Hard candy is a complex and crunchy candy that is rich in variety and taste. Our hard candy-making machine transforms granulated sugar into hard candy step by step, which needs to go through the process of melting, boiling, cooling and moulding.

What is hard candy? What are the properties of hard candy?

Hard candy is a candy that is boiled at a high temperature. The dry solid content is high, about 97% or more. The sugar body is hard and brittle, so it is called hard candy. It belongs to the amorphous non-crystalline structure. The specific gravity is between 1.4~1.5, and the sugar content ranges from 10~18%. It dissolves slowly in the mouth and is resistant to chewing. The sugar body is transparent, translucent and opaque, and there are also pulverized ones.

Types of hard candy

The flavour is divided into fruit flavour type, creamy flavour type, excellent flavour type, etc. The requirement of fruit flavour type hard candy is the same as the colour, fragrance, taste and shape of that fruit.

Composition of hard candy

Hard candy is composed of two primary components: sugar and flavouring and colouring materials.

1. Sugar:

Including double monosaccharides, high sugar, dextrin and other carbohydrates. The composition of various sugars in hard candy is as follows.
Sucrose 50~80%, reducing sugar 10~20%, dextrin high sugar 10~30%.

2. Flavoring:

The flavouring used in hard candy has two parts: fruit-flavoured hard candy and natural food, and the sauce used in fruit flavouring have spices, herbs and organic acids. The most ideal is the natural flavouring; not only is the fragrance mellow, but also non-toxic and harmless. Synthetic extracts are made from aromatic compounds such as esters, aldehydes, ketones, alcohols, acids and alkenes. The aroma is strong, and adding too much will hinder food hygiene, and the amount added should not exceed the limits of food hygiene standards. Citric acid is the leading organic acid used for flavouring in confectionery. Also, tartaric acid, lactic acid or malic acid can be used. Dressing plays a vital role in forming the flavour of hard candy.

Another type of flavouring for hard candies is natural foods. Examples include dairy products, cocoa products, tea, cream of wheat, nuts, etc. After adding, it improves the flavour of hard candy and changes the structure and state of hard candy, which gives hard candy a unique style.

3. Coloring materials:

Hard candy colouring materials used are natural colouring agents and synthetic colours. Advocate the use of biological colouring agents in the candy because of high food safety. When using artificial colouring, the restrictions set by food hygiene standards must be strictly observed.

In the design and production of hard candy, both the sugar body and the packaging materials must meet the colour, aroma, flavour, and shape requirements needed for that candy.

Physicochemical principle of hard candy

Granulated sugar is a crystal made of many sucrose molecules arranged neatly. When dissolved with water, the sucrose molecules are dispersed and dissolved in the water. When boiled under acidic conditions, part of the sucrose molecules is hydrolyzed to transform sugar. The starch syrup added is concentrated to form a sugar billet, a non-crystalline structure composed of a mixture of sucrose, convert sugar, dextrin and maltose.

The non-crystalline structure of sugar blanks is characterized by instability and has the property of gradually becoming crystalline. To maintain the relative stability of non-crystalline sugar blanks, anti-crystalline substances need to be added. There are various anti-crystalline substances, such as colloids, gum extracts, reducing sugars and some salts. Still, the commonly used anti-crystalline importance in candy production is a mixture of gum extracts and reducing sugars, i.e. starch syrup, which improves the sugar's solubility and viscosity solution and limits the return sand of the rearranged sucrose molecules. Also, converted sugar cooked with a sucrose conversion agent can also be used as an anti-crystalline substance for candy making.

Another characteristic of non-crystalline structured sugar blanks is that they do not have a fixed freezing point. After pouring the cooked syrup into the cooling table, the syrup's viscosity increases as the temperature decreases, and the fluid-like syrup becomes malleable and finally becomes solid. In other words, it changes from liquid syrup to multi-solid sugar billets with a wide range of temperatures and a fixed freezing point. This is also a common characteristic of non-crystalline substances. Candy production takes advantage of this property by adding flavourings, mixing, cooling, stretching, and moulding operations. The property that sugar billets do not have a fixed freezing point is the theoretical basis for developing operating procedures for candy production.

How does our hard candy-making machine produce hard candy step by step?

The balance of dry solids of materials and also raw materials must be determined in raw materials. The sum of each material's dry solids added to the raw material should be equal to the sum of dry solids in the finished product and the dry solids lost in production. To achieve good technical and economic results, it is necessary to continuously improve the technical level, reduce production losses, and improve the finished product rate. The wet weight of each material is multiplied by the sum of each material's dry solids content, which is the total weight of dry solids to be input. The finished product's total weight is multiplied by the content of the finished dry solids to get the total weight of the finished dry solids. The total sum of each material's dry solids in the raw material minus the weight of dry solids in the finished product, which is the loss of dry solids during the production process. The data of moisture and dry solids in each material and the finished product can be sought by laboratory analysis.

