Purpose: We aimed to estimate the surface free energies of noroviruses, fresh foods and agri-food surface, calculate their interfacial free energies of interaction and evaluate adsorption.
Methods: Virus-like particles (VLPs) of GI.1 and GII.4 noroviruses and feline calicivirus have been produced, purified and used. Surface free energies of those viral particles and of surfaces such as lettuce, strawberry, polyethylene and stainless steel have been estimated using contact angle method. Norovirus adsorption was also tested according to pH, ionic strength and temperature.
Results: Almost all surface free energies and all total interfacial free energies of interaction predicted spontaneous adsorption for the VLPs tested. As expected, GII.4 VLPs adsorbed clearly on stainless steel, polyethylene and lettuce and adsorption percentages on all surfaces were in the same order with maxima (~94% of 0.35 µg, n = 2) at pH 4 near the isoelectric point, and decreased with higher pH. Adsorption increased with increasing ionic strength, as well as increasing temperature at pH far from pH 4.
Significance: Physicochemical conditions are likely more important than surface free energies in adsorption amplitude. Acidic pH, high ionic strength and temperatures in agri-food sector should matter during processing as they can contribute in norovirus adsorption on surfaces and foods.