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Sol-gel-based stainless steel surface reduces fouling and biofilm formation during milk pasteurization

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By Jim Cornall+


A study looked at the benefits of a Thermolon coating of stainless steel surfaces. Pic:©iStock/Oskanov
A study looked at the benefits of a Thermolon coating of stainless steel surfaces. Pic:©iStock/Oskanov

Milk fouling and biofilms are common problems in the dairy industry for many types of processing equipment. Fouling requires frequent clean-in-place, leading to increased down time and reduced production.

Previous studies have stated that the effect of fouling on the dairy industry accounts for up to 80% of total operating costs.

One way to reduce the problem is to modify the characteristics of milk contact surfaces.

Researchers at the Department of Animal Sciences and Industry/Food Sciences Institute, Kansas State University, and Midwest Dairy Foods Research Center, Dairy and Food Science Department, South Dakota State University, studied the viability of using Thermolon (made by Porcelain Industries Inc., Dickson, TN), a sol-gel-based surface modification of stainless steel, during thermal processing of milk.

The findings were published in April’s Journal of Dairy Science.

Hydrophobic surface

The researchers used stainless steel 316L as a control, and a sol-gel-modified surface to evaluate fouling behavior and bacterial adhesion.

The surface roughness as measured by an optical profiler indicated that the control surfaces had a slightly smoother finish.

Contact angle measurements showed the modified surface led to a higher water contact angle, suggesting a more hydrophobic surface.

The authors of the study said they observed a significant reduction in the amount of fouled layer on the modified surfaces.

They also examined the adhesion of Bacillus and biofilm formation, and observed the modified stainless steel surface offered greater resistance to biofilm formation.

Reduced fouling

Overall, the Thermolon-modified surface showed potential in the thermal processing of milk, offering significantly lower fouling and bacterial attachment than the control surface.

Sol-gel surface modification, the researchers noted, converts inorganic liquid substances into a gel that can be applied on metal surfaces to improve the surface properties. According to its manufacturer, “It is environmentally friendly, durable, and most importantly, it has been approved by the FDA as a food contact surface.”

The authors of the study said the results provide evidence for the potential of using Thermolon-modified heat exchangers in dairy thermal processing to reduce milk fouling and biofilm formation, increasing process efficiency and enhancing the microbial quality of the final product.

Future studies will investigate the reusability of the Thermolon surface modification.

The work was financially supported by the National Dairy Council.


Source: Journal of Dairy Science

Short communication: Evaluation of a sol-gel–based stainless steel surface modification to reduce fouling and biofilm formation during pasteurization of milk

Dylan Zhe Liu, Shivali Jindal, Jayendra Amamcharla, Sanjeev Anand and Lloyd Metzger

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