A pitfall in determining the globulin/albumin ratio in amaranth grains

Area of Science:

• Agricultural Science
• Biochemistry
• Food Science

Background:

• Amaranth grains (Amaranthus hypochondriacus L. and Amaranthus cruentus L.) are pseudocereals with significant nutritional value.
• Previous studies reported conflicting globulin/albumin ratios (G/A) in amaranth proteins, suggesting extraction inconsistencies.

Purpose of the Study:

• To identify and characterize albumin fractions in amaranth grains.
• To resolve discrepancies in the reported globulin/albumin ratio (G/A) of amaranth proteins.

Main Methods:

• Differential protein extraction from amaranth grains to isolate albumin fractions (Alb-1 and Alb-2).
• Comparative protein extraction from buckwheat, quinoa, and barley seeds.
• Quantification of protein fractions to determine the globulin/albumin ratio (G/A).

Main Results:

• Two distinct albumin (Alb) fractions, Alb-1 and Alb-2, were identified in amaranth.
• Alb-2 constituted approximately 30% of the total albumin and globulin content.
• Proteins analogous to amaranth Alb-2 were not detected in buckwheat, quinoa, or barley.
• A revised globulin/albumin ratio (G/A) for amaranth grains was determined to be 0.3-0.4.

Conclusions:

• The presence of the unique Alb-2 fraction in amaranth significantly influences protein composition analysis.
• Accurate determination of the globulin/albumin ratio (G/A) requires accounting for the Alb-2 fraction.
• This finding clarifies previous inconsistencies in amaranth protein research.