Agar agar is a hydrophilic colloid extracted from red algae plants. It is one of the seaweed gels that were first used in the food industry and are currently the most widely used in the world.
Agar has been used all over the world for hundreds of years, and its food safety has been proven. The United Nations World Health Organization has approved agar for use in the food industry. At the same time, it is also recognized by regulations in many countries such as China, Britain, the United States, and France.
It is widely used in food industry, pharmaceutical industry, daily chemical industry, bioengineering and many other aspects.
In the food industry, agar is used as a gelling agent, bulking agent, thickener, emulsifier, stabilizer, excipient, suspending agent, and moisture retaining agent, which can significantly change the quality of food and improve the quality of food. Grade, become an important food additive.
01
Physicochemical properties of agar
1. Solubility
At room temperature, agar is insoluble in water and inorganic and organic solvents, it is only slightly soluble in ethanolamine and formamide, but it is soluble in water and certain solvents under heating conditions.
Dry agar can absorb water and swell at room temperature, and the water absorption rate can reach 20 times. It can be dissolved in water to form a solution when heated to 95 ° C. The agar solution can form a gel at room temperature. It has the strongest gel ability at the same concentration, even a 0.1% agar solution can solidify at about 30°C.
Agar can also be dissolved in boiling low-concentration ethanol (30%~50%) solution. In some high-concentration electrolyte solutions, such as sodium sulfate, magnesium sulfate or ammonium sulfate, it can be salted out and precipitated. Studies have found that agar can also be dissolved in many other solvents.
2.
Add 10 times volume of ethanol, isopropanol or acetone to flocculate agar solution to flocculate and separate agar from aqueous solution. Similarly, saturated calcium sulfate, magnesium sulfate, or ammonium sulfate solutions can cause salting out of agar solutions.
Utilizing this feature, it can be used for agar gel dehydration in the agar extraction process.
3. Gel temperature hysteresis
Agar gel is a thermally reversible gel, which melts when heated and solidifies after cooling, and can be repeated. The freezing point of agar solution is generally between 32°C and 43°C, while the melting point of agar gel is generally between 75°C and 90°C.
It is a unique phenomenon of agar that the melting point is much higher than the freezing point, which is called "hysteresis". The advantages of many applications of agar are reflected in its high hysteresis.
4. Viscosity The viscosity of
agar aqueous solution (sol) varies with the type of raw material, raw material quality, extraction conditions, solution pH, amount of inorganic salts, agar concentration, temperature and electrolyte added during measurement.
Generally speaking, natural polysaccharides with strong coagulation ability have a lower solution viscosity, and agar has a strong coagulation ability and lower viscosity.
During the extraction process, industrial agar is damaged to a certain extent due to chemical reagent treatment, and its viscosity is low. In addition, the viscosity of agar drops significantly when the agar solution is subjected to high temperature, electrolyte, inorganic acid or acid salt.
5. Non-acidic degradation
A large number of experiments and studies on viscosity, diffraction and gel strength have proved that pure dry agar has good stability and is difficult to degrade at room temperature.
However, factors such as impurities, high temperature, ultrasonic waves, strong γ-rays, and strong stirring can cause the molecular chains of agar to break and degrade, and some physical and chemical properties of agar will deteriorate.
6. Gel The most important feature of
agar is its gelatinity. Even an agar solution with a concentration of 0.004% can form a gel at room temperature. Compared with other substances that can form a gel, it can gel at the same concentration Maximum strength. When agar forms a gel, no coagulant is needed. The strength of the gel is related to the type of raw material, growth environment, collection season and extraction method, and is also closely related to its chemical composition and structure.
02
Applications in the food industry
Agar has the stability of gelation and gel, and has the functions of bulking agent, thickener, emulsifier, gelling agent, stabilizer, excipient, suspending agent, and moisture retaining agent in the food industry. Widely used in the food industry.
1. Application
in confectionery Agar is used as a gelling agent in the confectionery industry, mainly used to make soft candies. According to the gelling ability of agar, the amount of agar in the fudge is generally 1%-2.5%, and the carbohydrates are mainly sucrose, supplemented by starch syrup, and the ratio is about 3:2.
The soft candy made of agar has better transparency, quality and taste than other soft candies. Although agar has been used as a traditional gel substance in candy making for a long time, practice has shown that its taste characteristics are relatively simple. In recent years, gelatin, modified starch, fruit juice/fruit puree or melon and fruit are often added, which helps candy to mix materials. The diversity of composition is conducive to the improvement of flavor and mouthfeel.
