http://www.chemistry-blog.com/2011/10/12/fruit-ripening-how-does-it-work/
" A more productive method of inhibiting ripening is to inhibit ethylene perception. This can be done by gassing the molecules with 1-methylcyclopropene (1-MCP). 1-MCP binds tightly to the ethylene receptor and blocking the effects of ethylene (competitive antagonist). 1-MCP is sold commerically as SmartFresh and is approved and accepted for use in more than 34 countries (including the EU and US). It is used in the fruit industry to prevent premature ripening, but it is also used in the horticultural industry to maintain the freshness of ornamental flowers. While there are benefits to consumers (fresher produce, lower cost due to increase supply), some have concerns that consumers may be purchasing fruit older than expected.
Current practice for longer-term fruit storage includes cold temperatures and charcoal scrubbing of the atmosphere to absorb ethylene and keep the concentration of ethylene very low..."
It explains some of my puzzles, but not all, what makes my banana taste bad and feel so firm ? it is still unknown...