What are the food additives of the thickener that you must not know?

Definition of Food Gum
Usually refers to dissolved in water, and under certain conditions can be fully hydrated to form a viscous, slippery or jelly liquid macromolecular substances, in the processing of food can play a role in providing thickening, viscosity, adhesion, gel-forming ability, hardness, brittleness, tightness, stable emulsification, suspension, etc., so that the food to get the required variety of shapes and hard, soft, brittle, viscous, thick and other kinds of taste, so it is also often referred to as food Thickeners, viscosifiers, gelling agents, stabilizers, suspending agents, edible gums, gums and so on.
Classification of food gum:

1、Natural
Plant polysaccharide substances: pectin, gum arabic, guar gum, locust bean gum and so on;
Algae polysaccharide substances: agar, alginate, carrageenan, etc;
Microbial polysaccharide substances: xanthan gum, thrive mold polysaccharide;
Polysaccharides: crustaceans; protein: gelatin.

2、Synthesis
Sodium carboxymethyl cellulose, propylene glycol, modified starch and so on.

Functional properties of food glue

Thickening; gelling; dietary fiber function; emulsification, stability, as a filming agent and capsule; suspension and dispersion; water retention and water retention; control crystallization.

I. Properties
(A) Gel
When the system is dissolved in a specific molecular structure of the thickener, the concentration reaches a certain value, the system also meets certain requirements, through the following effects, the system forms a three-dimensional space network structure:
Cross-linking and chelating between thickeners’ macromolecule chains.
Strong affinity between thickener macromolecules and solvent molecules (water).
Agar: gel formation at 1% concentration
Alginate: thermally irreversible gel (does not dilute when heated) – raw material for artificial jelly

(ii) Interactions
Minimizing: Gum Arabic reduces the viscosity of Yarrow Gum
Synergizing: after a certain time, the viscosity of the system is greater than the sum of the viscosities of the respective thickeners used alone.

In the practical application of thickeners, often use a separate thickener does not get the desired effect, often need to be compounded to play a synergistic role.
Such as: CMC and gelatin, carrageenan, guar gum and CMC, agar and acacia bean gum, xanthan gum and acacia bean gum and so on.

Second, the efficacy and application
1, to give the required rheological properties of food, change the texture and appearance of food, so that the liquid or slurry food to form a characteristic form, with a viscous and smooth and palatable feeling. For example: the quality of ice cream and other icy treats depends largely on the state of ice crystal formation. Adding thickener can prevent the ice crystals are too large (so as not to feel the organization of rough slag), so that the ice crystals subtle, smooth texture, fine and uniform structure.

2, so that the products are uniform and stable, rich in characteristics. For example: the preparation of yogurt must be added to organic acids, but will cause milk protein coagulation and precipitation and stratification. Adding thickener helps to solve the problem of stratification.

3、Improve the foaming and stability. Such as: ice cream often use locust bean gum, sodium alginate, etc. to do the foaming agent

4, film-forming: the formation of a smooth film on the surface of the food, the role is as follows.
Prevent moisture absorption: frozen food, solid powder food;
Prevent water loss: fruit and vegetable preservation, and polishing effect.
This type of thickener is also known as the film-forming agent, is one of the development trends of the thickener, such as: alcohol soluble protein, gelatin, agar, alginate, etc..

5、Water retention
Because the thickener has a strong hydrophilic effect, in meat products, flour products can improve the quality of the role.
Flour food: improve the water absorption of the dough, accelerate the speed of water penetration to protein molecules and starch particles, which is conducive to the modulation process of the dough.

The use of thickeners holding water and gel, can increase the weight of the product, viscoelasticity and starch  level, not easy to aging and water loss.

Third, China allows the use of edible gum examples
(A) guar gum (guar gum)
Guar gum, also known as guar gum, guanidine gum, is currently the international cheaper and widely used one of the edible colloids. Guar gum is an edible polysaccharide compound isolated from the seeds of the guar tree.

