PRINCIPLES -METHODS -EQUIPMENT -FORMULAS [617042]

MAKING
COMMERCIALLY
PRINCIPLES -METHODS -EQUIPMENT -FORMULAS
B*lAgriculture
CanadaCanadian Agriculture Library
Bibliotheque canadienne deI'agnculture
Ottawa K1A0C5
1
::•|J*;i;
%^H
|
1:||PUBLICATION 1144 OCTOBER 19621
CANADA DEPARTMENT OFAGRICULTURE Jill
[K J I
»: :::::.::i;';-..j-.-.'*.?:-r-*-:vi :!?:!!; :t:;:':::::: :-:-..'.vr.-….r•.:•;-:::•:::-:•:

CONTENTS
Page
Legislation 3
Canadian standards forjam 3
Containers andlabels 3
TwoMethods ofMaking Jam 4
Open-kettle process 4
Vacuum process 4
Advantages ofthevacuum process 4
Disadvantages ofthevacuum process 4
Ingredients 4
Fruit 5
Sweetening agents 5
Preparation ofinvert syrup 5
Glucose 6
Pectin 6
Acid 6
Processing 7
Open-kettle process 7
Using fresh fruit 7
Using frozen fruit 8
Control offinishing point 8
Vacuum-kettle process 9
Using fresh fruit 9
Using frozen fruit 9
Quality Control 9
Processing Equipment 12
Thesmall plant 12
Kettles 12
Holding tank 13
Fillers andcappers 13
The large, manually operated plant 13
Kettles 13
Fillers andcappers 16
Coolers 16
Labelers 16
The large, mechanized plant 18
Kettles 18
Holding tanks 21
Inspection tables 21
Fillers 22
Coolers 22
Container driers, labelers, casers andcase sealers 22
1

Page
Formulas 22
Formula calculations 22
Sugar requirements 22
Acidrequirements 23
Pectin requirements 23
The testbatch 23
Reducing thefruit content 24
Using frozen fruit 24
Adjusting thesugar ratio 24
Tested jamformulas 24
Apricot 25,Black currant 25,Black currant-prune 25,Sweet
cherry 26,Sweet cherry-black currant 26,Sour cherry 26,
Peach 27,Italian prune plum 27,Raspberry 27,Strawberry 28.
Acknowledgments 28
References 28

MAKING JAM
COMMERCIALLY
Principles •Methods •Equipment •Formulas
A.W.Moyls2
,CC.Strachan3
,and F.E.Atkinson4
Research Station, Summerland, B.C.
This publication wasprepared forthesmall manufacturer orprocessor
thinking ofentering thejam-making business. Itgives information gained from
laboratory studies, practical experience andother sources.
The principles involved inthemanufacture ofhigh quality jamarebriefly
discussed. Foramore thorough treatment oftheoretical aspects, consult the
excellent bookbyRauch (5)andthePreservers Handbook (9).Larsen (4)gives
further information ontheuseofpectin injams.
Only themanufacture ofpure fruitjams isdiscussed inthispublication.
However, thesame procedures apply toother grades.
LEGISLATION
Regulations governing themanufacture ofjam inCanada arecontained in
theMeatandCanned Foods Act (2)andtheFoodandDrugs ActandRegulations
(3).Aprocessor considering making jamcommercially should bethoroughly con-
versant withboth these acts.
Canadian Standards forJam
Canadian standards forjam callfordefinite, minimum percentages offruit
andtotal soluble solids inthefinished product. Thepercentage offruit varies
withthegrade andkind ofjam.Theminimum percentage offruit forallCanadian
jams except strawberry is45;forstrawberry itis52.That is,every 100pounds
offinished jamcontains 45or, ifitisstrawberry, 52pounds offruit.
Theminimum percentage ofsoluble solids is66.Aspractically allofthe
soluble solids aresugar solids, thisfigure isagood indication ofajam's totalsugar
content. Aside from thelegal aspects, jamcontaining lessthan65percent sugar
issubject tospoilage from yeasts andmolds.
Containers andLabels
Jam fortheretail trade inCanada ispacked inboth glassandmetal con-
tainers. The sizes listed intheMeatandCanned Foods Act (2)are2\,6,9,12,24
Contribution No.B3,Research Station, Summerland.
2Food Technologist, FruitandVegetable Processing Section.
3l)irector, Research Station.
4Head, Fruit andVegetable Processing Section.

and48fluidounces. Byweight, these areabout 3J,8and12ounces and 1,2and
4pounds, respectively. Alllabels must beapproved bytheMinister ofAgri-
culture. Special dispensation maybegranted topackjam incontainers smaller
than 2\fluidounces andlarger than48fluid ounces.
TWOMETHODS OFMAKING JAM
Jam ismanufactured byeither theopen-kettle orthevacuum-kettle process.
Ingeneral, because oflower processing temperatures, jamsmadebythevacuum
process have better colorandflavor than thosemade inanopen kettle.
Open-kettle Process
Intheopen-kettle process thejam isboiled under atmospheric conditions.
During theboiling process thebatch temperature mayexceed 225° F.Prolonged
heating athightemperatures, however, should beavoided asitcauses excessive
caramelization ofsugar, lowflavor andpoor color. This process canbeused to
advantage insmall-scale operations, such asspecialty packs. (Formore details
onadvantages anddisadvantages ofthismethod see"Vacuum process".)
Vacuum Process
Inthevacuum process thebatch temperature should notexceed 160° F.
except forabrief period before filling, when itmayberaised to180-190° F.to
ensure agoodvacuum and sterile fill.
Advantages oftheVacuum Process
1.Short, low-temperature boilpreserves color, flavor andwholeness offruit
pieces.
2.There islessinversion ofsugar thanwhenjam isboiled atatmospheric
pressure andtemperature.
3.Overheating isavoided, since sizeofbatch isnotinfluenced bytemperature
andtime ittakes forsteam bubbles topassthrough thebatch.
4.Larger batches canbeprocessed thanwith theopen-kettle method.
5.Sugar penetration tothecenter ofthefruit isbetter and easier.
6.Lessmanual labor isinvolved.
7.Ester recovery canbepractical.
Disadvantages oftheVacuum Process
1.Initial installation ofequipment isvery expensive.
2.Expensive automatic control instruments arenecessary when processing
large batches.
3.Alargevolume ofcooling water isrequired forcondensers.
4.Vacuum equipment isnotpractical except forlarge runs orbatches.
5.Sulphur dioxide removal fromS0 2-preserved pulps isnotsatisfactory.
Vigorous boiling ofS0 2pulpunder atmospheric conditions isrequired toremove
sulphur dioxide from thepulp. This defeats thepurpose ofavacuum process.
INGREDIENTS
Besides fruit,jamcontains sugar orother sweetening agents, pectin, acidand
water. Thesugar andacidcause thepectin toundergo aphysical change, when
conditions areright, forming agelinwhich thefruit issuspended. Theactive
acidity (pH)must becarfully controlled toobtain agelformation. Infact, all
ingredients must bepresent indefinite proportions ifajam ofdesired setorcon-
sistency istobeobtained.

