<h2 class = "rich_media_title" > food glue is a very important and unique food additive, with thickening, gelling, emulsification, suspension, stable clarification, as a dietary fiber and other important functions, can be widely used in frozen food, beverages, dairy products, condiments, pastries, starch, candy, wine, food preservation and refrigeration. </h2>
1. Basic characteristics of food glue
1) Concept
Food glue, also known as hydrophilic colloid, hydrosol, is able to dissolve or disperse in water, and under certain conditions, the hydrophilic groups in its molecules, such as carboxyl, hydroxyl, amino and carboxylates, etc., can be hydrated with water molecules to form a viscous, slippery solution or gel, in food processing play a thickening, viscosity, adhesion, gel formation, hardness, brittleness, tightness, stable emulsification, suspension and other roles, so that food to obtain the need for a variety of shapes and hard, soft, brittle, viscous, thick and other taste, Therefore, it is often called food thickener, tackifier, gelling agent, stabilizer, suspension agent, colloid and so on.
2) Composition and structure
The main components of food glue are polysaccharides or protein macromolecular substances, polysaccharide food glue, the basic composition is monosaccharides and their derivatives. The chemical structure is a macromolecular polysaccharide formed in units of monosaccharides, due to the different types of monosaccharides, the degree of polymerization, the bonding and arrangement between the sugar units, the substitution of hydroxyl groups on the sugar units, etc., resulting in different functional characteristics, mainly reflected in solubility, viscosity, fluid characteristics, the stability of the glue solution to acid and alkali and temperature, the gel-forming ability and gel strength, the compatibility of the glue solution with other electrolytes, the pseudoplasticity and the synergistic complementarity between various polysaccharides. Protein food gels, generally composed of amino acids, directly affect and restrict their functional characteristics due to the type, quantity and spatial structure arrangement.
2. Functional characteristics of food glue
1) Gel action
The role of the food gel is that the hydrophilic colloid cross-links each other under the action of hydrogen bonds, electric field polarization forces or the bond bridges of some high-valent ions in the solution, and its long chain molecules are cross-linked to form and the liquid is wound and fixed, and a solid and tight structure is obtained to resist external pressure and ultimately block the flow of the system.
The winding degree of the three-dimensional network, the number and properties of molecular crosslinking, the mutual attraction and repulsion of the units that form the network, and the difference in the interaction with different solvents form different gelling characteristics of various food glues. Some food gels do not gel when present alone, but compound with others exhibit thickening and gel synergistic effects.
2) Thickening effect
Almost all food gels have a thickening effect due to the hydration of their molecules. Different types of food glue produce different thickening and rheological characteristics due to their own structure, the same kind of food glue, the greater the relative molecular mass, the greater the viscosity of the system with the same mass concentration.
The viscosity of food increases to varying degrees with its increase in concentration, showing a certain positive correlation, but negatively correlated with the system temperature. Generally, the temperature rises, the viscosity decreases; the temperature decreases, and the viscosity rises. The food glue solution is affected by the electrolyte, pH and pressure of the system and shows obviously different variations, which are mainly related to the structural differences of the food glue molecules themselves.
3) Emulsification stabilizing effect
After the food glue is added to the food, the viscosity of the system increases, the dispersion phase in the system is not easy to gather and agglomerate, and the dispersion system is stable, which can be used as an emulsification stabilizer for fruit juice drinks, beer foam, pastry mounting, etc., but is not a real emulsifier or a foaming agent, and its mode of action is not carried out in accordance with the hydrophilic and oil-friendly balance mechanism of the general emulsifier, but by thickening or increasing the viscosity of the water phase to prevent or weaken the migration and polymerization tendency of the dispersed globules.
4) Suspension dispersion
Most of the food glues have surface activity and can be adsorbed on the surface of the dispersed phase, making it have a certain degree of hydrophilicity and easy to disperse in the water system. Food glue added to the food system can increase viscosity, according to Stokes's law, the greater the viscosity of the liquid phase, the slower the particle sedimentation rate, can delay the precipitation of solid particles.
5) Dietary fiber function
The vast majority of food glues used in food can also play a functional health role in dietary fiber. In recent years, there have been many research reports on the physiological role of polysaccharide edible gum as dietary fiber at home and abroad, such as guar bean gum, pectin, konjac gum, chitosan and xanthan gum, which have significant physiological effects as dietary fiber.
Food glue is widely used as a fat substitute in the production of low-fat foods, therapeutic foods and health foods. At present, most of the fat substitutes are food glue as the main raw material or food colloid as the key ingredient.
6) Crystallization control effect
Many important properties in food, such as shape, brightness, chewability and melting, are directly related to crystal structure.
There are 3 ways for food glue to crystallize:
(1) Compatibility: binding with the crystal and attaching to the surface of the growing crystal, changing the normal growth mode of the crystal;
(2) Competitiveness: competing with crystals to form crystals;
(3) Binding: Binding with other substances, which in turn affects crystal growth.
Therefore, used in candy, dairy products, frozen food, can improve the expansion rate, reduce the possibility of ice crystal precipitation, can make the product taste delicate, improve the resistance to melting and preservation stability, improve the system shape and tissue structure.
7) Film agent and capsule action
Food gels are used as coating agents and can be covered on the surface of food to form a protective film. Protect food from contact with oxygen or microorganisms. It can also be used to make edible films for quality preservation, freshness preservation, fragrance preservation or glazing.
