Cleaning Validation of Food Production Equipment by TOC and TN Measurement

Importance of the Topic

Food production equipment must be thoroughly cleaned to prevent cross-contamination and ensure consumer safety and product quality. Measuring residual organic carbon and nitrogen compounds provides quantitative evidence of cleaning efficacy.

Objectives and Overview

This study demonstrates a rapid method for evaluating cleaning validation by simultaneous measurement of total organic carbon (TOC) and total nitrogen (TN) in rinse water from stainless steel containers previously used for rice vinegar or brown-rice black vinegar.

Methodology and Instrumentation

A round stainless steel container (700 mL) was coated with vinegar and subjected to three consecutive rinse steps using purified water. TOC and TN were measured simultaneously in approximately 5 minutes per sample using a Shimadzu TOC-LCPH analyzer equipped with a TNM-L total nitrogen unit and TOC/TN catalyst. Calibration was performed with a single point for TOC (250 mgC/L potassium hydrogen phthalate) and two-point for TN (0 and 5 mgN/L potassium nitrate). An autosampler enabled automated multiple sample analysis.

Main Results and Discussion

Initial rinse water from rice vinegar exhibited TOC of 196.2 mgC/L and TN of 1.62 mgN/L, decreasing to 3.36 mgC/L and 0.076 mgN/L in the second rinse, and 0.127 mgC/L and 0.046 mgN/L in the third rinse, matching purified water levels (0.123 mgC/L, 0.038 mgN/L). Brown-rice black vinegar showed a similar pattern: 129.4 mgC/L/3.63 mgN/L (1st), 0.535 mgC/L/0.062 mgN/L (2nd), and 0.116 mgC/L/0.040 mgN/L (3rd). These results confirm effective removal of organic residues.

Benefits and Practical Application

This combined TOC/TN approach offers rapid, automated, and reliable assessment of equipment cleanliness with minimal manual intervention, enhancing quality control workflows in food manufacturing.

Future Trends and Possibilities of Use

Future developments may include integration into in-line process monitoring, expansion to other contaminant classes, real-time data analysis, and compliance with evolving regulatory standards.

Conclusion

Simultaneous TOC and TN measurement using thermal decomposition-chemiluminescence provides a fast, accurate, and practical tool for cleaning validation in food production.