Fruit
Jamsmaybeprepared from fresh, frozen orcanned fruit orS0 2pulp. Only
fullymature fruit ofcharacteristic color, flavor andtexture should beused. Fresh
andfrozen fruitproduce thebestquality jamandaretheonlyones dealt with in
thispublication. InCanada, strawberry andraspberry pulps preserved inSO2are
notpermitted inpure jams.
Carefully sortandwash fresh fruit. Pitapricots, cherries andprunes, either by
hand orbymachine; peeland pitpeaches; andstem strawberries andcurrants.
Simmer firmfresh fruits such ascherries, plums andapricots inasmall quantity
ofwater tosoften theflesh before adding anysugar. Most berries donotneed
thistreatment.
Sweetening Agents
Themain sweetening agents used injamarecaneandbeetsugar (sucrose),
cornsugar (dextrose), cornsyrup (glucose), invert sugar (dextrose andlevulose)
andhoney. They differ insolubility and intheir effects onthecolorandflavor of
thejam.Acombination ofsucrose andinvert sugar isusually thebestsweetener
fortheinexperienced jammaker touse.
Technically, invert sugar isamixture ofequal parts ofdextrose andlevu-
loseand isformed when sucrose isbroken down byacids orcertain enzymes.
This process iscalled inversion. Dextrose andlevulose arealsocalled simple, or
reducing, sugars. The fruit inajamcontains these twosugars indifferent pro-
portions aswell asother simple sugars. When ajam isanalyzed allthesimple
sugars aregrouped together andreported aspercent reducing sugar. Generally,
theindustry refers tothese sugars as"invert".
Injammaking, some inversion takes place during thecooking. Therateand
amount arecontrolled bythepHofthejam, theboiling temperature andthe
length oftheboil.
Jammusthave aproper balance ofsucrose andinvert (reducing) sugar, or
oneortheothermay crystallize during storage. Jamwith total soluble solids of
68to70percent should analyze 20to28percent reducing sugar. Inother words,
30to40percent ofthesugar present inthejamshould beinvert.
Because itisnotalways possible toobtain theproper sucrose-invert sugar
ratio during theboiling process, some preinverted sugar syrup isusually added.
This isparticularly true inthevacuum process, inwhich, because ofthelow
boiling temperature, practically noinversion occurs. Even intheopen-kettle
method, low-acid fruits would have tobeboiled solong togetsufficient inversion
that itwould affect thecolorandflavor ofthejam.
Preparation ofInvert Syrup
Invert syrup ismade from cane orbeetsugar dissolved inwater andtreated
withanacid,such ascitric, tartaric, hydrochloric orphosphoric. After inversion,
andbefore cooling, sodium bicarbonate issometimes added toneutralize mostbut
not alloftheacid.However, ifthesyrup istobeused with low-acid fruits no
neutralization isnecessary.
The following method gives alight-colored, invert syrup of70percent
soluble solids that areatleast 96percent invert sugar. Dissolve 100pounds of
canesugar in45pounds ofwater andadd5ounces ofcitric acid.Keep themixture
at212° F.for 1hourwith agitation. Immediately coolthesyrup toabout 100° F.
andadjust withwater to70percent soluble solids.

Glucose
Some manufacturers useglucose (corn syrup) for5to15percent ofthesugar
inajambecause they feel itimproves thequality. Glucose isslightly lesssweet
than sucrose, hasahigh viscosity andseems tobrighten thejam. Italsoretards
thecrystallization ofsucrose.
When glucose issubstituted forpart ofthesucrose inajam,anequalamount
ofsugar solids must beprovided. Forexample, iftheglucose contains 60percent
sugar solids, use——X1=1.67pounds ofglucose toreplace 1pound ofsucrose.
60
Pectin
Allfruits contain some pectin buttheamount andquality vary with the
fruit, itsripeness andtheconditions under which itwasgrown. Forthisreason it
isusually necessary toaddcommercial pectin toobtain jam ofuniform consis-
tency.
Pectin canbepurchased bygrade ineither powdered orliquid form. Grade
doesnotrefer toquality butindicates thenumber ofpounds ofsugar 1pound of
pectin will setintoastandard sugar-pectin jellyunder specific conditions. For
example, 1pound of100-grade pectin willset100pounds ofsugar intoastandard
jelly of65percent soluble solids, ifenough acid ispresent. Onegrademaybe
substituted foranother ifproper adjustment ismade; that is,forthesame gelling
power of1pound of100-grade pectin youwould need 2pounds of50-grade pectin.
Twotypes ofpectin areused injammaking: rapid setandslow set.With
rapid-set pectin thejamthickens soon after theacid isadded. This helps tokeep
fruit pieces uniformly distributed throughout thejaminstead offloating tothe
top.Normally thecontainers are filled hot,above 185° F.,andcooled without
agitation.
Foralow-temperature fill,often usedwithvacuum jamandjam filled asep-
tically, slow-set pectin isused. Itisalsoneeded ifcontainers aretobespin-
cooled. Spin-cooling jamsmade with rapid-set pectin destroys thegelandgives a
weak setorrunny jam.According toSeymour (7),slow-set pectin willnotstart
togelforatleast40minutes attemperatures aslowas165° F.This allows time
tofill,cap,washandlabel thecontainers before thejam starts toset.
Pectinmaybeadded tothejameither asadrypowder orinsolution. The
pectin must becompletely dissolved tocontribute togelling. Pectin dissolves best
ifthesugar solids arelessthan20percent. Therefore, ifpowdered pectin isbeing
added directly tothejam itmust bemixed with part ofthesugar andadded at
thestart oftheboil, before thebulk ofthesugar isadded. Ontheother hand, a
pectin solution maybeadded atanytimeduring theprocess. This isanadvantage
because prolonged cooking, especially withacid fruits, usually destroys some ofthe
pectin, lessening itsgelling power.
A10percent pectin solution isthemost practical touse.Prepare itasfollows:
Mix 10parts ofpowdered pectin with20parts ofsugar inadrycontainer. Add
thismixture slowly to70parts ofboiling water, with constant agitation. Con-
tinue stirring until thepectin iscompletely dissolved—thistakes only afew
minutes. Asthepectin solution isnotstable (itlosessome jellying strength on
standing), prepare onlyoneday's supply atatime.
Acid
Fruits contain natural acids butmany ofthem donothaveenough fora
satisfactory setorgel.Tomake upforthisdeficiency, andtoaddtartness and
improve theflavor, acids such ascitric and tartaric arenormally included in
6

