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Anita Kruger time@mfm.sun.ac.za 072 5454 959 FOOD CHEMISTRY 3 FCHE30 FACULTY OF SCIENCE Department of Horticulture & Food Technology SEMESTER 2 MODULE 4 Other Carbohydrate Gels CARBOHYDRATES Monosaccharides Polysaccardies & Oligosaccharides Storage Carbohydrate – Animals

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anita kruger

Anita Kruger

time@mfm.sun.ac.za

072 5454 959

food chemistry 3 fche30

FOOD CHEMISTRY 3FCHE30

FACULTY OF SCIENCE

Department of Horticulture & Food Technology

SEMESTER 2

MODULE 4

Other Carbohydrate Gels

carbohydrates
CARBOHYDRATES
  • Monosaccharides
  • Polysaccardies & Oligosaccharides
  • Storage Carbohydrate – Animals
    • Glycogen (from Glucose)
  • Storage Carbohydrate – Plants
    • Starch
  • Structural Polysaccharide – Plants
    • Cellulose
      • Gums
pectin substances plant gums
Pectin Substances-Plant Gums
  • Heteropolysaccharides
  • “Hydrocolloid” – water-binder
    • Hydrophillic colloid: imbinding large quatities of water
  • Fill intercellular spaces, middel lamella of plant tissue
    • Wide channels in young fruit tissue
pectin substances plant gums5
Pectin Substances-Plant Gums
  • Plant cell wall showing Pectin
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Pectin Substances-Plant Gums
  • Role of Pectin in Plant Tissue (fruits)
    • In outer cell walls, closely associated with cellulose – precursor of pectin: Protopectin
    • Absorb water and transfer it among cells
    • Responsible for firmness, texture (fruits & veggies)
    • Softening during ripening
    • Breakdown of colloidal stability in fruit juices
pectin substances plant gums8
Pectin Substances-Plant Gums
  • Change in pectin substances during ripening
    • Protopectin in middle lamella between cell walls soluble pectin
      • Reduce cell wall thickness
      • Softening & Ripening
        • Decrease the degree of esterification of carboxyl groups with methyl alcohol
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Pectin Substances-Plant Gums

Pectin is a polymer of α-Galacturonic acid with a variable number of methyl ester groups.

  • Methylated ester of Polygalacturonic acid
  • Chains of 300 to 1000 glalacturonic acid units
  • Joined with 1α→4 linkages
  • This structure shown here is three methyl ester forms (-COOCH3) for every two carboxyl groups (-COOH)
  • hence it is has a 60% degree of esterification, normally called a DE-60 pectin
pectin substances plant gums10
Pectin Substances-Plant Gums
  • Transformation of Protopectin to Pectin
    • Pectin-rich Plant Materials (Pomace, Citrus)
    • Heated with acidified water - Hydrolyzed
    • Protopectin (cellulose) form water soluble pectin (Same transformation during ripe fruit)
    • Precipitated form aqueos solutions by alcohol/acetone as jelly-like coagulum, which dissolve in water (water soluble)
    • Pectin = Negatively charged colloid/electrolite
    • Commercial pectin contains a number of impurities: hemicelluloses, pentosans, galactoses
    • Can be purified by repeated precipitation and redissolution (more later…)
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Pectin Substances-Plant Gums
  • General Structure
    • Long, “unbranced” chains of polygalacturonic acid, with carboxyl groups partially esterfied with methyl alcohol - Heteropolysaccharides
    • High molecular masses (20 000 – over 400 000)
    • Joined by a-1,4 glycosidic bonds
    • Gums have acid groups as well as hydroxyl groups and long-chain structures = Good emulsifier
      • Acidic goups act as strongly hydrophilic portion of molecule
      • Rest of molecule in the chain act as less hydrophilic portion (almost hydrophobic)
pectin substances plant gums12
Pectin Substances-Plant Gums
  • Guar Gum / Locust Bean Gum
    • Polysaccharide: Galactomannans
    • Structure: Galactose-phosphate and galacomannan groups
    • Guar gum (legume)
      • is the ground endosperm of seed from the guar plant (similar to soybean)
      • Molecular mass: 220 000
      • Not able to bond easily with proteins/other polysaccharides
      • Form gels at 2 – 3% concentration
      • Five to eight times the thickening of starch
      • Many uses in pharmaceutical industry
        • food stabilizer/source of dietary fiber
pectin substances plant gums13
Pectin Substances-Plant Gums
  • Approximately 85% of guar gum is guaran
  • water soluble polysaccharide consisting of linear chains of mannose with 1β→4 linkages to which galactose units are attached with 1α→6 linkages
  • The ratio of galactose to mannose is 1:2

