There is an old adage in which the question is begged: what makes a sandwich, a sandwich? If you consider the definition from Merriam Webster, a sandwich is:

  1. Two or more slices of bread or a split roll having a filling in between
  2. One slice of bread covered with food

Does that mean a hot dog is a sandwich? What about a burger – is that a sandwich? Ask anyone this question and you’ll receive a myriad of answers. Some may argue what holds the filling is what determines a sandwich, while others will argue the filling is what determines the sandwich-ness of something. If we are talking filling, does it matter if it’s animal byproduct or peanut butter and jelly? What about plant-based meats?

Regardless of what constitutes a sandwich in your mind, it’s summertime here in Minnesota and, as soon as the days get longer and the weather gets warmer, you’ll find us firing up our grills for some delicious foods. Pretty much anything can be grilled these days, including Balsamic Honey Peaches with Feta (which, if you haven’t tried, I highly-recommend you do) but a common staple is the hamburger.

A new trend in burgers (and meat overall) is the creation of plant-based meats. Foods like the Impossible Burger or any of the products made by Beyond Meat. This got us wondering – how are plant-based burgers made? This brings us to this month’s edition of How It’s Made with PMG.

When looking at the production of these burgers, it’s important to not only look at the equipment used but also the ingredients.


  1. Heme
  2. Plant Proteins
  3. Compounds
  4. Fat

Ingredient #1: Heme

Heme is largely what gives animal-based meat its flavor.

Heme lives in globin. Hemoglobin is its name when referring to blood.  Myglobin is its name when referring to muscle. Leghemoglobin is its name when referring to plants like soy roots. The globin in soy and the globin from animal muscle are similar in structure.

Although soy root globin matches that of animal muscle globin, it’s still very taxing on our natural resources and environment to grow soybeans for the purpose of yielding the globin and thus the heme.

Therefore, we can get heme from a variety of sources, but when looking at a plant-based heme, we have to consider the environmental and natural resources it takes to grow the plant. Although the heme from soy roots is very similar to that of the heme from animal muscle globin, it’s far too taxing to grow the soy for the purpose of yielding heme. Therefore, scientists decided to engineer the soy root heme rather than take it from its natural resource. This engineering is done through the modification of Pichia pastoris yeast. To modify, add yeast, sugar and minerals. This prompts the growth of heme. This is the ingredient in plant-based burgers that provides the flavor.

Ingredient #2: Compounds

plant based burgers 1To create the aroma, we have to recreate the wide-variety of compounds that animal-based beef has within it. In order to determine the compounds in animal-based beef and the general makeup of the compounds, a process called Gas Chromatography Mass Spectrometry is used. Determining the makeup of these compounds has allowed us to engineer the compounds in a lab and then use in the making of plant-based burgers.

Ingredient #3: Proteins

Texture in animal-based beef comes from protein. Additional science tests and analysis identify the specific makeup of the protein in ground beef. Once this analysis was complete, scientists were able to find the same proteins in plants. The proteins found in wheat and potatoes give firmness, chew and the ability to hold water.

Ingredient #4: Fat

Coconut with flavor removed.


Manufacturing equipment processes these ingredients through a variety of thermal and mechanical stresses. Through rapid heating and cooling, the structures of the ingredients change and blend. Machinery extrudes the product in its final shape. In this case, it’s is a hamburger patty.


With all that said, I bring back the question of what makes a sandwich, a sandwich and is a hamburger a sandwich? Does your answer change if the filling between the bun is plant-based?

For similar posts, check out our How It’s Made – Hand Sanitizer article!