A Sweet Alternative to Pasteurisation of Liquid Sugar
As featured in this months edition of Food Processing, Diane White of atg UV Technology explains how UV Systems can provide a cost effective, power saving alternative to pasteurisation of liquid sugar solutions in food and beverage production
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 grime 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. 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 the requirement for large plant rooms to install the equipment has led many manufacturers to look to UV irradiation as a low energy consumption, physical, chemical-free technology.
The alternative to traditional pasteurisation
Unlike chemicals, UV treatment does not introduce any residual agents or byproductss 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. Using high-intensity UVC radiation at a 254nm wavelength, UV treatment will typically provide a 99.99% reduction in microorganisms in a single pass.
UV disinfection treatment has been around for many years and was first applied to sugar solutions in the 1980s, so it is a well proven technology, but the properties of syrups make the application unsuitable for standard UV disinfection units.
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. Most food and beverage manufacturing is carried out in batch processes.
If the flow of syrup stops with the UV unit full and in normal operating mode there is a danger that excess heat generated from the UV lamps can caramelise the sugar. Automatically adjusting the UV system’s operating power in response to the flow or batch controller avoids this problem.
atg UV’s SSL liquid sugar range of UV disinfection systems has been designed specifically to deal with the high viscosities encountered in sugar solutions up to 69°Bx at 10% UVT and utilises the latest in advanced thin-film quartz and UVC lamp and chamber designs.
The UV chambers are specially designed for high viscosity non-Newtonian flow and constructed to sanitary standards in 316L stainless steel. The control system features automatic power adjustment as standard and is designed to interface easily with most SCADA systems via MODBUS or PROFIBUS options.
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.