jamformulas. Theamount ofacidused varies with thefruitandmaybeadded
either asaliquid orasapowder.
ThepH(active acidity) should bedetermined withanelectric orbattery-
operated pHmeter. Inajam of68to70percent total soluble solids, keep the
pHbetween 3.2and 3.4.Nogelwillformabove apHofabout 3.6,while below
3.0thejamtends tosweat, causing excessive weeping orbleeding later.
Tobring outacharacteristic fruit flavor, itwasoften necessary inourstudies
touseapHslightly higher orlower than thetheoretical ideal. Thismeant we
hadtousealittlemore pectin orpossibly accept alighter set,buttheimprove-
ment inquality wasoften worth thechange. Wehadtobecareful, however, to
keep thepHwithin thelimits necessary forsatisfactory gelformation.
PROCESSING
Thesteps inmaking jamareoutlined intheflowsheet (Figure 1).Whether
theoperations aremanual orautomatically controlled depends onthescale of
production (seeProcessing Equipment, page 12).Inanycase theequipment
must achieve thefollowing togivegood quality jam: (a)arapid boilsothat
batches canbefinished in7to8minutes (this requires asteam working pressure
onthekettles of70to100pounds persquare inch)
;(6)arapid coolfrom the
boiling temperature to160° to190° F.(thistemperature depends onthetype
offill) ;and (c)final cooling ofthejam inclosed containers to90°F.before casing.
Frozen or
SO*Fruit Fresh Fruit Canned Fruit
Washing
Stemming, peeling, pitting, etc.
Slicing orcutting
Adding sugar
Concentrating
Filling
Cooling
Labeling
Casing
Figure 7.—
Flow sheet formaking jam.
Open-kettle Process
Using Fresh Fruit
1.Place theweighed fruitandwater (usually about 20percent byweight
ofthefruit) inthekettle. Turn onsteam andsimmer fruit for3to5minutes
with agitation, tosoften fruit pieces.

2.Addthesugar andbring batch toavigorous boilwith agitation. After
5minutes (assuming total boiltime is7to8minutes) addpectin solution (see
page 6).
3.When jamthermometer shows mixture is3degrees from finishing point,
addacid.
4.When finishing point isreached, shut offsteam andcheck soluble solids
onacooled sample ofthejam, using arefractometer (seepage 10).
5.Draw offjam, fillcontainers at185to190° F.andsealimmediately.
6.Water-cool cansandair-cool jarstoatleast 90°F.(Glass jarsareavailable
that themanufacturer claims canbehot-filled andimmediately subjected to
cold-water sprays orimmersed incoldwater without breakage.)
Using Frozen Fruit
Frozen fruitcanbethawed inthekettle. However, itisusually preferable
toremove thefrozen fruitfrom coldstorage andallow ittothaw overnight at
room temperature. Inmost instances, water canbeomitted from theformula
unless there isinsufficient freeliquid from thethawed fruit todissolve thesugar
andprevent scorching.
Drain thejuice offthethawed fruit intothekettle, dissolve thesugar init
andbring toaboilwith agitation. Addthefruitandreheat mixture totheboil.
After approximately 5minutes addthepectin solution. Finish asoutlined in3,4f
5and 6,above.
Aquicker method istoplace thethawed fruit (including juice) andthesugar
inthekettle together, instead ofdissolving thesugar inthejuice assuggested.
Inlarger plants apredissolving kettle isusedandthemixture ispumped tothe
kettles asneeded. Jammade thisway, however, hasfewer pieces ofwhole fruit.
Control ofFinishing Point
When using theopen-kettle process, check theboiling point ofthewater at
least twice aday.The boiling point ofaliquid depends ontheatmospheric
pressure inthearea.Adecrease inpressure ofJinch ofmercury lowers theboiling
point ofwater 1°F.Variations inatmospheric pressure during theday, orfrom
daytoday,may cause theboiling point tovary asmuch as2°F.Anerror of
1°F.inthefinishing point ofajamcauses anerror ofalmost 2percent inthe
soluble solids ofthefinished product. Ifajam isfinished to70percent soluble
solids instead of68,themanufacturer islosing 2percent onthebatch. Over a
season's pack theaccumulated losscould becostly tothecompany.
Ifwater boils at212° F.,jamshould becooked toafinishing point of222.2° F.
ifitistocontain 68percent soluble solids. Inother words, whenjam inthekettle
reaches 222.2° F.,asshown onthethermometer, thesoluble solidswhen checked
bytherefractometer should be68percent.
Therefractometer reading ismade onasmall portion ofjamcontaining a
representative mixture offruitand liquid. Place thesample inatesttube, cork
itquickly and cool itrapidly incold water. When thecontents arecooled,
thoroughly mixanymoisture thathascondensed onthesides ofthetube orcork
with thejamanddetermine thesoluble solids byrefractometer. Ifthepercentage
ofsoluble solids istoohigh,add sterile water toreduce it;iftoolow,continue
cooking until thedesired level isreached. (Ifthejamcontains ahighproportion
oflarge pieces orwhole fruit itisparticularly important tohave arepresentative
sample, orelsetherefractometer reading may indicate ahigher percentage of
soluble solids than willactually bepresent inthe final, equalized product.)
8