The pumpkin soft candy developed by Gu Yong and others has a ratio of 200g of sucrose, 15g of agar, 250g of pumpkin, and 0.3g of citric acid. sugar.
2. Application in canned food
In poultry and meat canning, agar acts as a gelling agent and excipient, forming a gel that effectively binds minced meat and eliminates brittleness of food tissue in cans. Its dosage is 0.2% -2.0% of the clear soup in the can.
In eight-treasure porridge, white fungus bird's nest, soup canned food, use 0.3%-0.5% agar as thickener
Agents and stabilizers can improve the taste, disperse other additives uniformly, and prevent precipitation and stratification.
3. Application in beverages
Agar is used in beverage products as a suspending agent to make the solids in the beverage evenly suspended and not sink. Its suspension time and shelf life are long, which cannot be replaced by other suspending agents. The product has better transparency, fluidity, smooth taste and no peculiar smell.
It shows excellent suspending effect in fruit beverage, and the concentration of 0.001% -0.005% can make the fruit suspend evenly.
4. Application
in jelly Adding agar in the jelly manufacturing process can be used as a stabilizer and gelling agent, which can make the particles suspend evenly without sedimentation or stratification. According to the gelling ability of agar, the general dosage is 0.15%-0.3%.
5. Application in cold drinks
Agar is used in cold food, such as popsicles, ice cream and other frozen products, which can reduce ice crystals, improve resistance to heat and melt, and make the product more refreshing.
In the production of ice cream, agar can improve the tissue state of ice cream, increase the viscosity and expansion rate of ice cream, prevent the precipitation of ice crystals, and make the structure of the product fine and smooth. The usage amount is about 0.3%. Agar, combined with locust bean gum and gelatin, plays an excellent role in the texture and flavor stability of cold drinks, and can prevent syneresis and surface crusting.
The optimal concentrations as stabilizers are: agar 0.12%, locust bean gum 0.07%, and gelatin 0.2%.
6. Application in baked food
Agar can be used as a filler, leavening agent and water retention agent, and is widely used in a variety of baked foods. For example, bakery food production plants use agar for the shell of cookies, cream sandwich pies, pies, meringues on the surface of pastry sweethearts, meringue cones, etc. As a slightly binding additive: agar has no nutritional value, but also as a filler and leavening agent, can replace starch to make oatmeal paste, starch-free bread and post-dinner snacks, and make it a low-calorie food. Biscuits also play a moisturizing and insurance role.
In baked goods, the amount of agar used is generally 0.1% -1.0%.
7. Application in dairy products
Agar can effectively reduce the synergy of dairy products, enhance stability and emulsification, and is widely used in dairy products. Adding agar to French cottage cheese, cream quiche, and fermented milk products has good stability and toughness, and also helps to improve the consistency and sliceability of cheese. The amount of agar used in dairy products is generally 0.05%-0.85%, and it is better to use it in combination with manna gum and xanthan gum.
8. Application
in sugar-coated food In sugar-coated food, agar can be used as a stabilizer for sugar coating, and can also prevent the food from sticking to the package. The content of agar in sugar-coated food is usually between 0.2% and 0.5%.
Based on the amount of sugar required, when the concentration of agar reaches 0.5%-1.0%, it can be used as a stabilizer for the transparent sugar coating of the oil cake. The agar stabilizer improves the viscosity of the transparent sugar coating and the adhesion on the surface of the oil cake, and promotes faster gelation. Solidifies and increases flexibility to reduce surface defects and cracks.
While the melting temperature of the gel is increased, the liquid absorption and softening tendency of the oil cake is reduced. In applications, agar is often mixed with other vegetable gums such as guar and locust bean gums.
9. Application in meat products
Agar is used in meat product processing, which can effectively maintain the flavor of the product. Agar is used for stuffing sausage, smoked or calf meat products, which can obviously protect its colloid and prevent its flavor loss.
For this purpose, the cooked ham can also be covered with a solution containing agar and ascorbic acid. After packaging, the meat products treated with agar retain their original flavor better than untreated meat products and meat products treated with ascorbic acid alone.
10. Other food applications
In the brewing industry, agar is used as a clarifying agent for beer, soy sauce and edible vinegar to accelerate and improve product clarification; agar is used as a substitute for gelatin because of its unique physical and chemical properties, such as high melting point and low mold resistance. side use.
https://www.arshinefood.com/detail/Industry-Information/The_application_and_characteristics_of_agar.html
THE APPLICATION AND CHARACTERISTICS OF AGAR
Agar agar is a hydrophilic colloid extracted from red algae plants. It is one of the seaweed gels that were first used in the food industry and are currently the most widely used in the world.
