Gel

A gel consists of polymers linked through covalent and/or non-covalent
interactions, to create a three-dimensional network. In whole egg as well as in
white and yolk, proteins are responsible for the gelling properties. Gelation
occurs when the protein stability in solution is modified, i.e., when the
equilibrium between attractive (Van der Waals) and repulsive (electrostatic,
steric) interactions is disrupted. The electrostatic repulsions vary with the net
charge of the proteins, that means with the ionisable protein groups and with the
physico-chemical characteristics of the solvent (pH, ionic strength). The
treatments that decrease the repulsive interactions, such as adjustment of pH
at proteins pI or addition of salts, induce destabilisation and thus can result in the
formation of aggregates or gels.
   Moreover, some treatments can modify the protein structure, with
consequences for the repulsive and attractive interactions mentioned above.
This is especially the case during heat treatments, which are the major techno-
logical treatments used in the food industry for egg white and yolk gelation.
Heat-induced gelation of egg conforms completely with the model of heat
gelation of globular proteins. It is a two-step phenomenon: in the first stage,
unfolding of native proteins occurs, disrupting the well-defined secondary and
tertiary structures and producing denatured proteins exposing their inner
hydrophobic regions; following unfolding, the denatured proteins interact to
form high molecular weight aggregates that can further interact with each other
to result in a three-dimensional gel . The unfolding and
aggregation steps depend on many factors (protein concentration, ionic strength,
pH, presence of sucrose, etc.) that can modify the number and/or the kind of
interactions, with final consequences on the gel rheology. In the heat-induced
gels of egg proteins, the interactions involved are predominantly hydrophobic
and electrostatic, but some highly energetic interactions can be observed
(disulfide bridges); thiol and amine groups are indeed very reactive, especially
in alkaline conditions.

Industries using guar gum

Guar gum is a white to creamy coloured, free flowing powder and free from extraneous matter. Its ability to suspend solids, bind water by hydrogen bonding, control the viscosity of aqueous solutions and form strong tough films, have accounted for its rapid growth and use in various industries. Industrial grade Guar Gum is used in Paper, Textile Processing, Explosives, Detergents, Drilling Fluids, Ceramics, Paints and many other industries. The purified grade is used in the Pharmaceuticals, Dialectic, Cosmetic and Food Industries. Guar gum is a natural product, and because it has the ability to swell by hydrolyzing with water, it can be used in a variety of water systems for food and industrial applications. Guar gum can viscosify, stabilize, and emulsify water systems as well as bind moisture to itself.

Applications of Guar Gum

Guar Gum for Food, Pharmaceutical & Dialectic Industries: Guar Gum in pure form when used in the ice creams acts as a superior stabiliser and gives the right texture by preventing the formation of coarse ice crystals. Guar gum is used as a thickener and stabiliser in food and pharmaceuticals. The present trend is to use agro-based Guar Gum only for Ice cream, without any Additives or Preservatives, in place of Carboxymethyl Cellulose (CMC), which is a chemical derivative of cellulose and therefore objectionable, in Europe , Japan and America for Food Products. In squashes, sauces and sherbets, it functions as a suspending agent and as a stabiliser. It has got a low calorific food value, and it is an excellent bulk laxative. It is used as a suspending agent for Calamine and Barium Sulphate. It increases the mechanical strength of tablets during pressing. It readily disperses in water. It is used in jellies and ointments as a thickener. It imparts good viscosity and gives better foam stability in shampoos. It is compatible with glycerol and is used in tooth-pastes.

Guar Gum for Bakery Industry: It is used in the Bakery Industry, in Bread, Pastry, Cakes and Cookies. On dry mixing prior to dough making in Bread, it helps to retain moisture and hence the weight of Bread. It keeps the Bread smooth, pliable and fresh for longer time and imparts milky white bleached appearance to Bread.

Guar Gum for Grass Growing / Erosion Control : Guar gum has a major application in the grass growing  and  erosion control industry where it is used as a water binder to retain moisture on the soil surface, particularly on slopes where the addition of guar gum to the water systems will help to anchor the hydro seeding mixture to the slopes and seal in the moisture. It is used in systems that protect against hydraulic lift and shear forces created by high-volume discharges, so whether grass is grown on slopes, channels, or straight-aways, from roadside to residential lawns, golf urses to athletic fields to parks, using guar gum prevents soil erosion and enhances grass growing.

Guar Gum for Cosmetics: Guar Gum is soluble in cold and hot water and this solution is not attacked by Bacteria. Guar Gum Protective colloid forming capacity results in emulsion stabilisation. It is also a good thickener and suspending agent in Cosmetics.

Guar Gum for Fish Farming : Guar gum is used as a binder in the fish feed pellets. The binder keeps the pellets from disintegrating quickly when placed in water and greatly reduces the consumption of fish feed in the pond.

Guar Gum for Oil Well Drilling : Guar Gum when used in oil well drilling muds, gives a better colloid thereby reducing water losses. It regulates the viscosity of mud solution, stabilises and regulates the flow properties of the drilling muds.

