Determination Of Free Amino Acids Research Articles

Determination of free amino acids in dairy whey and its hydrolysates using gas chromatography coupled with mass spectrometry

This work aimed to validate a method for the quantification of free amino acids in cheese whey protein concentrate and cheese whey protein hydrolysate via gas chromatography coupled with mass spectrometry (GC–MS). For this, free amino acid analysis was carried out with deproteinisation, where the efficiencies of acetonitrile and trichloroacetic acid were compared, prior to derivatisation with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide before GC–MS analysis. The results demonstrated that using trichloroacetic acid enabled the determination of 13 free amino acids (l-alanine, l-valine, l-leucine, l-isoleucine, l-proline, l-methionine, l-serine, l-phenylalanine, l-aspartic acid, l-glutamic acid, l-lysine, l-tyrosine, and l-cystine) in cheese whey protein concentrate and hydrolysate. The method was validated in terms of recovery (85–105%), limits of detection (0.03–0.77 μg mL−1), and limits of quantification (0.09–2.56 μg mL−1). This GC–MS methodology can be used in food laboratories for the quantification of some free amino acids, including branched-chain amino acids, in solid dairy products.

Application of Maillard Reaction Products Derived Only from Enzymatically Hydrolyzed Sesame Meal to Enhance the Flavor and Oxidative Stability of Sesame Oil.

The low-temperature roasting of sesame oil has become increasingly popular because of its nutritional benefits; however, the flavor is reduced. In order to improve the quality of sesame oil without exogenous addition, sesame meal was hydrolyzed and further used to prepare Maillard reaction products (MRPs) while protease hydrolysis (PH) and glucoamylase-protease hydrolysis (GPH) were used, and their respective Maillard products (PHM and GPHM) were added in the oils for reducing sugar and total sugar content determination, free amino acid determination, and color and descriptive sensory analysis, as well as electronic nose, SPME-GC-MS, odor activity value, and oxidative stability analyses. Results showed that the MRPs could be produced using the enzymatically hydrolyzed sesame meal without exogenous addition, and the oil flavor blended with GPHM (GPHM-SO) was significantly (p < 0.05) improved with the best sensory quality. The composition of pyrazines (119.35 μg/mL), furans (13.95 μg/mL), and sulfur substances (6.25 μg/mL) contributed positively to sensory properties in GPHM-SO, and 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, and 2,3-dimethylpyrazine were characterized as the key flavor compounds with odor activity values of 7.01, 14.80, and 31.38, respectively. Furthermore, the oxidative stability of the oil was significantly improved with the addition of MRPs, and the shelf life of GPHM-SO was predicted to be extended by 1.9 times more than that of the crude oil based on the accelerated oxidation fitting analysis. In general, the MRPs derived only from sesame meal can enhance the flavor and oxidative stability of sesame oil and can be applied in the oil industry.

Rapid stacking of amino acids in soybean and Dendrobium officinale by on-capillary sandwich derivatization in capillary electrophoresis

An online sandwich derivatization and stacking strategy using capillary electrophoresis was developed and successfully applied to the preconcentration of multi-amino acids in two functional food samples. Amino acids were derived with 4-Chloro-7-nitro-1, 2, 3-benzoxadiazole (NBD-Cl) to make the new compounds with chromophore in the stacking process, then the derivatives were stacked by on-column sample preconcentration and detected at 475 nm UV wavelength. The novel sandwich injection sequence was amino acids, NBD-Cl, and amino acids separately. Additionally, the running buffer was 40 mM borax buffer (pH = 9.0). A succession of derivatization and stacking conditions were optimized, including buffer concentration, pressure, NBD-Cl injection time, waiting time, matrix concentration, and sample injection time. In the appropriate range, good linearity values (R2) were obtained for nine amino acids at 0.996–0.999. Intra-day and inter-day precision with a relative standard deviation < 6.23 % (n = 5), the limit of detection in the range of 2.8–25.2 μM, and recovery ranging from 83.2 to 108.2 % were obtained. Besides, the enrichment factors were in range of 8–62 for nine AAs. The stacking approach was successfully applied to soybean and Dendrobium officinale samples, which shows great potential in the determination of free amino acids in samples containing complex matrices.

Simple and Effective Derivatization of Amino Acids with 1-Fluoro-2-nitro-4-(trifluoromethyl)benzene in a Microwave Reactor for Determination of Free Amino Acids in Kombucha Beverages.

