Food safety practices used by food handlers are often monitored for research, inspection and regulatory purposes. However, if surveillance is not concealed, it can result in unintended behavioural changes.

These changes, known as the Hawthorne Effect, can render such observations meaningless.

"Direct concealed observations have been used to minimize the Hawthorne Effect during observational data collection in various settings, but some limitations can include the need to memorize observations or take notes out of sight of those being observed," explained Catherine Cutter, professor of food science at Pennsylvania State University.

In new research, researchers describe a newly developed smartphone and tablet application for use as a data collection tool for direct concealed observations.

The app helps create of checklists to record aspects such as hand hygiene, the adequacy of hand-washing facilities, the temperature in coolers holding ready-to-eat foods and the presence of potentially hazardous foods.

It allows observers to easily add photos, audio, videos and open-ended notes to their reports.

"The app can be used as a non-threatening tool to make direct, concealed behavioural observations and no one will ever realise you are doing it," Cutter added.