Mild UV-C light exposure, an invisible technology with a high potential

Although the short shelf life of fresh-cut fruit is a critical issue for the market operators, still limited tools are available to extend safety and quality of these products. The use of UV-C light has recently raised large attention. It is a powerful surface germicidal method, easy to use with favourable costs of equipments, energy and maintenance. It is safe to apply if simple precautions are taken and has not been reported to form known toxic or significant nontoxic by products. The aim of this research was to evaluate the effectiveness of UV-C light exposure on safety and quality of fresh-cut fruit. UV-C light was applied at increasing fluence up to 24000 J/m2 before and after packaging of apple slices and melon cubes. Assessment of dehydration kinetics, residual enzymatic activity, UV-C light penetration and microscopic analysis were used to study the effects of UV-C light on cells. Treated and control samples were then stored at 6 ?C for up to 14 days to simulate usual distribution conditions and analysed for microbial counts, colour, firmness, juice leakage, sensory properties and consumer preference. Independently on UV-C light fluence, all treatments imparted the same germicidal effect with 1-2 log reduction in total viable counts. Treatments at fluence exceeding 12000 J/m2 caused the loss of compartmentalisation of surface cells, activating dehydration and oxidative phenomena. By contrast, mild treatments allowed to obtained fruit derivatives much more stable than the untreated control in terms of microbial growth, colour modification and development of offflavours. These effects were attributed not only to the direct inactivation of spoilage microorganisms and oxidative enzymes by UV-C light but also to the formation of a thin dried film on the surface of the product. This edible protective film inhibited microbial growth and hindered dehydration and juice leakage during storage but was too thin to be perceivable by the consumers. Based on its better flavour and juiciness, UV-C treated fruit was significantly preferred to the untreated one. UV-C light exposure was demonstrated to be a high potential invisible technology for fresh-cut produce surface decontamination only if applied at mild intensity. Author L. Manzocco Dipartimento di Scienze degli Alimenti, University of Udine, via Sondrio 2/a, 33100 Udine, Italy, lara.manzocco@uniud.it Original tittle Impact of UV-C light on safety and quality of fresh-cut fruit Source Freshcut2011, Torino, ISHS, http://www.ishs.org Source of the pictureinfoalimentacion.com