Guaran is the principal polysaccharide in guar gum.

pectin substances plant gums14
Pectin Substances-Plant Gums
  • Locust Bean
    • Derived from the seed endosperm of carob trees
    • Form pliable gums
  • Both consist mostly of galactomannans
  • Cold water soluble
  • USES
    • Salad dressings
    • Ice-cream
    • Baked goods (stabilizing and water retention)
pectin substances plant gums15
Pectin Substances-Plant Gums
  • Agar / Carrageenans
    • Agar
      • extracted form seaweed
      • polymer of agarobiose, a disaccharide composed of D-galactose and 3,6-anhydro-L-galactose.
      • Consists mainly of galactose
      • Uses: Solid medium in microbiological applications, culturing bacteria, cellular tissue and DNA fingerprinting
      • Potent gel former
      • Forms gel at about 0.04%
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Pectin Substances-Plant Gums
  • Carrageenan
    • Extracted from seaweed
    • Differs from agar in that they have sulfate groups
    • (-OSO3-) in place of some hydroxyl groups
    • Complex sulphated galactan
    • Negatively charged on sulphate group
    • Form gels of varying viscosity based on Ca++ or K+
    • Can interact with protein due to ionic bonding
    • Uses: Stabilizers, thickener in instant puddings and desserts
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Pectin Substances-Plant Gums
  • Changes in structure during hydolysis
    • Undergo hydrolysis by acid or alkali or suitable enzymes (alkaline hydrolysis)
    • First step: Removal of number of methoxyl groups
      • Leaving ultimately polygalacturonic acid
      • Called pectic acid – completely free of methoxyl groups
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Pectin Substances-Plant Gums
  • Extraction of Pectin
    • Mainly form apple and citrus peels
    • Soak in warm water
      • Remove colloidel material, carbohydrates, acid and other water soluble inpurities
    • Rest of material are dried
      • Until moisture content of ca 10%
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Pectin Substances-Plant Gums
  • Extraction
    • Water:moist peel – 3:1
    • Water:dry peel – 30:1
    • Water:peel acidified until pH 1,3 and pH1,4
      • 1 hour at 90°C - 100°C (longer at 60°C)
    • Increase pH to pH 4,5 using Na2CO3
    • Press the mixture
    • Extraxt is filtered with EtOH/acetone/AlCl3
    • Pectin is floccultaed out of mixture
    • Neutralize mixture with Na2CO3 or NH4OH
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Pectin Substances-Plant Gums
  • Extraction…
    • Metal salts are removed from the presipitate later through acidified EtOH
    • Pectin is further purified by dissolving it in water and presipitating with EtOH until the product is pure
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Pectin Substances-Plant Gums
  • Marketing of Commercial Pectin
    • Available in the pure state
    • Characterized according to
      • 1. Jellying power (grade)
        • Increases with increasing molecular weight
      • 2. Degree of methoxylation
        • High methoxyl or low methoxyl pectins
        • Determines the mechanism of gel formation
      • 3. Rate of solidification of the jellies
        • Rapid/medium/slow set pectins
        • Rate and temperature of setting is also governed by the extend of esterification
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Pectin Substances-Plant Gums
  • Rapid pectins: higher degree of methoxylation
  • At equal degrees of esterification, pectins with a higher degree of polymerization require shorter setting times.
pectin substances plant gums24
Pectin Substances-Plant Gums
  • 1. Jellying Power – Pectin GRADES
    • Number of parts of sugar required to gel one part of pectin to acceptable firmness

