What is Glutelin?
Glutelin, a globular protein categorized within the prolamin proteins group, is commonly distributed among cereal grains, notably in wheat, barley, and rice. Its nomenclature is derived from its notable glutamic acid composition, a characteristic that underlies its distinctive properties and functionalities.
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Functionally, glutelin assumes a crucial role as a storage protein within seeds, serving as a reservoir for amino acids, particularly essential ones. This reservoir becomes a vital nutrient source during the germination phase, supporting the developmental needs of the plant embryo. In this capacity, glutelin becomes an indispensable element in the overall life cycle of plants.
The structural intricacies of glutelin are pivotal to its functionality. Characterized by a significant proportion of hydrophobic amino acids, it exhibits insolubility in water. Typically organized into subunits, the protein forms a three-dimensional structure that facilitates its diverse functions. This intricate architecture allows glutelin to engage in interactions with other proteins and molecules, influencing its behavior within biological systems.
Some Types
There are several types of glutelin, each with its unique characteristics and distribution across different plant species. Some notable types include:
Rice Glutelin
Found in rice seeds, rice glutelin contributes significantly to the nutritional content of this staple food. Its unique properties make it a valuable component in the rice plant's reproductive cycle and an essential dietary protein for millions of people worldwide.
Wheat Glutelin
Wheat glutelin is a key player in the formation of gluten, making it crucial for the baking industry. The combination of glutenin and gliadin in wheat flour gives rise to the elastic and cohesive properties that make bread and other baked products desirable.
Fig 1 Gliadins and glutenins fractions revealed by using acid polyacrylamide gel electrophoresis (A-PAGE) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), respectively (A) and RP-HPLC (B). ω, ω-gliadins fraction; γ, γ-gliadins fraction; α/β, α/β-gliadins fraction; HMW, high molecular weight glutenins subunit; LMW, low molecular weight glutenins subunit. (García-Molina MD, et al. 2019)
Biological Applications
Nutritional Enhancement in Crops
Researchers are exploring genetic modifications to enhance the glutelin content in crops, particularly in rice, to address global malnutrition. By increasing the nutritional value of staple foods, such as rice, through genetic engineering, scientists aim to combat nutrient deficiencies and improve overall public health.
Gluten-Free Product Development
In the wake of an escalating prevalence of gluten intolerance and celiac disease, a discernible surge in demand for gluten-free products has unfolded. Understanding the structure and function of glutelin allows food scientists to develop gluten-free alternatives that mimic the desirable properties of gluten, providing consumers with options that cater to their dietary needs.
Table 1 Health benefits of gluten-free products made from gluten-free cereals. (Khairuddin MAN, Lasekan O, 2021)
| Gluten-Free Products Made from Gluten-Free Cereals |
Health Benefits |
| Bread |
High antioxidant activity |
| Reduces blood pressure for people with mild hypertension |
| Lowers the blood glucose level |
| High in vitro antioxidant activity |
| Increased antioxidant activity |
| Pasta |
High nutritional contents such as dietary fiber, protein and polyphenols, and antioxidant activity |
| Low glycemic index, contains polyphenol and high resistant starch that contributes to a reduced rate of sugar absorption and LDL-cholesterol, and consequently lowers the risk of several cancers |
| Higher antioxidant potential than regular durum wheat pasta |
| Has good dietary fiber, protein, mineral, and contains phytonutrients |
| Cookies |
High dietary fiber, antioxidant activity, and essential amino acids |
| High source of antioxidant capacity, phenolic contents, and a low glycemic index |
| Crackers |
Higher antioxidant activity than control wheat crackers |
| Non-alcoholic beverages |
Has potential for anti-hypertensive and anti-diabetic effects |
| Reducing effects of DNA fragmentation, peroxidation of lipids, and protein oxidation |
| High antioxidative properties |
| Kunnu with tigernut extract has enhanced antioxidative potentials |
| Addition of lactic acid bacteria to beverage made from sorghum and amaranth composites displayed an increased digestibility of protein, increased bio-accessibility of zinc and iron and a higher availability of lysine |
| Powdered drink mix |
Has antioxidant properties and is low in calories |
Biodegradable Films and Coatings
Glutelin's hydrophobic properties make it a promising candidate for biodegradable films and coatings, offering an eco-friendly alternative in areas like packaging, reducing environmental impact.
In summary, glutelin stands as a versatile protein, intricately woven into the fabric of various biological functions. Its role spans from serving as a reservoir for nutrients in plants to exerting an influence on the textural attributes of baked goods. A comprehensive understanding of its structure and diverse types opens avenues for innovative biological applications. This ranges from augmenting the nutritional profile of crops to the development of sustainable packaging materials.
References
- García-Molina MD, Giménez MJ, Sánchez-León S, Barro F. Gluten Free Wheat: Are We There? Nutrients. 2019, 11(3):487.
- Khairuddin MAN, Lasekan O. Gluten-Free Cereal Products and Beverages: A Review of Their Health Benefits in the Last Five Years. Foods. 2021, 10(11):2523.
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