Comparison of Fruit Respiration Rates Measured by IR and GC/ Jetanizer FID

Importance of the Topic

Measuring respiration rates of fruit and vegetables provides crucial insight into post‐harvest physiology, ripening stages, and senescence processes. Reliable CO2 production data support quality control, storage optimization, and shelf‐life predictions in research and industry.

Study Objectives

This study aims to compare two approaches for quantifying CO2‐based respiration rates: a portable infrared (IR) sensor and laboratory gas chromatography with flame ionization detection and in‐jet methanizer (GC/Jetanizer‐FID). Evaluation focuses on accuracy, dynamic range, and suitability across produce with slow to fast respiration rates.

Methodology and Instrumentation

Samples of avocado, broccoli, brussels sprouts, oranges, tomatoes, and lemons were sealed in 950 mL glass jars equipped with circulation fans, an IR CO2 sensor, and a septum for syringe sampling. IR readings were logged every 5 s. Gas samples (1 mL) were injected into an Agilent 7890 GC with a GasPro column (15 m × 0.32 mm), operating isothermally at 50 °C. The FID was coupled to a Jetanizer methanizer for CO2 detection. Calibration used certified CO2/ethylene gas mixtures.

Used Instrumentation

• Infrared CO2 sensor (CozIR, CM-0187)
• Agilent 7890 GC with GasPro column
• Flame ionization detector with Jetanizer™ for CO2 conversion
• Circulation fans and glass sample jars

Main Results and Discussion

• Above 10 mL CO2/kg·h, the IR sensor and GC/Jetanizer-FID results correlate closely, although the sensor overestimates rates by 20–40%.
• At low respiration rates (<10 mL CO2/kg·h), the IR sensor shows significant deviations from GC measurements, likely due to limited sensitivity and single‐point calibration errors.
• Produce with intermediate rates (10–20 mL CO2/kg·h) such as oranges and tomatoes exhibited similar trends between methods, with minor systematic bias in the sensor data.
• The GC/Jetanizer‐FID proved accurate across the full range of respiration rates and offers the capacity to measure other volatiles simultaneously.

Benefits and Practical Applications

• IR sensors deliver rapid, low‐cost monitoring for high respiration scenarios where extreme precision is not required.
• GC/Jetanizer-FID ensures high accuracy at both low and high CO2 production rates and enables multi‐gas profiling (ethylene, ethanol).
• Combined approaches facilitate flexible workflow designs in post‐harvest research, quality assessment, and controlled‐atmosphere storage studies.

Future Trends and Applications

Advances in miniaturized chromatography and enhanced IR sensor calibration algorithms will improve onsite respiration monitoring. Integration with automated sampling, real‐time data analytics, and multi‐analyte detection platforms can drive innovations in precision agriculture and supply chain optimization.

Conclusion

This comparison demonstrates that while portable IR sensors are suitable for rapid, cost‐effective measurements above 10 mL CO2/kg·h, GC/Jetanizer-FID provides greater accuracy across all respiration rates and supports comprehensive gas analysis. Selection of method depends on required precision, throughput, and analytical scope.

References

No specific literature references were provided in the source document.