OR

    • Number of parts of sugar that can be gelled by 1 part of pectin under standard conditions
    • Usual conditions (Standard conditions)
      • pH 3.2 – 3.5
      • Sugar 65 – 70%
      • Pectin 0.2 – 1.5%
    • Commercial grades: vary from 100 – 500
    • Gels of different firmnesses can be formed by playing around with the pectin:sugar:acid ratio
slide25
1. Jellying Power – Pectin GRADES…
    • Example: If you require a minimum of 0.1 g of pectin to 65% sugar and at a pH of 3.2 the pectin grade for that would be 650
      • 0.1 x 10 = 1 = 1 part of pectin
      • 65 x 10 = 650 = pectin grade
    • Factors contributing to the gelling properties of pectin
      • Chain length
      • Degree of methoxylation
      • pH
      • Sugar content
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Pectin Substances-Plant Gums
  • 2. Degree of Methoxylation
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Pectin Substances-Plant Gums
  • Pectin as extracted normally has more than 50% of the acid units esterified, and is classified as "high methyl ester (HM) pectin".

HM pectin formula

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Pectin Substances-Plant Gums
  • Modification of the extraction process, or continued acid treatment, will yield a "low methyl ester LM) pectin" with less than 50% methyl ester groups.

LM pectin formula

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Pectin Substances-Plant Gums
  • 3. Rate of solidification of the jellies
    • Rapid-set pectin
      • Degree of methoxylation over 70%
      • Forms gels with sugar and acid at optimum pH 3.0 – 3.4
      • Begins at 85ºC
      • Gel strenghts depend on molecular weight
        • The higher the molecular weight, the firmer the gel
        • Gel strength is not influenced by degree of methoxylation
      • Used in manufacturing of preserves in order to prevent whole fruit or chunks settling to the bottom or rising to the top of the jar, instead of being evenly distributed throughout the jam
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Pectin Substances-Plant Gums
  • Slow-set pectin
    • Degree of methoxylation 50 – 70%
    • Forms gels with sugar and acid at an optimum pH 2.8 – 3.2 and at lower temperatures than rapid-set pectin
    • Forms jelly below 55ºC
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Pectin Substances-Plant Gums
  • Uses of Pectin in Food Manufacturing
    • Jams, jellies, marmalades and preserves
    • Dehydrating agent must be present for pectin to form a gel
      • Typical dehydrating agents used for precipitation of pectin are alcohol or acetone
      • In jams and jellies it is the sugar that plays the dehydrating role
      • In forming a good jelly, suitable pectin-acid-sugar ratio should be maintained
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Pectin Substances-Plant Gums
  • Syneresis – “weeping”
    • If the pH drop lower than 3, you will find that the gel becomes firmer and may even exhibit syneresis.
    • Water is expelled from the gel
    • Common in Fruit Jellies
    • See syrup forms on the jelly after a couple of months in storage
    • Factors contributing to Syneresis
      • Low pH (too much citric acid added) leads to degrading of the pectin netwok – water cannot hold gel structure efficiently anymore
      • Excess water (low TSS)
      • Not enough pectin
pectin substances plant gums33
Pectin Substances-Plant Gums
  • Pectolytic Enzymes
    • Pectin enzymes are capable of degrading pectic substances
    • Commercially important for the treatment of fruit juices/beverages
      • To aid in filtration/clarification/increasing yields
    • Pectolytic Enzymes have to be added during production of most fruit juices and veggie soups
    • Also used for the production of galacturonic acids
    • Presence of pectic enzymes in fruit/veggies can result in excessive softening
    • Pectins may also cause “cloud” separation in tomato and fruit juices
pectin substances plant gums34
Pectin Substances-Plant Gums
  • Commercial Uses
    • Clarification of fruit juices/wines
    • Aiding the disintegration of fruit pulps
    • By reducing the large pectin molecules into smaller units, and eventually into galacturonic acid – compound become water soluble – loses their suspending power
    • Viscosity is reduced
