Amino Acid Analysis : Establishment of a GC-FID method for Amino Acid Analysis in Legumes

Abstract: Demands for plant-based diets sufficient in all required amino acids are increasing due to health and environmental advantages. As legumes offer a complementing source of quality protein to the already heavily consumed cereals, methods for determining amino acid compositions in legumes are needed. The aim of this thesis was to establish a GC-FID method for analyzing amino acids in legumes and to apply the method to analyze six locally grown legumes: Black beans, brown beans, red kidney beans, white beans, yellow and grey peas. White bean flour was used as an inhouse control sample. Legumes were hydrolyzed with acid and alkaline treatments;hydrolysates were purified and derivatized using an amino acid analysis kit (EZ:faast, Phenomenex) and quantified with GC-FID. All legumes were rich in Asp + Asn, Glu + Gln, Lys and Leu while limited in Met, Cys and Trp. Quality control trials showed a generally good precision of the method (between day CVs were ≤ 10% for 12 of 16amino acids ) and good linearity (r2 were 0,99 or above for 16 of 19 calibration curves). Limits of detection and quantification ranged from 2-46 nmol/mL and 7-154nmol/mL, respectively, depending on the amino acid. No accuracy trial was performed. In conclusion, a rapid GC-FID method for amino acid analysis was established and amino acid compositions of locally grown legumes was tentatively determined. However, further quality control trials are required to validate the method.