The amounts of free amino acids extracted from dried Gugija (Lycium chinensis Mill) were monitored under different extraction conditions. The response methodology was applied using the ethanol concentration (X1 0-80%) and extraction time (X2 1-5 h) as operational parameters with regard to various free amino acids (glycine, serine, alanine, threonine, proline, valine, methionine, isoleucine, leucine, tyrosine, tryptophan, phenylalanine, asparagine, lysine, arginine, histidine, carnosine, ornithine, aspartic acid, glutamic acid, phosphoserine, hydroxyproline, -γ amino-n-butyric acid, taurine, phosphoethanolamine, citrulline, β-alanine, β-amino-isobutyric acid, hydroxylysine, sarcocine, and ethanolamine) and their sum. Under the optimum conditions, the free amino acid contents were asparagine 186.28, phosphoethanolamine 166.21, proline 46.51, alanine 43.35, aspartic acid 27.23, hydroxyproline 21.17, glutamic acid 16.53, taurine 16.24, arginine 14.66, serine 11.65, γ-amino-n-butyric acid 10.82, leucine 10.52, tryptophan 8.75, ethanolamine 8.49, and total free amino acid 629 mg/100 g. The coefficients of determination (R2) of the models for methionine, arginine, histidine, carnosine, ornithine, aspartic acid, phosphoserine and γ-amino-n-butyric acid were within 0.9052-0.9810 (p<0.01-0.05). For the total free amino acids, the R2 of the model was 0.8608 (p<0.1), the extraction yield ranged from 282 to 641 mg/100 g depending on the extraction conditions and was the highest when extracted for 5 h with 20% ethanol.

• Gee-Dong Lee | 이기동 Corresponding author