The use of physicochemical methods to detect organic food soils on stainless steel surfaces

Abstract

Food processing surfaces fouled with organic material pose problems ranging from aesthetic appearance, equipment malfunction and product contamination. Despite the importance of organic soiling for subsequent product quality, little is known about the interaction between surfaces and organic soil components. A range of complex and defined food soils was applied to 304 stainless steel (SS) surfaces to determine the effect of type and concentration of soil on surface physicochemical parameters, viz surface hydrophobicity (DeltaG(iwi)), surface free energy (gamma(s)), Lifshitz van der Waals (gamma_LW(s)), Lewis acid base (gamma_AB(s)), electron acceptor (gamma_+(s) ) and electron donor (gamma_-(s) ) measurements. When compared to the control surface, changes in gamma_AB(s), gamma_+(s) and gamma_-(s) were indicative of surface soiling. However, soil composition and surface coverage were heterogeneous, resulting in complex data being generated from which trends could not be discerned. These results demonstrate that the retention of food soil produces changes in the physicochemical parameters of the surface that could be used to indicate the hygienic status of a surface.

The effect of surface properties of polycrystalline, single phase metal coatings on bacterial retention

“…Physicochemistry of the coatings was determined as carried out by Whitehead et al (2009). Surface tension parameters for polar and apolar liquids were used to calculate physicochemical parameters (van Oss et al, 1990;van Oss, 1995;van Oss et al, 1986) with modifications as described in Whitehead et al (2009).…”

Adhesion of Salmonella Enteritidis and Listeria monocytogenes on stainless steel welds

“…Welding process commonly provides greater roughness on stainless steel surfaces welded. Several studies have reported correlation between surface roughness and bacterial accumulation on surfaces (Whitehead et al, 2009;Wirtanen and Mattila-Sandholm, 1992). However, other studies have reported a lack of correlation between surface irregularities or roughness and the number of bacteria attached (Silva et al, 2008;Szlavik et al, 2012).…”

Developing application and detection methods for Listeria monocytogenes and fish extract on open surfaces in order to optimize cleaning protocols

“…If further organic material, cells, minerals, cleaning deposits and other debris are deposited onto a surface, this may be known as organic fouling. In food processing, there is constant fouling of surfaces by the food components being processed and this fouling forms the layer onto which microorganisms subsequently adhere (Whitehead et al, 2009a). This organic material may also potentially provide nutrients for the residual microorganisms, enabling multiplication and an increase in contamination of the surface, providing that other conditions conductive to growth are available (Whitehead et al, 2009b).…”

“…However, it has been shown that the susceptibility of cells to biocides may be reduced by the presence of organic material on the surface (Aarnisalo et al, 2000;Bagge-Ravn et al, 2003;Gram et al, 2007). Retained organic material on a surface may also impede the recovery of cells and methods of detection (Whitehead et al, 2009a). One of the most common ways to evaluate cell viability on surfaces is to use a swabbing and serial dilution method.…”

“…The food industry (and others) relies on cleaning and disinfection to remove organic material and kill bacteria and it is well-known that the type of organic material present affects the effectiveness of cleaning and sanitizing (Whitehead et al, 2009a). Chlorine is known to work primarily against proteins (Schwach and Zottola, 1984) and also depolymerizes exopolymeric substances (Kumar and Arand, 1998).…”