Protein, alongside fat & carbohydrate, joins the list of things that are essential for our lives. Our hair, muscle, hormones, enzymes are all proteins. They are a complex group of macro molecules, they have so many different functions, can be so many different shapes, can be soluble while others are not etc etc etc. Proteins are a very diverse group. 

In food, carbohydrate (sugar) can give us sweetness & fats can make a product have a beautiful silky texture. What does protein contribute to our experience of physically eating food (apart from the fact that it is necessary)? Of course it will depend on the protein however I think it effects the "chewability" of the food or how satisfying it is. For example if I make golden syrup dumplings using a starch & a powdered protein & make different batches, only varying the amount of protein added, there is a huge difference in how long it takes to chew the dumplings. For one of the batches I made, my son (the golden syrup dumpling monster) said

"Nah, these ones are no good. You put them in your mouth & they dissapear".

The dumplings with a small amount of protein were not satisfying. It became a case of too much, not enough & just right. Too much protein & you feel like you are chewing the food for too long (& may want to spit it out). Not enough protein & you are not satisfied. 

Protein is also important for baking. It is amazing the difference a bit of protein makes. For the majority of flours & starches I use I firstly make a cupcake out of them. My cupcake stress test involves making the cakes using a butter cake recipe that is close to sinking in the middle when made with wheat flour (photo below left). The cupcakes shown below differ in the flour/starch used were baked at the same time. If the protein is taken out of the flour, that is, mainly wheat starch is left then the resulting cupcake (below right) has lost some structure. The protein content of wheat will differ between strains, hard wheat contains the highest percentage. Plain flour (all purpose flour) has a protein content of ~9%, this value will vary between brands. Some may say that the difference between the two cupcakes may be due to the loss of the gluten component. But not all of the protein found in wheat flour is gluten. 

  

Maize flour & maize starch are the only other flour & starch combination that I could readily obtain that are from the same plant species. Maize flour has a protein content of ~8%, maize starch ~0.4%. The maize flour cupcake (below left) has a similar structure to the one made with wheat flour. It hasn't risen as much, but it hasn't sunk (bonus). 

 

The photo above right is the cupcake made with maize starch. Structurally it is very different from the one made with maize flour (above left) but it is remarkably similar to the one made with wheat starch. The main difference between the maize flour & starch is the minimal amount of protein in the latter. 

It is clear, protein is essential for the structure of the cupcake. At this stage however, we don't know whether the wheat flour cupcake rose higher than the one made with maize flour due to the gluten content of the former or for some other reason associated with the different proteins present in the flours. If a cupcake made with another gluten free flour can rise to an equal height as the one made with wheat flour then gluten is not essential for baking cakes. The following photos are of a teff flour cupcake (left) beside the photo of the wheat flour cupcake. Teff flour has a protein content of ~13%.

  

Gluten is not needed for baking cakes. 

For this cupcake recipe it is the presence of protein that helps with the structure. Some may say that it is the overall amount of protein that makes the difference. Of the cupcakes shown above teff flour does have the highest percentage of protein & maize flour the lowest. Unfortunately it is not that simple.  

The photo on the left is a cupcake made with chestnut flour; its protein content is ~6%. It has certainly risen higher than the cupcake made with maize flour. So it is not the overall percentage of protein in a flour that is important for cake structure. Proteins are so diverse in structure & function it is hard to determine what flour will be the best for baking cakes just on its protein content. 

 

 Protein Alternatives

Proteins can certainly help in baking and the following is a list of different protein sources, some relatively pure & some not. Unfortunately it is usually a protein component of a specific food that people have allergic reactions to. When using a protein to supplement your gluten free flour/starch ensure that it is suitable for all who will be tasting the product.

• Eggs - Natures little protein bombs, they are ~12.5% protein & 75% water. Animal product
• Egg - Powdered whole eggs - Available in the supermarket in the fresh egg section. The protein content of the powder is ~52%.  Animal product
• Egg - Powdered whites only - Available in speciality food stores (The Essential Ingredient - protein content of 79%) or online. The egg white powder I purchased on line also contained sugar & vegetable gums - no nutritional information was available. Animal product
• Gelatine - Comes in two forms; granules & sheet gelatine. For ease of use I prefer working with the latter. The protein content of powdered gelatine is ~84%. Both products are available in the supermarket. If your local supermarket doesn't stock leaf gelatine, it can be found in speciality food stores.  Animal product
• Pea protein isolate - Extracted from Golden peas, the isolate is ~88% protein. I source this product from health food shops. Plant product   
• Skim milk powder - Found in the supermarket the powder is ~34% protein. It is a relatively cheap source of protein however, it is also ~52% sugar (lactose). Animal product 
• Soy protein - Extracted from Soya beans the powder is 87% protein. The specific protein content will vary from brand to brand. Available in health food shops & sports shops selling supplements. Plant product 
• Whey protein - Whey protein is a major protein component of milk. The isolate I purchased is 78% protein. The specific protein content will vary from brand to brand. Available in health food shops & sports shops selling supplements. Animal product 

Some of the gluten free flours have a high protein content similar to or higher than skim milk powder. Following is a list of the flours with protein contents greater than 30%. The actual protein content will vary depending on the growing season therefore the values are approximates only. 

• Golden Flaxseed flour - 37% protein
• Hemp seed flour - 32% protein 
• Lupin flour - 39% protein
• Sesame seed flour - 45% protein
• Soy flour - 34% protein