Kombucha is a fermentation product of sweetened tea with a symbiotic culture of acetic acid and yeast bacteria, consumed worldwide for its health-promoting properties. Few reports can be found about free amino acids among the health-promoting compounds found and determined in kombucha. These compounds influence the sensory properties of kombucha, and they are precursors of bioactive compounds, which have a significant role as neurotransmitters and are involved in biological functions. The presented studies proposed a convenient, simple, and “more green” procedure of the synthesis of amino acid derivatives, assisted by microwave energy, followed by chromatographic determination. The structure of 1-Fluoro-2-nitro-4-(trifluoromethyl)benzene was used as a suitable reagent for the derivatization of free amino acids in fermented kombucha beverages prepared from selected dry fruit such as Crataegus L., Morus alba L., Sorbus aucuparia L., Berberis vulgaris L., Rosa canina L., and black tea. The obtained results were discussed regarding the tested beverages’ application as a source of amino acids in one’s daily diet. The obtained results point out that the proposed microwave-assisted derivatization procedure prior to HPLC analyses allows for a significant time reduction and the limitation of using organic reagents.

Determination of free amino acids in Eriocheir sinensis by ultra-high performance liquid chromatography-high resolution mass spectrometry

游离氨基酸不仅是一类重要的营养物质,更与中华绒螯蟹独特的滋味和香味密切相关。对游离氨基酸含量进行测定,能为中华绒螯蟹产品的品质评价和风味研究提供有价值的信息。该工作通过优选提取溶剂、优化仪器测定参数,最终使用5%(v/v)高氯酸水溶液提取目标物,采用XDB-C18色谱柱(100 mm×4.6 mm, 1.7 μm),以0.1%(v/v)甲酸水溶液-乙腈为流动相进行梯度洗脱,在电喷雾正离子电离、选择离子扫描模式下进行检测,外标法定量,建立了超高效液相色谱-高分辨质谱(UHPLC-HRMS)测定中华绒螯蟹中17种游离氨基酸含量的方法。结果表明,17种氨基酸在10.0~200.0 mg/L范围内线性关系良好,相关系数(R2)≥0.9990,仪器检出限为0.3 mg/L,仪器定量限为1.0 mg/L。在中华绒螯蟹可食部分中按三水平进行加标回收试验,各目标物的回收率在78.4%~105.3%之间。通过对仪器和方法精密度进行评估,发现17种氨基酸测定仪器重复性的RSD≤4.2%,方法重复性试验的RSD≤5.2%,再现性试验的RSD≤11.4%,精密度数据均在合理范围内。利用该研究建立的检测方法对20个中华绒螯蟹样本进行了实际样品检测,总结了17种游离氨基酸在蟹肉、蟹膏、蟹黄中的分布特点,验证了该方法是一种前处理简便、选择性好、准确度高的检测技术。

Rapid determination of free amino acids and caffeine in matcha using near-infrared spectroscopy: A comparison of portable and benchtop systems

Matcha is gaining popularity around the globe, because of its worthy compositions and health benefits. This work proposed to predict free amino acids (FAA) and caffeine contents in matcha using a portable near-infrared (NIR) spectroscopy system combined with two different acquisition techniques (integrating sphere, IS; and fiber probe, FP) in comparison to a benchtop Fourier transform-NIR (FT-NIR) spectroscopy system. The prediction models were built using multi-variable selection algorithms such as synergy interval (Si), competitive adaptive reweighted sampling (CARS), and bootstrapping soft shrinkage (BOSS). Results in the current work showed that BOSS-PLS (BOSS-partial least squares) models yielded satisfactory results for both NIR spectroscopy types. In addition, the portable NIR-IS system has a prediction ability comparable to the benchtop FT-NIR, with coefficients of prediction (Rp) of 0.8920 and 0.8992 for FAA and caffeine, respectively. Consequently, the portable NIR-IS system has great compatibility for the rapid, accurate and on-site prediction of matcha compositions.

Comparison of the ionisation mode in the determination of free amino acids in beers by Liquid Chromatography tandem mass spectrometry

A comparison of positive and negative ionization modes in LC-ESI-MS/MS was carried out for the analysis of derivatized amino acids in 15 different beer samples. 22 free amino acids were derivatized using Diethyl ethoxymethylenemalonate (DEEMM) and their content was determined.When using the DEEMM as derivatization reagent the negative ionization mode provided analytical performance equal to or in some cases even superior to the positive ionization mode. For 6 amino acids (Thr, β-Ala, α-Ala, Met, Val and Orn) the negative mode led to lower LoQ values, while the positive mode offered lower LoQ values for 5 amino acids (Arg, Asp, Glu, GABA, and Pro). The remaining 11 amino acids showed similar LoQ values in both modes. Because of this, negative ionization mode allowed to detect and quantify amino acids such as: β-Alanine, threonine, and ornithine whose concentrations were low in most of the analysed samples. The relative standard deviation (RSD) for the results in both modes were similar. The method's linearity was determined to be in the range of 1 to 130 ppb with r2 > 0.99. Recoveries ranged from 93 to 112%. Negative mode was less affected by matrix effects the main effect was signal enhancement. In contrast, the positive ionization mode suffered from signal enhancement as well as signal suppression.

Determination of Free Amino Acids in Milk, Colostrum and Plasma of Swine via Liquid Chromatography with Fluorescence and UV Detection.

