Articles
In situ real-time measurement of respiration rate of fresh produce using a newly developed modular respirometer
Article number
1386_42
Pages
309 – 314
Language
English
Abstract
Monitoring of respiration rate and respiratory quotient are crucial for identifying the optimal needs for the long-term storage of fresh produce.
This study reports the application of a gas sensor and a modular respirometer for in-situ real-time monitoring of gas concentrations and respiration rate of fresh produce during storage.
The gas sensor consisted of an O2 (0 to 25%) and CO2 analyser (0 to 5%), while the modular respirometer consisted of a leak-proof arrangement with a glass chamber and a base plate containing water.
The modular respirometer (3.3 and 7.4 L) with fruit samples was placed inside a lab-scale CA chamber (190 L). The respiration rate was continuously recorded at regular cycles of gas data collection including 1 h of purging by an air pump to bring in fresh gas from CA chamber.
Measured gas concentrations along with mass of the product, the volume of the respirometer was processed in the terminal program to calculate respiration rate (RO2, RCO2) and respiratory quotient (RQ) in real-time at 1-min intervals.
Experiments were conducted on strawberries under air and low O2 (2 and 1%) and Pinova apples stored in a commercial CA storage (2% O2, 1.3% CO2, at 2°C). Mean Rо2 and Rсо2 of 20.2±1.2 and 27.0±2.8 mL kg‑1 h‑1, respectively, and an RQ of 1.33 were observed at 21% O2 and 10°C for strawberries.
For strawberries, lowering the O2 concentration resulted in lower Rо2 and higher Rсо2; while temperature changes also affected their Rо2 and Rcо2. During the initial storage, average Rо2 and Rсо2 of Pinova apples were 1.6±0.3 and 2.7±0.6 mL kg‑1 h‑1, respectively, but stabilised at 0.9±0.3 and 1.8±0.3 mL kg‑1 h‑1 when CA conditions were established.
No sign of anaerobic respiration was observed during the entire storage period.
The modular respirometer was found to be useful for in-situ real-time monitoring of respiration rate during storage of fresh produce and offers great potential to be incorporated into RQ-based dynamic CA storage system.
This study reports the application of a gas sensor and a modular respirometer for in-situ real-time monitoring of gas concentrations and respiration rate of fresh produce during storage.
The gas sensor consisted of an O2 (0 to 25%) and CO2 analyser (0 to 5%), while the modular respirometer consisted of a leak-proof arrangement with a glass chamber and a base plate containing water.
The modular respirometer (3.3 and 7.4 L) with fruit samples was placed inside a lab-scale CA chamber (190 L). The respiration rate was continuously recorded at regular cycles of gas data collection including 1 h of purging by an air pump to bring in fresh gas from CA chamber.
Measured gas concentrations along with mass of the product, the volume of the respirometer was processed in the terminal program to calculate respiration rate (RO2, RCO2) and respiratory quotient (RQ) in real-time at 1-min intervals.
Experiments were conducted on strawberries under air and low O2 (2 and 1%) and Pinova apples stored in a commercial CA storage (2% O2, 1.3% CO2, at 2°C). Mean Rо2 and Rсо2 of 20.2±1.2 and 27.0±2.8 mL kg‑1 h‑1, respectively, and an RQ of 1.33 were observed at 21% O2 and 10°C for strawberries.
For strawberries, lowering the O2 concentration resulted in lower Rо2 and higher Rсо2; while temperature changes also affected their Rо2 and Rcо2. During the initial storage, average Rо2 and Rсо2 of Pinova apples were 1.6±0.3 and 2.7±0.6 mL kg‑1 h‑1, respectively, but stabilised at 0.9±0.3 and 1.8±0.3 mL kg‑1 h‑1 when CA conditions were established.
No sign of anaerobic respiration was observed during the entire storage period.
The modular respirometer was found to be useful for in-situ real-time monitoring of respiration rate during storage of fresh produce and offers great potential to be incorporated into RQ-based dynamic CA storage system.
Authors
N. Keshri, I. Truppel, W.B. Herppich, M. Geyer, P.V. Mahajan
Keywords
CA storage, DCA RQ, apples, strawberries, O2 and CO2 sensor
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