Gel candy is an elastic and chewy food product made of edible gum and sugar as the main material, and its moisture content is higher than 10%. In the actual production of gel confectionery, due to the high moisture content, the selection of hydrophilic colloid will affect the final quality and characteristics of gel confectionery, on the gel confectionery commonly used edible gums and their characteristics, in order to provide a reference for the optimization of the process of gel soft candy.

Gel confectionery commonly used edible gum[1]

Pectin
Pectin is a polysaccharide polymer compound, widely found in plants, mainly extracted from citrus fruits, apples, beets, figs, potatoes, peanuts, sunflower and other plants, leaves, skin, stems and fruits, extracts are processed into powder or liquid. Most of the pectin powder is now used on the market, and pectin liquid accounts for less. Pectin is the main component of soluble dietary fiber, is a non-starch polysaccharide, dissolved in 20 times water into a viscous liquid, insoluble in ethanol and other organic solvents.

Pectin is weakly acidic in aqueous solution and is stable to heat and acid. Pectin has the role of gel, thickening and stabilization. Natural pectin exists in the original pectin, pectin and pectic acid in three forms. Soft candy made of pectin has the advantages of soft texture, fine structure, pleasant taste and long shelf life, and compared with starch soft candy, pectin soft candy production is easy and short cycle.

Pectin is also used in many other confectionery products to regulate the textural properties of the product, which has the properties of flavor release, high transparency and non-sticky teeth. The nature and amount of pectin determines the softness and firmness of the fondant. The production of soft candy is usually used to make a strong gel effect of high methoxyl pectin, the general additive amount is controlled at 2% ~ 3%. Too much calcium in the water used to dissolve pectin can lead to incomplete dissolution of pectin.

The methods to increase the solubility of pectin are to lower the pH value of the solution, increase the temperature, and lower the calcium content in the water. Pectin gummy candy has a refreshing taste, can release the flavor well, and is mostly used in the preparation of fruit-flavored gummy candy. Pectin fudge cut surface neat, short silk texture, chewiness is poor, while the gelation process on the pH value of the requirements of harsh, in the preparation of gel fudge application is limited.

Second, gum arabic
Gum arabic consists of about 98% polysaccharide and 2% protein. Gum arabic high solubility in water, the solution viscosity is low, 50% of the aqueous solution is still fluid, typical of “high concentration and low viscosity”, and other hydrophilic colloids do not have this feature. Gum Arabic is insoluble in organic solvents such as ethanol. The natural pH value of gum arabic solution is weakly acidic, generally at pH 4~5, with the characteristics of a more stable acid environment.

General heating will not change the nature of the gum in gum arabic solution, but the emulsification properties of the colloidal molecules will be due to the solution for a long time at high temperature heating and decline. Gum arabic has the role of preventing sugar crystallization, used as an anti-crystallization agent in gel candy, can prevent the precipitation of sucrose crystals.

Third, carrageenan
Carrageenan is based on red algae plants as raw materials, water or lye and other extracts. Carrageenan is odorless, tasteless white to yellow-brown powder. Due to the different sulfate binding forms in carrageenan, there are mainly 7 types of carrageenan: K-type, I-type, λ-type, γ-type, ν-type, ξ-type, μ-type, at present, the main production and use of K-type, I-type and λ-type 3 types of carrageenan, which is most common in K-type carrageenan.

Different types of carrageenan have different gel characteristics. For example, K-type carrageenan can form a hard and brittle gel, and I-type carrageenan can form a soft and elastic gel. Different types of K-type and I-type carrageenan can be compounded in the preparation of gel soft candy to meet different texture and taste requirements.

Fourth, gelatin
Gelatin, also known as animal gelatin, gelatin, etc., from animal bones, skin, tendons, tendons and scales and other raw materials obtained by moderate hydrolysis. Gelatin solution formed by the gel can not flow and has a certain hardness. When conditions such as the composition of the solution, pH, ionic strength, temperature, light intensity or electric field are changed, the gelatin gel undergoes abrupt changes and phase transition behavior occurs.