    • Insoluble pulp particles rapidly settle out
pectin substances plant gums35
Pectin Substances-Plant Gums
  • Pectic enzymes
    • Most microorganisms produce at least one pectic enzyme
    • Almost all fungi and many bacteria produce these enzymes
      • Which readily degrade the pectin layers holding plant cells together
      • Leads to separation and degradation of the cells – plant tissue becomes soft
    • Bacterial degradation of pectin in plant tissues is responsible for the spoilage known as “soft rot” in fruits/veggies
pectin substances plant gums36
Pectin Substances-Plant Gums
  • Pectinesterase (PE)
    • (or Pectin Pectyl-Hydrolase)
    • Found in bacteria, fungi, higher plants
    • Large amounts in citrus fruits & tomatoes
    • PE catalyzes the hydrolytic removal of the methoxyl groups (saponification) from the pectin molecule (methylgalacturonic acid)
    • Requires the presence of a free carboxyl group next to the methoxyl group to be saponified
    • Optimum activity at pH 7.5
    • Methoxyl group may be released as methanol
      • Could be considered a toxic by-product
    • Reaction is catalyzed by pectin esterase
    • PE is specific for galacturonide esters, will not attack nongalacturonide methyl esters to any large extent
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Pectin Substances-Plant Gums
  • HTST (high temperature short time) pasteurization is used to deactivate pectolytic enzymes and maintain cloud stability in fruit juices
  • Pectin is a protective colloid that helps keep insoluble particles in suspension
  • Cloudiness is required in commercial products – provide desirable appearance
  • Destruction of high levels of pectinesterase during production of tomato juice/puree is of vital importance.
  • Pectinesterase will act quite rapidly once the tomato is broken
  • HOT-BREAK method: the tomatoes are broken up at high temperature so that the pectic enzymes are destroyed instantaneously
pectin substances plant gums38
Pectin Substances-Plant Gums
  • Polygalacturonase (PG)
    • Also known as pectinase
    • Catalyses the Hydrolysis the glycosidic linkages (a-1,4 bonds) in individual units in pectin chains
    • Catalyses the glycosidic hydrolysis of the bond between galacturonic acid units
pectin substances plant gums39
Pectin Substances-Plant Gums
  • PG can be divided into
    • Endoenzymes: act within molecule on a-1,4 linkages – Endopolygalacturonases
      • Cause rapid decrease in viscosity of pectin solutions without considerable increase in reducing groups
      • Attack the molecule at random, breaking it to shorter chains – “liquefying” enzymes
      • Fruits/filamentous fungi, NOT in yeasts or bacteria
    • Exoenzymes: catalyze the stepwise hydrolysis (split) of galacturonic acid molecules, from nonreducing end of chain - Exopolygalacturonases
      • Plants (carrot/peaches)/fungi/bacteria
pectin substances plant gums40
Pectin Substances-Plant Gums
  • Some PG act principally on methylated substrates (pectins) – Polymethyl galacturonases
  • Other PG act on substrates with free carboxylic acid groups (pectic acids) – Polygalacturonases
    • Split glycosidic bonds between two unesterified units
pectin substances plant gums41
Pectin Substances-Plant Gums
  • Pectin Transeliminase (PT)
    • Catalyses a dehydration reaction that breaks the alpha-1,4 glycosidic bond
    • Splits the glycosidic bonds of a glucuronide chain by trans elimination of hydrogen from the 4- and 5-position of the glycuronide moiety
    • Attacks only glycosidic bonds between methoxylated units
    • Glycosidic bonds in pectin are highly susceptible to this reaction
    • PT are of the endotype and are obtained exclusively from filamentous fungi, Aspergillus niger
    • The purified enzyme has an optimum pH 5.1 – 5.2
pectin substances plant gums42
Pectin Substances-Plant Gums
  • Amount of enzyme required for clarification of juice
    • Depends on type of enzyme
    • Amount of bentonite/glucose powder
      • Bentonite is an activated clay used to form a heavy complex with colloidal material and to remove the presipitate through filtration.
    • Type and pH of Juice
    • Time and temperature of method used
pectin substances plant gums43
Pectin Substances-Plant Gums
  • Enzyme treatment is usually followed by a pasteurisation process
