Silicone vs. EPDM rubber tubing: Does it make a difference in milk processing applications?

Processors and farmers alike are well aware of the negative effects poor equipment sanitation can have on product quality, hygiene and production efficiency in milking applications.

Proper equipment is a large part of maintaining both a high-quality milk product (i.e., safety/hygiene), as well as compliance. As a component in milk processing (and storage) equipment, tubing plays a vital role in maintaining/upholding and transferring product safety, hygiene and quality.

To ensure proper sanitary conditions, the inner surfaces of milking equipment and pipelines, or tubing, should be cleaned daily. Regular product sampling and testing are also necessary throughout various stages of the milk collection and transfer process to ensure product quality.

Most dairy farm and processing equipment is made of stainless steel, where alkaline and acid-based detergents and sanitizers are run through the system components to flush them clean of bacteria and other particles or debris. If not properly sanitized, the unwanted buildup of protein and organic material — or milk fouling (proteins, mineral deposits and fats) — can occur.

This build up, which can occur on rubber tubing, can lead to microbial contamination if not cleaned properly. Contaminated tubing can create multiple negative effects including a breach in regulatory compliance, textural and taste issues, and reduced efficiency for processors.

In many cases, deposits produced from fouling may be dislodged by flowing milk, causing contamination. Milk fouling can occur during both the collection and processing stages, which can negatively impact quality and hygiene in the finished dairy product — along with milk-brand quality and integrity.

Tubing considerations: Silicone vs. EPDM rubber (hereafter stated as rubber)

Chemicals in rubber tubing may leach into milk​

Chemicals leaching from the tubing composition into milk can have a negative effect on the product’s organoleptic properties, but may have an even more damaging impact on processors’ ability to achieve compliance with regulatory standards that govern the health and safety of foods and beverages for consumer consumption.

Over time, rubber tubing can lead to a buildup of an unsanitary colored residue/extractables, potentially including carbon black, which is a chemical material used in rubber and plastic products, among others.

The issue with carbon black and other such chemicals is that if they leach into milk, they could cause taste and odor issues and/or regulatory and health concerns. 

Tubing tests: Rubber and silicone ​

The Saint-Gobain Northboro Research & Development Center — the second largest multi-disciplinary R&D center for the Saint-Gobain Group located in the US — tested tubing samples, including rubber tubing and silicone tubing.

The goal was to relatively compare the amount of organic semi-volatile and non-volatile extractables between silicone and rubber tubing after soaking it in DI water (representing the aqueous nature of the milk) and 0.5% nitric acid solution (representing the cleaning chemicals used to clean the tubing).

GCMS analysis for the silicone tubing showed one silicone-related peak with each solvent; the rubber tubing extracted at least 24 distinct chemical compounds. These findings clearly demonstrate that silicone is a much cleaner tubing material vs. rubber under these testing conditions.

Protection through appropriate tubing selection​

Tubing selection and solutions​

One effective course of action dairy farmers and processors can take to ensure product quality, safety and regulatory compliance in milking applications is to evaluate and specify appropriate tubing solutions.

It is critical in specifying proper equipment to ensure organoleptic properties are unaffected (or have limited effect) from dispensing tubing materials.

From initial collection to transfer, processing and more, tubing is a key component in nearly every part of the milking process. This means that there are several touchpoints or opportunities for milk to become contaminated if proper tubing is not specified.

Plus, unclean milking systems foster bacteria growth, which can lead to hygiene issues and milk products with limited shelf life — not to mention potentially harmful implications for consumers.

A key consideration in the selection process should include tubing that exhibits performance properties that meet the milking equipment industry’s specific needs, such as flexibility in hot

and cold temperatures (for proper fitting installation and retention), resistance to kinking, hardening, fat absorption and durability (to ensure long and reliable service life), among others.

Additionally, it is important to ensure the milk tubing has been rigorously tested and proven to perform under the various conditions that can be encountered in a milking application.

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Iuliana Nita is global marketing manager, food & beverage, process systems, Saint-Gobain; Charles Golub is senior research engineer, fluid systems, Saint-Gobain; Joe Guesman is applications engineering manager, process systems, Saint-Gobain; Mike Tzivanis is R&D group leader, fluid systems, Saint-Gobain. ​

Saint-Gobain designs, manufactures and distributes materials and solutions, including industrial applications, for sectors such as the dairy industry. Saint-Gobain creates a variety of silicone tubing for the dairy industry. ​

You can ​download Saint-Gobain’s white paper '​​Silicone vs. EPDM rubber tubing: Does it make a difference in milk processing applications?' here​​