High-shear mixing helps solve sticky food production issues

June 21, 2017

Replacing conventional mixing equipment with high-shear technology generates better raw ingredient yields and reduces waste costs for a large confectioner.

Many confectionary products, especially gummy sweets, and other food products such as yogurts, salad dressings and jellies rely on the properties of gums such as pectin, xanthan, locust bean, carrageenan and acacia to give the end product the characteristics manufacturers and consumers desire.

These gums are used as stabilizing and thickening agents and have other functional properties, such as improving the "mouth feel" and texture of the end product. But incorporating these gums into a product can cause some problems during the manufacturing process, and they can be difficult to disperse and hydrate correctly and efficiently.

Most gums are prone to forming agglomerates when added to water, and conventional agitators do not produce sufficient shear to rapidly break down these agglomerates. Long mixing times can cause gum degradation and result in poor quality dispersion. Filtering agglomerates out of the mix further adds processing time and is a waste of costly raw materials. As a result, many formulations contain unnecessarily high levels of gums to compensate for the poor yield, which again increases raw material costs. Premixing the gum with other powdered ingredients before adding it to the water is often carried out to reduce the formation of agglomerates, but this is only partially successful and extends the processing time.

Ideally, high-shear mixing equipment should be used to obtain the best results. A rotor/stator mixer can produce an agglomerate-free dispersion and hydrate difficult gums and thickeners in a fraction of the time used by conventional agitators.

The high-shear action of the mixer ensures that in a short mixing cycle all material passes many times through the machine workhead, progressively reducing the particle size and exposing an increasing surface area of powder to the surrounding liquid to accelerate the hydration of the gum. As the product is forced back into the body of the mix, any agglomerates are broken down as they pass through the rotor/stator workhead. This process is rapidly completed, significantly cutting mixing times.

Processing times can be further reduced with a high-shear mixer, as premixing the gum with other powders or non-aqueous phase ingredients is not required — this also simplifies the mixing process.

Other advantages of using high-shear mixing technology include obtaining the maximum yield from raw ingredients. As all the agglomerates in the mix are broken down by the high-shear action of the mixer, there is no waste, which often allows the manufacturer to reduce the gum content and their raw material costs.

In a recent application, one of the world’s leading confectionary companies combined a mixture of sugar, fruit pulp and pectin powder to produce fruit gummy sweets, but operators experienced problems when they tried to disperse the powder.

As with any thickening or stabilizing agent, agglomerates can easily form when dispersing the powder into water, and great care must be taken when introducing the powder into a mixture to try and reduce the formation of "fish eye" lumps. Fish eyes are agglomerations of partially hydrated material with a core of dry powder.

The conventional mixers the confectioner company used to disperse the pectin did not produce sufficient shear to properly incorporate the powder or break down agglomerates. Partially hydrated pectin then had to be removed during filtration, which reduced the yield of costly raw materials and, therefore, increased costs.

To solve the problem, the company inquired about high-shear mixing equipment from Silverson.

After a series of trials using a high-shear batch mixer, the company established it could produce its fruit jelly candies in a fraction of the time. The resulting mix was smooth and agglomerate-free.

In addition to improving the quality of its product by opting to use high-shear mixing equipment instead of conventional agitators and stirrers, the company predicted savings on its raw material costs as it achieved better yield. As processing times were significantly reduced, it also predicted saving money on production costs.

Waste not, want not

Silverson D450 reclamation plant

Another common manufacturing problem in the food and confectionery industry is the large amount of waste product, which can arise, for example, when products are out of specification. By reclaiming or reprocessing this out-of-spec product, manufacturers can save money and reduce their raw material costs.

With high-speed, high-volume production, minor problems can often rapidly result in large amounts of waste product. One solution to this common, expensive problem is the reclamation of "off-spec" product. Expensive raw materials can be dissolved or reclaimed and used as ingredients in new batches.

Confectionary and other food products may require reclamation or reworking for many reasons, for example, when high-speed production lines stop because of a problem downstream, such as a fault or a breakdown in the packing line. Another cause of waste product is when sweets and food items are rejected for being misshapen or otherwise out of specification. Ingredients produced on a continuous basis are often diverted into scrap bins until the line is running again, since stopping production may be difficult and costly. The reclamation of waste product can be difficult, which in the past has resulted in product simply being scrapped. However, the high cost of raw materials, such as sugar and cocoa in candy products and other costly ingredients in other food products, means that it is increasingly important to try to reclaim and rework off-spec product to save on raw material costs.

It is especially important in today’s economic environment that manufacturers in the food industry can quickly and efficiently reprocess out-of-spec product to help reduce waste and costs. Using a reclamation plant makes the process simple, fast and effective — and therefore economically viable.

A standard reclamation plant consists of a bottom entry mixer, in-line mixer, 250-liter vessel and control panel for high-speed reclamation and disintegration of waste and out-of-spec materials without the need for pre-grinding or chopping.

A large bakery company recently invested in a reclamation plant after forecasting savings of £2.5 million per year by using the plant for the disintegration of waste bread products, such as tortilla wraps and naan breads. The out-of-spec bread will be made into a usable slurry. Then the company will be able to begin reclaiming two tons of waste material produced each day for use as an ingredient in new batches of the same bread product.

Other applications include the pulping and disintegration of fresh and dried fruit and preparation of vegetable smoothies. In the confectionary industry, misshapen sweets can be disintegrated and dissolved, so the sugar can be reclaimed and reused in a single operation. The reclamation plant can process large quantities of both individual sweets or clumps of sweets stuck together.

Depending on the application and batch size, reclamation plants can be custom-designed and built to meet a manufacturer’s exact requirements and to help solve specific manufacturing problems.

Author’s note:  Learn through online demonstrations how to get the best results from various key ingredients in the food industry, including how to mix xanthan gum and high-speed sugar dissolving at ambient temperatures. Visit www.youtube.com/user/silversonmixers.

Zoë Gates is a marketing communications assistant at Silverson Machines Ltd., U.K. For more than 70 years Silverson has specialized in the manufacture of quality high shear mixers for processing and manufacturing industries worldwide. The company specializes in powder/liquid mixers, hygienic mixers and disintegrator/dissolvers for the food, pharmaceutical, cosmetics and chemicals industries.

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