The food, beverage and brewing industries operate under exacting safety and quality standards. Any microbial contamination in the process can cause discoloration, affect flavor and shorten shelf life, not to mention create potential health risks for consumers. Effective microbial disinfection of the whole process is therefore essential.
An increasingly popular non-chemical disinfection method is ultraviolet (UV). UV eliminates all known spoilage microorganisms, including bacteria, viruses, yeasts and molds (and their spores). It is a low-maintenance, environmentally friendly technology that eliminates the need for chemical treatment while ensuring high levels of disinfection.
How It Works
UV is the part of the electromagnetic spectrum at 185 to 400 nm (known as UV-C). These wavelengths of light have a strong germicidal effect, destroying microorganisms by inactivating their DNA and other intracellular molecules. It is especially effective against microorganisms such as Listeria, Legionella and Cryptosporidium (and their spores, which are resistant to chlorine).
A typical UV disinfection system for processing applications consists of a UV lamp housed in a protective quartz sleeve and mounted within a cylindrical stainless steel chamber. The liquid enters at one end and passes along the entire length of the chamber before exiting at the other end. Virtually any liquid can be effectively treated with UV, including raw municipal water, filtered process water, viscous sugar syrups, beverages and industrial effluent.
UV disinfection has several advantages. It does not introduce toxins or residues into process water, nor does it alter the chemical composition, taste, odor or pH of the fluid being disinfected.
UV treatment can be used for primary water disinfection or as a backup for other water purification methods, such as carbon filtration, reverse osmosis (RO) or pasteurization. Because UV has no residual effect, the best position for a treatment system is immediately prior to the point of use. This ensures that incoming microbiological contaminants are destroyed and there is a minimal chance of post-treatment contamination.
UV disinfection has a variety of applications within the food and beverage processing industries.
Direct contact water. Although municipal water should be free from harmful or pathogenic microorganisms, it should still be treated before entering the process. Water from private sources such as natural springs or boreholes — often used in mineral water — could be contaminated and must be treated. Any water used as an ingredient in food or beverage products, or coming in direct contact with the product, could be a source of contamination. UV disinfects this water without chemicals or pasteurization. It also allows the reuse of process water, saving money and improving productivity without risking the quality of the product.
Clean-in-place (CIP) rinse water. It is essential that the CIP final rinse water used to flush out foreign matter and disinfecting solutions is microbiologically safe. Fully automated UV disinfection systems can be integrated with CIP rinse cycles to ensure final rinse water does not reintroduce microbiological contaminants.
Filter disinfection. RO and granular activated carbon (GAC) are often used to filter process water, but can be a breeding ground for bacteria. UV is an effective way to disinfect both stored RO and GAC filtered water and has been used in the process industries in this way for many years.
Dechlorination. GAC filters also are commonly used to dechlorinate process water, removing the “off” flavors often associated with chlorine disinfection, helping the flavor of the final product remain untainted and free from unwanted flavors or odors. Placing UV systems ahead of GAC filters used for dechlorination improves the performance of the filters and results in longer carbon runs, decreasing operating costs.
Cooling media & chiller disinfection. Some meat and dairy products are subject to contamination after heat treatment or cooking. UV provides a way to protect foods from contamination by contact-cooling fluids.
Sugar syrups. Sugar syrups can be prime breeding grounds for microorganisms. Although syrups with high sugar content do not support microbial growth, any dormant spores may become active after the syrup has been diluted. Treating the syrup and dilution water with UV prior to use ensures that any dormant microorganisms are deactivated.
Liquid sweeteners. Sucrose-based sweeteners also can be breeding grounds for microorganisms. UV systems are available specifically for treating these syrups.
Brine. Brines also can be breeding grounds for harmful pathogens, so effective disinfection is essential. UV slows the growth of microorganisms, allowing the brine to be used for longer, saving costs for the producer. UV also will not affect the taste or appearance of the product being used in the brine.
De-aerated liquor. De-aerated liquor is added as part of the high-gravity brewing process, often in the packaging operation. This liquor is added directly to beer, so it needs to be kept free from contamination by gram-negative bacteria, which can cause off flavors and acidity.
Yeast preparation. The problems associated with yeast preparation in breweries are well known and include hazes, altered fermentation and surface membranes on packaged beer. A single cell of Saccharomyces (var. Turbidans) in 16 million cells of pitching yeast will cause detectable hazes. UV destroys all known yeasts and their spores.
Wastewater. Effluent from food, beverage and brewing facilities can be treated without the use of environmentally hazardous chemicals. This ensures all discharges meet with local environmental regulations. Because process water can be treated with UV and reused, this also leads to a reduction in the amount of wastewater produced.
Bottled Water & Bromates
Aquionics’ U.K. sister company, Hanovia, has recently been working with Nongfu Spring Co. Ltd., a Chinese producer of bottled water and beverages, to supply UV systems for its production plants across China. This is a milestone for the bottled water industry in China, because presently in that country virtually all bottled water is disinfected using ozone. Around the world, ozone is the disinfection method of choice for many producers.
The decision by Nongfu Spring to opt for UV was driven by a number of reasons, not least of which was concerns about ozonation byproducts such as bromate. Bromide ions occur naturally in some spring water and on their own pose no problem. The presence of ozone, however, can cause conversion of bromide into bromate, with the consequent potential for consumer health problems. The World Health Organization (WHO) lists bromate as a carcinogenic substance and recommends its maximum limit in mineral water be set at 0.01 mg/L. In July 2008, the Chinese General Administration of Quality Supervision, Inspection and Quarantine recommended in a revised draft national standard for drinking water and mineral water that a maximum limit for bromate in bottled water be in line with WHO guidelines. This limit has been in place since October 2009.
Meeting the rigorous hygiene standards required in the production of food and beverage products is a challenge. If improvements need to be made to plants and equipment, they need to bring quick returns on the investment and measurable improvements in product quality.
For manufacturers seeking to improve the quality of the end product, UV is an economic, realistic option. It is an established method of disinfecting drinking water throughout the world, and is also widely used for high-purity applications such as pharmaceutical processing and microchip manufacturing, where water of the highest quality is essential.