There are two sources of reducing sugars in the finished product. One is the reducing sugar added to the material, and the second is the reducing sugar produced during the sugar and sugar cooking process. The sum of these two reducing sugars is the reducing sugar in the finished product. The amount of reducing sugar produced in the material production can be obtained by analysis in the chemical examination room. The amount of reducing sugar produced in the output must be determined by the factory's experience and the starch syrup's acidity.

2. Melt the sugar:

Melting sugar is done by fully melting sugar crystals with the appropriate amount of water. Otherwise, the sugar solution concentration increases during sugar boiling, and the unmelted sugar crystals become crystals in the saturated sugar solution, which is especially serious when the machinery and piping are rubbed together, which is especially likely to happen in the vacuum sugar boiling pot and iron plate.

To fully melt the sugar crystals, a certain amount of water needs to be added, but adding too much water necessitates longer cooking time, increased sugar content, deeper colour and energy consumption. Therefore, the requirement for melting sugar is to add the right amount of water to dissolve the sugar in a short time completely. To achieve this, it is necessary to increase the saccharification temperature with hot water, reduce the amount of water added and shorten the saccharification time.

In terms of sucrose's solubility, the saccharification task can be accomplished with 20% water at a temperature of 90°C. However, in actual production, it is not enough to rely on this theoretical data alone. As a rule of thumb, 30% of the dry solids need to be added—the water in this packet material.

3. Boiling sugar

The purpose of boiling sugar is to remove the excess water in the sugar solution and concentrate it. Attaching water to the sugar solution is much more complex than removing water from other foods. This is because as the concentration of sugar liquid increases, sugar liquid's viscosity becomes larger and larger. The more difficult it is to remove the water in the concentrated sugar liquid. It becomes difficult to remove the excess moisture in the sugar paste using the general method. The evaporation and concentration of water in the sugar liquor require to be done in a continuous heating process. This requires boiling at high temperatures.

The sugar boiling equipment can be divided into atmospheric pressure sugar boiling, continuous vacuum sugar boiling, and constant vacuum film sugar boiling.

(1). Atmospheric pressure sugar boiling: The atmospheric pressure method is to boil sugar under normal atmospheric pressure, known as open fire sugar boiling or empty pot sugar boiling. As the concentration of sugar gets more extensive, its boiling point gets higher. When the concentration of sucrose solution is 94.9%, the boiling point is 130℃. At a concentration of 98%, its boiling point is 160°C. Therefore, if you want 2% complex sugar, you need to boil it to 160°C.
At the beginning of boiling sugar, the syrup foam is large and easy to break. As the concentration gradually increases with boiling, the foam gradually becomes smaller while jumping slowly. As the temperature increases further, the concentration increases, the viscosity increases, the surface foam becomes smaller, and the sugar solution with slow jumping turns from light yellow and golden yellow to brownish-yellow. At this point, a small amount of syrup can be dropped into cold water and immediately made into a hardball, chewed brittle and cracked to reach the end of cooking sugar. Of course, you can also insert a thermometer to control the temperature of the pan.

The greater the sugar solution's acidity, the higher the cooking temperature, the longer the cooking time, and the higher the amount of reducing sugar produced, the decomposition products, and the coloration, etc. To get the ideal outcome, these three conditions, namely acidity, temperature and time, must be controlled in sugar's boiling by the atmospheric pressure method.

(2). Continuous vacuum boiling sugar: The advantage of vacuum boiling sugar is to use a vacuum to lower the boiling point of sugar liquid, evaporate a large amount of water at low temperature, avoid sugar decomposition and discoloration at high temperature, improve product quality, shorten sugar cooking time and increase production efficiency.
The continuous vacuum cooking device mainly consists of three parts: heating, evaporation and vacuum concentration. The heating part's main component is the serpentine heating tube, through which the sugar solution is heated to about 140℃ in a short time, with a concentration of close to 96%. Then it enters the evaporation chamber. After removing the secondary stream in the sugar solution, the sugar solution enters the vacuum concentration chamber. The vacuum is kept above 700 mm of mercury column to remove a small amount of water. The temperature of granulated sugar drops to 112-115℃ and flows into the pot to complete the sugar boiling operation.

