Confectionery Gum and Jelly Products

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Pectins for the production of confectionery

Due to their various possibilities ofapplication and their technologicaladvantages pectins are becoming moreand more important as texturizing gellingagents and thickeners in the confectioneryindustry.

The confectionery sector comprises a widerange of articles which vary substantiallyin texture.

By far the most widespread use of pectinsis in the so-called gum and jelly products,namely jelly fruits, fruit gums, ptes defruits and pastilles. For these applicationsH&F offers an assortment of standardizedpectins which determine not only the in-tended gelling behaviour but also specifictextures.

H&F Classic Pectins are also ideal for themanufacturing of products like biscuitlayers, dominos, muesli bars, Turkishdelight, fillings for biscuits, chocolates andhard candies, aerated sweets like marsh-mallows and zefir.

Pectin based jellies for sweets can beproduced very efficiently and specificallytailored to formulations and productionparameters.

In contrast to other hydrocolloids, ClassicPectins are standardized to constant gel-ling strength, they dissolve rapidly andthey are heat-resistant even with low pH-values. Classic Pectins allow sufficient timefor depositing but at the same time setrelatively quickly.

After a relatively short standing time theproducts can be processed quickly. Thisguarantees an optimal use of the existingproduction capacities.

Jellies made with Classic Pectins are fur-thermore distinguished by a unique texturewhich can be determined individually. Thistexture ranges from firm and elastic tosmooth and viscous. Due to this textureand the neutral taste of Classic Pectins thenatural fruit taste or the added flavour cancome into its own.

4

OO

O

O

OCH3

C=O O

HO

H

HO

OCH3

C=O O

HO

H

HO

C=O O

HO

H

HO

OHC=O O

HO

H

HO

OHC=O O

HO

H

HO

OH

O

O

Theoretical principles

Structure of pectinPectin is an important structural elementof all plant cell walls. From a chemicalpoint of view, pectin is a macromoleculecomprising polygalacturonic acid as themain component. The carboxyl groups arepartially esterified with methanol and thesecondary alcohol groups can be partiallyacetylated. If the degree of esterificationexceeds 50% we refer to it as high me-thylester pectin, whereas compounds ofless than 50% are known as low methyl-ester pectins. The pectin chains are inter-rupted by rhamnose and linked to neutralsugar side chains composed of arabinose,galactose and xylose. The compositionhowever depends on the raw material.

The production of pectinMany plant materials with a high pectincontent are suitable for the production ofhigh quality and high molecular pectins.These include apple pomace or citrus peelsbut also sugar beet chips.The water insoluble protopectin present inthe raw material is brought into a solubleform by mild acidic extraction. The pectinextract obtained is clarified mechanicallyand concentrated in a gentle process.

The concentrated liquid pectin with a highdegree of esterification is processed withclose observance to the pH-value and tem-perature.

During this processing, methylester groupsare continuously separating from the pec-tin molecule in the acidic medium. This so-called de-esterification can be controlledvery precisely. If ammonia instead of acid isused for de-esterification amidated pectinswill arise at which a part of the methylestergroups will be replaced by amid groups.

Pectins with exactly defined degrees ofesterification can be obtained by de-esteri-fication. As soon as the desired degree ofesterification is reached, the pectin is preci-pitated in alcohol, then pressed,gently dried, ground into a powder and blended homoge-neously.

As pectins are extracted fromnatural plant materials in a prac-tically unchanged form, they de-monstrate different propertiesdepending on the quality of the raw mate-rial. Therefore quality control and stand-ardization of the pectins are very importantcriteria.

Pectins for use in confectionery productsare standardized to constant processingproperties with sugars and buffer salts, ifappropriate.