Vacuum-kettle Process
Using Fresh Fruit
1.Place thefruit, water andsugar inasteam- jacketed vacuum kettle and
heatto160°F.with agitation. (Before adding sugar tofirm fruits, such ascherries,
peaches, plums andsome berries, simmer thefruit tosoften it,asforopen-kettle
jams.)
2.Apply avacuum of28inches andkeep theheatbelow 140° F.until the
soluble solids oftheproduct areatleast80percent. (Unless thekettle isequipped
with adirect reading refractometer thetime element hastobeworked out
experimentally.)
3.Break thevacuum slowly. Add pectin solution with agitation and raise
thevacuum to28inches. When rapid-set pectin isusedwith very acid fruits,
keep thetemperature above 170° F.toavoid presetting. Youmayhave toapply
alittle heat togetthebatch torollslightly inthepan.
4.Once again break thevacuum slowly. Heat to170° F.(oratemperature
highenough toavoid presetting when acid isadded). Addtheacidwith agitation;
check soluble solids andadjust toproper value with sterile water.
5.Heat thebatch to190° F.Agitate itcontinuously.
6.Draw offjamand fillcontainers at185° F.orhigher andsealimmediately.
7.Cool containers asdirected under method foropen-kettle jams.
Vacuum jamsmaybecooled efficiently byuseofthevacuum itself. This
method isgenerally usedwhen alow-temperature aseptic fill isused. After
heating thejamto190° F.(step 5),turn offthesteam andapply avacuum of28
inches until thetemperature drops tothedesired level. Ifcompressed airiscon-
nected tothevacuum kettle, use ittotransfer thecooled jamtotheholding tank
forfilling.
Using Frozen Fruit
Forajamcontaining ahighpercentage ofwhole fruit pieces, drain thejuice
offthethawed fruit intothekettle, addthesugar andheat to160° F.with
agitation. (Ifwhole fruit pieces arenotdesired thefruitandthejuice canbe
added tothekettle with thesugar.) Proceed with step 2.Release thevacuum
slowly, addthedrained fruitandreheat to160° F.with constant agitation. To
keep thefruit evenly distributed throughout thejam, apply avacuum of28
inches, reduce steam pressure onkettle andallow temperature todrop to140°F.;
break thevacuum slowly. This stepmayberepeated several times during the
cooking process. Itcreates, bymechanical means, aforce thatimpregnates the
fruitwithsugar andkeeps itfrom floating tothetop.
Heat thebatch to170° F.,addpectin solution and finish asoutlined insteps
3,4,5,6,and 7,above.
QUALITY CONTROL
Quality control isessential forthecontinued production ofuniform jam.
The tests used aresimple andrequire neither askilled chemist noranelaborate
laboratory. Allyouneed isatechnician with alittle training, elementary lab-
oratory equipment, some standard chemicals andreagents andasmallroom with
asinkandseveral electrical outlets.
Testevery batch ofjam forpercentages oftotal soluble solids andinvert
sugar (reducing sugar), pHandconsistency; record thedatawith thebatch code.
Useyour laboratory also forevaluating theingredients going intothejam.
Forexample, check thesoluble solids andacid inrepresentative samples offruit
9

todetermine theamount ofsugar andacidtoinclude intheformula forabatch
ofjam.Seymour (7)suggests thatsmall-batch testjamsbeprepared inthecontrol
laboratory when youstart touseanewsupply offruit, orwhen youusefruit
thathasbeen stored foralong time.Hehasfound thatexperience gained from
these small-scale tests helps reduce waste oftimeandmaterials intheplant.
Itisbeyond thescope ofthispublication togointo details ofanalytical
methods. Theprocedures, chemicals andequipment forsugar determinations are
fullycovered inOfficial andTentative Methods ofAnalysis (1)andinthelaboratory
manual byRuck (6).Arapid method ofsugar analysis (8)developed atthe
Summerland laboratory isadaptable tojams. Ifyoucarry outtheprocedure as
outlined, itgives results asaccurate asthose obtained bythemore complicated
andtime-consuming official methods.
Inaddition toroutine laboratory equipment forsugar analysis thefollowing
willaidconsiderably incontrol work:
(1)Refract ometers (Figures 2and 3).Useadirect sugar-reading typewith
ascale calibrated toread 0.2percent between 60and80percent soluble solids.
Although notessential, asecond refractometer covering thesugar range ofthe
fruits tobeused ishelpful.
(2)pHmeter—battery operated orelectric.
(3)Spreadmeter (Figure 4).This isaplexiglass plate engraved with a
series ofconcentric circles. Thejamsample isreleased ontothecenter oftheplate
Figure 2.—Sugar refractometer fordetermining solids, range 0-95
percent.
10

Figure 3.—Hand refTactometer, range0-80 percent soluble solids.
Figure 4.—Spreadmeter forevaluating theconsistency orsetofafinished jam.
11

bycareful removal ofboth topandbottom ofthecontainer. Thespread, after 5
minutes, isread ateight points ontheplateandtheresults areaveraged. The
useofthisinstrument islimited totincontainers.
PROCESSING EQUIPMENT
Processing equipment forthree types ofplants isdiscussed under the fol-
lowing headings:
•Thesmall plant—possibly forspecialties.
•The large, manually operated plant—withsome mechanical oper-
ations.
•The large, mechanized plant—withfewmanual operations.
TheSmall Plant
Kettles
Usually asmall plant has: (a)oneormore stainless-steel5
,double-jacketed,
steam kettles (Figure 5)operated byasmall oil-orgas-fired steam boiler, or
(6)several small, gas-fired kettles. Oneplant thatconcentrates onspecialty packs
uses b,each kettle providing 8pounds offinished jamperbatch.
5Stainless steeldoesnotcorrode ascopper doesbut ithasaslower heating rate.Consequently
some English kettles aremade ofstainless steel except fortheheating area, which iscopper.
Nickel hasafaster heating ratethan stainless steelbut ismore expensive.
Figure 5.—Stainless-steel kettles maybeobtained innumerous sizes.
12

