발효단백질의 유리아미노산 정량

Conditions of Quantitative Analysis for free Amino Acid in Fermented Proteins

발효단백질 중의 유리아미노산을 효과적으로 정량하기 위하여 정량방법(추출조건, 제단백(除蛋白) 및 발색법)에 따른 영향을 검토하였다. 낙농발효품의 수용성 유리아미노산은 $75^{\circ}C$, 40분, 대두발효품은 $40^{\circ}C$, 3시간에서 효과적으로 추출되었다. 여러 침전방법(95% ethanol 처리, $100^{\circ}C$, 3분 가열 및 1% picric acid phthaldialdehyde로 발색시켜 D.L.-lysine을 표준아미노산으로 삼아 정량, 계산하였을 때가 아미노산자동분석기에 의한 결과에 가장 접근하였으나 ethanol로 침전시킨 뒤 OPDA로 발색시킨 결과도 이와 유사하였다. TNBS(2,4,6-trinitrobenzensulfonic acid)에 의한 발색정량에는 ethanol 침전처리가 가장 효과적이었으나 종래의 동감법(銅監法)(copper salt method, Spies and Chamber, 1958.)에 의한 결과는 다른 비색정량 및 아미노산자동분석기에 의한 결과에 비하여 시료에 따른 과소의 차이가 심하였고 재현성이 결여되었다.

This study was performed to provide the optimal conditions of quantitative analysis for free amino acid in fermented protein foods. The water extractable free amino acid from dairy fermented foods was extracted effectively at $75^{\circ}C$ for 40 min., while it were extracted from fermented soy products at $40^{\circ}C$ for 3 hours. A close results of free amino acid content to those from amino acid analyzer were obtained using OPDA method with lysine standard after deproteinizing with 1% picric acid. 95% ethanol used as a deproteinizing reagent could give a comparable results to those from picric acid treatment in determining free amino acid content using OPDA method. Therefore, ethanol treatment was more recommendable than picric acid treatment which has some troubles in removing excess picric acid through Dowex resin column. The most desirable precipitation method for free amino acid determination using TNBS method was 95% ethanol treatment among the various deproteinizing procedure. The copper salt method was not suitable owing to its lacking reproducibility and pronounced discrepancy in determining free amino acid.