Re: Why are blueberries green inside?
That was a terrible response on my part. This is the short story long:
First, as they mature on the plant, plants release a natural plant hormone called ethylene that allows them to become sweet and develop the color, texture and flavor that we associate with ripeness.
Next, there are two kinds of fruits. Climacteric and non-climacteric.
Climacteric plants can be picked before they reach full maturity and shipped. When they reach their destination port, they are put in chambers exposing them to a gaseous, synthetic form of ethylene, which allows the ripening to continue well-past the time in which they were immaturely harvested. Bananas and tomatoes fall into that category.
Non-climacteric plants like grapes, pineapples, and orange do not have a burst of ethylene as they mature, but instead have other hormones like abscisic acid that cause them to ripen. These fruits don't ripen when put in ethylene chambers. Blueberries only marginally respond to ethylene treatment.
All fruits do continue to ripen after harvest, but when thinking about harvesting on an industrial level, it's a less likely that you will find blueberries, grapes, and pineapple at the perfect level of sweetness when you purchase them in a store - because they weren't treated. For non-climacteric fruits, it's a much bigger headache to harvest and ship without the fruit being too ripe or underripe. This is one of the reasons blueberries are a lot more expensive than bananas.
Blueberries are also large-window fruits, which means that on the same plant, some berries will be green while others will be beyond peak ripeness. With automation, you can see why there tends to be arange of ripeness in the basket that you purchase.
So, you have untreated blueberries that were picked too green and are at the mercy of ripening on their own without the help of the mother plants, cannot be treated with ethylene to stimulate their ripening, and were picked with other berries with a range of ripeness.
Poor little fellows.