1, the structural composition of guar gum
Guar gum is a linear galactomannan, belonging to the non-ionic polymer.
Structurally, with β-1,4 bond interconnected D-mannose unit as the main chain, unevenly in the main chain of some D-mannose unit of the C6 position and then connected to a single D-galactose (α-1,6 bond) for the branched chain, the ratio of its galactose and mannose 1:1.8, simplified to 1:2. In fact, the distribution of galactose in mannose on the main chain is not uniform, there are some segments of the main chain of its There is no galactose, while in some other parts are highly substituted areas.

2, the physical and chemical properties of guar gum
(1) solubility. Guar gum can be dissolved in cold/hot water and at the same time quickly begin to hydrate, and ultimately obtain a translucent viscous solution. But can not be dissolved in organic solvents such as ethanol.

2) Viscosity. Guar gum is one of the highest viscosity of natural colloids, its 1% aqueous solution viscosity between 4~5Pa-s.

3) Thermal stability. When the temperature rises, the viscosity of guar gum solution decreases.

4) Acid stability. The natural pH of guar gum solution is neutral, pH changes in the range of 4~10 on the properties of the gum solution is not obvious.

5) Rheology. Guar gum and its derivatives of the solution are non-Newtonian pseudoplastic flow characteristics, that is, with the role of stirring thinning.

3、Application of guar gum
China’s regulations (GB 2760-2014): guar gum can be used in various types of food, according to the production needs of the appropriate amount of use.
Thin cream: the maximum use of 1.0g/kg;
Formula food for larger infants and young children: the maximum use amount is 1.0g/L.
Specific functions of guar gum in different foods:

(ii) Gum Arabic (Arabic gum)
Arabic gum is derived from the trunk exudates of the Acacia genus of the legume family. Natural gum arabic pieces are mostly teardrops of varying sizes, slightly transparent amber in color and odorless, while refined gum powder is white.
The highest quality gum arabic should be translucent, amber-colored, without any taste, ellipsoidal gum.

1, the structure of gum arabic composition
Gum arabic is a weak acidic macromolecular polysaccharide containing calcium, magnesium, potassium and other cations, with arabinogalactan-based, multi-branched complex molecular structure.
Hydrolysis of gum arabic can obtain D-galactose, L-arabinose, L-rhamnose and D-galacturonic acid.
The structure of arabinose is also linked to about 2% of the protein

2, the physical and chemical properties of gum arabic
(1) Solubility: Gum arabic has a high degree of solubility in water, can be easily dissolved in cold and hot water, but insoluble in organic solvents such as ethanol.
(2) Viscosity: gum arabic is a typical “high concentration and low viscosity” type colloid.
(3) Rheology: the concentration of the solution below 40% is still Newtonian fluid, when the concentration of up to 40% above, began to show pseudoplastic fluid properties.
(4) Acid stability: pH 4~8 range is more stable, when the pH is lower than 3, the viscosity decreases.
(5) Emulsification stability: very good hydrophilic and lipophilic, it is a very good natural oil-in-water emulsification stabilizer.
(6) Thermal stability: general heating of the gum solution will not cause changes in the nature of the gum.

Application examples of gum arabic:

(C) pectin
1, the structural composition of pectin
Pectin is made of D-galacturonic acid residues by α (1 → 4) glycosidic bond connected to the polymerization of acidic macromolecular polysaccharides, and galacturonic acid C6 on the carboxyl group there are many methyl esterated form, for the methyl esterification of the residual carboxyl group is in the form of free acid in the form of potassium, sodium, ammonium, calcium salts; in the carboxylic acid position in the C2 or C3 is often accompanied by acetyl and other neutral (polysaccharides) branched chain, such as L-rhamnose, galactose, arabinose, xylose, etc.

[Chemical structure]
Pectin consists mainly of a polymer of galacturonic acid and its methyl ester. Some of the carboxyl groups are methyl esterified. If all are methyl esterified, the methoxy content is about 16.3%.
High ester pectin: methoxyl content ≥7%.
Low ester pectin: methoxy content <7%.

[Properties]

Dissolved in 20 times the water into a viscous liquid, acidic solution is more stable than alkaline solution, insoluble in ethanol, can be wetted with ethanol, glycerin, sucrose syrup, and more than 3 times the sugar is more soluble in water.