In addition, it can also be used as an outer capsule for packaged food, mainly using the ionized food gel reaction of Western species containing different positive and negative charges to form complex compounds, while forming a microcellular membrane wrapped on the surface of the core material, and the core material that is coated and fixed can be released in the food through physical pressure, pH value or temperature change.
8) Foam formation
Food glue can be foamed, forming a network structure, its solution can contain a large amount of gas when stirring, and due to the increase in vascosity on the surface of the vascularity to stabilize it. Using protein heat denaturation, the food glue and hot syrup are mixed and stirred and then cooled to achieve foam stabilization, or the gel reaction of carrageenan, sodium alginate or locust bean gum can also be used to form a stable foam product.
9) Flavor fixation effect
Flavor immobilization technology is in the oil-water emulsification system, the use of suitable emulsifiers to embed small droplets of flavor, when the moisture is removed can prevent the evaporation of flavor, to prevent oxidation deterioration or absorb water from the air, and the embedded flavor droplets can be dissolved or effectively dispersed into the water medium, when the fragrance is released from the embedding film can obtain the same aroma.
Wrap the flavor in gelatin, put it in the gum, and chew it to release the fragrance. Gum arabic is currently the best carrier of all natural food gums or other substances, sucrose, starch and its derivatives also have the function of fixing flavors, but the effect is second only to gum arabic.
10) Multiplicative action
Many food glues have a fairly obvious multiplier effect. All kinds of monomer food glue in the use of the process of certain defects, difficult to meet people's needs and adapt to the increasingly fierce market competition, through compounding, can play a variety of food glue complementary role, produce "l + 1>2" synergistic effect, to meet the different needs of food production, expand the scope of use of food glue, improve the use of function.
11) Water retention stabilization effect
Food gum has a hydrophilic polymer, showing a strong hydrophilic effect, which can effectively improve the problem of dehydration shrinkage in food production or storage, and can also improve the structure and chewing taste.
12) Other features
Food glue also has some other functional characteristics, including adhesion, puffing effect, fat substitute, taste correction, etc., which play an important role in the processing and improvement of many foods. Studies have shown that under certain conditions, food glue can be adsorbed on multiple dispersion media bodies at the same time to make it coagulate, and can mask some bad odors.
3. The mechanism of action of functional characteristics
1) Physical action
The molecular structure of food glue contains many hydrophilic groups, such as hydroxyl, carboxyl, amino, carboxylate, etc., which are uniformly dispersed in solution after hydration to form a viscous colloidal solution, which slows down the movement of protein molecules, reduces the probability of protein molecules binding with each other and the sedimentation rate, so that it is evenly and stably suspended in the system. At the same time, it can also stabilize the suspended tissue, limit the activity of metal ions, and avoid condensation and precipitation of food ingredients.
2) Chemical action
Food glue macromolecules contain hydroxyl, carboxyl, alkoxy, glycoside bonds in the oxygen atoms and peptide bonds in the outer layer of nitrogen atoms contain sp3 hybrid orbitals, the orbital unused solitary electron pairs can be combined with water molecules with partial positively charged hydrogen ions to form hydrogen bonds, the bonding force of hydrogen bonds is extremely strong, when greater than the cohesion between the food glue molecular chains, the food glue molecular chain stretches, the food glue molecules and water combine to form a long molecular chain, and dissolved and dispersed in water, forming a thermodynamic stability system.
The stretching of food gum molecules makes a variety of groups fully exposed, and the polar groups and polar water molecules are mutually restricted by hydrogen bonds or dipole forces to form an inner water film. The inner layer of water is then associated with the outer water, the volume of sol molecules as a skeleton, a large amount of water is bound, the free movement of the medium is hindered, resulting in resistance between laminar flows, showing viscosity.
4. Application of edible glue in food industry
1) Application in meat products
The addition of food glue to meat products can not only improve the edible quality of meat products, such as color, flavor, texture, water retention and other functional characteristics, but also reduce production costs, with huge market application prospects and actual production value.
Carrageenan applied in chopped high-temperature ham sausage can improve product texture and sliceability, enhance meat protein gel, improve water retention, reduce oil production and other advantages.
2) Application in frozen food
Food glue added to frozen food can improve viscosity, improve gelling, prevent or inhibit the enlargement of micro-particle ice crystals, delay the emergence of ice slag, improve taste, internal structure and appearance state, and improve system stability and melt resistance.
3) Application in gel candy
Gel candy has become a new hot spot in the development of candy due to its good chewability, bite, non-sticky teeth, not easy to decay, low sweetness, low calorie and other characteristics. The food of the linear rubber granules is cemented into a large void mesh structure, and the fudge is elastic and tough by adsorbing more fillers.
4) Application in beverages and foods
Qiong gum, xanthan gum is a good thickening and suspension stabilizer of beverage food, its dosage is small, at low concentration can achieve the required viscosity and suspension, and the temperature and pH value are relatively small, at room temperature can maintain viscosity and suspension relative stability, maintain the taste and appearance of beverage food. Studies have reported that the application of 0.1% propylene alginate to fruit juice can not only improve the stability of the pulp, make the juice taste thick and taste better, and also play a stabilizing role in the oil components in the juice.
5. Outlook
The development of food glue in China is still in its infancy. With the current development trend of "natural, nutritious and multifunctional" food additives, the mature use of modern biotechnology (such as enzyme engineering and genetic engineering), the comprehensive development of food glue efficacy will become possible.
Source: Food R&D and Production
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