CE methods for the determination of non‐protein amino acids in foods

Abstract

CE methods for the determination of non-protein amino acids in foodsIn addition to the 20 amino acids universally distributed as protein constituents in living organisms, there are other amino acids of non-protein origin that can be found in foods. The determination of these non-protein amino acids is interesting since they can be indicative of the quality and safety of foods. This work presents for the first time an updated and comprehensive review devoted to show the possibilities of capillary electrophoresis for the determination of non-protein amino acids in food samples. The results reported have been classified according to the chemical structure of the non-protein amino acid studied. Separation conditions as well as detection systems used have been detailed since most of these amino acidic compounds do not posses chromophore groups detectable by conventional UV-Vis detection, being in this case necessary a previous derivatization step. Finally, the application of microchip electrophoresis to the determination of non-protein amino acids in foodstuffs is also included in this review.

Development of a CE‐ESI‐ITMS method for the enantiomeric determination of the non‐protein amino acid ornithine

“…Amino acid chirality has gained significant attention in food analysis due to the different biological activity that D-and L-enantiomers of amino acids may have [1]. Because Damino acids appearance in foodstuffs is possible due to many causes (food processing, presence of microorganisms, adulterations with racemic compounds, etc.…”

Capillary electrophoresis determination of non-protein amino acids as quality markers in foods

“…The determination of protein amino acids has been exploited for years in the food field because they can provide relevant information on the quality and safety of food samples [1][2][3]. In addition to these compounds, it is also possible to find other amino acids of non-protein origin in foods which exist as metabolic intermediates, as products formed during food processing or as additives in food to increase some nutritional and functional properties [4,5].…”

“…Therefore, taking into account that assuring product food quality, authenticity, and safety is the main demand in the food field, there is an increasing need of analytical methodologies enabling the determination of non-protein amino acids in foodstuffs. Among the advanced analytical techniques that can be used to solve some of the challenges that Food Science has to face, Capillary Electrophoresis (CE) has already demonstrated its high potential for the (achiral and chiral) determination of many compounds in foods, including amino acids, to ensure compliance with food and trade laws [1,16,19,20]. Among the CE modes used to determine non-protein amino acids in food samples, CZE (based on the free mobility of analytes in the aqueous solution under an applied electric field) and MEKC (based on the combination of electrokinetic migration and the partitioning mechanism between the bulk solution and micelles) are the most employed, whereas EKC and CEC (based on the interaction of each enantiomer with a chiral selector present in the mobile phase or with a chiral stationary phase, respectively) are the most employed CE modes to achieve an enantiomeric separation.…”

“…The present article reviews the most recent advances in the analysis of non-protein amino acids in foods using capillary electrophoretic methodologies (CZE, MEKC, EKC, and CEC) and microchip electrophoresis under achiral as well as chiral conditions covering the research articles published during the period February 2007 to February 2015, following the previous article published by our research group on this topic [1]. To make easier the discussion of the literature data and demonstrate the usefulness of CE to face different challenges related to food quality, this review has been divided in two different sections focused on the achiral and chiral determination of non-protein amino acids in foods.…”

Enantiomeric separation of ornithine in complex mixtures of amino acids by EKC with off-line derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate

“…Besides the 20 protein amino acids, there are other amino acids of non-protein origin present in foodstuffs [6]. ␥-Aminobutyric acid (GABA) and Ornithine (Orn) are examples of non-protein amino acids found in fermented beverages like wines and beers [1,5,[7][8][9][10][11][12][13][14][15].…”