Holding Tank
Aseachbatch ofjam isfinished itispumped totheholding tank.Thetank
should have amechanical agitator andbeeasy toclean. Inonewith ajacket
(Figure 6),jamcanbeeither heated orcooled. Thiscomes inhandy ifthe filling
linebreaks down, asunfinished jamcanbeputintothetankandheld atthe
proper temperature; ifleftinthekettles thejammight become overcooked.
Figure 6.—Holding tank with facilities forheating, cooling or
agitating thejambefore filling.
Fillers andCappers
From theholding tank thejamflowsbygravity tothe filler.Amultiple-
cylinder filler (Figure 7)isthebestkind asitiseasily adjusted fordifferent sizes
andtypes ofcontainers. Jarsarecapped either byhand orbypower.Amanual
capper withsteam forvacuum sealing isillustrated inFigure 8.
Capped containers arewashed withwarm water and lefttocoolontables
before labeling andcasing. Itisadvisable tospace thejarsfrom onehalftoone
inchapart tofacilitate cooling.
The Large, Manually Operated Plant
Kettles
This type ofplant hasseveral stainless-steel, steam-jacketed kettles but
most operations aremanual. Drysugar isweighed andadded byhand. Fruit or
fruitpulpmaybeadded byhand orpumped in(Figure 9).
The kettles areusually about 24inches indiameter and 19inches deep
(inside measure), largeenough tohold 125to150pounds offinished jam.They
13

Figure 8.—Manual capper.
14

Figure 9.—Several open keftles. Sugar being added byhand.
Figure 10.—Water-jacketed cooling pans.
15

maybeonabalcony, sothatthejamflowsdown tothecooling and filling equip-
ment below, oronthemain floor, where thejam ispumped from onepiece of
equipment toanother. Acommon plan isforthejamtoflowfrom thekettle to
aflatcooling panjacketed with coldwater (Figure 10).
Fillers andCappers
Asuitable filler, handling 2-and4-pound cans besides thevarious sizes of
glass containers, isshown inFigure 11.From the fillers cansgototheclosing
machines, glass jars toautomatic screw-top cappers andtumblers tocrimp
cappers. Forlarge-capacity lines handling glass, thesteam-vacuum, screw-top
capper illustrated inFigure 12isvery satisfactory.
Figure 11.—Large capacity jam filler.
Coolers
After capping, thejammust becooled toretain quality. Usually inthis
type ofplant afinewater mist issprayed onthecontainers asthey areconveyed
tothelabeling machines. Conveyors should notagitate ajammade with rapid-set
pectin. Long single-belt coolers, roll-through andwalking-beam coolers are all
used (Figures 13and 14).
Labelers
Glass containers, after cooling, dryrapidly andgodirectly tothespot-
labeling machine. Cans, because oftheir larger size,take longer todryandmay
beplaced onatable before going toawrap-around labeler andthen toacasing
machine.
16

Figure 12.—Steam-vacuum closing machine forscrew-top caps forplants of
large capacity.
Figure 13.—Roll-through cancoo/er.
17

Figure 14.—Walking -beam unitforcooling jam.
TheLarge, Mechanized Plant
Although theequipment inanautomatic jam linemaybearranged inseveral
ways, thatshown inFigure 15istypical.
Kettles
Ifopen kettles areusedyouneed atleast 12units, each largeenough tohold
a200-pound mixthat finishes to160pounds. Ifvacuum kettles areused, larger
batches canbemade.Asatisfactory arrangement would befour kettles holding
500-pound mixes ortwokettles holding 2,500-pound mixes.
Inbothmethods thefruitpulp ispumped inanddrysugar6orsugar syrup
isautomatically delivered (ormetered) tothekettles. Onemanadds special
ingredients such aspectin andacid toseveral kettles.
Delivery offruit pulp.—Fruit pulp isheld inatank serving thebattery of
kettles and isagitated constantly. Thepulp flowsbygravity toapositive dis-
placement pump (Figure 16)with avariable speed drive andtiming relay; the
jammaker merely presses abutton tohave therightamount ofpulp delivered
toakettle. Delivery isthrough sanitary piping thathasonevalve andaswinging
discharge pipeperpair ofkettles.
6Bulk drysugar isfairly expensive tohandle. Before installing anyspecial equipment for it,
besurethatthepotential savings ontheamount ofsugar used arelargeenough tomake thisa
sound investment. Even where drysugar istheonly sugar available inbulk,many operators
prefer tomake itintoaheavy hotsyrup tospeed up"cooks".
IntheVancouver, B.C., area, sugar-refinery tank trucks deliver bulkdrysugar in30-ton
loads contained inthree 10-ton compartments. Forunloading, thetruck hasaspecial fanand
motor that elevates thesugar tostorage binshighenough forgravity feed.
18

1 2 3
Figure 15.—Equipment foranautomatic jam line. 1.Vacuum oropen kettle. 2.Holding tank. 3.Jampump. 4.In-
spection table. 5.Filler. 6.Glass capper. 7.Two-pound closing machine. 8Four-pound closing machine. 9.Flat-top
chain conveyor. 10.Roll-through cooler. 11.Walking-beam cooler forglassand tin.12.Coo/er recirculating pumps.
13.Blower. 14.Drier. 15.Roll-through labeler forcans. 16.Spot labeler forglass. 17.2-pound cancasing machine.
18.4-pound cancasing machine. 19.Converging conveyor. 20.Case-sealing machine.
19