    • To destroy yeasts
    • Inactivate Pectolitic and oxidising enzymes
    • Denaturise proteins
pectin substances plant gums44
Pectin Substances-Plant Gums
  • Role of Pectin in Cloud Formation
    • When juices are produced from fruit, the initial extraction process produces a liquor (or serum) as well as a particulate component
    • Cloudy juices consist of a suspension of very fine particles in a clear medium (serum)
    • Some particulate will form a sediment – settle at the bottom of the tank
    • Rest remains as cloud in juice
    • Some juices require this cloud to give the juice its specific consumer appeal and mouthfeel
      • Tomato juice/guava juice/orange juice/lemon juice
pectin substances plant gums45
Pectin Substances-Plant Gums
  • Cloud Structure
    • Differs from one juice to another, although the basic structure is the same
    • In orange juice the cloud consists of micelles (colloidal particles) that contain a positively charged protein core coated by a layer of negatively charged pectin
      • Neg. charged due to the free carboxyl ( –COO-)groups on pectin
    • These neg. charges cause electrostatic repulsion between micelles (electrostatic charge of the suspended particles)
    • Prevents them from settling down
    • Maintenance of the cloud
    • Interference with the cloud structure will very likely precipitate it
pectin substances plant gums46
Pectin Substances-Plant Gums
  • Clarification of Cloudy Juices
    • Removal of the particulate matter
    • Negative charges (surface of particles) will create insoluble complexes with other soluble polyelectrolytes of opposite charge
    • Will then precipitate easily
    • WINE: polyethylenamine is used for the clarification of cloudy wines
      • The precipitate thus formed will settle, carrying with it all suspended matters as well as tannins
    • Another method for attaining similar effects consists of treating cloudy liquids with commercial preparations of pectolytic enzymes, “Pectinol”
      • Usually obtained from molds and contain PE and endo-PG
pectin substances plant gums47
Pectin Substances-Plant Gums
  • Clarification of Cloudy Juices
    • Can also be done by filtration of the juice of wine
    • Adsorbing the cloud onto a stationary phase
      • Requires you to run juice through a column or over a bed of adsorbent (ex. Polyethyleneamine)
      • Positive charges on the resin attracts negatively charged cloud and binds it
      • Bentonite is used in the wine industry
    • Adding a flocculant to the juice
      • Adding aluminium sulphate: the Al++ precipitates the cloud due to electrostatic attraction.
    • Using pectolytic enzymes
      • PE and PG can disrupt pectin and therefore cloud structure – leading to precipitation
pectin substances plant gums48
Pectin Substances-Plant Gums
  • Industrial Manufacture of Pectins
  • Commercial Pectins are manufactured in two main forms
    • “Liquid pectins”: concentrated solutions of pectins extracted from waste plant materials (pomace/citrus peels)
    • “dry-pectin powders”:
  • Commercial practice the resulting products are not pure substances
    • Their degree of purity depends largely on
      • The methods of manufacture
      • Molecular size of pectin substances
      • Degree of esterification
      • Amount of accompanying ballast material present
pectin substances plant gums49
Pectin Substances-Plant Gums
  • Manufacturing procedures comprise the following main steps
    • (1) Removal of material
    • (2) Removal of ballast
    • (3) Acid hydrolysis of protopectin and dissolution of pectin
    • (4) Precipitation
      • By alcohols or acetone
      • Or mineral salts such as aluminium hydroxide with opposite electric charge to negatively charged pectinic acids
    • (5) Purification and drying
pectin substances plant gums50
Pectin Substances-Plant Gums
  • The use of HM-pectin in fruit jellies/jams
    • Dissolving dry pectin
      • Pectin must be in a complete gel form to be used to maximum capacity
      • A standard pectin solution:
        • Dry pectin with correct amount of water
        • Mix quickly with Mechanical mixer
        • Until clear viscous solution
        • Measured part is added to jam mixture
        • Or dry pectin can be mixed with sugar before adding to jam – this will prevent lumps
