excellent examples of fat-based foodsoils.The equipment usedon the churn
deckof a margarineproductionplantwouldlikelybe soiledwithfat-based
residues. Likewise, the implementsinvolvedwithhandlingmeatemulsionsused
in sausage manufacturing wouldcertainly be fouled withfat residues.
Carbohydrate-basedresidues includethe simplesugars,starch,and starch-
containing compounds. Carbohydrate residues are associated with the
production of confectionaryproducts, bakedgoods,jelly,and juice products.
The mogulsusedin moldedcandymanufacturing are notoriousfor harboring
bothstarch and sugarresidues. Fruit and vegetable processing equipmentis also
likely to be contaminatedwithcarbohydrate residues.
Protein-based soilsarise in foodprocessingfroma diverserangeof foodstuffs
including, meat,milk,nuts, soy,shellfish, and variousgrains.Whenheated,
protein residues are easilydenaturated(coagulation).Denaturationmayalso
promote or contribute to film formation. Protein-based filmsare verydifficult to
remove. Milk(casein)and egg products(albumin)stabilized by heatingreadily
formprotein-based film.It is alsonoteworthythat protein residues, on food
processingequipment, are of greatconcernto the foodindustryand public
health officialsbecause of theirassociatedallergenicpotential.
Mineral salts,undercertainprocessingconditionstypically involving heat
and low pH, forminsolublecomplexes that precipitate ontothe surfaceof food
equipment. Typical mineral salts include milk stone (limestone), calcium
phosphate, and calciumoxalate (spinach). Other difficult mineral deposits
includeiron and manganese.
Understandingthe chemicaland physicalpropertiesof the varioussoil types,
as discussed above, is a necessary prerequisite for developing a coherent
cleaningprocess.For example,foodsoilsexhibit a widerangeof miscibility
and solubilityproperties. Witha perspectivetowarddeveloping a COPwet-
cleaningprocess,soil solubilitypropertiescan be a valuableindicatorof the
likelihoodthata cleaning process willbe successful. If the residueunder
considerationis not soluble in a proposed cleaningsolvent, it is reasonableto
conclude that a processbasedon that solvent will not be effective.Solubility
characteristics are frequentlyusedas a criterionfor groupingfoodsoilsinto
fourcategories:
- solublein water(sugars, somestarches, and salts);
- solublein acid(milkstone,mineral deposits,and calciumoxalate);
- solublein alkali (protein,fat emulsions);
- solublein water, alkali, or acid(carbohydrates, minerals, and fats).
Solubilitymaybe influencedby the physical condition of the residues. Burned-
on, desiccated and hardenedfoodfilmswill exhibitdifferentsolubilitycharac-
teristics fromtheirmoistcounterparts.It is also true that mostprocessedfoods
are formulated witha numberof foodingredients,all of which,independently,
mayexhibit differingsolubilityproperties; thereby,furthercomplicating the
design and implementationof a COPcleaning process. Soil classificationwith
the correspondingremovalcharacteristicsare summarizedin Table28.1.
450 Handbookof hygiene controlin the foodindustry