[Method]
Wash apple, citrus, grapefruit and other peels, add 1.8 times hot water, and then add 0.14% hydrochloric acid at 90 ~ 95 ℃ extraction for 30min, press filtration, vacuum concentration to the pectin content of 9 ~ 12%, precipitated with ethanol. Then wash, dehydration, drying, crushing and sieving to produce products

Lemon, tangerine and lime and other citrus fruit peel crushed, plus the amount of peel 4 times the 0.15% citric acid solution, in the heating conditions of impregnation, extraction of pectin.

Generally the methoxyl content in pectin extracted from plant peels is between 7~14%.
To increase the methoxy content in the product, the pectin can be methyl esterified with methanol.
To obtain low ester pectin, the use of deesterification process, commonly used: enzyme, alkali or acid method.

2, the physical and chemical properties of pectin
(1) solubility. Soluble in water, insoluble in most organic solvents
(2) the rheological properties of pectin solution. Dilute pectin solution is almost a Newtonian fluid; concentration greater than 1% of the pectin solution presents pseudoplastic phenomenon.

3）Stability
High ester pectin is stable at pH 2.5~4.5, destabilization occurs when pH is greater than 4.5; low ester pectin is more stable at high pH.

Use:
Production of jams and jellies – gelling agent
Stabilizer for mayonnaise, essential oils

Difference between high ester pectin and low ester pectin:
High ester pectin: used as a stabilizer for jams with acidic flavors, jellies, pectin fudge, candies, fillings, and lactic acid bacteria drinks.

Low ester pectin: stabilizer for jams, jellies, gelatinous fudge, frozen sweets, salad dressings, ice creams, yogurts, etc. with no or low acidity.

Precautions:
Pectin must be completely dissolved or dispersed before adding to avoid the formation of uneven gels. For this reason need high efficiency mixer, and slowly add pectin powder, so as to avoid pectin agglomeration, otherwise it is extremely difficult to dissolve or dispersion; can be wet with ethanol, glycerin or sucrose syrup, or mixed with more than 3 times of sugar, can improve the speed of dissolution of pectin; pectin is more stable in acidic solution than alkaline solution.

(D) gelatin
1, the structure of gelatin composition
Gelatin molecules have neither a fixed structure nor a fixed relative molecular mass.

Gelatin collagen protein is a three-helix structure of the peptide chain as the basic unit, connected to each other into the mesh structure, insoluble in water, through hydrolysis to make part of the connecting bond broken that is to become water-soluble gelatin, three-helix structure itself can be disassembled into a single α-chain, or α-chain plus β chain, or γ chain structure.

2、Physical and chemical properties of gelatin
(1) Solubility: warm water is the most common solvent for gelatine, gelatine can be dissolved in urea, potassium bromide or potassium iodide solution at room temperature, but also can be dissolved in acetic acid, salicylic acid and other organic acids.

(2) swelling performance: gelatin is not soluble in cold water but can absorb water to form a solid and flexible jelly, heating this jelly can become a solution.

(3) Foaming performance: the gelatin solution in the test tube according to a certain amplitude up and down shaking, the test tube will have a part of the gelatine to form a bubble, this is the gelatin foaming ability.

(4) Acid and alkali intolerance: gelatine can form compounds with acids, alkalis and salts.

5) Rheological properties:
Stirring will make the solution viscosity decrease
Static will make its solution viscosity increase
Temperature is an important factor affecting viscosity
Generally speaking, the lower the temperature, the faster the viscosity growth
The viscosity of gelatin solution is lowest at the isoelectric point

6) Gel properties
a) Freezing point and melting point:
Gelatin solution is cold to form jelly, the concentration of 10% of the gelatin solution began to condense the highest temperature to become the freezing point of gelatin. This jelly melting the minimum temperature required to become the melting point of gelatin.

(b) The melting point is highest at the isoelectric point.
Add a small amount of chromium salt or aluminum salt can make its melting point; add potassium salt, can make its melting point lower.

3、Gelatin application in food industry
China’s regulations (GB 2760-2014): gelatin can be applied to various types of food, according to the production needs of the appropriate amount of product application.

(E) Xanthan gum (also known as Hansen’s gum)
1, the structure of xanthan gum
Xanthan gum secondary structure is the side chain around the main chain backbone reverse winding, through the hydrogen bonding system to form a rod-shaped double helix structure.
The tertiary structure of xanthan gum is a helical complex formed by weak non-polar covalent bonding between the rod-shaped double helix structure.

