Experiment 8: Potato Latkes

Figure 1. Perfectly cooked latkes: burnt on the outside,

warm on the inside.

The Great Potato Massacre!

Introduction
What's the best way to celebrate the end of finals?  A latke party with your neurobuddies, of course!  Potato latkes are a traditional Jewish food that is eaten during the festival of Hanukkah.  However, just because Hanukkah is over, that doesn't mean that you have to wait another year to cook these.  In addition to Ashkenazi Jewish cuisine, latkes can be found in established cuisines all over eastern Europe.  Typically, latkes are primarily composed of potatoes and onions, but for our neurofiesta, we welcomed several new variations on the dish from fellow neurochefs.  Aside from traditional latkes, the stove saw the frying of three other varieties: Purple potato and celery root latkes, sweet potato latkes, and parsnip latkes. All of these varieties involved the same general procedure, just with different materials.  Here, we will focus on the standard latke recipe.

Our NFPA Ratings (Fig. 2):

Figure 2. Our NFPA Ratings for potato latkes.

Prep Time: This varies depending on the amount you are making, because shredding potatoes and onions takes time.  On the short end, preparing and frying will take 30 minutes all together, but with the amount we made, it took about an hour.

Difficulty: Making latkes is a lot like making dough, in that it it involves a few, common ingredients to put it all together.  Having said that, shredding potatoes can be a pain in the butt, but that is perhaps more of a complaint than a criterion for assessing the difficulty of preparing latkes.  Just be patient; only flip them when they are ready.

Course: Depending on the cuisine, latkes can either accompany a meal as a delicious side, or they can comprise the main course.  It all depends on your eating habits and they way you cook your latkes.

Figure 3. Step One: shred the potatoes

Materials
1) Yellow potatoes* - 4 lbs.
2) Eggs - 4 (1 egg per lb. of potatoes)
3) Chopped or shredded white or yellow onions** - 1 cup
4) Flour - 1 cup
5) Salt - 2 tsp
5) Olive oil - a lot

*Can be replaced with sweet potatoes
**Can be replaced with celery root

Procedure
1) Shred the potatoes and onions in a food processor or salad shooter, and place the shredded pieces in a bowl of cold water (Figure 3).

Figure 4. Strain and dry.

2) Drain all the water out of the potatoes (Figure 4).  Dry them as much as you can, then return them to a dry bowl.
3) Add the onions, eggs, and flour.  Mix!
4) Put a non-stick frying pan on medium to medium-high heat, and coat the surface with olive oil.
5) Scoop spoonfuls of the potato mix into the frying pan and flatten them into 3-inch circles while making sure they still sick together. Thinner latkes fry faster and are tastier (Figure 5).
6) When the bottom edges look burnt, flip the latke to brown or burn the other side.  When it's done, remove it from the frying pan.  Best served hot....straight from the frying pan.

Top with apple sauce, sour cream, or sugar for additional flavor.

Figure 5. Clump together and flatten for best results.

Figure 6. Top left: Sweet potato latkes starting to cook.

Top right: traditional latkes finishing up.

Results
When you are cooking latkes, the key is to make the oil hot enough.  The trick is to burn the outermost layer of the latke for texture, while leaving the middle only moderately cooked, in order to preserve the taste of the potato.  Fortunately, cooking dozens of latkes gave us the opportunity to learn this over time.  At first, we put the stove on medium heat, and not only did our latkes take a long time to cook, but the potatoes had a terrible time browning.  Our undercooked latkes fell apart and gave way to hash browns (Figure 8).

Figure 7.  Pretty Latkes!

After we turned up the heat to medium-high, everything really started cooking.  The bottoms burned, which made flipping much easier, made for much prettier latkes, and gave them a good crunch (Figure 7).  However, at this level of heat, our oil started to boil.  As a result, we went through a bit more oil than we had first anticipated (Goodbye, barely used bottle).

It was all worth it.  Why?

THEY WERE DELICIOUS!  They were full of that oily, onion-y flavor of our childhoods.  Straight from the pan, these golden beds of flavor lit up our taste buds and flooded our brains' reward systems with a deluge of dopamine.  Although it sounds counter-intuitive, burning the faces of the latkes brought forth a new dimension of texture that rounded out the experience.  Although we started with our own recipe, we re-discovered how to make the kinds of latkes that would have lived up to the expectations of our ancestors.