Agar has been used all over the world for hundreds of years, and its food safety has been proven. The United Nations World Health Organization has approved agar for use in the food industry. At the same time, it is also recognized by regulations in many countries such as China, Britain, the United States, and France.
It is widely used in food industry, pharmaceutical industry, daily chemical industry, bioengineering and many other aspects.
In the food industry, agar is used as a gelling agent, bulking agent, thickener, emulsifier, stabilizer, excipient, suspending agent, and moisture retaining agent, which can significantly change the quality of food and improve the quality of food. Grade, become an important food additive.
01
Physicochemical properties of agar
1. Solubility
At room temperature, agar is insoluble in water and inorganic and organic solvents, it is only slightly soluble in ethanolamine and formamide, but it is soluble in water and certain solvents under heating conditions.
Dry agar can absorb water and swell at room temperature, and the water absorption rate can reach 20 times. It can be dissolved in water to form a solution when heated to 95 ° C. The agar solution can form a gel at room temperature. It has the strongest gel ability at the same concentration, even a 0.1% agar solution can solidify at about 30°C.
Agar can also be dissolved in boiling low-concentration ethanol (30%~50%) solution. In some high-concentration electrolyte solutions, such as sodium sulfate, magnesium sulfate or ammonium sulfate, it can be salted out and precipitated. Studies have found that agar can also be dissolved in many other solvents.
2.
Add 10 times volume of ethanol, isopropanol or acetone to flocculate agar solution to flocculate and separate agar from aqueous solution. Similarly, saturated calcium sulfate, magnesium sulfate, or ammonium sulfate solutions can cause salting out of agar solutions.
Utilizing this feature, it can be used for agar gel dehydration in the agar extraction process.
3. Gel temperature hysteresis
Agar gel is a thermally reversible gel, which melts when heated and solidifies after cooling, and can be repeated. The freezing point of agar solution is generally between 32°C and 43°C, while the melting point of agar gel is generally between 75°C and 90°C.
It is a unique phenomenon of agar that the melting point is much higher than the freezing point, which is called "hysteresis". The advantages of many applications of agar are reflected in its high hysteresis.
4. Viscosity The viscosity of
agar aqueous solution (sol) varies with the type of raw material, raw material quality, extraction conditions, solution pH, amount of inorganic salts, agar concentration, temperature and electrolyte added during measurement.
Generally speaking, natural polysaccharides with strong coagulation ability have a lower solution viscosity, and agar has a strong coagulation ability and lower viscosity.
During the extraction process, industrial agar is damaged to a certain extent due to chemical reagent treatment, and its viscosity is low. In addition, the viscosity of agar drops significantly when the agar solution is subjected to high temperature, electrolyte, inorganic acid or acid salt.
5. Non-acidic degradation
A large number of experiments and studies on viscosity, diffraction and gel strength have proved that pure dry agar has good stability and is difficult to degrade at room temperature.
However, factors such as impurities, high temperature, ultrasonic waves, strong γ-rays, and strong stirring can cause the molecular chains of agar to break and degrade, and some physical and chemical properties of agar will deteriorate.
6. Gel The most important feature of
agar is its gelatinity. Even an agar solution with a concentration of 0.004% can form a gel at room temperature. Compared with other substances that can form a gel, it can gel at the same concentration Maximum strength. When agar forms a gel, no coagulant is needed. The strength of the gel is related to the type of raw material, growth environment, collection season and extraction method, and is also closely related to its chemical composition and structure.
02
Applications in the food industry
Agar has the stability of gelation and gel, and has the functions of bulking agent, thickener, emulsifier, gelling agent, stabilizer, excipient, suspending agent, and moisture retaining agent in the food industry. Widely used in the food industry.
1. Application
in confectionery Agar is used as a gelling agent in the confectionery industry, mainly used to make soft candies. According to the gelling ability of agar, the amount of agar in the fudge is generally 1%-2.5%, and the carbohydrates are mainly sucrose, supplemented by starch syrup, and the ratio is about 3:2.
The soft candy made of agar has better transparency, quality and taste than other soft candies. Although agar has been used as a traditional gel substance in candy making for a long time, practice has shown that its taste characteristics are relatively simple. In recent years, gelatin, modified starch, fruit juice/fruit puree or melon and fruit are often added, which helps candy to mix materials. The diversity of composition is conducive to the improvement of flavor and mouthfeel.
