The Great Banana Mystery.

June 8, 2007 3:43 PM

What makes the fragrance and taste of a banana change so drastically when turning from pre-ripe to spotty?

I hate spotty bananas! There seems to be a threshold past which the flavor and fragrance of a banana changes 180' and they don't resemble the firm bananas I love so much.

I can't think of any other fruits which change so signficantly during their ripening process. What causes these changes?

posted by Asherah to food & drink (12 comments total)

It's a conversion from starch to sugar.
posted by bitdamaged at 4:09 PM on June 8, 2007

BTW Virtually all fruits significantly change like this in their ripening process.. What you are noticing is that bananas convert much faster than other fruits.
posted by bitdamaged at 4:10 PM on June 8, 2007

I don't know the chemicals that give it the particular flavor and fragrance but I do know that bananas produce a huge amount of ethylene gas as they ripen, probably more than any other fruit or vegetable. As they ripen, they produce even more ethylene and that's why they go downhill so fast. It's like a positive feedback loop. That's why you'll never get a bunch of bananas where some are green and yellow - the level of gas ensures they all ripen together.

Avocados do this too and tomatoes to a lesser extent. But in each case, that's why it's best to keep them separate to prevent ripening and just pop them in a bag to quickly ripen them when you want to eat/use.
posted by junesix at 4:15 PM on June 8, 2007

I think that this paper answers your question. As bananas ripen, they produce a series of volatile esters and alcohols that make up their aroma. Once they start to turn brown, most of these flavor components stop being produced, however the levels of one called ethyl acetate continue to rise through browning. It's a common lab solvent, it smells like sort of a mix of acetone (nail polish remover) and Juicy Fruit gum. I don't find it particularly unpleasant, but some people do and a strong whiff of it can be cloyingly sweet.

Also, you might not like the alcohol that is produced during banana ripening. As the banana ripens, some of the starch is converted to sugar. Some of this sugar is then turned into alcohol. When the banana gets to the point where it's turning from yellow to brown, this process is kicked into overdrive and suddenly you have bananas that have a faint whiff of alcohol. This probably sends a "rotting fruit" signal to your brain, triggering your reaction of disgust.
posted by TungstenChef at 5:24 PM on June 8, 2007

The reason that bananas or any other fruit change drastically as they over-ripen is that the fruit becomes pre-putrescent, ready to become a seedbed for the seed.

Of course, bananas have lost (or had bred out of them) the ability to produce seed. This is unfortunate because bananas are a major staple crop in low-income countries, so the emergence of pathogens can't easily be overcome by crossbreeding.

The banana age you don't like is a step on the way to decay. Maybe someone knows the trigger?
posted by anadem at 7:35 PM on June 8, 2007

they don't resemble the firm bananas I love so much

Firm bananas are not fully ripened, green (or green-ish) bananas, and they contain indigestible starches, which give some folks tummy aches. Wait for the banana to be a little spotted for best results.
posted by frogan at 8:32 PM on June 8, 2007

As the banana ripens, some of the starch is converted to sugar. Some of this sugar is then turned into alcohol. When the banana gets to the point where it's turning from yellow to brown, this process is kicked into overdrive and suddenly you have bananas that have a faint whiff of alcohol. This probably sends a "rotting fruit" signal to your brain, triggering your reaction of disgust.

Interestingly, my disgust point seems to be far beyond Asherah's. For me, the banana tastes best when the skin is about half-spotted and the banana fruit has just enough consistency to not fall apart. But then, I'm probably reacting positively to the sugar and alcohol content....

Not that this helps the OP much, but for me there's a few days' race to eat the bananas after they get flavorful but before they get mushy. When they get mushy, I get to make banana bread, so it's a win-win race.
posted by dhartung at 1:20 AM on June 9, 2007

Asherah, a lot of fruits only ripen when still attached, whereas bananas will ripen after harvest. Interestingly avocados share this property, but will not start ripening while attached.
posted by BrotherCaine at 2:36 AM on June 9, 2007

I'm with you dhartung, I think that a banana is at its peak of flavor starting right as it turns yellowest, and for a few days into the brown spots until it gets mushy with an alcoholic twang. My wife on the other hand, likes them when they're still green-yellow, and won't touch them as soon as the first brown spot appears. It's always a battle to make sure she leaves me a few.
posted by TungstenChef at 3:41 AM on June 9, 2007

Can I also just take this opportunity to rant about bananas that now turn spotty and brown while they're still basically green? This is a totally new phenomenon to me, and I assume it's a result of forced ripening, where industrial grocers pump green bananas with ethylene (like they do most other fruits), but it drives me crazy.

I hate bananas that taste green at all, but lately, every banana we've bought, from a bunch of different stores, all start turning brown and rotten while they're still green and starchy. They never seem to hit that yellow, sweet point that is the essence of "banana" to me. Has anyone else noticed this, or am I just getting old and cranky?
posted by LairBob at 5:13 PM on June 9, 2007

_{[And yes, I know that at most high-end, dedicated produce stands, you're likely to get better results. It's just that when you're shopping for a family, combing the farmers' market just for a decent banana seems a bit much. I'm just kind of cheesed off that I can't seem to get home from a grocery store with a decent banana any more.]}
posted by LairBob at 5:19 PM on June 9, 2007

LairBob: I've noticed this, but thought it was something to do with South Africa (lived here 2.5 years). I like them speckled, myself, but not too far gone. Usually the store has them insanely green.
posted by Goofyy at 3:58 AM on June 11, 2007