A durometer, acoustic impulse-response and special UV-VIS spectrophotometer are all instruments used to detect avocado ripeness and usually work well. A durome

A durometer, acoustic impulse-response and special UV-VIS spectrophotometer are all instruments used to detect avocado ripeness and usually work well. A durometer is the cheapest at about $40. If you're right that it's impossible to tell by hardness then it wouldn't work. But you might find that it's more sensitive than your fingers and so it can work? I would be interested to know the result of a durometer test on your fruits because about 85% of consumers report firmness as a useful measure - a lot but certainly not everyone. So yes maybe there is some granularity to discover there: specific situations where firmness just doesn't work well?