What causes internal breakdown of apple fruit?

 

Internal browning is a low-temperature storage disorder of certain apple cultivars which develops in some fruit stored at or just below freezing.  A cross section of an apple typically shows affected tissues to be brown and firm and usually radiating out from the core. Occasionally, the browning may be confined only to the core or the core area can be normal and browning is in the outer layers.  Firm fruit allows the diagnosis of internal browning from the other internal …