Ethylene is released by the apples during the storage which triggers the ripening.
If we want to store them longer, we need to remove the ethylene.
I have found
this research which looks into clay minerals soaked in potassium permanganate (Cody's crystals) and its effect to absorb ethylene.
The technology of ethylene absorption with commercially existing potassium permanganate absorbents such as Bi-On® is an effective method to maintain apple quality during cold storage. The high rate of ethylene production of apple is a challenge for the practical application of potassium permanganate absorbents, but it can be overcome using the already existing innovative air filtration equipment.
I believe using something like bentonite or straight dry clay would work too.
Apple season is approaching in the Southern hemisphere and my
trees are full at the moment. If I can protect them from codling moth and fruit fly, I want to store them a little longer this time.
I will be preparing trays of clay, soaked in PP under my
apple trays.