Metal Detectable Brush Bristles: Do They Work?

Introduction:  If a food is contaminated by a foreign body, the repercussions for the food business can be expensive and damaging. One source of foreign body contamination is food industry brushware. Recently, brushes with metal detectable bristles have been marketed to the food industry as a way of detecting foreign bodies from this source. But, do they work?

Purpose:  This study investigated the durability, detectability, functionality, and cleanability of metal detectable brush bristles.

Methods:  To determine durability, metal detectable and plastic bristles were investigated with regard to their strength and elasticity using a Zwicki 5kN (Zwick Roell). Metal detectable bristles were investigated with regard to their detectability using a Mettler Toledo metal detector, with and without the presence of wet and dry food. Functionality, the ability of metal detectable bristled brushware to clean a surface of a wet and a dry food, was compared with that of a plastic bristled brush, using a robotic cleaning rig (Vikan). And to assess cleanability, metal detectable and plastic bristles were contaminated (Brownes test soil, Steris), and cleaned under the same conditions.

Results:  Durability testing showed that plastic bristles were 68% stronger and more than twice as elastic as metal detectable bristles. Metal detectable bristles were not detectable in the presence of food. Based on visual inspection, metal detectable bristled brushes were no more effective at cleaning than plastic bristled brushes and microscopic inspection showed that metal detectable bristles were rougher and harder to clean.

Significance:  Metal detectable bristled brushware offers no advantage, with regard to cleaning efficacy, and are unlikely to minimise the risk of bristle contamination in food. In fact, they may increase it due to their reduced strength and elasticity; and a perception that any metal detectable bristles will be controlled via the metal detector.