Xu Xiaofei et al. showed that the hardness of gelatin soft candy increased with the addition of gelatin, chewiness became stronger, and the viscosity was minimized when the gelatin addition was 6%. The gelatin gelatine made from pig skin is hard and chewy; the gelatine made from fish scales is small in hardness, weak in chewiness, poor in thermal stability and sticky; the gelatine made from cow skin and cow bone is moderate in hardness and chewiness.

In the production process of gelatin candy, gelatin with water absorption and support the role of the skeleton, gelatin dissolved in water can form a net-like structure, so that the soft candy can maintain a stable form, enhance the candy load bearing degree, not easy to deform.

V. Modified starch
Modified starch is also called modified starch. The use of modified starch good gelling properties, film-forming properties and viscosity, modified starch in soft candy as a gelling agent, to provide gel structure for the product, can be an appropriate alternative to gum arabic, so that the product has good sensory properties, but also the use of modified starch film-forming properties and viscosity will be used as a polishing agent for candy, the formation of glossy and transparent film, and can reduce the rupture of the product.

Six, agar
Agar is composed of agarose and agar pectin without the ability to gel, can only be dissolved in boiling water, is currently the most effective neutral gelling agent, the formation of the gel is hard, brittle, rough, but the gel of agar has a significant temperature lag, low concentration of agar has a better thermal stability and suspension. The main raw material for agar production is various red algae.

Agar is divided into strip and powder, insoluble in cold water, soluble in hot water. Agar gel transparency is poor, heat-resistant, acid intolerance, especially in acidic conditions for a long time heating, can lose the ability to gel, but its acid resistance can be improved in the candy. The acid resistance of agar is higher than gelatin and starch, and lower than pectin and propylene glycol alginate. Agar is often added to fruit juice in soft candy, the content is usually about 2.5%.

Gellan gum
Gellan gum, also known as Ke Ke gum or clean cold gum, by the Pseudomonas syringae pure species culture of carbohydrates after fermentation, after fermentation, adjust the pH value, clarification, precipitation, pressing, drying and milling and other steps processed and made. Gellan gum has a double helix structure, good stability, acid resistance, high temperature resistance, thermal reversibility, but also resistant to microorganisms and enzymes and other properties.

Gellan gum is a kind of microbial extracellular polysaccharide, often as a multifunctional thickener, gelling agent, stabilizer, etc., widely used in food, medicine (such as soft and hard capsules), cosmetics, chemical industry and many other industries. In the field of confectionery production, it is mainly used in starch jelly, pectin jelly, filling and fruit pulp soft candy.

The application of compound gel agent in gel confectionery[2]

Accompanied by the development of science and technology, the study of two or more natural polymers mixed and compounded has gradually increased, and some of the research is the use of mixed polymer systems for the study and preparation of food instability system.

Natural polymers also account for a large proportion of research, such as pectin, xanthan gum, sodium alginate, carrageenan, heat-denatured whey protein, locust bean gum, guar gum and so on. Due to the single use of edible gum more or less in one aspect have some disadvantages, such as the use of gelatin alone is less elastic, carrageenan is poor water retention, modified starch transparency, poor taste, and when they are in accordance with a certain proportion of the compounding words, it will improve the shortcomings of the use of separate, will be one of the advantages of the maximum, so in the application of gel confectionery, compounding gum is more and more extensive, the various compounding gum of the Formulation, properties and other research will be more and more extensive.

First, carrageenan – gelatin compounding
Carrageenan and gelatin can be used alone as a gelling agent in the gel confectionery, but if so, there are certain limitations when using. Carrageenan in a very low concentration can form a gel, but the formation of the gel has the fatal flaws, namely, the brittleness of large, small elasticity, and poor water retention, which is for the gel candy taste, texture, preservation is a great impact.

