Processing technology of hard candy
Hard candy is a candy made by boiling at high temperature. The dry solid content is very high, about 97%. The sugar body is hard and brittle, so it is called hard sugar. It belongs to amorphous amorphous structure. The specific gravity is between 1.4 and 1.5, and the reducing sugar content ranges from 10 to 18%. It dissolves slowly in the mouth and is chewable. Sugar bodies are transparent, translucent and opaque, and some are drawn into mercerized shapes.
The types of hard candy include fruit flavor, cream flavor, cool flavor, white control, sand mixing and roasted hard candy. The requirements for fruit flavored hard candy are to be the same as the color, aroma, taste and shape of the fruit.
It includes carbohydrates such as double monosaccharides, high sugars and dextrins. The composition of various sugars in hard sugar is as follows:
80~50% sucrose reducing sugar 10~20% dextrin high sugar 10~30%
The flavoring materials used in hard candy include two parts: one is fruit flavored hard candy. The flavoring materials they use include spices, essence and organic acids. The ideal natural flavor is not only mellow, but also non-toxic and harmless. Synthetic essence is composed of esters, aldehydes, ketones, alcohols, acids, terpenes and other aromatic compounds. The aroma is strong, and excessive addition will hinder food hygiene, and the amount of addition shall not exceed the limit of food hygiene standards. Citric acid is the main organic acid for flavoring in candy. In addition, tartaric acid, lactic acid or malic acid can also be used. The flavoring materials play an important role in forming the flavor of hard sugar.
Fruit hard candy
Fruit hard candy
Another flavoring material for hard candy is natural food. Such as dairy products, cocoa products, tea, wheat milk essence and nuts. After addition, not only the flavor of hard candy is improved, but also the structure and state of hard candy are changed, making hard candy unique.
The materials used for hard sugar tinting include natural colorants and artificial pigments. It is recommended to use natural colorants in candy because of its high edible safety. When using synthetic pigments, the limit specified in the food hygiene standard must be strictly observed.
When designing and producing hard candy, both the sugar body itself and the packaging materials should meet the color, fragrance, taste and shape requirements of the candy.
Granular sugar is a crystal formed by many sucrose molecules arranged in order. When water is added for dissolution, sucrose molecules will disperse and dissolve in water. When heated and boiled under acidic conditions, part of the sucrose molecules are hydrolyzed into invert sugar, which together with the added starch syrup is concentrated to form a sugar blank. The sugar blank is an amorphous structure composed of a mixture of sucrose, invert sugar, dextrin and maltose.
The characteristics of the amorphous sugar compacts are instability. They have the characteristics of gradually transforming into crystals, which is called sand return. In order to maintain the relative stability of amorphous sugar, it is necessary to add anti crystallization substances. There are many kinds of anti crystallization substances, such as colloidal substances, dextrins, reducing sugars and some salts. However, the mixture of dextrins and reducing sugars, namely starch syrup, is often used in candy production to improve the solubility and viscosity of sugar solution and limit the sand return caused by rearrangement of sucrose molecules. In addition, inverting agents can also be added into the sucrose solution, and the invert sugar produced by boiling can be used as an anti crystallization substance to manufacture candy.
Another characteristic of amorphous sugar is that there is no fixed freezing point. When the boiled sugar paste is poured into the cooling table, the viscosity of the sugar paste increases as the temperature decreases, and the liquid sugar paste becomes a plastic sugar paste, which becomes a solid after cooling. That is to say, there is a wide temperature range from liquid sugar paste to solid sugar paste without a fixed freezing point, which is also the common property of amorphous materials. This feature is used in candy production to add seasonings, mix, cool, pull and shape. The characteristic that candy has no fixed freezing point is the theoretical basis for formulating candy production operation rules.
The dry solid balance and reducing material balance of materials should be determined in the batching. The sum of the dry solids of each material added in the ingredients shall be equal to the sum of the dry solids in the finished product plus the dry solids lost in the production process. In order to achieve better technical and economic results, it is necessary to constantly improve the level of technology to reduce the loss in the production process and improve the yield. The wet weight of each material multiplied by the sum of the percentage content of dry solids of each material is the total weight of dry solids. The total weight of the finished product can be obtained by multiplying the total weight of the finished product by the percentage of dry solids in the finished product. The sum of dry solids of each material in the ingredients minus the weight of dry solids in the finished product is the loss of dry solids in the production process. The data of moisture or dry solids in various materials and finished products can be obtained through the analysis of the laboratory.
