Food-contact applications-food packaging, closures, and food-service items-require thermocouples that meet the food-safety regulations in addition to the thermal requirements. The regulations address the materials that contact the food, the cleanability of the surfaces, and the documentation that demonstrates compliance.
The first requirement is the material's food-contact compliance. The sheath, the transition, and the connector materials that contact the melt must be listed in the applicable regulation-the FDA's food-contact substance listings in the United States, the EU's plastics regulation, or the equivalent national scheme. The supplier should provide the compliance documentation for each material, and the documentation should be held with the mold's records.
The second requirement is the cleanability. The probe's surfaces should be smooth and free of crevices that can retain food residue, and the transition and connector should be sealed to prevent the residue from entering. The surface finish that was described for medical service applies, and the cleaning procedure should be compatible with the food plant's sanitation chemicals.
The third requirement is the temperature's accuracy. A food-contact part's thermal history affects its taste, its migration behavior, and its mechanical properties, and the probe's accuracy should be selected for the part's sensitivity. The Class 1 probe is the baseline, and the calibration should be verified at the process temperature.
The fourth requirement is the documentation. The food-contact compliance, the material certificates, the calibration certificates, and the cleaning procedure should be documented and held with the mold's records. The documentation is the evidence that the auditor will request, and the audit is the point at which the absence is discovered.
The fifth requirement is the change control. A supplier that substitutes a material without notification breaks the compliance basis, and the change-control commitment described earlier is more critical in food-contact service because the substitution may be a regulatory violation rather than a performance degradation. The specification should require notification before any material change, and the notification should include the new material's compliance documentation.
The practical specification for food-contact applications is a food-grade 316L sheath with a sealed transition, a smooth finish, a Class 1 calibration, and a documentation package that includes the compliance certificates and the change-control commitment. The premium over a general-purpose probe is small, and the cost of a non-compliant probe-a recall, a decertification, or a regulatory action-is large. A mold that uses a general-purpose probe for a food-contact part is a mold where the compliance is assumed rather than demonstrated, and the assumption is the risk.