A precisely defineddegree of esterifi-cation and homo-geneous blendingguarantee optimalprocessing properties

Poly-D-Galacturonic acid partially esterified (pectin)

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OOC

O

COOH

COO

2H O

2H O2H O 2H O

2H O

2H O

2H O

HOOC

COO Na+- Na OOC+ -

COO K+- K OOC+ -

HO

O O

H H H

H H

H COOC33COOCH

Hydrate Cover

Hydrate Cover

Gelling mechanisms of high methylester pectins

Gelling mechanisms

1. Gel formation of high methylester pectinsAssociations of pectin chains lead to theformation of three-dimensional networks,i.e. to gel formation. Two or more chainsegments bond together and start to in-teract, thus becoming longer segments ofregular sequence, which are interruptedby rhamnose or by branching of the pec-tin chain. The spatial association of thechain segments to bonding zones withhigh methylester pectins is favoured bytwo decisive factors:

A. The addition of neutral sugars, e.g.sucrose, dehydrates the pectin molecules,which facilitates the approach of thepolymer chains and enables the cross lin-kage by hydrogen bridges.

B. The lowering of the pH-value suppres-ses the dissociation of the free carboxylgroups thus reducing the electrostaticrepulsion between the otherwise nega-tively charged pectin chains so that aspatial approximation becomes possible.

According to modern gelling theories, theassociation of high methylester pectin

chains is the result of two different me-chanisms.

In the first step, the methylester groups,the hydrophobic part of the pectin, at-tempt to cluster in a way that the surfaceof contact with water remains as small aspossible. They are responsible for the firstaggregation of the pectin chains and de-termine the setting temperature of thehigh methylester pectins.

Bonding zones inthe gel network

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2. Gel formation of lowmethylester pectinsLow methylester pectins, which are lessimportant in the manufacture of gum andjelly products, also gel according to themechanism described above. However,they are capable of forming a gel even re-latively independently of the soluble solidscontent and pH-value if multivalent cat-ions are present.

In this case, the association of pectinchains occurs by the reaction with multi-valent cations, e.g. calcium ions. Due to their bent shape, they create cavitiesbetween them, which become occupiedby carboxyl and hydroxyl groups. Both carboxyl and hydroxyl groups favour theassociation of pectin chains by calciumgelation.

3. Gel formation of high methyl-ester, amidated pectinsIn principle the gelation of high methyl-ester, amidated pectins is also effected ac-cording to the sugar-acid-mechanismcomparable to the high methylester, non-amidated pectins.In their hydrated condition the amidatedgroups in the molecule lead at first to asterical interference which means that thepectin chains cluster together under heatinfluence more slowly than high methyl-ester, non-amidated pectins do. Subse-quently the amidated groups contributeadditionally to the stabilization of the gelnet by the linkage of hydrogen bridges re-sulting in very firm gels with elastic-viscousgel texture.

Gelling mechanisms

In the second step, hydrogen bridgesare formed between the free undissocia-ted carboxyl groups. They stabilize the ag-gregates formed in the clustering processof the methylester groups and hold themtogether. The smaller the part of dissocia-ted carboxyl groups, that means the lowerthe pH-value in the system, the better theformation of hydrogen bridges.

Due to the higher amount of possiblebonding sites, pectins with a high degreeof esterification and a lot of hydrophobicmethylester groups need less acid for thestabilization and formation of the gel net-work than pectins with a low degree ofesterification.

H +

COOCH3

C

O O

O

OH

O

OH

OOH

OH

O

O

COOCH3O

OH

O

OH

OOH

OH

O

O

C

O OH

Dissociation of carboxyl groups

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3.6 3.4 3.2 3.0 2.8 pH

80

75

70

65

60

55solu

ble

so

lids

Brix

liquid

gelled

pre-gelled

The gelation of high methylester pec-tins depends on the soluble solids con-tent and on the pH-value of the product.Three ranges have to be differentiated:

A range, in which gelation does notoccur due to a lack of sufficient bondingsites. The gel preparation remains liquid orhighly viscous.

A range, in which the pH-value andsoluble solids match perfectly, resulting inwell gelled products.

A range, in which there are so manybonding sites that gelation starts at tem-peratures above the filling temperature.During depositing, the forming gel will be partially destroyed, which results inproducts with a mushy, viscous texture.This effect is called pregelation.

The figure explains that sugar and acidmay substitute each other within certainlimits in their contribution to gel forma-tion. A lower sugar content requires alower pH-value for gelation. Higher pH-va-lues are possible when the sugar contentis high.

High soluble solids contents of approx.78%, usual in the production of gum andjelly products, require relatively high pH-values to prevent pregelation and toachieve long depositing times.

For taste reasons, a high product-pH is notdesire