      • At high temperature pectin are degraded (Grade of pectin)
      • Ideally pectin will be added in the final stage of the evaporation process when the jam mixture are boiling
pectin substances plant gums51
Pectin Substances-Plant Gums
  • Solidification of Pectin – Gelling
    • Pectin are generally safe but precautions need to be taken against “preset”
    • There are two main gel forming characteristics that have an important role in the quality of fruit jellies
      • (1) Gel point/Gel temperature/solidification point/solidification temperature
      • (2) Solidification time
pectin substances plant gums52
Pectin Substances-Plant Gums
  • (1) Gel point/Gel temperature/solidification point/solidification temperature
    • The gel strength at the gel point is very weak. But increases first rapidly and then more slowly until maximum gel strength are reached after a couple of weeks
    • Factors influencing solidification temperature are:
      • Rate of cooling down
        • The faster the product cools down – the lower the solidification point
      • Degree of esterification (DE)
        • The higher the DE – the higher the solidification temp.
        • DE can be determined by titration with an alkali – the amount of free carboxyl groups will be accounted for
pectin substances plant gums53
Pectin Substances-Plant Gums
      • pH of the Jelly
        • Lower pH – higher solidification temperature
  • (2) Solidification time
    • The solidification time is the time elapsed since the ideal conditions for gel forming where reached until the time the actual solidification process starts
    • Factors influencing solidification time are:
      • Rate of cooling down
        • The faster the product cools down – the faster solidification process starts and the solidification temperature is reached sooner
      • Degree of esterification (DE)
        • At the same rate of cooling down, rapid set pectin will solidify at 88°C and slow set pectin will only solidify at 54°C – this is due to differences in DE
pectin substances plant gums54
Pectin Substances-Plant Gums
      • Molecular Mass (Mr) of the Pectin
        • The higher the Mr – the shorter the solidification time
        • Solidification time differs from 1 to 6.5 minutes, depending on all the factors influencing it.
  • Setting of pectin can start all ready during the evaporation process
    • When this occurs the structure of gel will be disrupted and made weaker due to turbulence
    • Gel lumps will form and the product will have a appearance
    • Therefore setting of gel may only start after the fill process – especially for pure jellies like apple/guava
pectin substances plant gums55
Pectin Substances-Plant Gums
  • Setting of pectin can also take too long
    • Especially in whole fruit/jelly combinations such as marmalade
    • The suspended fruit material can settle down
    • In this case the gel structure must form quickly for the solid materials to stay in suspension
  • The solidification time must therefore be controlled
    • It is of most important to use a pectin of correct DE
    • The rate of cooling can e adapted
    • But the filling process must continue smoothly to prevent “preset”
pectin substances plant gums56
Pectin Substances-Plant Gums
  • ERH and Microbiological Stability of Jam
    • The preservation of jam depends on the increase of the osmotic pressure or the decrease of the ERH (Equilibrium Relative Humidity)
    • Little microbiological spoilage occurs in jam with 68°– 70°Brix, but at 65°Brix molds can develop at the surface of jam
    • Jam with a relative low TSS can be manufactured to have less of a sweet taste and a more distinct fruit taste
      • In this case a preservative must be added to prevent molds forming – Sorbic acid can be used
pectin substances plant gums57
Pectin Substances-Plant Gums
  • During cooling condensation of water occurs on the inside surface of the tin
    • The top layer of jam becomes diluted
    • If the inside of the tin is not sterile, then microbiological spoilage can occur during and after storage
  • The fill temperature of jam therefore needs to by high enough to sterilize the tin and cover, because the final product will not undergo further heat treatments