Figure 16.—No.725DOWaukesha pump.
Figure 17.—Stainless-steel vacuum kettle.
20

Vacuum kettles.—Vacuum kettles inthelarge operation aresimilar totheone
inFigure 17.Thejacket isconstructed sothat either steam orcooling water can
beturned into it.Avacuum-breaker valve onthehead ofthepan isnecessary
sothat ingredients, such aspectin and acid, canbeadded near theendofthe
boil. Intake and outlet valves areonthebottom. Through theintake valve,
fruit, juiceandsugar aresucked byvacuum from thedissolving kettle intothe
pan.Todischarge thejamthrough theoutlet valve, livesteam orsterile air
under pressure isinjected intothepanthrough thevalves above thelevel ofthe
cooked batch.
Cook end-point controllers.—Intheopen-kettle method, end-point controllers
feedthesteam toadouble-jacketed kettle through wide-open, three-way valves
until thejamreaches thedesired temperature. Atthispoint thecontroller auto-
matically shuts offthesteam, opens thethird port inthevalve and"blows down"
orreleases anyinternal pressure onthekettle.
Automatic kettle discharge.—Ifholding tanks arelargeenough tohandle the
jam,equipment forautomatic discharge maybeinstalled onkettles.Agatevalve,
operated byadiaphragm motor, isplaced onthedischarge ofthekettle. Assoon
asthefinishing point isreached, thevalve opens todischarge thebatch. The
jamthen flows either bygravity totheholding tank orintoapositive displace-
mentpump that delivers ittothetank.Attheendofapractical holding cycle
fordischarging, thegatevalve closes automatically.
Holding Tanks
U-shaped holding tanks, liketheoneinFigure 6,arerecommended. This
tank hasanagitator consisting ofpaddles that constantly wipe thesidesand
bottom clean. Theheat transfer isgood asnewjam iscontinually incontact
with themetal ofthetank.
Inspection Tables
Before itreaches the filler thejamshould bechecked forvisible foreign
material. Anilluminated tablemade from asheet offiberglass (Figure 18),with
Figure 78.—
Inspection table with illuminated fiberglass bottom forinspecting jam.
21

thejamflowing over it,simplifies theinspection jobandmakes iteasy toremove
undesirable pieces.
Fillers
Itissuggested thatthejam lineinlarge plants besplit atthispoint, sothat
onelinetakes care of2-pound cansandtheother 4-pound cans.Apiston-type
filler (Figure 11),with acapacity of80to90pounds perminute, isrecommended.
Coolers
Design andnumber ofcoolers depend ontype ofcontainer, space available
andtemperature desired inthefinished product. Enough cooling units should be
installed forthetemperature ofthejamtobelowered toatleast 90°F.before
casing, toavoid stack burnanddarkening oftheproduct.
Aroll-through cooler (Figure 13)efficiently lowers thetemperature ofhot-
filledjam in2-and4-pound cans to140° F.Thistype ofcooler should notbe
used forjammade with rapid-set pectin asitmay disturb the set,andgivea
runny jam. Also,jampacked inglass containers should notbeputthrough a
roll-through cooler because breakage istoohigh. Forboth ofthese products a
walking-beam cooling unit(Figure 14) isrecommended.
Container Driers, Labelers, Casers andCase Sealers
When thecontainers leave thewalking-beam, theymust bedrysothat
labels canbeapplied. Onekind ofdrier that isvery efficient isinstalled nearthe
exitofthecooling units.Thedrier provides alargevolume ofairintwostreams—
onevertical andtheother atanangle. Itdries offjarsthoroughly butmaynot
remove allwater from thelidsofcans. However, anywater onthelids rolls off
when thecans areturned ontheir sides forlabeling. After labeling, thecontainers
arepacked incartons. From thecaser thecartons areconveyed tothecase
sealer andaccumulated attheendofthelinetoform fullpallet loads.
FORMULAS
Formula Calculations
Tocalculate thetheoretical output (yield) ofacorrectly composed formula
youshould know thesoluble solids content ofalltheingredients going intothe
jam.However, inpractice youcanneglect those contributed bytheacidand
pectin asthey areusually lessthan 1percent ofthefinished weight ofthejam.
Sugar Requirements
Todetermine theamount ofsugar required forabatch ofjam,youmust
know thesoluble solids content ofthefruit. This isbestdonebytaking arefrac-
tometer reading ontheexpressed juice ofthefruit itself. However, ifyouare
using frozen fruit containing added sugar, this isnotconvenient andanaverage
value taken from tables offruitcomposition willhave tobeused.
Suppose youwish tomake a100-pound batch ofjamfrom fresh fruit using
theopen-kettle method. Thejam istobefinished to68percent total soluble
solids andcontain 50percent fruit.Thesugar youneedmaybecalculated as
follows:
Example 1
Soluble solids offruitbyrefractometer 13 percent
Total soluble solids desired per100pounds ofjam 68.0pounds
Soluble solids in50pounds offruit at13percent 6 .5pounds
Amount ofsugar needed 61.5pounds
22

When youcook thismixture of61.5pounds ofsugar and50pounds offruit
toafinishing temperature 10.2° F.above theboiling point ofwater, thejam will
weigh 100pounds. Itwillcontain 50percent fruitandhave atotal soluble solids
content of68percent.
AcidRequirements
Todetermine theamount ofacidrequired inajam,takea1-pound, repre-
sentative sample offruitandrun itthrough ameat grinder, ormix itwell ina
Waring blendor. Addabout 10percent water, mixthoroughly and titrate with
astandard acid solution (citric ifitistobeused intheactual process) tothe
desired pH.Thisshould beabout 0.1pHlower (more acid) than required inthe
finished jamasitwillincrease bythisamount during theboil.
Prepare astandard citric acid solution bydissolving 2ounces ofcitric acid
crystals inpurewater andmaking itupto100milliliters. Each millileter ofthis
solution contains 0.02ounces ofcitric acid.
Ifa1-pound sample ofyour fruit required 8.8ml.ofthestandard citric acid
solution tolower thepHto3.1,determine theamount ofpowdered citric acid
required by50pounds offruit asfollows:
Example 2
1pound offruit requires 8.8ml.ofstandard solution.
Now, 1ml.ofstandard solution contains 0.02ounces ofcitric acid.
88Therefore, 1pound offruit requires —j—X.02=0.176 ounces ofcitric acid.
Thus, 50pounds offruit require 50X.176=8.8ounces ofpowdered citric acid.
Pectin Requirements
Thebestway todetermine pectin requirements ofajam isbypreparing
small testboils inthecontrol laboratory. Suppose thatthefruityouareusing is
fresh Blenheim apricots tobeprocessed bytheopen-kettle method. You will
note, from theapricot jamformula (page 25),thata200-pound batch ofjam
made from thisvariety offruitbytheopen-kettle process requires 3ounces of
pectin. Thus, a100-pound batch would require 1.5ounces ofpectin, and if
your testbatch istobefinished to5pounds tryadding (5/200X3)or.075
ounces ofpectin.
TheTestBatch
Youarenowready toproceed with theassembling ofingredients andactual
cooking ofthetestbatch. Prepare amix,using theingredients intheproportions
togiveajam of5pounds finished weight. Your testformula isasfollows:
Weight per Weight per
Ingredient 100-pound batch 5-pound batch
Water 5pounds .25pounds
Fruit 50pounds 2 .50pounds
Sugar 61.5pounds 3 .08pounds
Acid 8.8ounces .44ounces
Pectin 1.5ounces .075ounces
Finished weight 100 pounds 5 pounds
Carry outtheprocess outlined foropen-kettle jam(page 7).About 12hours
after processing, examine thetestjamorganoleptically andcarry outacomplete
chemical analysis. Ifthejam issatisfactory, convert theingredients toamounts
necessary forfactory-size batches; ifunsatisfactory, continue experimentation on
asmall scale.
23

