In the dynamic and demanding food sector, the packaging of bulk products in 5–25 kg sacks is a vital link in the supply chain. From chocolate chips that add a touch of sweetness to industrial baked goods to flours that form the basis of countless products, right through to sugars, sweeteners, bakery mixes, additives (flavourings, colourings, binders), cooking mixes and cocoa powder, the range of products is as wide as the needs of professionals.

Despite this vast range, the flexible industrial packaging lines that handle these formats share a number of crucial common features, driven by efficiency, food safety, automation and sustainability.

Regardless of the specific technology used, the objective is always the same: to ensure the product reaches the end customer in optimal condition, whilst maintaining productivity, food safety and industrial efficiency. In this article, we discuss what we consider to be the key aspects of industrial packaging to bear in mind.

The starting point: precise reception and dosing.

Product reception and preparation.

Every packaging line begins with the reception and preparation of the product. Whilst this stage forms part of the product manufacturing process, understanding how the product will reach the packaging stage is of great importance in preventing product alterations such as segregation or breakage and deformation of grains, as well as ensuring a constant flow to the dosing and weighing system.

It is also key to understand how operations are conducted – whether working with short batches or continuous production, a single product or multiple products, and which cleaning processes should be applied, etc. These factors, amongst others, will determine the choice of downstream packaging equipment.

Product dosing.

The dosing stage is one of the most critical in any food bagging line in terms of accuracy and cost-effectiveness.

Given the variety of products, weighing systems must be versatile and accurate. For granular products such as chocolate pearls, sugars, cereals or extruded products, gravity or vibrating chute dosing (or a combination of both) offers exceptional speed and accuracy.

Conversely, for powdered products such as flours, cocoa, sweeteners or additives, screw-fed dosing systems, whether in a horizontal or vertical configuration, are more suitable, as they control the product flow even when flowability is very low.

From there, the choice between net weight, gross weight or loss-in-weight systems will depend on the required capacity, the desired accuracy and the specific behaviour of the product.

Here, repeatability and the minimisation of ‘wasted’ product due to overweight, shrinkage or significant deviations from the target weight,are primary objectives, directly impacting the profit margin.

Bagging as the central end-of-line process.

Once the product has been metered, the bagging machine becomes the operational hub of the entire facility.

Although various configurations exist, most industrial packaging lines opt for solutions that balance speed with package integrity.

The most common bagging technologies include:

• Open-mouth bagging machines: these are the most flexible and common choice. These machines open and position the bag (usually made of multi-layer paper or plastic laminates), fill it, stabilise the product inside and finally transfer it to the sealing system. They are ideal for a wide range of products and offer great versatility.
• FFS (Form-Fill-Seal) bagging machines: for products requiring greater protection against moisture or oxygen, or to optimise packaging material, FFS machines are an efficient alternative. These use a flat film reel or a tubular reel, forming the bag, filling it and sealing it in a continuous process, offering high speed and an excellent protective barrier. The use of tubular film can simplify the bag-forming process and reduce the number of additional sealing points.
• Valve bagging machines: Specially designed for powdery or fine granular products, such as certain sugars or powdered sweeteners, these bags have a filling opening (valve) in one of the top corners. The product is forced in using compressed air, and once full, the internal pressure closes the valve; however, in the food sector it is almost always mandatory to supplement this with an ultrasonic seal for greater safety.
• Big bag filling machines: or FIBCs, bulk bags, jumbo bags… Increasingly common in industrial settings, both for internal processes and for B2B operations. They present packaging challenges almost as complex as those involved in bagging into 5–25 kg sacks.

Regardless of the type of bagging machine, adaptability to different sack materials and the ability to handle various product densities are shared and essential characteristics.

Furthermore, the ability to adapt to format changes between 5 and 25 kg sacks is an increasingly sought-after capability, enabling producers to meet diverse market needs using the same production line, thereby minimising downtime caused by adjustments.

The sack sealing process to ensure the integrity of the packaging.

In food packaging, the closure determines the protection of the product, its preservation and safety during transport and storage. A faulty closure can compromise food safety, the product’s shelf life and the brand’s image.

In this regard, packaging lines share robust and reliable solutions:

• Stitching: for open-mouth sacks, industrial stitching machines have long been the standard. Fitted with high-speed, heavy-duty sewing heads, they create a durable and simple seal that can be complemented by folding or edging the bag’s opening. The drawback is that the seal is not 100% airtight, and the thread piercing the bag can introduce contaminants into the product, particularly when the bag is opened.
• Heat sealing: for plastic or laminated bags, heat sealers are the go-to solution, creating an airtight seal that protects the product from external factors such as moisture, oxygen or light. However, the airtight nature of this type of closure requires the residual air to be extracted from inside the bag beforehand to ensure stable palletising.
• Pinch Top: this closure system for open-mouth paper bags with an inner lining folds and seals the top of the bag using heat and pressure, combining an attractive appearance with effective protection. It requires a high degree of precision when transferring the bag from the bagging point.
• Double fold + heat-sealed tape application: Whether or not it includes heat-sealing the inner film layer in paper bags, this is one of the most secure closure systems offering the best finish, albeit at the cost of higher operating costs for consumables and greater complexity.
• Stitching + heat-sealing: for maximum security and an extra barrier against moisture, some production lines combine stitching the paper bag with subsequent heat-sealing of the inner film layer. This offers a good balance between performance and simplicity, without compromising on food safety.
• Ultrasonics: this is the preferred technology for valve bags, where high-frequency vibrations generate localised heat to fuse the valve material, creating a clean, airtight seal without the need for excessive external heat.