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Pectin Substances-Plant Gums
  • Points to consider during Production
    • (1) Yield
      • Fruits/sugar/citric acid and pectin needs to be in the correct ratio during the evaporation process to reach a TSS-value of 62°– 73°Brix
      • The final TSS-value are determined by the type of product
      • TSS has an influence on
        • Taste
        • Colour
        • Gel strength
        • Profit of process
      • Each ingredient of the jam mixture contributes to the cost of the jam manufacturing
pectin substances plant gums59
Pectin Substances-Plant Gums
  • Example of the composition of jam
  • This mixture contains 55.5 g solved solids for 100.5 g and need evaporation to be concentrated until 68 g/100 g (68°Brix)
pectin substances plant gums60
Pectin Substances-Plant Gums
  • (2) Control of TSS in manufacturing of Jam
    • Strict control over TSS-value is important in the final stage op production
    • Jam thermometers are used to monitor the evaporation process
    • When a predetermined boiling temperature is reached the process will be stopped
    • Refractometers are used to control the process
    • The boiling point of jam is determined by the
      • TSS-value
      • Air pressure of mixture
pectin substances plant gums61
Pectin Substances-Plant Gums
  • (3) Evaporation rate and boiling pot construction
    • There are more than one reason for the evaporation rate to be as fast as possible
      • Non-enzymatic browning being the most important, needs to be limited
      • For the same reason the cooling time needs to be as quick as possible
    • Jam pots are made of Red Copper
      • Excellent conductivity
      • Build in steam coil - Hasten the process
      • Red Copper can enhance the colour of green figs and watermelon jam
      • Can also leaf off tastes and destroys ascorbic acid in fruit
pectin substances plant gums62
Pectin Substances-Plant Gums
    • Evaporation rate depends on
      • Amount of water per charge that needs to be evaporated, in other words, the amount of fruit per boiling cell
      • Total availability of heating surface and conductivity of metal used to manufacture boiling pot
      • Steam pressure – determines the heat capacity and amount of steam that is available for evaporation process
  • Today more than 80% of the worlds jams are manufactured in open pots
pectin substances plant gums63
Pectin Substances-Plant Gums
  • (4) Crystallization of sugar
    • The degree of saturation of sucrose-solution is 67.1°Brix at 20C. Jam are in most cases evaporated until 68° – 69°Brix and whole fruit jam as high as 70°Brix
    • Lots of water are bound by pectin, thus leading to a very low amount of unbound water in jam
      • To low to prevent crystallization
    • Sucrose inversion takes place during evaporation, and therefore crystallization occurs seldom
pectin substances plant gums64
Pectin Substances-Plant Gums
  • (5) Inversion of Sucrose
    • Sucrose are inverted to Glucose by fruit acid or added Citric acid during the boiling process
    • The inverted product can also be added through additional invert sugar that has been pre-produced with citric acid or hydrochloric acid
    • Inversion takes place at ‘n high temperature when enough acid is present
    • Crystallization usually occurs in jams with no gel structure because sufficient acid where not available for the inversion of these products
    • Inversion are usually taken to 28 – 32% - At this level the sugar will not crystallize
      • Unless the TSS-value are abnormal
      • If the pH is too low, due to too much acid – inversion will go too far and the danger occurs where glucose can be crystallized out
diabetic jams
Diabetic Jams…

Example 1

  • They are made with the same great tasting fruits as our regular jams, but we use “Sugar Care” sweetener instead of sugar, and LMO Pectin, made specifically for Diabetic Jam.
  • “Sugar Care” is one of the newest Diabetic sweeteners on the market and has NO aftertaste. Sugar Care is made by Hormel Health Labs.
  • Because of the sweetener and the LMO Pectin some of the Jams will not be as clear or transparent as those made with regular Sugar and Pectin.

Example 2

  • Diabetic Jam-Using Sorbitol and Pectin
  • the commercial pectin, saccharin tablets andgelatin