Waterqualityand chemistry
Thefirstand foremost consideration in evaluatingthe suitability of a water
sourcefor use in any foodprocessing application, including cleaning,is its
potability. A watersource that containsno harmfulelements and is deemed
suitablefor drinking is generally considered potable. While the nationsof the
worlddifferin theirinterpretationof harmfulelements, it is safe to say that their
primary focusis on precludingpathogenic microorganismsand other toxic
substances fromwaters that are intended for humanconsumption.Again, and it
is worth emphasizing, all waterused in foodprocessingestablishments should
be derived froma potablesource.
Wateris the basicsolvent usedin a majority of wet-cleaning applications.Its
primary functions are to containand deliverthe cleaningagentto the target
substrate. Water is also frequentlyusedas the applied motive force,essentialfor
removing foodfilmand residues. The importantfunctionsof waterin a COP
processmaybe negativelyinfluencedby its chemistry.
Asidefrompotability,perhapsthe mostimportantcharacteristic of a cleaning
watersourceis its hardness. Originally, waterhardness was understood to be a
measure of the capacityof waterto precipitate soap(AmericanPublicHealth
Association,1985).Soap precipitated in wateris chiefly caused by the presence
of calcium and magnesium ions. Otherpolyvalentcationsalso mayprecipitate
soap,but theyare oftenin complexforms,frequentlywithorganic constituents,
and theirrole in waterhardnessmaybe minimaland difficult to define.Water
hardness is frequently discussedas eithercarbonate or non-carbonatehardness
(Bakka, 1997).Theformeris also referredto as temporary hardnessand is
removedby heat.Non-carbonatehardness or permanent hardness is not affected
by heat.Consistent withcurrentpractice, totalhardness is definedas the sum of
the calcium and magnesiumconcentrations, expressedas calcium carbonate, in
milligramsper liter of water. The hardness mayrangefromzeroto hundreds of
milligramsper liter,dependingon the sourceand treatment to whichthe water
has beensubjected (AmericanPublic Health Association,1985).Totalwater
hardness is calculated using the followingformula:
Table28.1 Foodsoil removalcharacteristics(afterGuthrie,1972)
Soil type Solubility Removal Reactionsto heat
properties characteristics
Sugar Water Easy Caramelization,more
difficultto clean
Fat Alkali Difficult Filmformation,more
difficultto clean
Protein Alkali Verydifficult Denaturation,more
difficultto clean
Starch Waterand alkali Easy±moderate Glue-likeformation
Monovalentsalts Water/acid Moderate Not significant
Polyvalentsalts Acid Difficult Reactions
Improvingcleaning-out-of-place(COP) 451