Reducing theFruit Content
Ifyoureduce thefruit content ofajam, first, calculate thesugar andacid
required (Examples 1and 2)onthereduced fruit basis.You will, also,have to
usemore pectin. Forexample, ifyouareusing aformula containing 50percent
fruitandreduce thefruit content to45percent, tryatestbatch containing at
least50/45 oftheamount ofpectin stipulated intheformula.
Using Frozen Fruit
When using sugar-packed frozen fruit,you willhave tomake allowances for
thesugarwhen composing aformula. Forexample, ifyour fruit isfrozen apricots
(4-f-1),withevery 5pounds ofmixyouareadding 4pounds offruitand 1pound
ofsugar. Ifthesoluble solids ofthefruit is13percent, altertheformula appearing
onpage 23asfollows:
Weight per
Ingredients 100-pound batch
Water 5pounds
Fruit(4+ 1)
62 .5pounds (50pounds offruit+12.5pounds of
sugar)
Sugar 49pounds (61.5-12.5)
Acid 8.8ounces
Pectin 1.5ounces
Adjusting theSugar Ratio
Suppose youwish toraise theinvert-sugar (reducing-sugar) content ofyour
jamfrom 15to25percent. Todothistheingoing weight ofsucrose sugar must
bedecreased andthat ofinvert increased 10percent. Astheinvert-sugar solution
contains 30percent water, reduce thequantity ofwater added atthestart ofthe
boilbythisamount. Your apricot jamformula willnowappear asfollows:
Weight per
Ingredients 100-pound batch
Water 5-(30/100 X8.8) 2.36pounds
Fruit 50 pounds
Sugar (sucrose) 61.5—6.15 55.35 pounds
Sugar (70percent invert) 100/70X6.15 8 .8pounds
Acid 8 .8ounces
Pectin 1.5ounces
Tested JamFormulas
Alljamsmade from formulas given inthispublication (pages 25to28)
have been thoroughly tested, both chemically and organoleptically, andhave
stored well foratleast 12months at70°F.Their fruit content, strawberry 55
percent and allothers 50percent, ishigher than theminimum specified ingovern-
ment regulations. For thisreason ajammaker, unless putting upaspecialty
pack, should usethese formulas chiefly asabasis fordeveloping formulas ofhis
own.
Theformulas areself-explanatory butcomments onsome ofthespecific
itemsmaybehelpful. "Soluble solids offruit" istherefractometer reading on
theexpressed juice ofablended representative sample offruit actually used inthe
batch. Pectin is100-grade rapid-set, powdered citrus pectin. Itwasadded asa
solution prepared aspreviously outlined using sugar andwater withheld from the
batch forthispurpose. Acidandsucrose sugar were alsoadded inthedrystate.
Where invert sugar wasused itwasadded inliquid form asa70percent solution
andwasnotneutralized.
24

Apricot Jam
(50percent fruit)
Water
Fruit (soluble solids 13.0percent)
Pectin7(100grade, rapid set)
Sugar8
Acid
Yield (approx.)
Analytical Specifications
Soluble solids ofjam
Reducing sugar
PH18pounds
100pounds
0-8.5 ounces
123pounds
7-26ounces
200pounds
68.0 percent
22-28 percent
3.30-3.32
Black Currant Jam
(50percent fruit)
Water
Fruit (soluble solids 11.7percent)
Pectin9(100 grade, rapid set)
Sugar10
Acid
Yield (approx.)
Analytical Specifications
Soluble solids ofjam
Reducing sugar
pH20pounds
100pounds
0-21 ounces
124pounds
200pounds
68.0 percent
22-44 percent
2.93-3.03
Black Currant-Prune Jam
(50percent fruit)
Water
Black currants (soluble solids 11.7percent)
Italian prunes (soluble solids 20.4percent)
Pectin11(100 grade, rapid set)
Sugar12
Acid
Yield (approx.)
Analytical Specifications
Soluble solids ofjam
Reducing sugar
pH20pounds
50pounds
50pounds
4-10.6 ounces
120pounds
200pounds
68.0 percent
20-36 percent
3.2-3.23
7Moorparks required nopectin foropen-kettle jamsandabout 2ounces per100pounds of
fruit forvacuum jams. Blenheims required about 3ounces foropen-kettle jamsand6ounces for
vacuum jam.
875to100percent inopen-kettle and70to80percent invacuum jams should besucrose, the
balance "70" invert.
9Use little ornopectin inopen-kettle jamsandupto21ounces invacuum jams.
10Noinvert sugar required.
"Use thesmaller amount inopen-kettle jamsandthelarger invacuum jams.
12Noinvert sugar required.
25

