Hot filling or cold filling?

 

I. Introduction of PET material

1, Definition: PET plastic refers to polyethylene terephthalate, English name is Polyethylene terephthalate, commonly known as polyester resin.It is the most important resin in thermoplastic polyester.

2,  Features:

(1). It has good mechanical properties.Its impact strength is 3~5 times that of other films, and has outstanding bending proof performance.

2). Resistance to oil, fat, olefinic acid, dilute alkali, and most solvents.

3). It has excellent resistance to high and low temperatures, can be used for a long time within a temperature range below 120°C, can withstand high temperature of 150°C and low temperature of -70°C in short-term use. And high and low temperature has little effect on its mechanical properties.

4). The permeability of gas and water vapor is low, and it has excellent resistance to gas, water, oil and odor.

5). High transparency, can block ultraviolet rays, and good gloss.

6). Non-toxic, tasteless, good hygiene and safety, and can be directly used for food packaging.

 

II, The production process of PET bottles

The production methods of PET bottles are divided into one-step method and two-step method.

The common molding method is the two-step method, because the advantage of the secondary blowing is that due to the high temperature of the heating treatment makes the crystallization ratio correspondingly increased, and the heat resistance can reach 90℃-95℃;

Due to the heating treatment process can be carried out independently, it can achieve a higher production efficiency and a relatively large production capacity, which is suitable for large-scale production needs.

The two-step process is to use an injection molding machine to inject a PET preform firstly, then put the preform into an oven to pre heat, and put it into the automatic blowing machine to blow air from the mouth of the bottle till it turns into the finished mold shape. then take the bottle out and cool it down.

 

III. Brief introduction of hot filling process

1,  Introduction: Hot filling is generally divided into two types, one is high temperature hot filling, that is, after instantaneously sterilized by UHT for the material, the temperature is cooled to 85-92°C for filling. Meanwhile,the product is returned to maintain a constant filling temperature, and maintain the temperature to sterilize the bottle cap;

The other is to pasteurize the material at 65-75°C for sterilization and filling and add preservatives. These two methods do not need to sterilize the PET bottles and plastic caps separately, only need to keep the product at a high temperature for a long enough time to achieve the sterilization effect.

 

2, Features: Hot filling is generally used in the production of concentrated and reduced juice production lines.

This type of juice is made of concentrated fruit juice or fruit powder, mix with syrup and beverage additives, keep for about 30 minutes, and finally filled.

This kind of fruit juice beverage has a long shelf life, usually about one year, but due to the sterilization method uses hot filling, the material is kept in a high temperature state for a long time, which seriously affects the taste of the product,the color and content of heat-sensitive nutrients such as vitamins.

Furthermore, hot-filled PET plastic bottles need to withstand a high temperature of 85-92°C and do not change its nature, this requires that the wall of the PET bottle used should be thick enough and the thermal stability should be enhanced.

IV. Brief introduction of cold filling process

1, Introduction: PET aseptic cold filling, Firstly, the material is instantaneously sterilized at UHT high temperature, then rapidly cool to room temperature of 25 ℃, and then enter the aseptic tank for temporary storage, use chemical disinfectant to sterilize the plastic cap and emtpy plastic bottle body, then fill it in a sterile environment, and leave the sterile environment until it is completely sealed.

The heating time of the materials in the whole process is short, the filling operation is carried out in an aseptic environment, the filling equipment and the filling area must undergo anti-virus treatment, and the safety of the product can be guaranteed.

 

2, Features: Cold filling is generally suitable for the production of natural juices or heat-sensitive beverages, or neutral beverages such as milk. This kind of juice does not add any additives and water in the production. After being sterilized by an ultra-high temperature instant sterilizer, it is filled in a relatively aseptic environment. Usually, the shelf life of this kind of beverage is about one month at the longest. The production, transportation and storage of the product must be in a low temperature environment.

This kind of beverage tastes good, and there is basically no loss of nutrition, which is the general trend of beverage production, and this type of filling bottle can use lightweight bottles, which greatly reduces the cost.

V. Conclusion

Compared with hot filling, PET aseptic cold filling has the outstanding advantages of high quality and low cost. The saving of raw materials, the reduction of energy consumption and the reduction of production line workers make the low-cost advantages of aseptic cold-filling products can be revealed in a short time, and the practicability is wide. It will gradually replace hot-filling and become the main method of beverage packaging.

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