU)andtheAmericanFood
andDrugAdministration(FDA)tocontrolthelegalityofuseforalltheadditives.Methods
forthemonitoringofadditivesandtheirmetabolitesarealsodiscussed.
The classes of food additives that are discussed in this book include: antioxidants and
radicalscavengers;emulsifiers;stabilisers,thickenersandvegetablegums;sweeteners;fra-
grances, flavourings and flavour enhancers; food acids and acidity regulators; colourings
and colour retention agents; flour treatment/improving agents; anticaking agents; humec-
tants;antifoamingagents;mineralsandmineralsalts;glazers;preservatives;nutraceuticals,
nutrigenomicsandnutrigenetics;probiotics;prebiotics;synbioticsandmicro(bio)capsules.
This book is expected to be a valuable asset to scholars, especially those enrolled in
postgraduatecoursesandresearchprogramsintheareasoffoodchemistry,foodprocessing
andfoodtechnology,andalsotoindustrialistsandresearchersinrelatedareas.
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Introduction
Foodisoneofthemainbasichumanrequirementsoflifeandissourcedmainlyfromplants
oranimals(andotherminorsourcessuchasfungie.g.mushroomandalgaee.g.Spirulina).
Generally, human foods are never consumed raw; rather, they undergo special processing
treatmentswithorwithoutheattomakethemmorepalatable.Thestepsinvolvedinthefood
processingtreatmentsvarydependingonthetypeoffoodbeingprepared.Wherenecessary,
some nutritive additives essential for health are added. The process of adding additives in
foodsinvolvesmixingtogethervariousingredientsbeforeorduringaheat-treatmentstepto
givethefoodtheintendedflavour,taste,textureorappearance.Toattainabalanceddiet,it
has been necessary to add to certain foodstuffs some ingredients missing in that particular
dietsuchassalt,aminoacidsandvitamins.Incaseswherefoodisprocessedforfutureuseor
wherethereisanecessitytoavoidspoilagebytheactionofmicrobes,specialtreatmentssuch
assmokingorsaltingareusedtokeepthefoodsafeforlongperiodsoftime.Thetendency
to make foodstuffs more appealing and palatable has paved way for the incorporation of a
variety of ingredients or some special treatments to impart a desired quality to foodstuffs.
Thistendencyechoesthesaying:‘peoplefirsteatwiththeirnose,thenwiththeireyesand
finallywiththeirmouths’.Aroma,flavour,tasteandappearanceareallequallyimportantin
theappealoffoods.
Foodadditivesaresubstancesincorporatedinedibleproductsinordertoperformspecific
roles and functions, such as preservation of foodstuffs by either increasing shelf life or
inhibiting the growth of harmful microbes. Other roles include imparting desired colour,
odour or a specific flavour to food. Food additives may have a natural origin in the sense
thattheymaybefoundexistingnaturallyformingpartoftheindigenouscomponentsofthe
food,ortheymaybesyntheticbutreplicasofsubstancesfoundnaturallyinfoodstuffs.They
mayalsobeentirelyartificial,whichimpliesthattheyaresyntheticallyproducedandarenot
copiesofanycompoundsfoundinnature.
There are a number of additives and preservatives commonly used in foods including
antioxidants, acids, acid regulators and salts, emulsifiers, colouring agents, minerals and
vitamins,stabilisers,thickeners,gellingagents,sweetenersandpreservatives.Thesedifferent
foodadditiveshavedifferentrolestoplayinfoodsdependingontheirintendedpurpose.For
instance, emulsifiers tend to give food a good texture as well as good homogeneity such
thattheymakeitpossibleforimmiscibleitemssuchaswaterandoilstomixwellwithout
anyseparation,asisthecaseinice-creamsormayonnaise(Sumanetal.2009).Stabilisers,
thickenersandgellingagentsprovidestrongtextureandsmoothnessaswellasanincrease
inviscosity(Quemeneretal.2000).
Sweetenersareimportantasflavours,althoughthereareothertypesofsweetenerflavours
whichperformanimportantfunctioninthedietsofconsumerswithhealthproblemssuchas
diabetes(Hutteauetal.1998).
