6 Differences You Don’t Know About Hot Filling & Aseptic Cold Filling.

hotill vs cold filling for juice filling machine
After more than ten years of unremitting efforts, PET aseptic cold filling technology is getting better. And more and more beverage varieties are produced.

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After more than ten years of unremitting efforts, PET aseptic cold filling technology is getting better. And more and more beverage varieties are produced. Including fruit and vegetable juice beverage, tea beverage, sports drinks, carbonated beverage, water, etc. In the blowing process, the bottle’s air permeability is solved by adding an appropriate barrier layer. Which makes the application of PET bottles in the beer field more realistic.

hotill vs cold filling for juice filling machine


Essentials of PET aseptic cold filling technology

The product reaches a sterile state after UHT ultra-high temperature.

After the preparation is completed, the initial product’s ideal shelf life is achieved by high-temperature sterilization of the product. The PET aseptic cold filling generally adopts UHT ultra-high temperature sterilization to achieve this purpose. At present, there is no clear definition for ultra-high temperature sterilization. Generally, the sterilization method with a temperature of 138-145°C and 1-30 seconds is high-temperature short-term sterilization. That is, most aseptic packaged foods are usually used for craftsmanship.

For UHT, it is necessary to select the right temperature and time to maximize the sterilization value (Fo value). At the same time, to ensure that the product’s flavour and nutrients can be retained to the maximum extent. At present, aseptic cold filling mainly uses tube-type ultra-high temperature sterilizers.

The Sterilization Of Packaging Materials Is The Most Critical Step.​

As standard PET bottles are not heat-resistant, only chemical reagents can be used for sterilization. To ensure effective sterilization and to prevent chemical reagents from affecting the product, aseptic filling takes blow measures:

  1. It is required that the original colony count of the bottle blown does not exceed 10CFU/bottle.
  2. The bottle is conveyed with sterile air, equipped with an air conveyor belt.
  3. The inside of the bottle is sterilized with a peracetic acid disinfectant. Which can achieve a high sterilization effect.
  4. At the same time, disinfect the outside of the bottle with a disinfectant.
  5. The detergent has an automatic recovery and concentration measurement system to ensure concentration.
  6. Rinse the residual detergent in the bottle with sterile water, and then dry it with sterile air. Which ensure that the residual detergent will not affect the material.
  7. Bottle caps are generally immersed in detergent for sterilization. And the sterilization effect is ensured by controlling the soaking time.

Filling equipment reaches an aseptic state.

The aseptic cold filling requires a hygienic food-grade design, mainly in several aspects. Such as piping and valve technology, polishing material surfaces, surface design of important areas, selecting corrosion-resistant materials, etc. It also comes with a CIP system, sterilization (SIP) system, and an external foam cleaning system (COP). Besides, aseptic cold filling machines are designed with unique aseptic filling valve. These measures ensure the equipment does not bring secondary contamination to the material. 

Since the PET bottle will not shrink after cold filling, there will be some air between the material and the cap. The oxygen in it will slowly oxidize the material during the storage process. Thus causing the beverage to deteriorate. The filling machine will add a set of nitrogen (or other inert gas) replacement system to blow the top air away. To ensure that the product is not oxidized as much as possible.

Filling and capping are carried out in a sterile environment.

To maintain the aseptic environment, generally, adopt air purification room isolation. At present, the cleanroom used is developed from the pharmaceutical industry. And the technical level has a unified standard.

The filling machine area requires the D100 level aseptic room design, with a ten thousand level purification room. Through the purification to ensure the cleanliness of the air within the filling environment. So the material will not be suspended in the air microbial secondary pollution. By controlling the temperature and humidity of the purification to ensure the filling always in good condition. 

In the whole environment system, the operator is the biggest source of pollution. The air purification room purifies the air; it also well reduces the pollution brought by the personnel. The operators have to go through the spray sterilization when they enter the 10,000-grade purification room. The 100-grade purification room is designed to be small and practical. Which can make the operators operate without destroying its sterile environment. The inner surface of the purification equipment can be cleaned and disinfected automatically.

Establishment, monitoring, recording and control of key control points of the aseptic cold filling production line.

The PET aseptic cold filling line is a very responsible continuous production process. Any operational error or secondary microorganisms contamination may cause the whole system failure. Also, it will affect the entire batch of products’ safety. A scientific and perfect monitoring and control system is the key factor for the successful operation of the aseptic cold filling line. Moreover, the HACCP management system is commonly used in the beverage industry.

HACCP is the abbreviation of Hazard analysis and critical points (HACCP). It is a management method that identifies and controls potential hazards on production to prevent non-conforming products. It is a high degree of logic and evaluation system. The system includes a total of seven aspects of the basic principles. Identifying critical control points (CCP) to control hazards, the establishment of critical limits (CL) for each control point, and the establishment of procedures to monitor each control point are the key parts of the system. 

The process of aseptic filling is complex, and the aseptic control requirements are very strict. Only by managing and controlling according to the HACCP system can we truly ensure product safety.


Hot filling process

There are two types of hot filling process. One is high-temperature hot filling. After UHT sterilizes the material, the temperature is cooled to 85-92°C for filling. And the product needs to be refluxed to maintain a constant filling temperature. Then keep the temperature to sterilize the bottle cap. One is to pasteurize the material at 65-75°C and add preservatives after sterilization and filling. These two processes do not require separate sterilization of product, bottle and cap. But only need to keep the products at a high temperature for a long time to achieve the sterilization effect.


