I cut into this apple and it had these small brown streaks. The apple itself was firm and looked good on the outside with no obvious spots or bruises. I accidentally ate a small piece and it tasted normal and sweet.
These symptoms are characteristic of a physiological disorder called bitter pit, which is the result of a calcium deficiency. This may be the result of inadequate calcium in the soil.
Bitter pit does not necessarily indicate low soil calcium, although consistent bitter pit for several years certainly points in that direction. Anything that results in excessive foliar growth can cause bitter pit, because calicum gets diverted to the foliar growth. Heavy pruning, excessive nitrogen fertilizer, and excessive irrigation all can lead to bitter pit.