Use of silicon-based artificial surfaces of “Romaine” lettuce and spinach leaves for attachment and removal evaluation of Porcine Rotavirus strain OSU and Human Rotavirus strain ST3

Presenting author: Sindy Palma-Salgado

Co-authors: Helen Nguyen, and Hao Feng

Department of Food Science and Human Nutrition

One-in-six Americans suffer from a food-related illness caused by bacteria, viruses, and parasites every year. Leafy greens and fresh produce have been linked to most food-borne outbreaks caused by such microorganisms. Plant epicuticular wax and surface roughness play a key role in promoting attachment of bacteria and viruses to leafy greens. Fewer studies have examined all the conditions that promote initial adhesion and hinder removal of viruses. In this work, we present the use of a silicone-based artificial surface with different surface hydrophobicity, epicuticular wax and surface roughness to evaluate attachment of porcine rotavirus (PRV) strain OSU and human rotavirus (HRV) strain ST3. Silicon-based surfaces with topography, hydrophobicity and epicuticular wax similar to “romaine” lettuce and spinach leaves were developed. The spinach and lettuce artificial surface had roughness of 8 μm and 14 μm respectively, hydrophobicity of 70°& 110° and epicuticular wax similar to the real leaves. 100 μl of PRV and HRV culture was spot inoculated in the adaxial side of the artificial surfaces and allowed to incubate 2 hours to promote attachment. Disinfection was carried using chlorine, peroxyacetic acid, and malic acid + TDS, all in combination with ultrasound (US at 25 kHz). No significant differences in attachment of PRV to real and artificial romaine lettuce surface were observed, with attachment of 6.0 ± 0.3 Log PFU/ml and 6.0 ± 0.2 Log PFU/ml respectively. For the real and artificial spinach surfaces, the attachment was 6.2 ± 0.2 Log PFU/m and 5.8 ± 0.4 Log PFU/ml, respectively. No significant difference was observed for HRV attachment between romaine lettuce real leaf, spinach real leaf, and their respective artificial surfaces. Malic acid + TDS reduced HRV by 1.0 Log, while malic acid +TDS+US reduced HRV by 3.0 Log. Both Chlorine and peroxyacetic acid + US reduced HRV by 4.4 logs. Artificial surfaces provided a good tool to investigate the attachment and removal of PRV strain OSU and HRV strain ST3. Chlorine and peroxyacetic acid in combination with ultrasound are good sanitation methods due to a complete removal of initial load of rotaviruses present in the produce surfaces.