Guar Gum for Explosives (as Water Blocking Agent in Nitro-glycerine, Slurry Explosives, Ammonium Nitrate & Dynamite Explosives): By mixing Guar Gum in Ammonium Nitrate, Nitro-glycerine & Oil Explosives, even in wet conditions explosive property is maintained. This is due to the better swelling, water blocking and gelling properties of Guar Gum.

Guar Gum for Paper Industry: Guar Gum is used in paper manufacture as a better additive. It gives denser surface to the paper used for printing. Guar Gum imparts improved erasive and writing properties, better bonding strength and increased hardness. Due to improved adhesion, it gives better breaking, mullen and folding strengths. Guar Gum for Mining : Guar gum is used in mining potash, gold, copper and platinum group metals (PGM) as a flocculent and as a depressant.

Guar Gum is also used in the following industries: Insecticides & Pesticides Detergents & Soaps Paint Industry Electrodes & Brazing Fluxes Plywood Leather Industry Foundry Tobacco Processing Pencils Crayons Adhesives Mosquito Coils    source: guargum.co.in

La gomme de Guar E412

La gomme de Guar E412

 

Origine et fabrication

 

 

guar gum beansLe Guar fait partie de la famille des gommes issues des graines. Cette gomme est donc extraite d’une famille de légumineuses (Cyamopsis tetragonolobus) dont le fruit est une gousse et qui est cultivé en Inde et au Pakistan. Elle constitue les polyssacharides de réserves des légumineuses que l’on appelle les galactomannanes.

 

 

 

 

 

 

 

 

     Il existe 2 types de procédés pour extraire la gomme de Guar des graines : guar gum powder

 

Un procédé mécanique 

Tout d’abord, les coques des gousses sont éliminées puis un broyage modéré des graines est effectué pour dégager l’endosperme de la graine qui contient la gomme jusqu’à l’obtention d’une poudre. La poudre obtenue est opaque.

 

 

 

 

 

 Un procédé chimique 

Les graines sont solubilisées à chaud puis la solution est filtrée sur silice. Ensuite, le filtrat recueilli est précipité avec de l’alcool isopropylique. Le coagulum obtenu est alors lavé, pressé et broyé.

 

 

 

Structure

 

 

guar gum chemical 

Le Guar est un galactomannane constitué d'une chaîne de β-D mannose sur laquelle sont branchées des unités α-D galactose. Il y a 1 galactose pour 2 mannoses.

 

 

 

 

 

 

 

 

Propriétés de la gomme de Guar

 

       Solubilité 

 

 De part sa structure très ramifiée, le Guar est soluble à froid. En effet, la présence d’une quantité importante de galactoses ramifiés facilite la pénétration de l'eau à l’intérieur du grain et l'écartement des chaînes de mannose.

 

               Epaississantes 

 

La gomme de Guar, de part sa forte viscosité à température ambiante (1000 à 6000 mPa.s),  est un épaississant puissant. De plus, sa viscosité reste inchangée lorsqu’on applique de forts cisaillements.

 

               Synergie avec les autres gommes 

 

La gome de Guar présente des synergies par association intermoléculaire avec des polysaccharides linéaires : Xanthane, Kappa – Carraghénane.

Dans les applications alimentaires, le guar est rarement utilisé  seul, il est souvent associé à d’autres hydrocolloïdes.

 

  

 

Applications alimentaires 

  

Domaine	Propriétés du Guar	En association avec
Préparations ménagères	Soluble et visqueux à froid	Caroube, carraghénanes et xanthane
Boissons	Augmente la viscosité, donne du corps
Produits Laitiers	Augmente la viscosité, donne du corps	Caroube et carraghénanes
Panification	Renforce réseau gluten	Caroube et xanthane
Sauces	Epaississant	Xanthane et amidon

      Utilisation en cuisine moléculaire
La gomme de guar est employée à une concentration inférieure à 1% comme épaississant. 
Pour faciliter sa dispersion, il est aussi préférable de mélanger la gomme de guar avec du sucre ou  avec un autre ingrédient facile à disperser et plus abondant (farines, amidons). 
Cette gomme constitue le produit le plus courant pour apporter de la viscosité à toutes sortes de recettes car elle est sans interactions avec les autres additifs.guar gum
 source:  cuisine-et-molecule.fr

guar gum

Guar Gum History

Guar is a native to the Indian subcontinent. Guar is grown mainly in India, Pakistan, United States and also in some part of Africa and Australia.

In old times, Guar was only used as rich protein to feed cattle. It is also used as green vegetable in India. After Second World War there was major shortage of locust bean gum which adversely affected the textile and paper industries. At that time Guar Gum was found as the most suitable substitute for scarce locust bean gum. In 1953 the extraction technology of guar gum was commercialized in USA and India after decade of period.

Guar Plant

The guar plant is an annual plant known as 'Cyamopsis Tetragonaloba'. The important source of nutrition to human and animals is the legume, it regenerates soil nitrogen and the endosperm of guar seed is an important hydrocolloid widely used across a broad spectrum of industries.

