34.1 Introduction
Materials that retain few microorganisms after cleaning would be the hygienic
choice, and would present the least risk of cross-contamination. Surfaces that are
hard, inert, impervious, easy to clean and difficult to damage are desirable in
terms of hygienic status. The ability of these surfaces to actively repel or inhibit
the attachment, or reduce viability, of attached microorganisms without engen-
dering any resistance among survivors, would also be desirable. The develop-
ment of surfaces that present such novel properties may also require the
concomitant development of testing methods that retain the rigour of more
traditional tests, but that enable the properties of these substrata to be correctly
evaluated for their intended use. Furthermore, if hygienic status is focused only
on the removal of microorganisms, then the presence of residual organic soil,
perhaps from food, inorganic materials, or cleaning applications, is ignored. The
cleanability of the surface, as opposed to sanitizing, is also of concern in this
context, and the relative removal of the microbial and non-microbial
components of the fouling material should be evaluated. Lastly, surfaces that
are used repeatedly ± clearly an essential property of a hygienic surface ± will
alter over time, in terms of both chemistry and topography. Rigorous testing
methods used to evaluate the effectiveness of a surface, or a cleaning
application, should incorporate an assessment of long-term usage, in terms of
surface wear. The potential retention of material within surface features over
time, and the different behaviours of relevant soil and microorganisms, should
be considered.
There are many variables that should be addressed when determining which
testing methods to employ in evaluating the hygienic status of a surface and its
34 Testing surface cleanabilityin foodprocessing
J. Verran, Manchester Metropolitan University, UK