Nutritive additives such as minerals, vitamins, essential amino acids, etc., are added to
particular food products where they are missing (Nayak and Nair 2003) or in foodstuffs
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Introduction xi
specifically intended for people with deficiency of such additives, for example milk for
babies(Ikemetal.2002).Otheradditivessuchasantioxidantsareneededfortheprevention
offatandoilrancidityinbakedfoodsbyinhibitingtheeffectsofoxygenonfoodsandalso
preventingthelossofflavour,therebymaintainingfoodpalatabilityandwholesomeness.
Acidsandacidicregulatorssuchascitricacid,vinegarandlacticacidarefoodadditives
to control food pH (levels of acidity or alkalinity) and they play an important role in the
sharpeningofflavours(Populinetal.2007),aspreservative(BrulandCoote1999)andasan-
tioxidants.Someacidsandacidregulatorstendtoreleaseacidsonlywhentheyaresubjected
toaheattreatmentsuchaswithsomebakeryproducts(e.g.acidsproducedbytheleavening
agentsreactwithbakingsodatomakethebakeryproductsriseduringthebakingprocess).
Colouring and colour retention agents are added to foods to appease the eye of the
consumerorbeholder;theyarealsointendedtomaintainthecolouroffoodincaseswhere
itmayfade(MacDougall1999).
Generally speaking, the desire for a particular quality of food has resulted in the intro-
ductionofnumerousadditiveswithwideapplicationsindifferentculturesandcivilisations.
Currently,manydifferenttypesoffoodadditiveshavebeencommercialisedandarefinding
theirwayontothemarketsworldwide(Baker2010).Thistrendinbusinesshascontributedto
thespeedygrowthinfoodprocessingandotherrelatedindustries,wherefoodadditivesare
used en masse. The economic success of food additives has further encouraged the advent
ofnewtechnologiesintheprocessingoffoods.
However, these new technologies and additives have brought other unwanted outcomes
and are an issue of concern. Despite all the benefits and advantages of food additives and
preservatives,thereisstillapotentialdangerofchemicaladulterationoffoods.Additivesor
preservativesinfoodsmaythemselvestriggerotherhormonalorchemicalprocessesinthe
bodythatcangeneratenegativephysiologicalresponses.Themetabolitesproducedbyaddi-
tivesmayalsocausesideeffects,becausenotallfoodadditivesenterthemarketsafterbeing
thoroughly studied to prove their safety (Skovgaard 2004). Although most food additives
are considered safe, some are known to be carcinogenic or toxic. For these reasons, many
food additives and preservatives are controlled and regulated by national and international
healthauthorities.Allfoodmanufacturersmustcomplywiththestandardssetbytherelevant
authoritieswithoutviolatingthemaximumthresholdsstatedtoensurethesafetyofthefinal
producttotheconsumers.Inmostcases,foodprocessingindustriesmustseekstandardcerti-
ficationbeforeusinganynewadditiveorpreservativeorbeforeusinganyoriginallycertified
additiveorpreservativeinadifferentway(Pinhoetal.2004;Skovgaard2004).
REFERENCES
Baker,S.R.(2010)Maximizingtheuseoffoodemulsifiers.MScthesis,KansasStateUniversity,Manhattan,
Kansas,USA.
Brul,S.&Coote,P.(1999)Preservativeagentsinfoods:Modeofactionandmicrobialresistancemechanisms.
InternationalJournalofFoodMicrobiology50,1–17.
Hutteau, F., Mathlouthi, M., Portmad, M. O. & Kilcast, D. (1998) Physicochemical and psychophysical
characteristicsofbinarymixturesofbulkandintensesweeteners.FoodChemistry63(1),9–16.
Ikem, A. Nwankwoala, A., Odueyungbo, S., Nyavor, K. & Egiebor, N. (2002) Levels of 26 elements in
infantformulafromUSA,UK,andNigeriabymicrowavedigestionandICP–OES.FoodChemistry77,
439–447.
MacDougall,D.B.(1999)ColoringofFood,Drugs,andCosmetics.MarcelDekker,Inc.,NewYork,Basel,
USA.