Sugar content of ripening fruit

[leroyjenkens]

I noticed my plantains get sweeter as they get more ripe. When they're green, they're not sweet at all. When they're black, they're pretty sweet. So what's happening? Are some molecules being converted to sugar? Like, for example, complex carbs being converted to simple carbs? If so, does that mean if I eat a green plantain, I'm not ingesting nearly as much sugar as I am if I eat a black plantain?

 

[Pythagorean]

So what's happening?

Photosynthesis: The Calvin Cycle (for glucose at least). Not sure about fructose...

 

[leroyjenkens]

Photosynthesis: The Calvin Cycle (for glucose at least). Not sure about fructose...

Doesn't photosynthesis require light? Will fruit not ripen in the dark?

 

[Pythagorean]

The Calvin cycle is the light-independent part of photosynthesis:

http://en.wikipedia.org/wiki/Light-independent_reactions

 

[Ygggdrasil]

Photosynthesis (neither the light-dependent nor -independent) reactions are involved in the sweet flavor that develops as fruits ripen. In fact the photosynthetic material disassembles as fruits ripen (which accounts for the disapearance of their green color). Instead, the sweetness is due to gluconeogenesis (the production of glucose from proteins and amino acids) and the breakdown of complex carbohydrates into simple sugars. For more information see Prasanna et al. 2007. Fruit Ripening Phenomena–An Overview. Critical Review in Food Science and Nutrition 47:1. doi:10.1080/10408390600976841. Here's a relevant exceprt from the article:

The taste development is due to a general increase in sweetness, which is the result of increased gluconeogenesis, hydrolysis of polysaccharides, especially starch, decreased acidity, and accumulation of sugars and organic acids resulting in an excellent sugar/acid blend.