What is Protein?
Proteins are the building blocks of many biological systems and are essential components in our diet. Common sources of proteins include meat, poultry, fish, eggs, dairy products or cereal grains. In food systems, they provide nutrition and function.
Proteins are composed of peptides, or chains of amino acid chains. Their composition and size determine the protein’s:
- Nutritional value
The word ‘protein’ may have its roots in the Greek word ‘proteios’ which means primary. Proteins as a distinct group of biological molecules was recognized in the 18th Century based on their tendency to coagulate. Later, in 1838, the chemists Mulder and Berzelius identified proteins as molecules made up of chains of amino acids.1
Food proteins can come from various sources:
- Animals: poultry, eggs, red meat, fish
- Plants: legumes, cereal grains, vegetables, fruits
- Microbial: yeast, bacteria, algae
Large scale production of proteins varies by the source and what the end use will be. Typically, protein isolation from plant sources such as soy flour involves solubilization in water, precipitation and drying.
Membrane-based separation technology is typically used in extracting dairy-based proteins such as milk protein concentrate, caseins/ caseinates and whey-based protein and in some cases plant proteins. Depending on the extent of purification, proteins can be obtained in the form of:
- Concentrates (up to 80% protein)
- Isolates (higher than 80% protein)
Animal-based proteins typically contain most essential amino acids in adequate amounts. However, plant-based proteins are often labeled ‘incomplete proteins’ due to a lack of some essential amino acids.2 Consumption of protein provides 4 kcal per gram protein.
Wheat and some grains contain gluten proteins which can trigger an autoimmune response in people with celiac disease.
Proteins provide the following functions in foods and baked products:
- Flavor and color (mainly through Maillard reaction)
Bread wheat flours contain higher levels of gluten (protein) compared to cake flour. This is reflected in a dense, tough and chewy bite. However, cakes have a light and airy texture due to lower amounts of protein in the flour.
- Wheat Proteins: main fractions of gluten include glutenin, responsible for dough strength and elasticity while gliadin provides viscosity.
- Whey Proteins: major components are casein/caseinates and whey proteins. They contribute to flavor, texture and nutrition. Quick breads, cakes, muffins, bars, cookies, and other delicate baked goods are typically formulated with whey protein.
- Soy Proteins: provide baked goods with nutritional and functional benefits. Drawbacks include their beany flavor and potential allergenicity.
Food proteins are GRAS and their labeling is regulated by FDA (21CFR101.54).3
- Mulder, G.J. 1938. Sur la composition de quelques substances animales. Bulletin des Sciences Physiques et Naturelles en Neerlande, p. 104
- Hoseney, R. Carl. “Proteins.” Principles of Cereal Science and Technology. St. Paul, MN, USA: American Association of Cereal Chemists, (1986): 68.
- “CFR – Code of Federal Regulations 21CFR101.54” Accessdate.fda.gov. 01 Apr. 2019. https://www.accessdata.fda.gov/scrIpts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=101.54. Accessed 12 Nov. 2019.