|Syamaladevi, Roopesh - Washington State University|
|Adhikari, Achyut - Washington State University|
|Bhunia, Kanishka - Washington State University|
|Khingra, Amit - Washington State University|
|Sablani, Shyam - Washington State University|
Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2014
Publication Date: 9/16/2014
Citation: Syamaladevi, R.M., Adhikari, A., Lupien, S.L., Dugan, F.M., Bhunia, K., Khingra, A., Sablani, S.S. 2015. Ultraviolet-C light inactivation of Penicillium expansum on fruit surfaces. Food Control. 50:297-303.
Interpretive Summary: Inactivation of microbes on surfaces of plant products (especially fruits, vegetables, or seeds) is often critical for successful storage of the product. Chemical treatments (e.g., chlorine, hydrogen peroxide, fungicides) are routinely applied, depending on the product. Concerns over safety, plus consumer preference, have impelled research on alternative technologies. One such technology is exposure of plant product surfaces to ultraviolet (UV) light. Surface morphologies and composition may play roles in the efficacy of such treatments. In this research, fruits of various surface morphologies were used in experiments on inactivation (i.e., rendering nonviable) of spores of a common fungus responsible for fruit rots, Penicillium expansum. Although results indicated that UV light can greatly reduce populations of this fungus, surfaces that are rough and/or hydrophobic can lower the effectiveness of treatment.
Technical Abstract: Understanding the influence of fruit surface morphology on ultraviolet-C (UV-C 254 nm) inactivation of microorganisms is required for designing effective treatment systems. In this study, we analyzed UV-C inactivation of Penicillium expansum that was inoculated onto the surface of organic fruits. Results show that maximum reductions of 1.8 (apple), 2.4 (cherry), 2.6 (strawberry) and 2.8 (raspberry) log CFU/g were observed after 1.2, 2.1, 3.3, and 3.3 kJ/m2 of UV-C doses, respectively. The UV doses required to reduce 2 log CFU/g of P. expansum population on apples, cherries, strawberries, and raspberries estimated with the Weibull equation were 1.03, 1.28, 1.39, and 1.61 kJ/m2, respectively. Findings also show that the hydrophobic nature of raspberries, along with high surface roughness, resulted in a lower inactivation rate of P. expansum. This study shows that UV-C effectively reduces P. expansum populations on fresh fruit surfaces; however, the efficacy of treatment is dependent on fruit surface morphology.