5. edtion 0721 Significance Based on the findings of this study 1) Metal detectable bristled brushware offers no advantage with regard to cleaning efficacy and are unlikely to minimise the risk of bristle contamination of 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. Currently, only relatively thick metal detectable bristles are available, i.e., there are no brushes with bristle thicknesses of <0.35 mm. However, fine bristled brushes are more effective at removing fine powders, including some allergens. Consequently, the use of thicker bristled brushes may result in poor cleaning efficacy and therefore, increase the risk to the business/consumer. 2) The detectability of metal detectable bristles will depend on a number of factors (Figure 7) . The influence of these factors is variable and accumulative and they will affect the detection threshold. Consequently the ability of a metal detector to detect very small metallic objects is limited. Physical/ electronic vibrations Food product signal · Water content · Salt · Grease · Packaging · Bones · Frozen · Etc. Conveyor speed Figure 7. Factors affecting the metal detection threshold. Aperture size Detector type Bristle fragment size/ orientation/ position in the food Metal content Detection threshold Additionally, the data shown in Table 3 (Lock, 1990), indicates that, to achieve a similar detection to that of a standard ferrous test piece with a spherical diameter of 1.5 mm, metal wire lengths of between 3 mm and 8 mm would be required. Table 3. Lengths of metal wire required to obtain a similar level of metal detection to that of a 1.5 mm spherical diameter ferrous sphere. (Lock, 1990). Ferrous ball (spherical diameter) Pure steel paper clip (ferrous) 0.95 mm cross-sectional diameter Pure copper wire (non-ferrous) 0.91 mm cross-sectional diameter 1.5 mm 3 mm long 9 mm long Pure stainless steel wire EN 58/AISI 304L (part-ferrous) 1.16 mm cross-sectional diameter 8 mm long Currently brushes with metal detectable bristles are only available with bristle diameters of 0.35 mm, 0.5 mm and 0.6 mm, i.e., much thinner than the metal wires assessed in Table 3. It can be concluded therefore that even longer lengths of metal detectable plastic bristles would be required to achieve the same level of detection. Given this, it is unlikely that metal detectable plastic bristles/bristle fragments would be detectable in a food product, especially given detector and product variances, and that bristle fragments are likely to be small. 3) The roughness of the metal detectable bristles made them harder to clean. Residúal soil on brush bristles will increase the risk of cross contamination. Consequently, the material used to make them should be easy to clean, in line with bygienic design guidelines (EHEDG, 2018 & 2005). Conclusion: Metal detectable bristled brushes may in fact increase the risk of product contamination, due to their reduced cleanability, strength and elasticity, combined with a perception that they will be detected by the metal detector. Art. No: Metal_Detectable_brochure-EN Vikan is one of the world’s leading manufacturers of hygienic and effective cleaning solutions. We offer more than 100 years of innovation and a range of more than 1000 different cleaning implements. All our tools are tailor-made for use in industries where hygienic cleaning is essential. Visit us at vikan.com
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