The reducing sugar in the finished product comes from two sources: one is the reducing sugar added to the material; The second is reducing sugar produced in the process of sugar melting and boiling. The sum of these two reducing sugars is the reducing sugar in the finished product. The reducing sugar in the material can be analyzed by the laboratory to obtain data; The amount of reducing sugar produced in the production process must be determined according to the experience of our factory and the acidity of starch syrup.
The purpose of sugar melting is to fully separate the sugar crystal with proper amount of water. Otherwise, with the continuous increase of sugar concentration during sugar boiling, the uncooked granulated sugar crystal will become a crystal in the supersaturated sugar solution, causing a large area of sugar liquid to return to sand, which is especially serious in the case of mechanical or pipe friction, especially on the vacuum sugar boiling pot or iron plate.
In order to fully separate the granulated sugar crystal, a certain amount of water needs to be added, but too much water will inevitably prolong the sugar boiling time, increase the reducing sugar content, deepen the color and consume energy. Therefore, the requirement for sugar melting is: add an appropriate amount of water to melt the sugar in a short time. In order to achieve this goal, it is required to use hot water and increase the sugar melting temperature to reduce the amount of water added and shorten the sugar boiling time.
From the solubility of sucrose, it can be seen that at 90 ℃, only 20% water is needed to complete the task of saccharification. But in actual production, this theoretical data alone is not enough. According to experience, 30% of the total dry solids should be added with water. This includes moisture in wet materials.
The purpose of boiling sugar is to remove the excess water in the sugar solution, so that the sugar solution can be concentrated. It is much more difficult to absorb the water in the sugar solution than to remove the water in other foods. This is because the viscosity of the sugar solution becomes larger and larger as the concentration of the sugar solution increases. In the later stage, it is more difficult to remove the water in the concentrated sugar solution. It is difficult to remove the excess water in the sugar paste with general methods. In addition, the evaporation and concentration of water in the sugar solution should be completed in the continuous heating process. In this way, it needs to be boiled at high temperature.
According to different sugar boiling equipment, it can be divided into normal pressure sugar boiling, continuous vacuum sugar boiling and continuous vacuum film sugar boiling.
(1) Boiling sugar under normal pressure: Boiling sugar under normal atmospheric pressure is also called boiling sugar under open fire or open pot. As the concentration of sugar increases, its boiling point increases. For example, when the concentration of sucrose solution is 94.9%, its boiling point is 130 ℃. When the concentration is 98%, the boiling point is 160 ℃. Therefore, to obtain hard sugar with 2% water content, you need to boil it to 160 ℃.
When boiling sugar begins, the foam of syrup is large and easy to burst. With the boiling process, the concentration gradually increases, the foam gradually becomes smaller, and the beating is slow. With the further increase of temperature, the concentration increases, the viscosity increases, the surface foam is smaller, and the bounce is slower; The sugar liquid changes from light yellow and golden yellow to brown yellow. At this time, a small amount of sugar paste can be dropped into the cold water. If it forms a hard ball immediately and chews and cracks, it is the end of sugar boiling. Of course, you can also insert a thermometer to control the temperature of the boiler.
The higher the acidity of the sugar solution, the higher the boiling temperature, the longer the boiling time, and the higher the yield of reducing sugar, decomposition products, and color. In order to obtain an ideal product, these three conditions should be controlled in boiling sugar under normal pressure.
(2) Continuous vacuum sugar boiling: The advantage of vacuum sugar boiling is to use vacuum to reduce the boiling point of sugar liquid, evaporate more water at low temperature, and avoid sugar from decomposing and discoloring at high temperature, so as to improve product quality, shorten sugar boiling time, and improve production efficiency.
The continuous vacuum boiling device is mainly composed of heating, evaporation and vacuum concentration. The main part of the heating part is a serpentine heating tube. The sugar solution is heated to about 140 ℃ in a very short time through the serpentine heating tube, and the concentration is close to 96%. Then enter the evaporation chamber to remove the secondary steam in the sugar solution; After that, the sugar solution enters the vacuum concentration chamber, and the vacuum degree is maintained above 700mm Hg. Then a small amount of water is removed. The temperature of the syrup drops to 112-115 ℃, and it flows into the rotary pot to complete the sugar boiling operation.
(3) Continuous vacuum film sugar boiling: The vacuum film sugar boiling uses a sandwich pot, and its inner layer is equipped with a rotor shaft with many scrapers. When the rotor shaft rotates, the scraper rotates along the inner wall of the sandwich pot, and its top is equipped with an exhaust fan.