2、The physical and chemical properties of xanthan gum
1）Suspension and emulsification
Even at very low concentrations, the solution viscosity is still very high, this high viscosity characteristics make it an extremely effective thickener and stabilizer.

Xanthan gum can reduce the incompatibility between the oil phase and the water phase with the help of the thickening effect of the water phase, and can make the oil emulsified in water, so it is used as an emulsifier and stabilizer in many foods and beverages.

2）Water solubility
Xanthan gum can be dissolved quickly in water and has good water solubility. Especially in cold water can also be dissolved.

3）Thickening
Xanthan gum has good thickening properties, especially in low mass concentration with high viscosity. The viscosity of xanthan gum solution is about 100 times of gelatin in the same mass concentration.

4）Rheology
Xanthan gum solution is a typical pseudoplastic fluid, the solution has a high degree of pseudoplasticity, that is, shear thinning effect.

5）Thermal stability
Xanthan gum aqueous solution in 10 ~ 80 ℃ viscosity between almost no change, even if the low concentration of aqueous solution in a wide range of temperatures still shows a stable high viscosity.

Xanthan gum solution in a certain temperature range (-4 ~ 93 ℃) repeated heating and freezing, its viscosity is almost unaffected.

6）Stability to acid, alkali, salt
(a) very stable to acid and alkali
Between pH5~10, its viscosity is not affected.
In pH less than 4 and greater than 11 when the viscosity is only a slight change.
(b) It can be miscible with many salt solutions and its viscosity is not affected.
It can be stored in 10% KCl, 10% CaCl2, 5% NaCO3 solution for a long time (25 ℃, 90 days), the viscosity remains almost unchanged.

7) Stability to enzymatic reaction
Xanthan gum is very strong anti-enzymatic ability, food production, there are many enzymes such as protease, amylase, cellulase and hemicellulase can not make xanthan gum degradation.
3、The application of xanthan gum in food industry
China’s regulations (GB2760-2014) xanthan gum can be used in various types of food according to the production needs of the appropriate amount.

As a thickener, stabilizer application restrictions:
Thin cream, fruit and vegetable juice (pulp), spices: use in appropriate amounts according to production needs;
Raw and dried noodle products: the maximum use level is 4.0g/kg;
Butter and concentrated butter, other sugars and syrups: the maximum use level is 5.0g/kg;
Infant formula for special medical purposes: the maximum use level is 9.0g/kg;
Raw wet noodle products (such as noodles, dumpling skin, wonton skin, siu mai skin): the maximum use of 10.0g/kg.

(F) Carrageenan
Carrageenan is known as antler alga gum, carrageenan, extracted from certain red seaweed, is a polysaccharide composed of galactosides. Carrageenan aqueous solution has a high viscosity and gelling characteristics, its gel has thermal reversibility.
Application of carrageenan: China’s regulations (GB 2760-2014), carrageenan can be applied to all kinds of food, according to the production needs of the appropriate amount of use. Limitation of application as emulsifier, thickener and stabilizer:
Infant formula food: the maximum use amount is 0.3g/L;
Other sugars and syrups: the maximum use level is 5.0g/kg;
Raw and dried noodle products: the maximum use level is 8.0g/kg.

(G) sodium carboxymethyl cellulose
Sodium carboxymethyl cellulose abbreviated as CMC or SCMC, also known as cellulose gum, is the most important ionic cellulose gum, is an anionic linear polymer substances. It is usually made from short cotton thread (cellulose content up to 98%) or wood pulp, treated with sodium hydroxide and then reacted with sodium chloroacetate. According to the different reaction conditions, a wide range of carboxymethyl group substitution (i.e., 0.4~1.5, with the highest theoretical value of 3.0) can be obtained for CMC.

1, Molecular structure of sodium carboxymethyl cellulose:

Structural formula of the molecular chain of cellulose (number of glucose for D-, i.e. degree of polymerization)

Structure of the ideal unit of CMC with DS=1

2、Application of CMC in food industry
GB 2760-2014 stipulates that: sodium carboxymethyl cellulose can be used in all kinds of food in appropriate amounts according to production needs.