I need a way to calculate avocado ripeness rate in my experiment so I need a quantitative way, I'm not sure if calculating the cellular respiration for the avocado will result in ripeness rate for the fruit, if that's true I need references if you got. And if you got another better quantitative ways to get the "rate" of the fruit ripeness.
Generally, ethylene production is used to gauge fruit ripeness. This paper (PDF download) outlines an experiment measuring ethylene production from Hass avocados at different temperatures over several days. It appears they used gas chromatography to measure both ethylene and CO2 concentrations.