As published in this months edition of Process & Control, Diane White discusses how UV systems can provide a practical, power saving alternative to pasteurisation in food and beverage production
Waterborne micro-organisms are responsible for adverse effects on flavour, colour, odour and shelf life of products and, of course, potential health risks to consumers. A number of emerging pathogens, like Cryptosporidium and Giardia are highly resistant to conventional chemical disinfection. As a result, the food and beverage industry is tightening its already stringent microbiological safety and quality standards for process water, product water and sugar solutions. To avoid the changes in product quality that chemical additives can produce, and to respond to consumer demands for reductions in additives and preservatives, food and beverage manufacturers are looking for alternative techniques to protect their products from bacterial damage. For those products that can tolerate the temperature, pasteurisation may be an option, however rising energy costs and space restrictions have led many manufacturers to look to UV treatment as a low energy, small footprint, and chemical-free technology. Unlike chemicals, UV treatment does not introduce any residual agents or by products into the liquid and will not change the organoleptic properties of a product, whilst protecting against a wide range of micro-organisms including thermophilic spores that are tolerant to pasteurisation.
UV treatmenthas a long history in pharmaceutical and drinking water disinfection where it has been proven that 254nm UVC light, at the correct and consistent dosage, inactivates the whole range of spoilage microorganisms – viruses, bacteria, moulds and protozoans – even chemically resistant ones including thermophilic bacteria which are resistant to pasteurisation. UV systems are entirely chemical-free, low maintenance and cost-effective, and can achieve a 99.99% reduction in microorganisms in a single pass, making them suitable for a range of process applications, from CIP rinsing to liquid sugar treatment. atg UV Technology has developed a range of UV disinfection units to meet the needs of the food and beverage industry.
Syrups – solutions of sugars like sucrose, fructose and glucose - are key ingredients in thousands of food and beverage products, adding sweetness to soft drinks, fruit juices, confectionary and even tomato ketchup. In concentrations above 66°Brix (1°Bx is 1 gram of sucrose in 100 grams of solution) the osmotic pressure of the solution is so high that bacteria cannot survive, but many produce spores which lie dormant until the concentration is reduced when the syrup is added to the product. Then they start to multiply. Once active, these bacteria can cause discolouration, adverse flavours, unwanted odours, changes in texture, reduced product shelf-life and critically, an increased risk of causing infection and ill-health. Controlling bacterial growth is, therefore, an important issue.
Unlike water applications, the properties of sugar syrups make standard UV disinfection units unsuitable. Syrups have high viscosities and ultraviolet transmittance (UVT) can be as low as 10-15%, so a specialist UV chamber, using a ‘thin-film’ design that ensures the syrup is evenly exposed to the UV light is essential. atg UV’s SSL liquid sugar range has been designed specifically to deal with the high viscosities encountered in sugar solutions up to 69°Bx at 10% UVT. The units are constructed to sanitary standards in 316L stainless steel and their control systems feature automatic power to prevent the syrup from caramelisation. UV systems have been proven to work effectively on syrups made from both cane and beet sugar make-ups by leading brands including Britvic, Cevital, Coca-Cola and Pepsi.
The success of UV disinfection depends on ensuring that the applied dose is always sufficient to inactivate the target microorganisms. atg’s UV systems closely match the US EPA guidelines for equipment validation – the standard generally adopted for UV disinfection systems in municipal drinking water. And with continuous UV intensity monitoring as standard, you can be totally confidant that the UV dose is always being delivered.