How many did we make?

A lot.  Dozens.  We lost count because they were so delicious that everyone, human (n=16) and non-human (n=1) ate them as soon as they left the frying pan.  The leftover scraps from the pan, if they were not too burnt, were just as delicious, and were eaten just as quickly.  To be fair, we doubled the recipe to feed 16 hungry mouths.  One neurobuddy hung around the kitchen just collect the scraps from the frying pan.  Others crowded around the entrance to the kitchen so they could be first to devour the newly fried latkes.

Figure 8.  After a few rounds of cooking, a pile of hash browns started to

accumulate in the pan.

Discussion
We made this recipe up based on a review of a dozen or so other recipes.  While risky, this approach gave us the freedom to apply a fair amount of critical, scientific discussion to our choice of ingredients and cooking methods.

Science Part I: Food Chemistry
A few of our fellow neurochefs recommended that we submerge the potatoes in water after chopping them up.  Not surprisingly, we were curious about the effects of this submersion on the potatoes.  After a bit of research (mostly internet surfing), we learned that soaking chopped potatoes in cold water prevents discoloration of the potato pieces.  The cells that make up a potato contain an enzyme (protein that catalyzes reactions) called polyphenyl oxidase (Figure 9).  When oxygen contacts this enzyme in an oxidation reaction, potatoes turn brown (Helmenstine 2012).

Figure 9. Oxidation and Discoloration (Rotter 2011)

One way to prevent this oxidation reaction, and thus prevent the chopped potatoes from discoloring, is to submerge them in cold water (Helmenstine 2012).  This prevents the polyphenyl oxidase from coming into contact with oxygen.  Another way to prevent discoloration is to lower the pH of the potato's surface by adding lemon juice and creating an acidic environment in which the oxidation will either happen more slowly or not happen at all.

Science Part II: Neuroscience!

Figure 10. The Olfactory System
(MedicaLook: Your Medical World 2012)

Latkes have a certain smell, the smell of onion mix with that of fried foods.  It's the kind of smell that hangs around the house for a week.  So what's up with smells and science?  For starters, smell is the sense that is most closely tied to memory.  The senses of taste, vision, hearing, and touch all take a wayward route the sensory cortex in the brain, but the sense of smell heads straight there from your nose.  The area of the brain that is responsible for accepting smell signals is called the olfactory bulb (OB; Figure 10).  The OB sends this information straight to the memory center and reward center of the brain, thereby allowing people to make very strong associations between latkes, through their strong scent, and the people and places that were around when they were made.  This type of memory is called associative memory, because it's a learned association between two different stimuli, i.e. the smell of latkes and the environment in which you ate them.

For us, that means the smell of latkes instantly triggers memories of the people we ate them with as children.  Everyone has those foods, foods that their parents or grandparents made when they were kids, comfort food, the kind that returns feelings of warmth and pleasure.  It's all because of associative memory.  It could be the sight of cookies, the sound of boiling tea, or the texture of a braised beef on your tongue.  This phenomenon applies to all of the senses, but the sense of smell confers the strongest associations.

Future Directions

Coming soon: Deep dish pizza!

Acknowledgements
We would like to thank Kyler and Adam for coming up with the idea for holding a neurolatke party.  We would like to thank Jeff, Joe, and Carla for letting us borrow their food processors, Kyler and Cummings for cooking the purple potato and celery root latkes and recommending the use of yellow potatoes, and Tahra (Pi(e) Princess!) for cooking the parsnip and sweet potato latkes.  An additional thanks goes to Kyler for coming up for inadvertently coming up with the subtitle for our article.  We would also like to thank Alex for his very expressive positive feedback, Huey for licking the crumbs off the floor, and everyone else for attending the 2012 Neurolatke Conference!  This project was funded (very indirectly) by the Biological Sciences Division at The University of Chicago. 
 
Supplementary Materials  

Figure 1. Sliced purple potatoes, ready for shredding.

Figure 2. Sweet potato-apple mix.

References
1) Helmenstine, A.M. 2012. "Why do Cut Apples, Pears, Bananas, and Potatoes Turn Brown?" About.com Chemistry Edition.
2) 2012. "Olfactory Sense Anatomy." MedicaLook: Your Medical World.
3) Rotter, B. 2011. "Sulphur Dioxide." Improved Winemaking.