Need for Accurate and Standardized Determination of Amino Acids and Bioactive Peptides for Evaluating Protein Quality and Potential Health Effects of Foods and Dietary Supplements (original) (raw)
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Applied Physiology, Nutrition, and Metabolism
Protein quality (PQ) is the capacity of a protein to meet the amino acid (AA) requirements of an individual. There are several methodologies for determining the PQ of foods. The protein efficiency ratio is an animal growth bioassay. The protein-digestibility-corrected AA score considers the AA requirements of a reference population, and the true nitrogen digestibility coefficient for each ingredient. The digestible indispensable AA score is based on true ileal AA digestibility and better represents bioavailability of AAs. In vitro techniques for assessment of PQ are available but require validation against a greater range of protein sources. Isotopic methods, such as the indicator AA oxidation and dual tracer techniques measure AA relative bioavailability and digestibility, respectively, but require sophisticated equipment, and may not be cost nor time effective for the industry to adopt. The present review discusses advantages and disadvantages of methodologies for determining PQ o...
British Journal of Nutrition, 2012
In 1989 the Joint FAO/WHO Expert Consultation on Protein Quality Evaluation recommended the use of the Protein Digestibility Corrected Amino Acid Score (PDCAAS) method for evaluating protein quality. In calculating PDCAAS, the limiting amino acid score (i.e., ratio of first limiting amino acid in a gram of target food to that in a reference protein or requirement) is multiplied by protein digestibility. The PDCAAS method has now been in use for 20 years. Research emerging during this time has provided useful data on various aspects of protein quality evaluation that has made a review of the current methods used in assessing protein quality necessary. This paper provides an overview of the use of the PDCAAS method as compared to other methods and addresses some of the key challenges that remain in regards to protein quality evaluation. Furthermore, specific factors influencing protein quality including the effects of processing conditions and preparation methods are presented. Protein quality evaluation methods and recommended protein intakes currently used in different countries vis-à-vis the WHO/FAO/UNU standards are further provided. As foods are frequently consumed in complement with other foods, the significance of the PDCAAS of single protein sources may not be evident, thus, protein quality of some key food groups and challenges surrounding the calculation of the amino acid score for dietary protein mixtures are further discussed. As results from new research emerge, recommendations may need to be updated or revised to maintain relevance of methods used in calculating protein quality.
Total Amino Acids by UHPLC-UV in Infant Formulas and Adult Nutritionals, First Action 2018.06
Journal of AOAC International
common proteinogenic amino acids. Amino acids may be present either in their free forms or bound as part of the protein/ peptide component. Although cysteine fits the general structure for α-amino acids, its disulfide form, cystine, is obviously included in the working definition of amino acids. The two are equivalent from a nutritional point of view, and regulations treat them as such. Because of method overlap, taurine (Tau; 2-aminoethanesulfonic acid) is also included in this analyte category, despite not fitting the basic definition. In terms of nutritional significance, α-amino acids primarily reflect protein quality, because in nutritional products the protein is a vehicle for delivering amino acid substrates for protein synthesis. Free amino acids substitute for protein in elemental formulas (Table 1). Total AA analysis requires hydrolysis and analysis steps. Each step introduces its own complications: (1) complex collection of molecular structures; (2) no common structural features compatible with direct, sensitive detection; (3) asparagine (Asn) and glutamine (Gln) are converted to aspartic acid (Asp) and glutamic acid (Glu) during acid hydrolysis, resulting in a summed determination; and (4) as of this publication, no single method can release all of the amino acids from protein (cystine and tryptophane are destroyed during acid hydrolysis). AOAC Official Method 2018.06 Total Amino Acids by UHPLC-UV in Infant Formulas and Adult Nutritionals First Action 2018 Quantitative determination of total amino acids using 6-aminoquinolyl-N-hydroxy succinimidyl carbamate (AQC) derivatization followed by ultrahigh-performance LC (UHPLC) separation and UV detection. This method allows the determination, in one single analysis, of the following amino acids: alanine, arginine, aspartic acid (combined with Asn), cystine (dimer of cysteine, combined with cysteine), Glu (combined with Gln), glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, Tau, threonine, tyrosine, and valine. This method is not suitable for the determination of tryptophan. [Applicable to infant and adult/pediatric nutritional formulas and other matrices such as infant cereals and pet foods.] Caution: Refer to Material Safety Data Sheets prior to use of chemicals. Use appropriate personal protective
The Journal of Nutrition, 2016
The Protein Digestibility Corrected Amino Acid Score (PDCAAS) has been adopted for assessing protein quality in human foods since 1991, and the shortcomings of using the PDCAAS have been recognized since its adoption. The 2011 FAO Expert Consultation recognized that the Digestible Indispensable Amino Acid Score (DIAAS) was superior to the PDCAAS for determining protein quality. However, there were insufficient human data on amino acid digestibility before adopting the DIAAS. More human data were needed before DIAAS could be implemented. In 2014, FAO convened an expert working group to propose and agree on research protocols using both human-based assays and animal models to study ileal amino acid digestibility (metabolic availability) of human foods. The working group identified 5 research protocols for further research and development. A robust database of protein digestibility of foods commonly consumed worldwide, including those consumed in low-income countries, is needed for an informed decision on adopting the DIAAS. A review on the impacts of using the DIAAS on public health policies is necessary. It would be advantageous to have a global coordinating effort to advance research and data collection. Collaboration with international and national agriculture institutes is desirable. Opportunities should be provided for young researchers, particularly those from developing countries, to engage in protein-quality research for sustainable implementation of DIAAS. To conclude, the DIAAS is a conceptually preferable method compared with the PDCAAS for protein and amino acid quality evaluation. However, the complete value of the DIAAS and its impact on public health nutrition cannot be realized until there are sufficient accumulated ileal amino acid digestibility data on human foods that are consumed in different nutritional and environmental conditions, measured by competent authorities. A future meeting may be needed to evaluate the size and quality of the data set and to determine the timeline for full adoption and implementation of the DIAAS.
