Standardised methods for amino acid analysis of food

Abstract

Amino acids (AA) are essential nutritional components of a balanced diet and occur in foods in either the free AA form or as the building blocks of proteins. The analysis of AAs in foods is composed of a number of unit operations; the release of the AAs from the food matrix, the separation of the individual AAs and their quantification using calibration standards. Each of these steps has their own idiosyncrasies, e.g. different hydrolysis conditions are required for the optimal release of different AAs and there are a diverse number and type of food matrices, such that most laboratories adapt methods to best suit their applications. There is currently no official standardised method for AA analysis, although the Association of Analytical Communities (AOAC) has validated methods for a number of individual AA components. The established analytical techniques of HPLC (ion exchange or reversed phase) and GC-MS have recently been supplemented by a number of new methods. These include capillary electrophoresis MS and Ultra HPLC-MS, and LC with other detectors. This review will address the intricacies and concerns of the protein hydrolysis step, discuss what specifications or prerequisites need to be placed on the existing and new methods and laboratories using these methods, comment on whether one method can successfully satisfy the exacting requirements of the various unit operations, and finally pose the question 'Is there any merit in 'developing' a validated (e.g. AOAC) official method of analysis for AAs in food?'

Fast quantification of amino acids by microchip electrophoresis–mass spectrometry

“…Detection limits (S/N =3) were estimated to be 0.37 and 0.33 μM for Asp and Glu, respectively. This assay sensitivity is comparable with those of HPLC-MS methods, but far better than those of CE-MS methods [42]. Although it's not as sensitive as the CE methods with laser induced fluorescence (LIF) or electrochemical detection (ECD) [28, 32–36], the present method has the capability of peak identification because MS detection offers structural information of the compounds detected, which is essential in many cases of analyzing biological samples.…”

Liquid Chromatographic Isolation of Individual Amino Acids Extracted From Sediments for Radiocarbon Analysis

“…During protein hydrolysis by HCl, which frees amino acids by cleaving peptide bonds, tryptophan, cysteine, and methionine are partially degraded (Otter, 2012) and asparagine and glutamine are deaminated to aspartic acid and glutamic acid, respectively (Hunt, 1985). For these reasons, asparagine, cysteine, and glutamine were not included in the standard amino acid mixture.…”

Comparative Study on Nutritional Composition of Six Musa acuminata Pulp Varieties Available in Zaria, Nigeria

“…The Amino acid profile of the pulp varieties was determined using method described as referenced [11]. Exactly 60 µl of the hydrolysate was loaded into Applied Biosystems PTH Amino Acid Analyzer.…”

“…The Amino acid analyzer is aimed to separate and analyse free acidic, neutral and basic amino acids of the hydrolysate. The sample was allowed to run for 76 minutes [11].…”