As this is my second post about potatoes, the avid reader may wonder where my potato fascination is coming from. This is a fair question, and the answer is simple- when I retire, I plan to open a late-night, gourmet hash brown stand. In the mean time, I am bent on perfecting my knowledge of potatoes and hash browns. This post, though, is more an attempt to prove the internet wrong than to improve my hash browns.
Tool for success in life.
My interest today, I will admit, is more academic than useful: how can we stop potatoes from browning after we peel them? Although the question seems trivial, that apparently has not stopped the internets from being fascinated by it. It was amazing to me how many hits a google search on “stop potato browning” turned up, including this youtube video .
The most fascinating part is that preventing browning has no effect on eventually flavor (or for most dishes, color) of the potatoes, it just makes them look nicer while you prep your other ingredients. I find it fascinating how people can waste time on an issue that has no practical value. Having said that, I will now tell you about my experiments on preventing potato browning.
From the youtube video and google searches, I arrived on two key tricks to preventing potato browning, and a third occasionally offered idea:
1. Submerge the potato in water
2. Make the water cold, usually by putting it in the fridge
3. Use citric acid
Trick 1 is not surprising, since browning occurs when fruit is in contact with the air. Oxygen in the air triggers a chemical reaction causing tyrosine, an essential component of all living cells, to turn into brown or black pigments. This cascade only occurs when encouraged by tyrosinase, which is typically found in fruit and vegetables like potatoes. The result- oxygen causes browning of cells, but only in fruits and vegetables. Put the potatoes in water, and you lose your source of oxygen and voila! – no more browning.
Trick 2 struck me as weird. Sure, many chemical reactions depend on temperature so cooling the water may slow down the reaction, but it didn’t strike me as that important. Maybe if you were storing potatoes on a counter versus a fridge for a few weeks you might see a slight difference in browning, but who needs to store peeled potatoes for weeks?
Trick 3, well, we’ll come back to this later.
I decided to go with a simple test to challenge the cold temperature suggested in trick 2. In my last potato post (link), I found that the water squeezed from grated potatoes browned with time. This potato water seemed to be the perfect test subject for my experiment. Instead of waiting days-to-weeks to see how much a potato in water didn’t brown, I’d wait 20 min to see how much potato water did brown.
What’s the name of this shooter again? Water squeezed from potatoes, ready to go. Browning has already started in the 2 minutes it took to set up and take this picture.
Shotglasses turned out to be ideal for holding the potato water- they were readily available in my house (yeah, I like my booze), they were just the right size, and I could clearly see through them to visualize the browning.
I filled four shotglasses with potato water- they looked like a creamy Bailey’s shot at first, until the opaque starches settled out to the bottom. I put them in four spots at four different temperatures, in front of the heater, room temperature, in the fridge and in the freezer.
Arranged from hot to cold, with hot on the left. Starches on bottom, browning layer on top.
Twenty minutes later, the results were clear: they all browned. As expected, the top layer of potato water that had the most contact with the air browned the most. But the water in all temperatures browned equally, so putting your potato in the fridge probably doesn’t do much to further prevent browning. Take that, youtube lady. *
Same guys as the last picture, but stirred, not shaken. No real color difference.
As a sanity test, I tried a trick I remembered from childhood- sprinkle a little lime on your apple and they won’t brown. This trick was also occasionally suggested by the internet. Since the browning mechanism is the same in potatoes as it is in apples, I figured the trick should apply nicely to the potato water. Once again, the results are clear- squeezing lime juice prevents browning in potato water.
How tropical! Lime-potato-water on right, control on left. Same potato water in each, the greater volume is due to the lime juice.
It was nice reassurance to see something as simple as lime juice causing such a huge effect, when my temperature tests seemed to do nothing at all! As a further test, I put some lime juice in the water that had partially browned. I found that the water stayed brown, but browned no further, indicating that the lime juice wasn’t breaking down the pigments, but was likely preventing the chemical reaction that formed the pigments in the first place. The avid chemists might be interested in knowing that the food industry is all over this one– the acidity from the lime juice deactivates tyrosinase.
Same guys as last picture, with lime juice added to the left one after some browning occurred.
The lesson here- don’t trust the internets. The life lesson, though, is probably to stop fretting about your ugly-but-tastes-fine potatoes.
