Recipes are becoming more complex and the number of stock-keeping units is increasing in the soft drinks industry. A mixer should be able to handle this complexity without making things complicated.
Ten years ago, the recipe for the average soft drink was fairly simple: carbonated water, sugar, colouring, flavouring and stabilizers. In those days, a manufacturer might have long production runs feeding in the same ingredients for a whole week or even a month before changing to a new recipe. Now the situation is different as the market for soft drinks has become more diversified with not just carbonated soft drinks but also still drinks, ice tea, ready-to-drink coffee, energy drinks, functional drinks, kombucha, etc. Today, a soft drinks producer might be changing recipes several times a day with short production runs. So what are today’s biggest challenges and what are the things to pay extra attention to?
Gums are worth a special mention. What gives soft drinks more mouthfeel and stability are gums such as pectins, CMC, xanthan gum and guar gum. Their usual concentration in the final product is 0.2-0.4% so only a tiny amount is needed to have a big effect on mouthfeel. However, these powdered gums are difficult to add to a recipe because they resist wetting. The challenge is to avoid “fish eyes” – globules of gum with undissolved powder inside. The answer to this problem could be to invest in an expensive inline high shear pump or a high shear mixer. However, smarter mixing solutions such as radial jet mixers fitted with devices that create a high shear zone are available at a much lower cost for these low concentrations of gums.
The addition of powders in bulk into a batch is another challenging application. Sometimes hoppers are used for discharging powders into a pneumatic or screw conveyor connected to a mixer. As an alternative, if a producer opts for a recirculation loop, they can feed in ingredients to a mixer from several dosing points by hydraulic conveying. Unlike conventional systems for batch mixing, there is no need for a separate conveying line for each bulk powder ingredient.
Hydraulic conveying from several feeding points can be used to discharge bulk bags or feeding hoppers directly into the same recirculation loop via an injector. Where the feeding points are placed along the loop extension can be adapted to the layout of a producer’s plant to reduce ATEX requirements to a minimum.
Cross-contamination and microbiological issues that could arise in the interaction between wet and dry lines are avoided with the loop concept because the complete loop is fully cleanable. Therefore, there is no need for a split between dry and wet discharging lines. In contrast, conventional solutions based on pneumatic or screw conveyors offer no possibility for thorough cleaning using CIP.
The loop concept is also handy for dissolving ingredients such as reactive powders independently from the main batch to avoid unwanted reactions or to manage differences in acidity between the pre-mix and the main batch.
A pre-mix recirculation loop with a booster pump allows these ingredients to mix in circulation over the feeding hopper without interfering with the main mixing tanks, making it possible to prepare a small batch of as little as 300-400 litres using the feeding hopper instead of a separate vessel or pre-mix pump.
The result: a reduction in processing equipment investment need and a simpler mixing process. Switching between the pre-mix and standard mix is typically at the mere switch of a button.
A typical soft drinks producer doesn’t just handle a wide variety of ingredients but multiple ingredient packaging formats such as jerry cans, drums, sacks and bulk bags. How can you discharge them all efficiently into a pre-mix without investing in a lot of different equipment?
Ingredients can be divided into powders and liquids. To provide the necessary flexibility to match a producer’s ingredient and packaging specifications, a mixer needs to be equipped with a set of lances either for wet or dry intake by aspiration. The different types of lances use a vacuum to create suction and should ideally have a non-return suction valve. Large and small liquid lance sizes can handle high- and low-viscosity ingredients respectively. As regards free-flowing dry powders, a powder lance works well.
With a lance, no tipping or lifting of the drums or bags is required as they can be unloaded standing on the floor or on a pallet.
A basic type of batch mixer is fine when handling a few standard recipes with a few ingredients. But nowadays most producers of soft drinks need a batch mixer that gives them the flexibility to handle not just multiple ingredients but multiple packaging formats. A producer could be handling everything from 5-kilogram jerry cans to 1-tonne bulk bags. With greater complexity comes the need for greater flexibility. Of course, liquid and dry lances will go a long way, but feeding both wet and dry ingredients directly into a recirculation loop connected to the mixer is one innovative solution for handling recipe complexity more efficiently.