In production, when the pure sugar liquid flows from the upper part of the sandwich pan to the inner layer of the sandwich pan through the heating pipe, the scraper rotates on the inner wall of the sandwich pan. Due to the centrifugal force, the sugar liquid is thrown onto the inner wall of the sandwich pan. At the same time, the scraper scrapes the sugar liquid into a film about 1mm thick. The sugar liquid film and the inner wall of the sandwich pan conduct a rapid heat exchange process, and the moisture in the sugar liquid is rapidly vaporized. The hot steam is discharged by the exhaust air. At the same time, it also vacuumizes the sandwich pot. The concentrated sugar drops along the wall of the pot to the bottom of the vacuum chamber. Under the condition of reduced pressure, the syrup continues to remove the residual water, and at the same time inhales the measured acid solution of the pigment. The syrup is transported to another mixer along the pipeline and mixed with spices. Then, the film is molded and the sugar boiling cycle is very short, about 10 seconds.
Cooling and blending
The newly boiled sugar paste is very hot and needs to be cooled. After moderate cooling, add pigment, essence and citric acid. If the temperature of adding essence is too high, the aroma components will volatilize, while the temperature of adding essence is too low, and the viscosity of the sugar paste is too high, so it is difficult to mix evenly. Therefore, the temperature of adding essence must be well controlled.
After adding essence and seasoning to the candies, they need to be mixed and stirred immediately. The method of stirring is to fold the candies that touch the cooling table to the center of the candies and fold them repeatedly to make the temperature of the whole candies drop evenly. If improperly mixed, not only the essence and citric acid are unevenly distributed, but also the sugar briquettes are brittle due to uneven heating. It causes rough edges and broken corners during forming.
When the sugar is mixed until it is hard and soft with good plasticity, it must be immediately sent to the insulation bed for molding.
The molding process of hard candy can be divided into continuous stamping molding and continuous pouring molding.
(1) Continuous stamping: When the sugar briquette is cooled to a suitable temperature, it can be stamped. If the temperature is too high and the sugar body is too soft, it is difficult to form. Even the formed candy is easy to stick or deform. If the temperature is too low and the sugar body is too hard, the formed sugar particles are easy to darken and have missing edges and corners. The appropriate temperature for stamping is 80-70 ℃. At this time, the sugar blank has the most ideal plasticity. The stamping process is to use the characteristics of the sugar blank at this temperature, stretch the sugar blank into strips with a stretcher or manually, and then enter the molding machine for stamping.
During stamping, attention should be paid to the temperature and relative humidity in the molding workshop and the mold surface temperature of the molding machine, otherwise it is easy to break the strip or stick the machine. The molding temperature shall not be lower than 25 ℃ and the relative humidity shall not exceed 70%.
(2) Continuous casting molding: Continuous casting molding is a new technology developed. The sugar paste boiled from the continuous vacuum film is poured into the continuously running model plate through the casting die head, and then rapidly cooled and shaped, and then it is removed from the model plate.
The continuous casting molding machine has many advantages. It combines the processes of cooling, blending, turning, moisturizing, bracing, stamping, cooling and conveying before stamping into one process. It greatly reduces the working procedures, improves the labor productivity, reduces the floor area, improves the food hygiene conditions, improves the transparency and smoothness of products, and promotes the continuity and automation of candy production. The new candy pouring machine is not only suitable for pouring hard candy, but also suitable for pouring other candy.
Picking and packaging
Picking is to select out the unqualified sugar grains, such as missing corners, cracks, bubbles, impurities, and irregular shapes, to maintain the quality of hard sugar and avoid blocking the packaging machine.
Unqualified sugar grains selected shall be separated according to color and flavor, especially the impurities shall be removed to avoid polluting the good sugar. The returned sugar grains shall also be separated and shall not be mixed into the reworked products.
Hard candy is made by dispersing water under high temperature and vacuum. Its equilibrium relative humidity value is very low. As long as the relative humidity of the air is greater than 30%, it will be in a hygroscopic state. In order to keep the hard candy from melting and sanding, the molded hard candy should be packaged in time.
The function of packaging is to protect the hard candy from melting and sand, and to make the hard candy have a beautiful and attractive appearance.
The requirements for packaging are: tight, straight, no cracking, no belly breaking, no corner breaking, no wrinkles in the middle, no skew around the trademark, and the two ends should be twisted to 3/4 turn. The wrapping paper closely fits the sugar granules, leaving no space. It is not necessary to wrap sugar with wet wrapping paper or wrapping paper with wrong flavor.
Packaging paper is divided into mechanical packaging and manual packaging. The requirements for the packing room are: the temperature is below 25 ℃, and the relative humidity is not more than 50%. Air conditioning device is provided.