Alternative Tubing Eliminates Bacteria in Beverage Delivery Systems

With these applications becoming more common, consumers are recognizing there is now technology that is safe to use that can positively impact the things they utilize on a daily basis.

Silver as an Antimicrobial Agent

One of the top innovations is silver, which is a highly effective antimicrobial agent. Silver has long been known for its antimicrobial properties. Recently developed technology now allows for the “smart” release of the silver ions—slow and steady when necessary. This makes it ideal for food and beverage applications where bacteria can thrive.

Elemental ions attack multiple targets in the microbe to prevent it from growing to a destructive population. This tri-modal action fights cell growth in three ways:

• Prevents respiration by inhibiting transport functions in the cell wall
• Inhibits cell division (reproduction)
• Disrupts cell metabolism

Depending on the microorganism, antimicrobial technology has been shown to initially reduce microbial populate ions within minutes to hours while maintaining optimal performance.

Manufacturing innovations and new developments with polymers that accommodate this smart technology for silver have now made it possible to include this technology in delivery and dispensing systems of food and beverage products. Tubing and fittings are currently being manufactured with a PVC-free polymer that helps eliminate the potential harmful health and environmental effects of PVC coextruded with a silver lining constructed of this “smart” technology.

One such tubing was tested for its antimicrobial properties in beer and water by the Research Center Weihenstephan for Brewing and Food Technology in Germany. The research center, formerly the State Brewing Technology Testing and Experimental Station, was established in its present form in 2004 and is under the direct supervision of the TUM (Technische Universität München) administration. It is an unaffiliated, independent institute, serving the brewing and beverage industries, food producers, associated suppliers, regulatory authorities, and allied trade organizations as a neutral and competent partner.

Weihenstephan conducted a series of tests over several months to determine the antimicrobial activity of existing tubing currently being produced in the U.S. It was determined that there are four bacteria common in beer and other liquids and beverages:

Acetobacter lovaniensis: This acetic acid bacterium occurs in the early stages of biofilm formation. In wort and beer with high oxygen content, acetic acid bacteria can proliferate and cause an acidic off-flavor. It is commonly found on fruits, flowers, vinegars, and in fermented foods and drinks.

Wickerhamomyces anomalus (formerly: Pichia anomala): It’s frequently associated with spoilage or processing of food and grain products and is widespread among many production steps of alcoholic beverages. It belongs to the group of slow fermenting yeasts and is in carbonated beverages responsible for solvent-like off-flavors. This bacteria was detected in many cases in the brewing environment and its participation in biofilm formation was confirmed.

Lactobacillus brevis: It is by far the most frequently detected microorganism in beer. It’s classified as an obligate beer spoiler (i.e. it tolerates all selective characteristics of beer and deteriorates it by haze, acid formation, and off-flavors).

Pseudomonas aeruginosa: This can cause inflammations and infections. It ends up in the brewing environment, especially by the water, and contributes to biofilm formation as slime-forming bacterium. It’s a common bacterium that can cause disease in animals, including humans.

The following points summarize excerpts from two recent reports called “Flexelene Silver Tubing Analysis” from the Research Center Weihenstephan.

• Without water flow, the test with the silver lined tubing can be consistently regarded as positive. Despite vast inoculation of bacterial cells well over real contamination cell counts, the silver coating of the tubes was able to reduce the cell count of the four selected microorganisms significantly. The test results confirm that silver lined tubing could diminish the cell concentration of all the tested microorganism species up to 100.0 percent in the 24 hours test period.
• To determine whether taste can be detected in the tubing, a concentrate test was conducted called, “The influence of rubber material to smell and taste” (acc. to MEBAK IV, 2nd edition, issue 1998, “4.6 influence of rubber materials to smell and taste”). It was concluded that there is no significant difference on taste between the “treated” and the blank sample.
• After a circulation of 2,000 liters of water through the tubing, a positive result could be obtained as well. Considerable activity revealed through the tests against Lactobacillus brevis (the most frequently detected microorganism in beer), Acetobacter lovaniensis, and Pseudomonas aeruginosa where the cell concentrations could be reduced up to 100.0 percent in the 24 hours test period. The antimicrobial activity against the yeast Wickerhamomyces anomalus was, in two of three tests, slightly weaker, but still showed a reduced concentration.
• Even after a water throughput of 10,000 liters, the tubing showed positive antimicrobial activity against the acetic acid bacterium Acetobacter lovaniensis.
• To address potential concerns of the silver leaching into the flow path, testing was conducted after 2,000 liters, 10,800 liters, and 40,000 liters of water circulation. The analysis concluded that the flow directed through the silver lined tubing had no detectable silver traces in the water (detection limit of the method: 0.01 mg/l).

Overall, it was determined that the silver lined tubing was 100 percent effective against the top four beverage spoiling bacteria and was successful in reducing the concentrations of three of those bacteria in up to 2,000 liters of flow and Lactobacillus brevis up to 10,000 liters. The most impressive result is the notable reduction of Lactobacillus brevis, which is determined to be the most frequently detected microorganism in beer.

The Food & Beverage Industry

With the issues facing quality assurance stemming from PVC tubing and biofilm buildup in food and beverage applications, solutions are coming from an industry that is familiar with high-quality standards—the medical industry. Innovations such as silver lined tubing and fittings along with excellent alternatives to PVC have given the food and beverage industry an opportunity to significantly increase and control quality from production all the way to the consumer.