We have all been there.

Hungry for a thick slice of banana bread, solely to be caught with a bunch of inexperienced bananas. In an ideal world, we would merely pull a bag of overripe bananas from the freezer, however real-world stockpiles aren’t at all times so dependable. On these events, we’re left with few decisions: maintain off on banana bread, make do with greenish fruit, or faux ripeness by baking the bananas.

When you have the persistence, there’s nothing mistaken with choice A, however I am not wild in regards to the alternate options. Underripe bananas have a weak taste, whereas their excessive starch content material turns fast breads chalky and dry. Prebaking might blacken their pores and skin by way of oxidation and soften their pulp by breaking down its cell partitions, however these bananas will want as much as three hours of roasting to attain any vital starch-to-sugar conversion. (Do not take my phrase for it; simply ask Harold McGee.)

Luckily, I’ve discovered a fourth choice. A easy trick that takes bananas from starchy to candy in simply half-hour, with none bizarre components or main investments of time. The truth is, all you want is an egg. Properly, technically, only a yolk, which sounds kinda loopy, so bear with me as we dig into the backstory right here.

Unripe bananas have a carbohydrate content material of round 22%, which could be damaged down into roughly 14% starch and eight% sugar. After harvest, bananas start to provide ethylene gasoline, and several other kinds of enzymes begin to type. One of many enzymes breaks down chlorophyll to blacken the peel, and one other breaks down pectin to melt the fruit, however the third (the one we care about) turns starch into liquid sugar: maltose and glucose.

This enzyme is called amylase, and it is so efficient that by the point a banana turns fully black, the pulp incorporates no starch in any respect—which is why we so typically discover overripe bananas sitting in a pool of goo. When not making a sticky mess in your counter, that goo (glucose and maltose) offers banana bread a moist and tender crumb, together with that attribute sweetness we love.

As beforehand talked about, you possibly can merely let nature take its course and ripen a banana over time. You can even attempt to pace issues up by sticking the bunch in a paper bag to entice ethylene and hasten the manufacturing of amylase, however even that takes some time.

The bananas above got here from the identical bunch (pictured collectively, unripe, just a few paragraphs again). The trio on the left sat out on the counter, uncovered to open air, whereas the trio on the suitable had been stuffed in a paper bag. After three days, they had been vaguely extra yellow than these left within the open air, however not by a lot. That is as a result of no matter how a lot ethylene you entice, it takes a while for the bananas to synthesize amylase on their very own.

Which obtained me considering: Why wait? Amylase happens naturally in egg yolks, and it is the very factor that may cut back a superbly thick lemon meringue pie to a weepy mess in a matter of hours. That is why most recipes could have you cook dinner a starch-thickened custard till it is bubbling-hot. The eggs and starch will arrange properly at a lot decrease temperatures, but it surely’s all for naught if the amylase is not denatured (which occurs at round 170°F; a bit greater if sugar is concerned).

If just a few egg yolks can decimate a quart of custard, I figured they’d haven’t any bother breaking down a starchy banana. To place that idea to the check, I mashed some yellow-green bananas and egg yolks collectively, one yolk for each 4 ounces of fruit. Then I divided that combination into a number of equal batches by weight.

Subsequent, I grabbed a bottle of Lugol’s Iodine, a dark-orange answer of iodine and potassium iodide that turns blue-black within the presence of starch. I stirred just a few drops into one portion of the banana combination, which instantly turned a disgusting shade of ewwww.

Yup. That is one starchy banana.

I lined the remaining parts and deliberate to retest each half-hour, however to my shock, the very subsequent batch confirmed a stunning enchancment. Whereas the pulp itself had darkened from oxidation, the iodine revealed nothing various starchy patches.

The continued oxidation of the banana pulp made every subsequent check tougher to visually assess, however the marked distinction between the primary two batches was all I wanted to know that the amylase within the egg yolk was most actually doing its factor.

Granted, that is no assist with regards to snacking or making a banana smoothie (except you are open to the thought of a uncooked egg), but it surely’s a game-changer for banana bread. No matter your recipe, simply mash the required bananas and eggs collectively and wait at the least half-hour, longer in case your bananas are tremendous inexperienced.

In case your recipe is heavy on bananas and low on eggs, slip in an additional yolk to make sure you have sufficient gas for the conversion. It will make the banana bread barely extra wealthy and moist, a win/win state of affairs if I ever noticed one. If you happen to’d want to not alter your recipe, merely give the method a little bit extra time—about an hour for a two-egg/four-banana recipe.

Whether or not you are speed-ripening bananas for my recipe or yours, completely happy baking!

September 2016