Sweet Cherry Jam
(50percent fruit)
Water
Fruit (soluble solids 17.7percent)
Pectin13(100 grade, rapid set)
Sugar14
Acid
Yield (approx.)
Analytical Specifications
Soluble solids ofjam
Reducing sugar
PH20pounds
100pounds
5.6-8.5 ounces
136pounds
11-13 ounces
200pounds
68.0 percent
28.0 percent
3.56
Sweet Cherry-Black Currant Jam
(50percent fruit)
Water
Sweet cherries (soluble solids 17.7percent)
Black currants (soluble solids 11.7percent)
Pectin (100grade, rapid set)
Sugar15
Acid
Yield (approx.)
Analytical Specifications
Soluble solids ofjam
Reducing sugar
PH20pounds
76pounds
24pounds
5 .6ounces
120pounds
4ounces
200pounds
68.0 percent
21-26 percent
3.42-3.58
SourCherry Jam
(50percent fruit)
Water
Fruit (soluble solids 14.5percent)
Pectin (100 grade, rapid set)
Sugar16
Acid
Yield (approx.)
Analytical Specifications
Soluble solids ofjam
Reducing sugar
pH20pounds
100pounds
14ounces
122pounds
4.2ounces
200pounds
68.0 percent
28.0 percent
3.33-3.38
13Useslightly more pectin invacuum jams togivesame setasinopen-kettle jams.
i4,is,i6Add sucroseonly.
26

PeachJam
(50percent fruit)
Water 20pounds
Fruit (soluble solids 11.2percent) 100pounds
Pectin17(100 grade, rapid set) 8-12.5 ounces
Sugar18125pounds
Acid 7.4ounces
Yield (approx.) 200pounds
Analytical Specifications
Soluble solids ofjam 68.0 percent
Reducing sugar 23-26 percent
pH 3.30-3.35
Italian Prune PlumJam
(50percent fruit)
Water 20pounds
Fruit (soluble solids 20.4percent) 100pounds
Pectin19(100grade, rapid set) 7-9ounces
Sugar20136pounds
Acid 5 .6ounces
Yield (approx.) 200pounds
Analytical Specifications
Soluble solids ofjam 68.0 percent
Reducing sugar 23-27 percent
pH 3.41-3.45
Raspberry Jam
(50percent fruit)
Water 16pounds
Fruit (soluble solids 7.5percent) 100pounds
Pectin21(100 grade, rapid set) 4.2-8.4 ounces
Sugar22128pounds
Acid
Yield (approx.) 200pounds
Analytical Specifications
Soluble solids ofjam 68.0 percent
Reducing sugar 20-36 percent
pH 3.22
17Useslightly more pectin invacuum jams togivesame setasinopen-kettle jams.
1885percent inopen-kettle and70percent invacuum jams should besucrose, thebalance
'70" invert.
19Usesmaller amount inopen-kettle jamsandthelarger invacuum jams.
2086percent inopen-kettle jamsand70-75 percent invacuum jams should besucrose, the
balance "70" invert.
^Satisfactory setswerenotobtained onvacuum jams(pH3.22) with 4.2ounces ofpectin or
vacuum jams(pH3.12) withupto16.8ounces.
22Noinvert sugar required. IfCaC0 3isadded toraisepHofjamto3.3,probably invert
should beadded.
27

Strawberry Jam
(55percent fruit)
Water 32pounds
Fruit (soluble solids 7.8percent) 100pounds
Pectin23(100grade, rapid set) 3.5-5 ounces
Sugar24116pounds
Acid " 4.2ounces
Yield (approx.) 200pounds
Analytical Specifications
Soluble solids ofjam 68.0 percent
Reducing sugar 21-32 percent
pH 3.28-3.32
ACKNOWLEDGMENTS
Thekind cooperation ofthefollowing insupplying information and illus-
trations isgratefully acknowledged :Mr.W.R.Tutton, American CanCompany
ofCanada Ltd. ;Mr.W.Blankenbach, B.C.Sugar Refinery Ltd. ;Mr.A.S.Ellett,
Ellett Copper &BrassCompany Ltd.; Mr.Spence McNeill, Empress Manu-
facturing Company Ltd.; Mr.John Acheson, Continental CanCompany of
Canada Ltd. ;Canners Machinery Company Ltd.,andChisholm-Ryder Company
Ltd.
Special thanks areextended toMr.Thomas W.MacKay, T.W.MacKay
&SonLtd.,whoprovided many illustrations andmuch oftheinformation on
processing equipment.
REFERENCES
1.Association ofOfficial Agricultural Chemists. Official andtentative methods
ofanalysis. 8thed.Washington, D.C. 1955. 1008 p.
2.Canada Department ofAgriculture, Fruit andVegetable Marketing Service.
TheMeat andCanned Foods Act.Ottawa. 1954.
3.Canada Department ofNational Health andWelfare. TheFood andDrugs
ActandRegulations. Ottawa. 1954.
4.Larsen, H.Jamproduction—consistency —how todissolve pectin properly.
Food Technology inAustralia 11(3) :111. 1959.
5.Rauch, G.H.Jammanufacture. 1sted.Leonard HillLtd.,London, England.
1950. 201 p.
6.Ruck, J.A.Chemical methods foranalysis offruitandvegetable products.
Canada Department ofAgriculture Publication 1154. Inpress.
7.Seymour, J.D.Control ofpectin injammaking important. Food inCanada
17(8) :17.1957.
8.Strachan, C.C,and J.A.Kitson. Rapid method ofsugar analysis forcontrol
purposes. Canadian Food Industries 27(11) :22.1956.
9.Sunkist Growers Inc.Preservers handbook. 6thed.Ontario, California. 1954.
146p.
23Usevery slightly more pectin invacuum jams togivesame setasinopen-kettle jams.
24Addsucrose only.
28

CAL/BCA OTTAWA K1A0C5
3907300185083 5

Copies ofthispublication maybeobtained from :
INFORMATION DIVISION
CANADA DEPARTM ENTOFAGRICULTURE
Ottawa
ROGER DUHAMEL, F.R.S.C.
QUEEN'S PRINTER ANDCONTROLLER OFSTATIONERY
OTTAWA, 1962
4M-—29369—10:62 Cat.No.A73-1144