Wheat Protein Properties

Wheat stands out as a leading cereal primarily due to the distinct chemical and physical properties of the proteins found in its grain.

Its importance as a primary food crop is associated with various features, and a notable aspect is the exceptional ability of its protein to form a flexible, cohesive mass when mixed with water.

The wheat kernel comprises three main components: bran, germ, and endosperm. The endosperm, the starchy part of the kernel remaining after the removal of bran and germ, constitutes the white portion.

The wheat endosperm, containing starch ranging from 68 to 76% and protein from 6 to 18%, serves as the foundation for white flour. In this context, proteins act as binding agents, holding starch granules together in the endosperm.

Approximately 80% of the protein in flour consists of glutenin and gliadin. When combined with water and integrated into dough, these proteins give rise to the elastic substance known as gluten.

Gluten displays plasticity, strength, and elasticity, allowing it to deform under pressure, resist deformation, and return to its original form when pressure is released.

Other proteins present in white flour include enzymes, particularly amylase or diastase, responsible for breaking down starch into essential simple sugars for yeast fermentation.

Wheat proteins are categorized based on their extractability and solubility in various solvents:

• Albumin: soluble in water
• Globulin: insoluble in pure water but soluble in dilute NaCl solution, becoming insoluble at high NaCl concentrations
• Gliadin: soluble in 70% ethyl alcohol
• Glutenin: soluble in dilute acid or sodium hydroxide solutions

Celiac disease, an immune disorder, occurs when the body produces antibodies against gluten, resulting in inflammation and damage to the intestinal wall, ultimately causing the flattening of villi—fingerlike projections crucial for absorption.

The levels of protein in wheat play a crucial role in determining the prices of hard red spring wheat, especially in regions like Minnesota, Montana, North Dakota, and South Dakota. Higher protein content commands elevated prices in the market.
Wheat Protein Properties

Starches in wheat

Starch is the carbohydrate present in the greatest amount in the mature wheat kernel; in fact, it exceeds all other types of compounds, being several times larger than the next largest class of substances.

Wheat starch is low in protein, ash, and fiber and contains no residual sulfites. Approximately 6% of world wheat production is utilized for wet processing into starch and gluten.

Wheat starch is formed out of carbon dioxide and water by the process of photosynthesis and is deposited in plant cells as macroscopic particles of varying size and conformation.

The starch is generally not the main grain constituent of interest to the manufacturer but is rather of secondary importance after the wheat gluten.
While considered a pure carbohydrate, wheat starch contains minor components in the interior and exterior of the granules. Starch is the polymer of D-glucose, most of the hexose units being joined together by alpha-(1-4) bonds.

They are varying properties of amylose and amylopectin, the former being virtually a straight chain, but with a few branch points, while the latter contains numerous side chains attached by 4 to 5% alpha-(1-6)-D-glucosidic linkages.

The starch granules grow in the developing endosperm as single entities in amyloplasts. In wheat starch, they have a bimodal size distribution, with about 3 to 4 % being lenticular and 15 to 40 microns in size and the remainder being small, approximately spherical, granules ranging in size from about 1 to 10 microns.

Wheat starch pastes in foods have traditionally been known to provide a ‘melt-in-your-mouth’ sensation.

A fruit filling made from hydroxypropylated phosphate cross-linked wheat starch had a short, smooth mouthfeel with quick release from the palate.
Starches in wheat