The pumpkin soft candy developed by Gu Yong and others has a ratio of 200g of sucrose, 15g of agar, 250g of pumpkin, and 0.3g of citric acid. sugar.
2. Application in canned food
In poultry and meat canning, agar acts as a gelling agent and excipient, forming a gel that effectively binds minced meat and eliminates brittleness of food tissue in cans. Its dosage is 0.2% -2.0% of the clear soup in the can.
In eight-treasure porridge, white fungus bird's nest, soup canned food, use 0.3%-0.5% agar as thickener
Agents and stabilizers can improve the taste, disperse other additives uniformly, and prevent precipitation and stratification.
3. Application in beverages
Agar is used in beverage products as a suspending agent to make the solids in the beverage evenly suspended and not sink. Its suspension time and shelf life are long, which cannot be replaced by other suspending agents. The product has better transparency, fluidity, smooth taste and no peculiar smell.
It shows excellent suspending effect in fruit beverage, and the concentration of 0.001% -0.005% can make the fruit suspend evenly.
4. Application
in jelly Adding agar in the jelly manufacturing process can be used as a stabilizer and gelling agent, which can make the particles suspend evenly without sedimentation or stratification. According to the gelling ability of agar, the general dosage is 0.15%-0.3%.
5. Application in cold drinks
Agar is used in cold food, such as popsicles, ice cream and other frozen products, which can reduce ice crystals, improve resistance to heat and melt, and make the product more refreshing.
In the production of ice cream, agar can improve the tissue state of ice cream, increase the viscosity and expansion rate of ice cream, prevent the precipitation of ice crystals, and make the structure of the product fine and smooth. The usage amount is about 0.3%. Agar, combined with locust bean gum and gelatin, plays an excellent role in the texture and flavor stability of cold drinks, and can prevent syneresis and surface crusting.
The optimal concentrations as stabilizers are: agar 0.12%, locust bean gum 0.07%, and gelatin 0.2%.
6. Application in baked food
Agar can be used as a filler, leavening agent and water retention agent, and is widely used in a variety of baked foods. For example, bakery food production plants use agar for the shell of cookies, cream sandwich pies, pies, meringues on the surface of pastry sweethearts, meringue cones, etc. As a slightly binding additive: agar has no nutritional value, but also as a filler and leavening agent, can replace starch to make oatmeal paste, starch-free bread and post-dinner snacks, and make it a low-calorie food. Biscuits also play a moisturizing and insurance role.
In baked goods, the amount of agar used is generally 0.1% -1.0%.
7. Application in dairy products
Agar can effectively reduce the synergy of dairy products, enhance stability and emulsification, and is widely used in dairy products. Adding agar to French cottage cheese, cream quiche, and fermented milk products has good stability and toughness, and also helps to improve the consistency and sliceability of cheese. The amount of agar used in dairy products is generally 0.05%-0.85%, and it is better to use it in combination with manna gum and xanthan gum.
8. Application
in sugar-coated food In sugar-coated food, agar can be used as a stabilizer for sugar coating, and can also prevent the food from sticking to the package. The content of agar in sugar-coated food is usually between 0.2% and 0.5%.
Based on the amount of sugar required, when the concentration of agar reaches 0.5%-1.0%, it can be used as a stabilizer for the transparent sugar coating of the oil cake. The agar stabilizer improves the viscosity of the transparent sugar coating and the adhesion on the surface of the oil cake, and promotes faster gelation. Solidifies and increases flexibility to reduce surface defects and cracks.
While the melting temperature of the gel is increased, the liquid absorption and softening tendency of the oil cake is reduced. In applications, agar is often mixed with other vegetable gums such as guar and locust bean gums.
9. Application in meat products
Agar is used in meat product processing, which can effectively maintain the flavor of the product. Agar is used for stuffing sausage, smoked or calf meat products, which can obviously protect its colloid and prevent its flavor loss.
For this purpose, the cooked ham can also be covered with a solution containing agar and ascorbic acid. After packaging, the meat products treated with agar retain their original flavor better than untreated meat products and meat products treated with ascorbic acid alone.
10. Other food applications
In the brewing industry, agar is used as a clarifying agent for beer, soy sauce and edible vinegar to accelerate and improve product clarification; agar is used as a substitute for gelatin because of its unique physical and chemical properties, such as high melting point and low mold resistance. side use.
https://www.arshinefood.com/detail/Industry-Information/The_application_and_characteristics_of_agar.html
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