Nutraceuticals can encompass a wide variety of health-related products including vitamins, supplements, mineral blends and even various foods such as energy bars. Many of these formulations involve the fine blending of as many as 40-50 components, including powders and trace elements.
Although nutraceuticals are not strictly regulated like pharmaceuticals, the products still must substantiate any label claims, and a number are actually tested in clinical studies like medicines. “Whenever a nutraceutical makes a label claim, such as specific RDA or FDA allowances, vitamin percentages, or active components, it has to meet those criteria,” says George Paffendorf, director of operations at Advanced Powder Solutions (APS), a company that specialises in developing and optimising the blending of powders for various industries. APS is the in-house testing/engineering arm of GEMCO, a manufacturer of tumble blending and vacuum tumble drying equipment with technical, nutraceutical expertise.
As an example, APS helped to blend the various components for an energy bar (nuts, raisins, dried banana, flaked coconut, etc.), which were calculated to meet a minimum daily requirement for vitamins and minerals. “The blends had to be precise enough to meet the label’s nutritional claims,” says Paffendorf.
Creating Precise Blends With Trace Ingredients
One industry challenge is that the blending of solid ingredients is easier and more uniform if the ingredients are approximately the same size. However, it is more difficult to create precise blends with trace ingredients (<1%) that are vastly dissimilar in size and density. In some cases, this might require doing multiple key blends in a time-consuming and costly process.
Fortunately, with tumble blending equipment that is engineered to meet the requirements of the application, the process can be simplified to rapidly produce a more precise, homogenous blend containing all necessary components and trace elements in the specified amounts. Such blending can not only eliminate the need for key blends, but also produce a better distribution of active ingredients.
The Limitations of Traditional Mixing Equipment
Traditional equipment such as plough, ribbon and paddle mixers, which use blades or paddles to push material, are limited to moving the material within the confines of their active area. The mechanics force the material bed outward, leaving dead spots inside the vessel where material moves more slowly or remains stationary. A stationary port at the bottom of such machines further isolates the material.
Another issue lies in the positioning of the intensifier bars, which should ideally be located in the mixing zone, where every particle passes through. Many times, however, traditional mixers position intensifier bars in dead zones, resulting in material not being fluidised properly and active ingredients getting incorporated throughout the batch.
Traditional mixers also waste expensive additives. Because additives initially contact only a very small portion of material in the vessel, they get quickly absorbed into the material bed, so more additives are usually needed to achieve the desired mix concentration, which increases cost.
The Benefits of Tumble Blending and Vacuum Tumble Drying
To address the deficiencies of traditional mixers, a growing number of nutraceutical manufacturers use tumble blending. As a low-impact processing technique for handling sensitive or abrasive solids, tumble blending is commonly used to create precise nutraceutical blends that contain trace ingredients (<1%) that are vastly dissimilar in size and density.
In contrast to traditional mixing, to eliminate dead spots, tumble blenders apply even turbulence in all corners of the mix through a combination of macro and micro blending. This can eliminate the need for key blends and produce a better distribution of active ingredients.
Macro blending is achieved by rotating the shaped vessel, allowing the material bed to fall away from the vessel’s walls. Tumble blender vessel shapes are engineered to create a repeatable pattern in which the entire bulk material moves to form a homogenous mixture. The blender moves at a precise speed, with the vessel wall at a precise angle, so that the material cascades over itself. There is no additional force from paddles, ploughs or spiral ribbons – just gravity.
While this occurs, micro mixing (if needed) simultaneously proceeds via agitator blades located in the mixing zone centre of the vessel, where fine processing in the material transpires. This allows for a gentle repeatable pattern that maintains a superior blending design while preserving the product’s physical characteristics. Together, the macro and micro mixing evenly expose each particle to six times more active blending per revolution than traditional mixers.
APS Case Study
As an example, when APS worked with a large nutraceutical manufacturer in Nevada with a 40 component blend, the company was not using an agitator and had a laborious, overly complex blend process. “To make about 1,000 kilos of product a few times a year involved six or seven separate steps with key blends that had to be lab tested after each step to reach a final blend with the necessary traceability, materials and active components,” says Paffendorf.
Through onsite analysis of the manufacturer’s process, including examination of the physical characteristics of the powders used, APS determined that all of the components could be mixed in one step. This involved both macro and micro mixing using a GEMCO tumble blender with an agitator to complete the process in a fraction of the time without key blends or excessive lab testing.
“If you turn on the tumble blender agitator, it can fluidise the entire bed of material and you get great product distribution because it helps to spread it out through the micro-mixing zone. According to the customer, the new process using a tumble blender with an agitator saves them about US$875,000 a year by eliminating the need for key blends and all the intermediate testing,” says Paffendorf.
Douglas Van Pelt, a former part owner of a nutraceutical company, has also benefited from tumble blending. Van Pelt, who is now senior director of Operations at Sigmapharm Laboratories, a pharmaceutical company based in Philadelphia that develops, manufactures and markets generic and branded products, had successfully used tumble blenders at a previous company and trusted their capabilities. “At my previous employer, I made a product that had a narrow therapeutic range using a 30ft3 tumble blender by GEMCO,” says Van Pelt, who notes that blend uniformity specification was a very stringent 95.0% to 105.0%, not a typical 90.0% to 110.0%. “The potency was 0.125mg inside a 125mg tablet, and we were able to achieve blend uniformity in 15 minutes, with good repeatable results every time.”
According to Van Pelt, Sigmapharm has effectively implemented a 30ft3 V blender and a 1ft3 slant cone blender from the tumble blender manufacturer. “Over decades, GEMCO has essentially perfected tumble blending,” says Van Pelt. “They engineered the precise angles and speed of revolution needed to achieve proper blending inside the vessel and can adapt this based on product requirements.”
With the preciseness of the technology, a V-shape tumble blender is capable of achieving a standard deviation of less than 2%, and a slant cone configuration can achieve a standard deviation as low as 0.33%.
In the nutraceutical field, loading can be accomplished via drum loading. This includes a dust-free, GEMCOmatic loading option, where the tumble blender rotates until the drum inverts and the discharge valve opens, allowing the contents to flow into the blender. The valve then shuts automatically and the emptied drum returns to the loading position. The latest version allows for a pre-programmed discharge sequence.
For nutraceutical manufacturers that have sought to ensure product quality through the fine blending of many components, but were unsatisfied with traditional methods, tumble blending will help to optimise the process. With greater process control, manufacturers will even be able to significantly reduce blending steps and cost, while substantiating label claims and clinical trials.