Purpose To investigate the durability, functionality, detectability and cleanability of metal detectable brush bristles. Methods Durability - tests to assess the break strength and elongation of metal detecta ble and plastic bristles were performed by Zwick Roell, using a Zwicki 5kN (Figure 1) . Functionality - the ability of metal detectable bristled brushware to clean a surface of a wet (tinned chopped tomatoes) and a dry (mix of milk powder and coffee granules) food soil, was compared with that of a standard plastic bristled brush, using a robotic cleaning rig (Figure 2) . Metal detectability - in collaboration with Mettler Toledo, metal detectable bristles were investig ated with regard to their detectability using a Profile Advantage multi- frequency Metal Detector, with and without the presence of packed fresh chicken and packed granulated sugar (Figure 3) . Cleanability - Metal detectable and plastic bristles were contaminated (Figure 4a) with Brownes test soil (Isopharm Ltd.) and cleaned under the same conditions (Figure 4b) . Load Cell: 200N HP Extensometer: Crosshead Grips: Pneumatic Grips - 8190 Newtons Jaws Insert: Oxidceramics Clamping Pressure: 4 bar Pre-Load: 1 Newton Speed, Pre-load: 10 mm/min Test Speed: 20 mm/min Grip to Grip distance at start: 100 mm Figure 2. Robotic cleaning rig (Vikan, Denmark). Transport Speed: 18 m/m Aperture Size: 350 x 175 mm Results Durability - Plastic (polyester) bristles were 68% stronger and more than twice as elastic as metal detectable bristles (Tables 1a & 1b and Graphs 1a & 1b) . Functionality - based on visual assessment, metal detectable bristled brushes were no more effective at cleaning than standard plastic bristled brushes (Figures 5a & 5b) . Metal detectability - metal detect able bristles were not detectable in the presence of food (Table 2) . Cleanability - Visual inspection by microscope (Nikan SM21500) showed that metal detecable bristles were rougher and harder to clean (Figures 6a & 6b) . Figure 5a. Cleaning with a metal detectable bristled brush. Figure 3. Profile Advantage multi-frequency Metal Detector (Mettler Toledo, Denmark). Figure 5b. Cleaning with a plastic bristled brush. Figure 1. Zwicki 5kN bristle strength and elongation assessment equipment (Zwick Roell, Germany). Figure 4a. Brush contamination usig Brownes test soil. Figure 6a. Plastic bristles after cleaning (160x magnification). Figure 4b. Cleaning of the soiled brush. Figure 6b. Metal detectable bristles after cleaning (160x magnification).
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