Process equipment design and manufacturing company Anderson Engineering in January handed over a turnkey solution to Pietermaritzburg-based mayonnaise manufacturer Tasti Mayonnaise.
Anderson Engineering CEO and managing member Hans Coertse tells Engineering News that the solution, which can produce a 1 000 ℓ batch of mayonnaise in about 30 minutes, includes a 40 000 ℓ bulk holding tank for vegetable oil and a 25 000 ℓ tank for vinegar. It also comprises four premix vessels for the oil, water, acid and gumming agent phases.
The contents of each tank are premixed individually before they are sucked through a vacuum into a 1 000 ℓ Anderson Contramix vessel, which also forms part of the solution and mixes the various contents into the final product.
Anderson Engineering manufactured the Tasti Mayonnaise plant in about four months, with an additional eight weeks for installation and commissioning, which was completed in January this year.
Coertse notes that the project was not without its challenges, as the water premix vessel required a dual-mix function to ensure all the ingredients in the vessel come into contact with the emulsifier.
He adds that a gumming agent, needing a sheer action to mix with other ingredients, is then added to the water phase vessel. At a different stage of the mixing process, sugar, which requires low-level mixing, is added to the vessel, since the sugar drops to the bottom of the vessel. A lighter ingredient is also added, but, because this ingredient floats at the top of the vessel, Anderson Engineering needed to adjust the vessel to incorporate all three elements.
“The first step is to mix the sugar from the bottom, while the gumming agent is mixed midstream under liquid level. Finally, by creating a vortex from the top, the lighter ingredient can be drawn into the mix,” Coertse elaborates.
The Anderson Contramix vessel is a universal mixing vessel, ideal for food, pharmaceutical, chemical and dairy applications. The vessel has vacuum, pressure and counter-attacking mixing capabilities.
Manufacturing of the vessel, with a capacity ranging from 20 ℓ to 2 500 ℓ, can take up to six months and is done by Pietermaritzburg-based Anderson Engineering.
“It is known as a contramixing vessel, as it has a dual mixing action with an inner stirrer that rotates clockwise and an outer stirrer that rotates anticlockwise,” Coertse explains, adding that the dual rotation allows for aggressive mixing, which is ideal for mixing components that typically do not blend well, such as oil and water, to be blended using an emulsifier.
The Anderson Contramix vessel has been available in South Africa for the past 35 years, he says, adding that the company continually looks to reinvent the solution through research and development, such as the mechanical ball-screw and nut system, which was introduced in 2013 to raise and lower the top of the vessel.
“Previously, the system used hydraulics for the ‘raise’ and ‘lower’ functions. However, because hydraulic systems often leak, they are unhygienic and, therefore, cannot be used in food and pharmaceutical applications.”
Coertse points out that the mechanical system has also been combined with an automated locking and unlocking system, which allows for the vessel to be opened by an automatic control system, rather than the operator having to unwind a wheel lock, which uses a clamping band to close the vessel.