Chemistry Reference
In-Depth Information
7.6.2 Characteristics
Puresugars(mainlyfructose-glucose)remainingrapejuice,followingtheremovalofallnon-
sugarconstituents.Itisapure,colorless,odorless,andneutralproduct.Acidityisalmostzero,aswell
asitsconcentrationinsulphurandothersubstances(acids,tannins,coloringagents,andmetals).Itis
storedsafelywithoutanyfearofmicrobialspoilagebecauseofitshighconcentrationinsugars.Pure
grapejuiceconcentrateisaproductwithsimilarcontenttograpejuicebutwithoutsaccharose.
7.6.3 Manufacture of pure Grape Juice Concentrate
Duringthemanufactureofpuregrapejuiceconcentrate,cleanandwashedgrapesarecollected
andtakentopneumaticpresses,wheretheyarecrushed.
Duringcrushing,SO
2
isaddedtopreventalcoholicfermentation.Next,grapejuiceisilteredto
removethegrapesolids.Filteredgrapejuiceisthenpassedthroughanionexchangeresincolumn
tobecomepure,i.e.,toremoveallnonsugarconstituents(acids,tannins,colors,andmetals).
Followingpuriication,evaporationstartsat56°Bxundervacuuminthreestagesat90°C,65°C,
and45°C.Finally,thejuicereceivedconsistsofmainlysugars,suchasfructoseandglucose.The
manufactureofpuregrapejuiceconcentrateisshowninFigure7.7.
7.6.4 Quality Control
Eachproductionlotisexposedtoqualitycontrolanalysisfromtherelevantauthoritiesorthe
companyproducingitaccordingtothespeciicationssetup.
7.6.5 Use
Grape juice concentrate is used in juice manufacture, marmalades, confections, yogurt, ice
cream,andcannedfruit.
Addition of SO
2
Pneumatic
presses
Grapes
Grape juice
Centrifugation
(ion exchange resins)
Filtration
Evaporation
(three stages under vacuum)
Pure grape juice
concentrate
Figure 7.7
Manufacture of pure grape juice concentrate.
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