Printing data matrix code on food-grade tracers for grain traceability

A traceability system that enables grain to be traced from its point of origin throughout the supply chain is needed to improve food safety in cereal grains. Food-grade tracers – pill-sized particles with identity information printed on their surfaces – added to grain at harvest have been proposed as a means to realise a grain traceability system. Two types of such tracers (sugar-based and cellulose-based) have shown promise during previous research, but a means of applying identity information to them remains to be developed. In this study, a specialised ink-jet printer was used to print data matrix (DM) code symbols onto the tracers with food-grade ink, and the method's efficacy and the readability of the code were considered. Factors related to readability, including surface roughness of the tracers, were also considered. The printing of DM codes on sugar- and cellulose-based tracer particles was found to be readily feasible, and readability for both types was above 90%. The surface roughness of the sugar-based tracers was higher than that of the cellulose-based tracers, and readability of cellulose-based tracers was higher. However, for a given tracer type, readability increased slightly with surface roughness, indicating that some factor other than roughness – such as thermal conductivity of the tracer material – may be influencing the printing process and thus the readability of the code. Fundamentally, however, the successful printing of DM code onto food-grade tracers with food-grade ink is a novel and important step in developing a grain traceability system.