Bag-in-Box FAQs:
1. What is a bag-in-box?
2. What are the uses of a bag-in-box?
3. What materials are used for bag-in-box? Are they recyclable?
4. How is a bag-in-box filled?
5. Why is there a capacity discrepancy after filling?
6. After hot filling, the bag-in-box valve is difficult to open and the liquid does not flow out smoothly. What is the reason?
7. Why is there leakage at the connection between the faucet and the packaging bag?
8. Why does the product deteriorate?
1. What is a bag-in-box?
Bag-in-Box (BIB) is a liquid packaging format consisting of an inner flexible packaging bag and an outer rigid paper box. The outflow of the contents is controlled by a valve or tap. It combines the lightness of flexible packaging with the support of rigid packaging and is widely used in food, beverages, industrial liquids and other fields.
2. What are the uses of a bag-in-box?
In the food and beverage industry, bag-in-box (BIB) is suitable for packaging a variety of liquid or semi-fluid products due to its advantages such as high barrier properties, lightness, easy storage, and controllable costs. It is especially suitable for products with high requirements for shelf life, transportation efficiency, and ease of use.
3. What materials are used for bag-in-box? Are they recyclable?
Typically made from a multi-layer composite film (such as PET/aluminum foil/PE, PET/NY/PE, etc.), the film material combination is designed based on the characteristics of the contents (such as oxygen barrier, heat resistance, and puncture resistance).
The outer layer (such as PET) provides mechanical strength and printability;
The middle layer (such as aluminum foil, EVOH) blocks oxygen and light, extending shelf life;
The inner layer (such as PE, CPP) comes into direct contact with the contents and must comply with food contact safety standards and possess good heat-sealing properties.
We provide recycled materials and have test reports. Contact us to send you the latest report.
4. How is a bag-in-box filled?
Bag-in-box filling methods can be briefly categorized by aseptic requirements and operating methods. The key differences lie in their applicable scenarios and process precision:
1. Conventional Filling (Non-Aseptic Environment)
- Open-End Filling: The bag has a pre-opened opening, which is manually or mechanically filled with liquid and then heat-sealed. This is suitable for high-viscosity products containing particles (such as sauces) and small-batch production.
- Pre-Valve Filling: The bag is pre-installed with a valve, which is then filled through a nozzle and closed. This method is suitable for medium- and low-viscosity liquids (such as juices and oils) and offers a superior seal.
2. Aseptic Filling (Aseptic Environment)
- Aseptic Valve Filling: The packaging, liquid, and equipment are all sterilized, and liquid is filled through an aseptic valve. This method is suitable for products that require long-term storage at room temperature (such as fresh juices and plant-based milks).
- Aseptic Hot Filling: High-temperature liquids (80-95°C) are filled in an aseptic environment, utilizing residual heat for sterilization. This method is suitable for soups and sauces that require heat sterilization.
3. **By Level of Automation**
- Manual filling (small batches), semi-automatic filling (medium volume), fully automated filling line (large-scale production, fully automated).
5. Why is there a capacity discrepancy after filling?
Capacity deviations after hot filling of bag-in-box packaging are primarily related to changes in physical properties and process control in high-temperature environments. The core causes include:
Liquid thermal expansion and contraction: During high-temperature filling, the liquid expands due to heat and contracts after cooling to room temperature. If no allowance is made for shrinkage, the actual capacity may be lower than the stated value.
Packaging material thermal shrinkage: The inner composite film (especially materials like PE and CPP) may shrink at high temperatures, reducing the effective volume of the bag and indirectly affecting the actual capacity.
Insufficient venting: During filling, trapped air in the bag expands due to heat, potentially squeezing the liquid and causing overflow. Alternatively, after cooling, the air contracts, causing the bag to collapse, resulting in the appearance of insufficient capacity.
Equipment metering errors: High temperatures can affect the metering accuracy of the filling machine (e.g., viscosity changes leading to inaccurate flow rates), or parameters not compensated for temperature, leading to fill volume deviations.
6. Is the valve difficult to open and the liquid difficult to flow out?
The main reasons why bag-in-box valves are difficult to open and liquid flow is poor after hot filling are:
1. High temperatures cause deformation and adhesion of valve components (seals, valve body) (due to insufficient heat resistance);
2. Liquid contraction due to cooling creates negative pressure inside the bag, which attracts the valve components;
3. The viscosity of the contents increases after cooling, or particles clog the passageway;
4. Improper heat sealing processes cause compression of the valve structure.
7. Why is there leakage at the connection between the faucet and the packaging bag?
Leakage at the connection between the bag-in-box faucet and the bag is primarily caused by:
1. Improper seal (ring) dimensions or insufficient heat/chemical resistance;
2. Improper installation or defects in the heat sealing/bonding process (weak seal, uneven adhesive layer);
3. Loose connection due to transport pressure or repeated opening and closing;
4. Poor compatibility between the bag material and the faucet (swelling, aging).
8. Why does the product deteriorate?
Deterioration of bag-in-box products is primarily related to seal failure and insufficient barrier properties. Specific causes are as follows:
1. Bag damage (puncture, heat seal leakage) or valve leakage allows air and microorganisms to enter, causing oxidation and spoilage;
2. Damage or poor quality of the composite film barrier layer (aluminum foil, EVOH), which fails to effectively block oxygen and light, accelerating oxidation of the contents (such as rancidity of oils and discoloration of juices);
3. Substandard aseptic filling processes (e.g., incomplete sterilization of the environment or packaging), allowing residual microorganisms to multiply and cause deterioration;
4. Improper storage conditions (high temperatures, exposure to sunlight), accelerating material aging and chemical reactions of the contents.
Henan Baolai Packaging
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Post time: Mar-20-2025