Journal of Chromatography A, 2019
Amino acids are most often analyzed in reversed-phase liquid chromatography after a derivatization procedure to render them sufficiently hydrophobic and detectable with UV or fluorimetric detection. Simpler methods should be possible to avoid additional chemical reactions. We present an improved method to analyze free amino acids with unified chromatography, that is to say with a wide elution gradient starting with supercritical fluid chromatography (SFC) conditions (high percentage of carbon dioxide) and ending with high-performance liquid chromatography (HPLC) conditions (100% co-solvent). The mobile phase composition was carefully adjusted to permit the elution of 21 natural amino acids (among which 19 proteinogenic) with very good peak shapes from a zwitterionic cinchona-based stationary phase (Chiralpak ZWIX(+)). Chiral separation was not desired. The mobile phase finally selected comprised carbon dioxide and a co-solvent (methanol containing 2% water and 20 mM methanesulfonic acid), ranging from 10 to 100% in 7 min followed by 3 min re-equilibration at 25 °C. A reversed pressure gradient (15 to 11 MPa) and a reversed flow rate gradient (3 to 1 mL/min) were applied to avoid reaching the upper pressure limit of the pumping system (40 MPa) and to favor high chromatographic efficiency at every stage of the elution gradient. Detection was achieved with electrospray ionization-mass spectrometry (ESI(+)-MS). The method is then fast and straightforward as no derivatization step is necessary, and all isobaric species were chromatographically resolved. To demonstrate the applicability of the method, it was applied to the quantitation of amino acids in food supplements commonly consumed by sportsmen, containing taurine (a common natural amino acid) or branched-chain amino acids (BCAA), namely valine, and the isobaric leucine and isoleucine. A standard addition method was examined for sensitivity, linearity, repeatability and intermediate precision.
A REVIEW ON PROTEIN QUALITY AND BIOAVAILABILITY OF AMINO ACIDS
IJARW, 2021
Proteins have a wide range of responsibilities and functions in our body's metabolism, ranging from pure nitrogen storage molecules to the ability to construct tissue structures, as well as catalyzing various reactions as active enzymes and assisting in the transfer of insoluble components. If amino acids are not present in the right amounts, the body's ability to use protein will be damaged. Protein deficiency has been linked to a wide range of organ and system problems. The amino acid content of food proteins and the efficiency with which they are digested to promote amino acid absorption impact their capacity to provide nitrogen and essential amino acids (EAAs) for human growth and function and this capacity is described as protein quality. Protein quality assessment aims to determine how effectively food protein sources and diets can supply the metabolic demand for amino acids and nitrogen. Protein bioavailability, or the percentage of any nutrient that can be absorbed and used from food, is, of course, a metric of protein quality. One of the most critical aspects determining the nutritional value and quality of food protein sources is amino acid bioavailability.
Ingredient classification according to the digestible amino acid profile: an exploratory analysis
Brazilian Journal of Poultry Science, 2005
This study aimed: 1) to classify ingredients according to the digestible amino acid (AA) profile; 2) to determine ingredients with AA profile closer to the ideal for broiler chickens; and 3) to compare digestible AA profiles from simulated diets with the ideal protein profile. The digestible AA levels of 30 ingredients were compiled from the literature and presented as percentages of lysine according to the ideal protein concept. Cluster and principal component analyses (exploratory analyses) were used to compose and describe groups of ingredients according to AA profiles. Four ingredient groups were identified by cluster analysis, and the classification of the ingredients within each of these groups was obtained from a principal component analysis, showing 11 classes of ingredients with similar digestible AA profiles. The ingredients with AA profiles closer to the ideal protein were meat and bone meal 45, fish meal 60 and wheat germ meal, all of them constituting Class 1; the ingredients from the other classes gradually diverged from the ideal protein. Soybean meal, which is the main protein source for poultry, showed good AA balance since it was included in Class 3. On the contrary, corn, which is the main energy source in poultry diets, was classified in Class 8. Dietary AA profiles were improved when corn and/or soybean meal were partially or totally replaced in the simulations by ingredients with better AA balance.
International Journal of Food Sciences and Nutrition
The need for analytical control of food supplements and " energy " drinks containing amino acids is huge. In the literature there are describes various analytical techniques for their qualitative and quantitative analysis. Most preferred methods is HPLC because of its range, accuracy and speed. Despite the wide variety of methods, there isn't coherent analytical system associated with the standardization of food additives containing amino acids.
Validation of an HPLC method for the determination of amino acids in feed
Journal of The Serbian Chemical Society, 2013
The subject of this study was the validation of a high-performance liquid chromatography method for the analysis of amino acids in fodder. The contents of amino acids were determined in maize, soybean, soybean meal, as well as in their mixtures enriched with different amounts of methionine, threonine and lysine. The method involved the acid hydrolysis of the sample (6 h at 150 °C), automated derivatisation of the amino acids with the aid of o-phthaldialdehyde and 9-fluorenylmethyl chloroformate reagents, separation on a ZORBAX Eclipse-AAA column and detection using a diode-array detec- tor. The method is characterized by high specificity (the difference between the retention times of the fodder samples and standard mixtures were below 1.7 %), wide linear range (from 10 to 1000 nmol cm -3 , r 2 = 0.9999), high accuracy (recovery 93.3-109.4 %), and the precision of the results (RSD below 4.14 % in the case of repeatability and below 4.57 % in the case of intermediate precision). The l...