(3). Continuous vacuum film boiling sugar: Vacuum film boiling sugar utilizes a sandwich pan with a rotor shaft equipped with many scrapers in the inner layer, and when the rotor shaft rotates, the scrapers rotate along the inner wall of the sandwich pan without an exhaust fan in the upper part.
In production, pure sugar liquid through the heating pipeline from the upper part of the sandwich pan into the inner layer of the sandwich pan when the scraper rotates in the inner wall of the sandwich pan, under the action of centrifugal force to throw the sugar liquid to the inner wall of the sandwich pan at the same time, the scraper will scrape the sugar liquid to about 1 mm thick film sugar liquid film and the inner wall of the pan for rapid heat exchange process, the moisture within the sugar liquid quickly vaporized. The hot steam emission is exhausted at the same time, and it also evacuates the sandwich pan into the vacuum; the concentrated sugar solution falls along the wall of the pan into the vacuum chamber at the bottom, under the condition of reduced pressure, the syrup continues to remove the residual water while inhaling the measured solution of pigmented acid. The syrup is piped along to another mixer where the spices are added and mixed. Then the mould is poured and moulded. The film cooking sugar cycle is short, only about 10 seconds.

4. Cooling and blending:
Freshly boiled syrup, with high temperature, needs to be cooled. After moderate cooling, add colouring, flavouring and citric acid. A too high temperature of adding seasoning will volatilize the aroma components. A too low temperature of adding seasoning will make the syrup viscosity too high and difficult to blend evenly, so we must grasp the temperature of adding flavouring.

After adding flavouring and seasoning to the syrup, it must be blended and mixed immediately. The mixing method is to fold the syrup in contact with the cooling table to the center of the sugar block and fold it repeatedly to reduce the sugar block's overall temperature evenly. If not mixed properly, the flavouring and citric acid are not evenly distributed. The sugar briquettes are brittle due to uneven heat, causing broken corners during moulding.

When mixing and blending until the sugar billet is soft and moderate with good plasticity, it must be sent to the heat preservation bed for moulding immediately.

5. Forming:

Complex sugar moulding technology is divided into continuous stamping moulding and continuous stamping moulding.

(1). Continuous stamping forming: When the sugar billet is cooled to the proper temperature, it can be stamping formed. If the weather is too high, the sugar is soft and difficult to be started, and the sugar block is also easy to stick or deform. Simultaneously, if the temperature is too low, the sugar billet is complex, and the formed sugar grains are easy to have hair darkening and edge fracture. The appropriate temperature for stamping and forming is 80-70℃ when the sand sugar billet has the ideal plasticity. Stamping and forming uses the characteristics of the sand sugar billet at this temperature, stretch the sand sugar billet with a drawing machine or manually, and enters the forming machine for stamping and forming.
When stamping and moulding, attention must be paid to the temperature and relative humidity within the moulding site and the temperature of the moulding machine's mould surface. Without that, it is easy to break or stick to the device. The moulding room should preferably be above 25℃ and relative humidity not more than 70%.

(2). Continuous casting moulding: Continuous casting moulding is a new technology developed in recent years. The syrup cooked by continuous vacuum film is injected into the pouring machine head in a continuously running template, rapidly cooled and shaped, and finally dislodged from the template.
The advantages of continuous pouring mould forming machines are many. The processes of cooling, blending, mixing, moisturizing, stretching, press moulding, cooling and transporting before press moulding are combined into a circle. It dramatically reduces the process, increases labour productivity, reduces floor space, improves food hygiene, improves product transparency and cleanliness, and promotes continuous and automated candy production. This new type of candy pouring machine is not only suitable for hard candy but also other candies.

6. Screening and packing:

Screening is to select sugar particles that do not meet the specification after moulding, such as missing corners, cracks, air bubbles, impurity particles, uneven form, etc., to maintain the quality of hard candy and avoid blocking the packing machine.

Screening does not meet the specifications of sugar particles, according to the colour, aroma separation, especially to remove impurity particles, do not pollute the sugar, also need to separate the sugar particles returned to the sand, shall not be mixed with the returned products.

Complex sugar is made by dispersing water under high temperature and vacuum. Its equilibrium relative humidity value is low and becomes hygroscopic whenever air's relative humidity exceeds 30%. To keep the hard candy from melting, the moulded hard candy must be packed immediately.

The purpose of packaging is to protect the hard candy from melting and give it a beautiful appearance.

The packaging requirements are tightly wrapped, not crooked, not cracked, no wrinkles in the middle, no skew around the trademark, wrapping paper and sugar grains are closely connected, leaving no gaps, no wet wrapping paper or fragrance type of the wrong wrapping paper wrapping sugar.

Wrapping paper is divided into mechanical packaging and manual packaging. The requirements of the packaging room are temperature below 25℃ and relative humidity below 50%. It is better to set up an air conditioning unit.

We need to maintain and repair the complex candy-making machine in production operation time, so what needs our attention? Let's read this post; click to learn → Equipment maintenance.

SINOFUDE is a hard candy-making machine manufacturer. If you are looking for candy equipment, welcome to contact us, our kit includes a hard candy machine, soft candy machine, Chocolate Enrobing machine, etc. 

We have professional after-sales engineers to fully assist and support our customers who purchase the equipment, to help you get a better experience. To help you achieve a better experience and help you achieve tremendous success.