Diffusion: Getting Flavor Where You Want It to Go

Getting flavor where you want it to go is a big part of successful cooking. And understanding the concept of diffusion can be a big help in cooking flavorful food.

Diffusion is the tendency of molecules to move from an area of higher concentration to an adjacent area of lower concentration.

So when we want to make flavorful food, we need to make sure we have the concentration of flavors in the right places.

Up Your Pasta Game With Concentration

Boiling pasta is often one of the first skills people acquire when learning to cook. Whether it be for a blue box of mac and cheese or making spaghetti, pasta cooking is an essential ability for most home cooks.

But what often goes overlooked is the importance of salting the water when cooking pasta.

Pasta in itself is relatively bland and without enough salt, the pasta can bring down the flavor of the whole dish. But with the right amount of salt, pasta can add some of its own flavor while boosting the overall tastiness of a dish.

So how much salt should you add to your pasta water? This is where concentration comes in.

Thankfully not the mental kind of concentration; life takes enough of that as it is. This concentration is the amount of salt relative to the amount of water you cook your pasta in.

With a higher salt-to-water ratio, the concentration of salt molecules in the water will be higher than in the pasta and diffusion will work in your favor, with the salt moving into the pasta.

1 teaspoon salt per quart (4 cups) of cooking water is a good ratio for cooking pasta. Start by measuring out the water and salt, taste it to get an idea of the saltiness, and with experience you can then forgo the measuring and add the salt as needed.

In the ‘Geometry of Cooking’ post, we went over a quicker method for cooking pasta. In this method, you add the pasta to the pot, cover with water, add the salt, and then cook. This method saved time due to the reduced energy required by the smaller amount of water.

This method also requires less total salt as you are using less water and therefore need less salt to get to the desired concentration. While salt is not overly expensive and you aren’t going to save the big bucks all the insurance commercials promise you, it is nice to know you are not using more than you need to get your pasta cooked.

With enough salt, diffusion moves the salt molecules into the pasta. Diffusion also works in the opposite direction. Pasta is made up mostly of starch and during the cooking process this starch moves out into the water as well.

This starchy water can be great for making velvety sauces such as in Cacio e Pepe, a famous and simple Italian dish that features black pepper and parmesan cheese. We also use the starchy pasta water in our Italian Sausage and Dark Greens Pasta recipe.

And if you use the method above, your water will be extra starchy because there is less water used, leading to a higher concentration thanks to diffusion.

Time is Diffusion’s Friend

Understanding the importance of concentration is the first step in harnessing the powers of diffusion. The next step is realizing that diffusion can take time.

Diffusion is not an instantaneous process. Similar to the flow of heat, the movement of molecules between substances can meet resistance and take time based on the conditions and distances the molecules need to move.

In the case of pasta, there is little resistance as the noodles readily absorb the salt and water and it doesn’t have far to go, so diffusion can happen in the minutes it takes to cook the pasta.

Meat, on the other hand, can provide higher resistance and in the case of roasts, salt and flavors may have to travel a relatively long distance to get to the center of the meat.

Diffusion is the movement of molecules from higher concentration to lower concentration, and the smaller the difference in concentration, the slower that diffusion will occur.

Meat provides resistance because it already contains a high concentration of proteins, minerals, and organic compounds. So to move salt and flavors into the meat requires some time.

When we give directions for cooking a roast, we recommend that you add a dry rub seasoning a day or more in advance of cooking. This gives time for the flavors to reach the center and permeate the roast.

And as an added bonus, the salt that has moved into the roast will help it hold on to more moisture, making for juicier roasts. The salt also interacts with the proteins in the meat to make the roast more tender.

Salting early is one of the best tips for cooking delicious meat. On the other hand, if you salt your meat right before you cook, you can actually pull out moisture and make your meat drier.

When you place salt on the surface of meat, before diffusion can start moving it into the meat, the salt will pull moisture out of the meat to the surface.

For this reason, in our post on ‘Maxing the Flavor of Ground Beef’, we recommend adding salt and flavorings after you have cooked the ground beef to help retain the moisture in the meat.

Once moisture has been pulled to the surface, the salt and flavorings combine to make a highly concentrated fluid that then allows diffusion to work, pulling the salt and flavors into the meat.

With time, diffusion will pull the salt and flavorings all the way to the center of the meat until the concentrations have reached equilibrium and the flavor permeates the meat.

Making Diffusion your Friend

Once you understand the basics of how diffusion works, you can make the flavor go where you want and create delicious meals.

With the right concentration of flavor and time, diffusion will be your friend.

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John and Sarah Gilbert farm with their family in North Central Iowa. They care for pigs, cows, and the land to bring you beef and pork you can love. They have a passion for cooking and helping others develop the skills they need to put healthy and delicious home-cooked meals on the table. They can be contacted by email and through Facebook and Instagram.