The ability to ensure the integrity of the packaging through a consistent, airtight seal is a common feature, crucial for product preservation, spill prevention and the avoidance of contamination.

The final step: identification, traceability, palletising and pallet protection.

Identification and traceability.

Once the bag is sealed, another critical phase begins: identification, monitoring and traceability.

In the food industry, the individual monitoring of each unit has become an operational standard. Weight verification systems, foreign body detectors, X-ray inspection or presence checks ensure that each bag meets the defined specifications before moving on to the identification and traceability system.

Bag marking and identification systems, such as automatic labelling, TTO or inkjet printing directly onto the bag, or laser marking systems, apply vital information: batch number, date of manufacture, use-by date, ingredients and instructions, and often barcodes or QR codes for full traceability throughout the entire supply chain – a legal and safety requirement in the food industry.

The choice between these marking technologies will depend on the bag material and the required durability and legibility.

Palletising and pallet protection.

Following this quality control, it is time for palletising. Automatic palletisers – whether robotic (offering exceptional flexibility and adaptability), layer-based (designed for high speeds with fixed patterns) or hybrid (combining handling grippers with layer formation) – are responsible for arranging the bags efficiently and securely on pallets.

Subsequently, strapping or stretch wrapping systems secure the load for transport, preventing movement and damage. Additional protection can also be provided by inserting a sheet of corrugated cardboard between the pallet and the film.

What modern food processing plants have in common.

Beyond the differences in products, formats or bagging technologies, modern food packaging plants share the same industrial logic, which can be summarised as follows:

Hygiene and food safety (HACCP).

This is, without doubt, the most critical common feature.

Machine design must be hygienic, with smooth, easy-to-clean surfaces, manufactured from food-grade materials and featuring easy access points for inspection and sanitisation.

The prevention of cross-contamination is a constant priority, particularly with products such as colourings, flavourings or sweeteners, which require strict control of allergens and cleanliness to prevent residues.

The option to use automatic CIP (Clean-In-Place) systems for the internal cleaning of equipment is a crucial added value, particularly for products that may generate adhered residues.

Foreign body detection.

The identification and removal of foreign bodies is an essential quality control measure.

Technologies such as magnetic separators, metal detectors or X-ray systems integrated into the production line ensure that any potential contaminants are detected and rejected before the product leaves the factory, safeguarding consumer safety and the brand’s reputation.

Automation and control.

The integration of PLCs (Programmable Logic Controllers) and HMIs (Human-Machine Interfaces), often connected to higher-level control systems, enables full control over the production line, real-time monitoring, fault diagnosis and parameter optimisation, thereby reducing reliance on manual labour and human error.

The use of open communication protocols such as OPC-UA and a standardised industrial language facilitates this.

Operational efficiency (OEE).

Measuring OEE (Overall Equipment Effectiveness) is a key metric. The aim is to maximise speed and uptime, whilst minimising downtime and waste, to ensure profitability.

Flexibility.

The ability to carry out rapid format or product changes is increasingly valued, enabling companies to adapt swiftly to market demands.

Sustainability.

With growing environmental awareness, production lines are designed to reduce energy and water consumption, optimise the use of packaging materials and facilitate the use of recyclable or biodegradable materials in the bags.

Documentation.

An aspect often ‘overlooked’ in other sectors, but of vital importance when it comes to food. Well-defined and documented processes ensure that a consistent and stable level of performance and safety can be maintained over time.

Adaptation and innovation as keys to success in food packaging.

Bag packaging lines, whilst adapted to the specific characteristics of each food product and industrial environment, reveal significant synergy in their operational and technological principles.

The pursuit of precision in dosing and weighing (essential for high value-added products), efficiency in bagging using various technologies such as open-mouth, FFS or valve filling, packaging safety and traceability, automation in palletising and optimal pallet protection for transport are shared cornerstones.

However, it is the understanding and integration of food hygiene at different stages along the production line, the control and identification of sacks, operational efficiency and sustainability that truly define the success of these facilities.

Investing in advanced technologies and well-designed processes not only guarantees the quality and safety of the product that reaches our homes and businesses, but also positions food companies to thrive in an increasingly competitive and conscious market.

At TMI, every project is based precisely on this holistic vision: integrating dosing, bagging, control, palletising and traceability into a single system designed to ensure food safety, operational stability and long-term efficiency.

Written by Gerard Martinez Xuriguera
Key Account Manager / Sales Area Manager

If you are developing a new food packaging project or wish to optimise your current bagging and palletising line, TMI’s technical team can help you identify the most suitable solution for your production, hygiene and traceability requirements. Contact us.