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A: Bill Noonan, Marion Process Solutions, says:

Four techniques are used in combination to keep oils from smearing or creating lumps in baking goods:

  • Controlled temperature environments
  • Carbon dioxide (CO2) injection for cooling
  • High-speed choppers to eliminate lumps and chunks of oil or shortening
  • Vacuum for reducing the melting point of oils

When you pick up a box of cake or muffin mix, at least a delicious one, the box can feel heavy — however, powder normally doesn’t feel so heavy. The reason is because the moisture of baking goods comes from fat. The challenge is getting that fat to mix evenly and aesthetically into the powders without lumping, agglomerating, or smearing.

For baking goods, manufacturers use oils such as canola or vegetable or plasticized shortenings. When in liquid form, oils smear and can stick to the drum of the mixer, which creates a situation where it’s hard to know the precise measurement of the oil that’s mixed with the powder and also creates a mess. Furthermore, waste of oils can be costly, particularly with the recent trends where baking goods manufacturers are using newer and more expensive oils and shortenings for their high-end products.

In order to prevent smearing, the first step in mixing oils with powders for baking goods is to cool both the base media and the oil or shortening and ensure that it stays cool while the mixing is taking place. Today, many manufacturers keep the temperature down by mixing in controlled environments where the ambient room temperature is kept cool. When the oils are added to the powders in a controlled environment, the temperature is cool enough for those oils to stay solidified.

Environmental control works well as long as the mix can be kept controlled. To ensure the controlled temperature, injection of CO2 is commonly used in the industry. Injection manifolds are installed in the lower parts of mixers, where both the fats and the CO2 enter the machine. Fats are added through a manifold. When choosing the injection manifolds, manufacturers will want to consider the sanitation of those parts. Fully removable parts for cleaning out of place (COP) is best. In the case of removable parts, it’s best practice to have an extra set on hand. One set can be cleaned while the machine continues operation with the alternate set. Downtime costs money. Having and maintaining spare manifolds provides a significant return on investment.

In order to break up clumps and inject the fats in a way that creates smooth mixtures, manufacturers use high-speed choppers, again, placed at the location where the fats are injected. Similar to injection manifolds, chopper manifolds are available as COP. The agitator friction and high-speed choppers could potentially create some heat. With the injection of CO2, the heating effect is completely neutralized. This allows fats or oils to be chopped up into small particles that mix easily and homogeneously with the flour, sugar, and other powdered ingredients for baking goods.

After the injection of CO2, an additional way to keep the fats solidified is to apply a vacuum on the entire mix. Vacuum lowers the melting point of the fats, which means the entire mix is less susceptible to melting. The CO2 works only at the point where it’s injected, while the vacuum is applied to the entire mix, which is important. As the fats are being distributed throughout the mix evenly by the agitator in the mixer, it’s important to ensure that the oils continue to maintain their integrity and mix evenly with the rest of the ingredients. Once a vacuum has been applied, even in environments as warm as 40.1°F (4.5°C), it’s possible to maintain the solidity of oils throughout the mixing process. Note that anywhere from slight vacuum to full vacuum can result in a perfect blend, depending on the application.

Another benefit of using vacuum in addition to cooling methods is that it speeds up the drying process, meaning greater throughput for the mixer. Applying vacuum deaerates the material, allowing it to flow more evenly inside the mixing chamber. The result is a denser powder blend that’s rich in shortening. If air is entrapped inside a blend, agglomerates tend to collect and create lumps around the air pockets. This is similar to the school experiment where ping-pong balls are placed in a glass jar and gaps and voids are created in the jar.

Ensuring that the mixer has precise controls will result in better quality as well as faster throughput. Another key element here is to complete the proper testing. Having a test laboratory or using a supplier’s test laboratory to try different configurations can result in significant time savings and improve the quality of these mixes.

By the way, some of these techniques are relevant beyond baking goods. Vacuum mixing is also used for drywall mud, window caulk, and body putty. In other words, wherever you have pasty or sticky materials and require declumping while mixing and drying, these techniques are applicable.


Marion Process Solutions, Marion, IA, manufactures and supplies industrial mixing and blending equipment.