Gelatin in low concentrations of solution viscosity is small, and gel temperature is too low, the gel melting point is also too low, not suitable for gel forming at room temperature. The concentration of gelatin must be increased to form a better gel, which makes the amount used larger and results in a waste of resources.

Individual use has defects, in order to improve this limitation, try to carrageenan and gelatin mixing, found that the effect is better, to solve the carrageenan alone poor water retention, poor elasticity of the problem, but also solved the gelatin gel temperature is low, the gel time is long, so there is a synergistic effect of the compounding of carrageenan in order to overcome this limitation, to expand the scope of use of the food glue, drawing on the research of carrageenan and other proteins (soybean isolate protein, cow milk protein) In order to overcome this limitation and expand the use of food gums, carrageenan was compounded with gelatin to change its rheological properties to meet the needs of processing by drawing on the results of research on carrageenan and other proteins (soybean isolate protein, cow’s milk protein), and exploring the application of compounded gum as a gelling agent in the production of soft candies.

Liu Bo et al. studied the effects of shear rate, gel solution concentration, and measurement temperature on the apparent viscosity of κ-carrageenan and gelatin solutions, and compounded the two, and investigated the effects of the compounding ratio, the concentration of the compounded gel solution and the measurement temperature on the apparent viscosity of the compounded gel solution.

Second, modified starch – gelatin compounding
Chen Xiangzhi used modified starch-gelatin compound gum instead of gelatin to produce anti-deformation milk candy; by comparing the gelatin solution and compound gum solution gel properties, viscosity, emulsification and other characteristics, part of the gelatin by the modified starch instead of the results show that gelatin milk candy and compound gum milk candy finished product sensory evaluation and texture analysis error is very small, and compound gum candy has anti-deformation ability. To a certain extent, it solves the defects of small hardness and poor gel characteristics of finished products.

Third, carrageenan – gelatin – sodium alginate compounding
As a kind of plant polysaccharide thickener, sodium alginate is a kind of extracted from seaweed, which is widely used in the food industry, especially in the gel confectionery, through the use of gelatin and carrageenan and other compounding, can play a synergistic effect, give the gel confectionery taste smooth, pliable characteristics.

Fan Suqin et al. mainly explored the effect of sodium alginate on the elasticity, hardness, chewability and other textures of the new gel soft candy, using sodium alginate, carrageenan and gelatin complex polysaccharides three kinds of compound gel as gelling agent, through orthogonal optimization design, to produce a variety of flavors of the gel confectionery, as a reference for other research. Through the one-way and orthogonal test to determine the optimal formula and process of the soft candy as follows: 24% gel content (500MPa-S sodium alginate 4%, carrageenan 4%, gelatin 16%), 15% sugar, maltose syrup 50%, boiling temperature of 108 ℃, the gel time of 12h, the gel strength of the gel can reach the maximum value, gel soft candy taste better.

Fourth, carrageenan – konjac gum – xanthan gum compounding
Konjac gum, carrageenan and xanthan gum are natural gelling agents, and are water-soluble macromolecules, widely used in the food industry. Konjac gum and carrageenan have gel, can form a gel, and xanthan gum does not have the characteristics of the formation of gel, but has a strong thickening, and other colloids when used, can play a role in enhancing the gel. Konjac gum and carrageenan have a very good synergistic effect, can significantly enhance the gel properties such as: water retention, elasticity and so on.

Konjac gum and xanthan gum compound use, on the one hand, can enhance the viscosity, on the one hand, can reduce the amount of additives when used alone, the co-mixture ratio of the two is 7:3, the total concentration of polysaccharides 1%, can form a solid gel, therefore, konjac gum and xanthan gum compound gum is not only a thickener can also serve as a gelling agent, the effect of its effect is much stronger with the nature of the colloid used alone.

Chen Zhemin et al. mainly studied the gel properties of konjac gum, κ-carrageenan and xanthan gum composite gel, the study shows. Its gelation and thickening properties are greatly improved.