The guar plant flourishes in extremely drought resistant and semiarid regions where most plants perish. It grows best in sandy soils. The ideal areas for farming are West, Northwest India and parts of Pakistan. The major processing centers of Guar Gum are in the North Western states in India.

The guar plant grows from 2 feet to 9 feet high. The plant’s flower buds start out white and change to a light pink as the flower opens. The flowers turn deep purple and are followed by fleshy seed pods which ripen and harvested in summer.

The seed pods grow in clusters giving guar the common name cluster-bean. A gum extracted from the guar beans forms a gel in water, commonly referred to as guar gum. Guar is extremely drought resistant and thrives in semi-arid regions where few plants thrive. When limited moisture is available the plant will stop growing but does not die. Guar gum is also known as guarkernmehl, guaran, goma guar, gomme guar and galactomannan.

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Guar Harvesting period

A growing season of guar is 14 to 16 weeks and requires reasonably warm weather and moderate flashing rainfall with plenty of sunshine. Too much rain can cause the plant to become more 'leafy' resulting thereby reducing the number of pods or the number of seeds per pod which affects the size and yield of seeds. The crop is generally sown after the monsoon rainfall in the second half of July to early August and is harvested in late October early November. The Guar is a naturally rain fed crop. Depending on the monsoon rainfall the total size of Guar crop varies from year to year. After harvesting, when the pods become dry through sunlight, they are beaten off and during this process, the seeds come out of the pods.

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Guar Extraction Methodology

Contagion of the natural gums available at present occurs mostly due to poor handling. There are various tools and system available through which natural gums can be extract completely hygienic from the tree.

Guar Scientific classification

Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Fabales
Family: Leguminosae
Tribe: Indigofereae
Genus: Cyamopsis
Species: C. tetragonoloba
Botanical name: Cyamopsis tetragonolobus (L.)
Synonyms: Cyamopsis psoralioides L.
Part Used: Seeds
Vernacular Name: Guar

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Guar Standard Specification

Minimum standards for good quality guar gum have been defined in the United States FCC and by European Union Specifications as under:
Moisture: 14% max. Ash (total): 1.5% max.
Acid Insoluble Residue: 4% max.
Galactomannan: 75% min.
Protein: 7% max.
Arsenic: 3 ppm max.
Lead: 10 ppm max.
Zinc: 25 ppm max.
Copper & Zinc: 50 ppm max.

Guar Gum Components

Guar Gum mainly consists of hydrocolloidal polysaccharide with a high molecular weight, which consists of galactopyranose- and mannopyranose- units in glycoside linkage which can be chemically described as galactomannan.

Name of Guar Gum in different countries

English: Guar Gum
German: Guarkernmehl
French: Gomme Guar
Spanish: Goma Guar, Guaro Dervo

source : guargum.biz

Guar Gum Manufacturing

GuarGum Manufacturing

Depending upon the requirement of end product various processing techniques are used. In the commercial production of Guar gum is normally undertaken by using process of roasting, differential attrition, sieving and polishing.

Stage wise process of manufacturing food grade guar gum is as under.It is very important to select guar split in this process. Guar Gum split is screened to clean and soaked to prehydrate in a double cone mixer. Prehydrating stage is very important in process as it derives the rate of hydration of the final product.

Soaked splits, has reasonably high moisture content, is passed through Flacker. Flaked Guar split is grounded to desired particle size followed by drying of the material. The power is screened through rotary screens to deliver required particle size of Guar . Oversize is either recycled to main Ultra fine or regrinded in separate regrinding plant, as per viscosity requirement of Guar.

This stage helps to reduce the load at the grinder. The soaked splits are difficult to grind. Direct grinding of those generates more heat in the grinder which is not desired in the process as it results in insoluble or reduced hydration of the product. Through heating, grinding & polishing process the husk is separated from the endosperm halves and the refined Guar Gum split are obtained. Through grinding process the refined Guar split are then treated and converted into powder.

During split manufacturing process, husk & germ are obtained which are used as a cattle feed as they are rich in protein. It is widely sold in international market as “Guar Meal” and has contents of “Oil & Albuminoids”. These contents are about 50% in germ whereas it is about 25% in husks. Quality of food grade Guar gum powder is defined from its particle size, rate of hydration and microbial in it.

Guar Gum: Stage wise Process

Guar Seed

• First, Guar Pods are dried in sunlight, manually separated from the seeds.
• The Guar seeds are supplied to the industry for processing.
• Guar by-products, churi and korma are used for Cattle feed.

Undehusked Guar Splits

• The Guar gum is commercially extracted from Guar seeds essentially by
  a mechanical process of roasting, differential attrition, sieving and polishing.
• The seeds are broken and the germ is separated from the endosperm.
• Two halves of the endosperm are obtained from each seed and are known as Undehusked Guar Splits.

Refined Guar Splits

• Refined Guar Splits are obtained when the fine layer of fibrous material, which forms the husk, is removed and separated from the endosperm halves by polishing.
  

Guar Powder

The refined Guar Splits are then treated and finished into powders by a variety of routes and processing techniques depending upon the end product desired.