Comparison of two filling technology

The biggest difference between the two fillings is the beverage’s different heating time. As we know, the longer the heat treatment time, the greater the impact on the quality of the beverage. Aseptic cold filling only uses UHT ultra-high temperature instant sterilization. The material is heated for a short time, less loss of nutrients, quality, and taste is not significantly changed. Moreover, the sterilization effect can be fully guaranteed at high temperatures. In contrast, the hot filling puts the material in a high-temperature state for a long time. Which seriously affects the taste, colour and heat-sensitive nutrient content of the product. 

The hot filling process determines that the hot filling method is only suitable for highly acidic products. Because the high acidic environment itself has an inhibitory effect on microorganisms. But, for low-acid beverages, product safety cannot be well ensured. And the product defect rate is high. If the hot filling is used to produce neutral tea beverages, preservatives need to be added. Since the aseptic cold filling is carried out under aseptic conditions, it is highly adaptable. Including neutral tea beverages, dairy beverages and various other beverages. With only appropriate adjustments to the pre-treatment equipment to change the product types.



Hot filling technology

Aseptic cold filling technology

Quality requirements for bottles and caps

Requires the use of crystalline heat-resistant PET bottles (which can withstand high temperatures of 85°C-92°C without deformation) and special heat-resistant bottle caps

Can use ordinary PET bottles (maximum heat-resistant temperature 60) and standard caps

Material requirements

Keep it at high temperature for a long time and add preservatives

UHT sterilize the material and cool it to room temperature

Requirement for bottle sterilization

No sterilization or simple rinse with ozone water or chlorine water

Must be immersed in disinfectant or sprayed for sterilization

Requirement for bottle cap disinfection

It can be irradiated by UV or simply rinsed with chlorinated water

Must be immersed in disinfectant or sprayed for sterilization

Requirement of filling environment

Requires no aseptic cold irrigation as high as one hundred thousand grade purification is enough

100-level purification in the filling area; 10,000-level purification in the filling room and pre-filling line, and almost no microorganisms exist

Requirement of filling equipment

The filling system adopts an external circulation method and requires CIP

The non-contact filling method is adopted, which requires a complete CIP and SIP system, and has strict requirements on the filling space requirements and external packaging delivery methods

Requirement at the later stage of filling

Need to invert the bottle sterilization chain and spray cooling equipment

No need for post-processing

Practical operability

The process environment is simple to operate, and the quality control management is relatively loose

The process environment operation is extremely complicated, and the quality control management requirements are extremely strict

Operational risk



Impact on product flavor

Have a certain impact

Minimal impact


Comparison of two kinds of PET bottles

The two filling methods have different requirements for PET bottles. The hot-filling requires the PET bottle can withstand a high temperature of 85-92°C without deformation. Which requires increasing the crystallinity of the PET material. At the same time, it has to limit the induced stress when blowing. The PET bottle has the following characteristics: 

  • the bottle wall is thick and requires a high degree of crystallinity to enhance thermal stability; 
  • the high elongation rate has reached rigidity; 
  • there are clear bottle wall ribs to prevent heat shrinkage; 
  • a crystallization bottle mouth is required, 

The freedom of bottle design is greatly restricted.

The aseptic cold filling can use standard PET light-weight bottles (maximum heat-resistant temperature is 60℃) and standard caps. Which greatly reduces the cost of bottles and caps. And can freely design unique bottle shapes according to product characteristics for personalization package.


The outstanding advantages of PET aseptic cold filling compared with hot filling.

High quality

The shortening of product heating time; 

the manufacturing and maintenance of the aseptic environment and scientific management ensure the high quality of products.

Low cost

The saving of raw materials, energy consumption, and personnel make the low-cost advantage shown quickly.

Wide applicability

The improvement of aseptic filling makes the filling process of various beverages closer and closer. And the applicability is getting higher and higher.



hotfill PET bottles

Aseptic cold filling PET bottle

Bottle weight




Special crystal bottleneck

Standard bottleneck

Ratio of raw materials

High standard


Bottle design

Special bottle type with thermal ribs

Customizable bottle design

Tolerable temperature



Oxygen permeability

Bottle wall thickness, low oxygen permeability

The bottle wall is thin, and the oxygen permeability is high

Bottle cap

High temperature resistant bottle cap

Standard cover

The cost of bottle and cap





Comparison of investment

Hot-filling: The blow molding machine is slow and consumes much power. Under the same production capacity, the investment is much higher than the cold-filling.

Aseptic cold filling: The blow molding machine used for aseptic cold filling has a fast blowing speed and low power consumption. Furthermore, the blow molding machine is fast and consumes less power. However, the aseptic cold filling process is complicated, and there are more filling auxiliary equipment. Overall, an aseptic filling production line’s initial investment is higher than that of a hot filling production line.

Please click below to watch the production process of bottled water production.

John Lau.

John Lau.

John Lau, a project manager holding an engineering bachelor's degree, became fascinated with optimizing beverage production equipment during his university days. As an overseas project manager, he firmly believes that educating clients on achieving efficient workflows through customized equipment design is one of the most impactful aspects of his job.

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