Cold filling stands out as a shining star of innovation, promising improved quality and extended shelf life for countless products. But even with its allure, there is a common misconception about this technique that even insiders have. In this article, we’ll delve deeper into this ground-breaking method, breaking down its complexity so that any aspiring beverage manufacturer can understand it.
One of the most common techniques used in the beverage-filling industry is cold filling
What is cold filling exactly?
In beverage production, cold filling is a method used in the filling/bottling stage. Here, a beverage mixture is filled into the container in a cold filling room. The cold-fill beverage mixture must be kept at between 3-5oC during and after the filling/bottling stage. By contrast, the hot fill process requires the beverage mixture to be at around 80oC.
Both the beverage mixture and container must be pasteurized/sterilized before this stage. A special system will heat up the beverage mixture to pasteurize it. This mixture will be cooled down rapidly to ideal temperatures. As for the packaging, it will be cleaned separately using chemicals or other methods.
Cold filling has enabled many new innovations in the beverage market. This method can have significant benefits to consumers and beverage companies.
- It does not require a 2nd pasteurization. Beverages using other filling methods usually need to be pasteurized once more after filling. Meanwhile, cold-filled can be shipped off directly after filling and packing.
- It preserves flavors and taste. Cold-filling minimally impacts taste and flavor compounds like protein or enzyme. As a result, cold filled beverages can preserve a better drinking experience.
- It requires very little preservatives. Cold filled beverages usually need to be refrigerated to preserve flavors. This means preservative use is not compulsory.
- It can produce organic, fresh beverages. Cold filling allows for minimally processed and minimally formulated beverages. It has created a whole new market segment for organic beverages.
However, cold filling is not only used in the beverage industry. For other household goods sectors, aerosol spray products are manufactured using pressurized cold fill. You can check out this process here.
What types of beverages can use cold filling?
For fresh goods like milk and juice, cold filling is a popular technique. To be precise, in order to preserve their freshness and quality, these drinks need to be filled at the same temperature—that is, 5–6°C—during the filling process.
Cold filling for fruit juices
Cold filling is usually required for fresh and organic fruit juice products, most notably cold-pressed juices. This method helps to preserve the natural flavours, aromas, and nutrients of the juice by minimizing exposure to heat, which can degrade these qualities.
The primary steps in the production of fruit juice are pretreatment of the fruit raw materials, juice extraction, clarification and filtration, homogenization, deoxidization, concentration, adjustment of the ingredients, sterilization, and packaging.
The goal of the sterilization process is to eliminate any microorganisms and minimize their impact on the product’s quality. High temperature and short time (HTST) is the approach that is most often utilized.
In a sterile environment, chilled juice is poured into previously sanitized containers. The use of aseptic filling ensures that the juice is not contaminated when being filled. The equipment and filling environment are kept under rigorous sterility requirements.
Aseptic cold fruit juice filling machine
Many types of fruit juice need cold filling production in the factory:
- Organic, real juices: Juices such as orange, apple, and grapefruit, which are prized for their natural flavours and nutrients, are often cold-filled to preserve quality. Furthermore, artificial preservatives and additives are not used in organic juices.
- Cold pressed juices: Cold-pressed juice is extracted using a press that applies thousands of pounds of pressure to fruits and vegetables. This gentle method preserves the original nutrients, making the juice more nutrient-dense than other methods.
- Real, fresh coconut water: Fresh coconut water has a delicate, natural flavour that is easily changed or degraded by heat. A cold filling helps maintain the authentic flavour and aroma of coconut water, ensuring that the final product retains its health benefits intact.
To sum up, cold filling keeps the juice’s nutrients and fresh flavor intact, but it needs to be handled carefully and refrigerated to avoid spoilage.
Cold filling for HTST milk/dairy drinks
For HTST (High-Temperature Short-Time) milk and dairy drinks, cold filling is the process of pasteurizing the milk at high temperatures for a brief amount of time, usually 15 to 30 seconds, between 71.5°C (160°F) and 74°C (165°F). The milk is quickly cooled to a temperature of 4°C (39.2°F) to 5.5°C (42°F) after pasteurization, and then it is filled into aseptic packaging.
Cold filling prolongs the shelf life, nutritional value, and sensory qualities of HTST milk or dairy drinks. It also preserves the integrity of heat-sensitive ingredients and reduces the possibility of flavour deterioration by eliminating the need for additional heat treatment during the filling process.
However, HTST milk must be refrigerated during transportations and storage. This is because many ingredients inside the milk are still chemically active due to the cold fill process.
The following describes how milk and dairy products pass through a plate heat exchanger (PHE) to achieve efficient pasteurization:
Initial Chilling
The balance tank receives a flow of 4°C chilled milk from the bulk milk tank. It is then pumped into the Plate Heat Exchanger’s regeneration section (PHE).
Regenerative heating
In the regenerative heating section, the chilled milk takes up heat from the pasteurized milk that is leaving the system. The heat exchange that takes place with counter-current motion across PHE plates raises the temperature of the milk to approximately 40°C for standardization and 60°C for homogenization.
