Is UV the answer to combat microbial spoilage?

Abstract

Microorganisms certainly play a crucial role in wine production (Mauriello et al., 2009; Ruiz et al., 2010), however some yeasts and bacteria can have a negative impact on the quality of wine due to spoilage (du Toit and Pretorius, 2000). Good hygiene practices together with excellent winemaking procedures are recommended in the cellar to continuously control the growth of microorganisms throughout wine production. Traditionally, microbial growth is effectively controlled in grape juice and wine by the addition of sulphur dioxide (SO2). Since more consumers are allergic to SO2, its use is currently under review (Jackson, 1994). Besides SO2 usage, alternative additives such as potassium sorbate, Velcorin? (dimethyl dicarbonate), natamycin and lysozyme are also known to have inhibitory effects on microorganisms. Filtration is also very efficient in controlling microbial growth but, can however affect the colour, flavour and palate of wine negatively (Su?rez et al., 2007). Ultraviolet (UV-C) radiation along with flash pasteurisation, pulsed electric fields (PEF) and high hydrostatic pressure systems are classified as innovative technologies with the potential of inactivating microorganisms in liquid food products without affecting the sensorial properties of the product (Sizer and Balasubramaniam, 1999; Pu?rtolas et al., 2009). The effectiveness of UV-C radiation to inactivate microorganisms has already been investigated in a range of fruit juices, beer and milk (Koutchma et al., 2009; Lu et al., 2010). However, the feasibility of this technology to control wine-related microorganisms in grape juice and wine is still unclear. The aim of the study was therefore to investigate the efficacy of UV-C radiation as an alternative technology to inactivate microorganisms in red and white grapes juices and wine