Infant nutrition manufacturing can be a complicated process that involves recipes incorporating many ingredients, some of which can be very small in volume. The handling, weighing and conveying of these small additions are error-sensitive operations can at times be very labour intensive.
The industry deals with this issue through premixing. Instead of weighing out the minor and micro ingredients for each batch run individually, pre-mixing involves the group of these ingredients into larger quantities and blending them before dosing out the right quantity of the mix to be added to the base ingredients for each batch run.
The process helps save the number of weight measurement required and at the same time reduces the amount of labour and possible errors involved.
However, the pre-mixing process is quite a complicated one. For a start, minor and micro ingredients vary considerably in volume, weight, particle size and bulk density.
There may be 10g of a dense mineral to be mixed with 10kg of light lactose and mixing these diverse ingredients together as a pre-mix is a challenging task.
Conventional horizontal ribbon mixers are limited in what level of homogeneity they can achieve. Quite often, it is necessary to use more sophisticated and modern mixing techniques such as plough share, fluidised bed or vertical ribbon mixers.
The greater challenges come after mixing the ingredients. How to empty the mixer without risking segregation? How to transfer the perfect pre-mix in the exact correct quantity? How to create efficient handling in a central pre-mix area if several big production lines are running different recipes?
Segregation & Homogeneity
To date, there has been no assuring answer to all of these questions. As a result, manufacturers, who can ill afford to take risks, continued to operate at lower efficiency and rely on manual techniques for each and every batch run.
Loading the minor and micro ingredients one recipe at a time is not only time consuming for the operators, but stringent traceability requirements demand that every ingredient is scanned before being tipped into the mixer. This means that the mixer is standing idle during this refill time, so the overall equipment effectiveness (OEE) is severely reduced as a result.
Add to this downtime the need for cleaning time if many recipes changes are being made too.
The alternative is an immediate bulk container (IBC) solution that can provide flexibility and are large enough to scale up the minor and micro ingredient quantities into larger batches. The technology also facilitates direct premix emptying into the process below.
Filling and cleaning are done off-line, so the OEE rates are kept high. However, there have been two fundamental flaws with IBC technology that have hindered the process:
- The ability to empty the pre-mix without causing segregation
- Achieving a homogenous mix across all the different recipes, regardless of the proportion of ingredient volumes and particle sizes.
One way to resolve the segregation issue to the adoption of a cone valve technology that ‘holds back’ the powder in the centre of the IBC and promotes flow from the side, as a result, create mass-flow and avoiding any rolling effects which cause segregation.
Used in conjunction with a discharge station, there is a much reduced risk of segregation during transfer and accurate dosing can be performed without the need for additional cross-feeders, thereby reducing the cleaning burden.
Homogeneity on the other hand has been resolved by suppliers of stationary tumble mixers (double cone or V) by inserting a central intensifier. This vastly improves blending speed and performance, as well as providing the opportunity to include oil or liquid to the dry blend. But doing the same with mobile IBC blenders is a far greater challenge.
The development of an integrated intensifier technology in an IBC blender started around seven to eight years ago and over time, the design has been improved, both in terms of mixing performance as well as hygiene.
There are two key areas within infant nutrition manufacturing where pre-mixing can be considered—prior to spray drying and post spray drying of the milk into powder.
In the first scenario, the production of slurry prior to spray drying must be considered. The spray drying process itself is continuous—the dry ingredients are typically mixed batch-wise into large slurry tanks. While the number of companies applying dry ingredients in this phase is generally decreasing, for long campaigns, this is still a viable and efficient concept releasing one to two operators per shift.
The second area is final blending after spray drying. This area is growing both in volume and complexity. More and more nutritional ingredients or flavourings are being incorporated to add value and competitive edge to the product SKUs.
Since the ingredients are contaminants, this makes the use of an IBC blender even more relevant as there is no risk of cross-contamination between batches as the product is all contained within the IBC and cleaning is done off-line.
Users of the technology are able to achieve OEE rates on the IBC blender in the region of 70 percent. In addition, there are further manpower savings as there is no need to clean the mixing room and surrounding area as there can be with fixed mixers.
Doubling Mixing Capacity
Like many baby food and nutritional product companies, Hero Spain was experiencing increased market demand coupled with increasing hygiene, allergenic and ATEX regulations.
They realised that the key to taking advantage of this demand and gaining increased market share was to significantly upgrade their existing manufacturing system and improve their capacity and flexibility, allowing them to produce a wider diversity or products.
The Alcantarilla plant focuses on producing large volumes of cereal and specialty baby foods and has done so for many years. They considered the most efficient operating method to be pre-mixing of the specialty ingredients, many of which are allergens.
However, this was causing a huge burden on the front end of the plant process. They were using a horizontal ribbon blender to blend the pre-mix. While the actual blending time might be just minutes, the ribbon blender had to be supervised by an operator, took hours to fill and empty and demanded one to two hours for a full clean-down.
This resulted in the pre-mixing stage being painfully slow and labour intensive with large amounts of down time between different batch runs. The system was not only limiting production capacity, but also hampering the flexibility of the production system.
The company found an alternative pre-mixing method which removed the need for cleaning the ribbon blender between batches, thereby dramatically increasing capacity and eliminating the bottleneck issue.
The use of an IBC blender system meant that changeovers could happen instantaneously. As mixing of ingredients takes place directly within the IBC, the blender is considered to be a ‘non-contact’ part which means there is no need for cleaning between recipes. The system is ready to accept the next batch immediately regardless of the formula.
While the actual blending time with the IBC blender may take 15 minutes to reach homogeneity, as there is no cleaning involved between batches, the full cycle-time is only around 20 minutes compared to the one to two hours with the ribbon blender. Therefore, significantly more batches can be processed each shift.
The use of the IBC blender provides substantial efficiency gains and helps to increase throughput. At the same time, safety is maintained as there is no risk of cross-contamination.
As the system is decoupled, the IBCs can be filled while another is being cleaned offline. Such parallel processing creates a lean working environment. The company estimated that the new mixing system has helped increase its capacity by 100 percent.
Mixing in an IBC created new methods of working both upstream and downstream of the mixing process. It enabled to company to pre-mix very small additives, such as vitamins and minerals, intro bigger and more manageable ‘lots’ for dispensing automatically into large recipe batch IBCs.
Previously, it was a very labour-intensive task to weigh out these ‘micro-ingredients’ for each batch and required numerous human controls and checks to avoid mistakes.
Downstream of the blender, batches can be transferred for further processing or taken directly for consumer packing. This has given the company the flexibility to respond quickly to changing demands, which in turn has significantly reduced the amount of work in process or expensive finished goods inventory.
The company was able to reduce product in stock by up to 25-30 percent and reduce average production lead times from one week to less than one day.
By adopting a lean mixing approach, the company estimated that it has doubled its mixing capacity without any increase in either manpower or space utilisation.
It has also enabled to the company to upgrade the zoning of the particular part of the plant to ‘zone 8’, which further minimise the risk of cross-contamination and exposure to the powder, ensuring an even higher quality and product. At the same time, ATEX compliance has been achieved far more easily than would have been the case with the old installation.