Heating and Pasteurization
The milk is homogenized and standardized before going into the heating section, where steam raises the temperature to over 72°C, meeting the requirements for HTST (High-Temperature Short-Time) pasteurization.
Holding time
After that, the milk is poured into holding tubes that have been calibrated to guarantee that it will remain at the pasteurization temperature for at least 16 seconds—long enough to kill any pathogens.
Flow diversion
To guarantee that the milk is sufficiently pasteurized, a flow diversion valve directs it back to the heating section if it does not reach the necessary temperature.
Cooling down
Fully pasteurized milk returns to the regenerative heating section to heat incoming chilled milk, reducing the pasteurized milk’s temperature to about 32°C.
Final chilling
The pasteurized milk is finally sent to the cooling section, where coolant or chilled water is used to bring the temperature back down to 4°C.
Line of milk production using aseptic cold filling machine
Cold filling for UHT milk/dairy drinks
The process of “cold filling” for UHT (Ultra High Temperature) milk and dairy drinks entails sterilizing the product for a brief period at extremely high temperatures, usually 135°C (275°F), which effectively kills all bacteria and spores. Then, the milk is quickly cooled to a fill-temperature range of 4°C (39.2°F) to 5.5°C (42°F).
The cold filling process of UHT milk and dairy beverages is necessary to preserve the sterility achieved during UHT processing. After cold filling, UHT milk can be kept at room temperature during transport and storage.
Here are the steps involved in UHT milk pasteurization:
Milk chilling
While it is not a part of pasteurization, chilling is an important step when handling large quantities of milk. When milk exits the cow’s udder at a temperature higher than room temperature, bacteria multiply quickly and cause spoiling.
Before pasteurization, the temperature is lowered to a range of 2 to 5°C, which stops bacterial growth and metabolism and maintains the quality of the milk. Prolonged refrigeration, on the other hand, can compromise the quality of the product by causing casein micelle structural alterations and a bitter taste due to proteolysis. This can affect the quality of cheese.
Pre-heating (Regeneration) and Standardization
Milk is chilled and then heated to approximately 40°C to help separate the butterfat during standardization. This step makes use of regenerative heating, in which the chilled milk cools the pasteurized milk while the heat from the pasteurized milk warms the incoming chilled milk.
A consistent butterfat content is the aim of standardization, leading to the production of different products such as skim milk, low-fat milk, and high-fat milk. In order to achieve the appropriate butterfat content in the finished product, this process also involves figuring out how much cream to separate.
Clarification
Using centrifugal clarifiers and tubular metallic filters, clarification eliminates foreign particles from milk. By cleaning one filter while the other runs, the filters can be operated in parallel twins, which enables continuous processing. Cleaning must be done on a regular basis (every two to ten working hours) in order to stop bacterial growth.
Standardization
Standardization guarantees that milk fat content remains constant to accommodate varying consumer preferences, including those for high-fat, low-fat, and skim milk. Additionally, it separates butterfat for use in the production of cream and other fat-based goods like butter and ghee.
Homogenization
To stop cream separation, homogenization is a physical process that reduces milk fat globules to tiny droplets. A milk homogenizer running at 100 to 170 bars splits fat globules into tiny droplets to ensure uniform fat distribution in the milk.
Heating section
In the heating section, milk is heated with steam to kill Clostridium botulinum spores, from 60°C to 72°C. PHE plates are used for the heat exchange, which moves in a countercurrent direction. If the milk does not reach the proper temperature, a flow diversion valve at the end of this section is controlled by a temperature sensor, which sends the milk back to the heating section.
Holding section
After heating, milk is poured into holding tubes that are calibrated to guarantee that it stays at the pasteurization temperature long enough to kill bacteria—at least 16 seconds. The flow diversion valve returns the milk to the heating section when a sensor senses a drop in temperature. After being properly pasteurized, milk cools to about 30°C and returns to the regeneration section to warm incoming chilled milk.
Cooling/Chilling section
The pasteurized milk is finally sent to the cooling section, where it is cooled to 4°C using PHE coolant or chilled water. After cooling, the milk is prepared for aseptic packing and cold room storage.
The quality, flavor, and texture of milk are maintained through the cold fill method
Conclusion
Understanding the nuances of cold filling for beverages is necessary to maintain product quality. Whether it is processing fresh fruit juice or dairy drinks, cold filling ensures that nutrients, flavour and product integrity are retained. This approach plays a key role in meeting growing consumer demand for natural, minimally processed beverages.
For beverage manufacturers looking to take advantage of the benefits of cold filling, partnering with an experienced and trustworthy company is vital. Leading the industry in both original design manufacturing (ODM) and original equipment manufacturing (OEM) for a large variety of beverage products is Tan Do Company. With modern facilities and a commitment to quality, we can help you realize your beverage vision.
Contact us today to explore the possibilities and take the first step towards delivering your drinks to customers.
