Question:
Which class of cereal proteins tends to lower the nutritional quality of the cereal grains?
Which class of cereal proteins tends to lower the nutritional quality of the cereal grains?
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Prolamines = Poor quality.
They are high in "P" (Proline) but low in "L" (Lysine).
Maize (Zein) is the "Poster Child" for this nutritional deficiency. Rice (Glutelin) is the "Hero" of the cereal nutrition world.
They are high in "P" (Proline) but low in "L" (Lysine).
Maize (Zein) is the "Poster Child" for this nutritional deficiency. Rice (Glutelin) is the "Hero" of the cereal nutrition world.
Updated On: Aug 21, 2026
- Albumin
- Globulin
- Prolamine
- Glutelin
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the Question:
Plant proteins are classified by their solubility (Osborne classification). The question asks which of these storage proteins is associated with poor biological value (low nutritional quality) in human and animal diets.
Step 2: Detailed Explanation:
• Storage Proteins in Cereals: Cereals store nitrogen in the form of specific proteins in the endosperm. The two most abundant are Prolamines and Glutelins.
• Characteristics of Prolamines: Prolamines (e.g., Zein in maize, Gliadin in wheat, Hordein in barley) are soluble in 70-80% ethanol.
• Amino Acid Profile: Prolamines are rich in Proline and Glutamine (hence the name), but they are characteristically deficient in essential amino acids, particularly Lysine and Tryptophan.
• Nutritional Impact: Since humans cannot synthesize essential amino acids, a diet dominated by prolamine-rich cereals (like low-quality maize) leads to malnutrition. For example, maize contains about 50-60% prolamine (Zein), which contains almost zero Lysine.
• Comparison with other classes:
- Albumins (water-soluble) and Globulins (salt-soluble) have balanced amino acid profiles and high nutritional value, but they are present in very small amounts in cereals.
- Glutelins (dilute acid/alkali-soluble) have a better balance of amino acids than prolamines. Rice is nutritionally superior to maize because its main storage protein is Glutelin (Oryzenin), not Prolamine.
• Biotech solutions: Quality Protein Maize (QPM) was developed to reduce prolamine levels and increase other high-quality proteins.
Step 3: Final Answer:
Prolamines are responsible for lowering the nutritional quality of cereals because they lack essential amino acids like Lysine.
Plant proteins are classified by their solubility (Osborne classification). The question asks which of these storage proteins is associated with poor biological value (low nutritional quality) in human and animal diets.
Step 2: Detailed Explanation:
• Storage Proteins in Cereals: Cereals store nitrogen in the form of specific proteins in the endosperm. The two most abundant are Prolamines and Glutelins.
• Characteristics of Prolamines: Prolamines (e.g., Zein in maize, Gliadin in wheat, Hordein in barley) are soluble in 70-80% ethanol.
• Amino Acid Profile: Prolamines are rich in Proline and Glutamine (hence the name), but they are characteristically deficient in essential amino acids, particularly Lysine and Tryptophan.
• Nutritional Impact: Since humans cannot synthesize essential amino acids, a diet dominated by prolamine-rich cereals (like low-quality maize) leads to malnutrition. For example, maize contains about 50-60% prolamine (Zein), which contains almost zero Lysine.
• Comparison with other classes:
- Albumins (water-soluble) and Globulins (salt-soluble) have balanced amino acid profiles and high nutritional value, but they are present in very small amounts in cereals.
- Glutelins (dilute acid/alkali-soluble) have a better balance of amino acids than prolamines. Rice is nutritionally superior to maize because its main storage protein is Glutelin (Oryzenin), not Prolamine.
• Biotech solutions: Quality Protein Maize (QPM) was developed to reduce prolamine levels and increase other high-quality proteins.
Step 3: Final Answer:
Prolamines are responsible for lowering the nutritional quality of cereals because they lack essential amino acids like Lysine.
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