Amino acids are ubiquitous components of mammalian milk and greatly contribute to its nutritional value. The compositional analysis of free amino acids is poorly reported in the literature even though their determination in the biological fluids of livestock animals is necessary to establish possible nutritional interventions. In the present study, the free amino acid profiles in mature swine milk, colostrum and plasma were assessed using a targeted metabolomics approach. In particular, 20 amino acids were identified and quantified via two alternative and complementary reversed-phase HPLC methods, involving two stationary phases based on core-shell technology, i.e., Kinetex C18 and Kinetex F5, and two detection systems, i.e., a diode array detector (DAD) and a fluorescence detector (FLD). The sample preparation involved a de-proteinization step, followed by pre-chromatographic derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl). The two optimized methods were validated for specificity, linearity, sensitivity, matrix effect, accuracy and precision and the analytical performances were compared. The analytical methods proved to be suitable for free amino acid profiling in different matrices with high sensitivity and specificity. The correlations among amino acid levels in different biological fluids can be useful for the evaluation of physio-pathological status and to monitor the effects of therapeutic or nutritional interventions in humans and animals.

Determination of Free Amino Acids in Bee Pollen by Liquid Chromatography with Fluorescence Detection

Bee pollen is one of the hive products that is of most interest today due to its multiple beneficial health properties, making it an increasingly popular food supplement. Bee pollen contains many bioactive compounds, such as fatty acids, vitamins, minerals, proteins, and amino acids, among others. In the present study, the free amino acid content was determined in bee pollen by using liquid chromatography coupled to a fluorescence detector. Sample treatment consisted of a solvent extraction of the free amino acids with ultrapure water and a further centrifugation of the extract, which was repeated twice. After that, it was necessary to perform a pre-column derivatization of the amino acids using a combination of two reagents (o-phthalaldehyde and 9-fluorenylmethyl chloroformate) prior to their separation in a Gemini® C18 reverse phase column in gradient elution mode. The analytical performance was evaluated, and several commercial bee pollen samples were analyzed. Significant differences in the free amino acid profile and concentration, which ranged between 19 and 192 mg/g, were observed depending on the botanical origin of the samples.

Development of a Simple, Underivatized Method for Rapid Determination of Free Amino Acids in Honey Using Dilute-and-Shoot Strategy and Liquid Chromatography-Tandem Mass Spectrometry.

A simple, fast and reliable analytical method was developed for 20 free amino acids (FAAs) determination in honey samples through a dilute-and-shoot strategy and hydrophilic interaction liquid chromatography tandem mass spectrometry. Compared with previous reports, direct dilution by water has significantly reduced the matrix effect and facilitated full extraction of FAAs. Further, a 5 min determination method was established with an acetonitrile–water mobile phase system with 0.1% formic acid addition. The established method was validated and demonstrated several advantages including short detection time, wide linear range over 3–4 orders of magnitude, high sensitivity down to 0.1 ng/mL and negligible matrix effect. Twenty FAAs were determined in 10 honey samples from different botanical origins by this method, and 19 FAAs were found. This general applicable method was also promising for fast determination of FAAs in other practical samples.

Study on Optimization of Enzymatic Hydrolysis of Fish Bone Paste and Flavor Characteristics of Hydrolysates

Taking the ultra-fine fish bone paste prepared from cod bones as the object, the conditions of enzymatic hydrolysis of fish bone paste were optimized by using the single factor experiment and response surface design based on the degree of hydrolysis as an indicator. Meanwhile, the changes of flavor characteristics of fish bone paste and its hydrolysates were analyzed by employing electronic nose, electronic tongue, gas-phase ion migration chromatography(GC-IMS), and free amino acid determination. The results showed that the optimal enzymatic hydrolysis conditions were obtained at hydrolysis time of 5 hours, enzyme addition of 1.0%, material-liquid ratio of 1:1 by using flavor protease, yield 43.8% of hydrolysis degree. The electronic nose analysis results showed that the aromatic substances in the hydrolysate increased, while the content of undesirable compounds such as alkanes and ammonia decreased. The results of electronic tongue analysis showed that the acidity of the hydrolysate was increased, while the bitterness was reduced, and the overall taste was good and rich. There were 29 volatile compounds of hydrolysate and fish bone paste were detected by GC-IMS. In fish bone paste, the main volatile flavor substances were aldehydes and ketones, and the main flavor substances in the hydrolysate were ketones and esters. These types and contents of volatile flavor substances were significantly different. The hydrolysate increased the content of flavored amino acids and the hydrolysate had a good flavor.

Use of Rapid Capillary Zone Electrophoresis to Determine Amino Acids Indicators of Herring Ripening during Salting.

Currently, herring fillets are salted with acetic acid to activate muscle proteases. This causes a change in the composition of free amino acids, compared to salting of whole fish with viscera proteases. Therefore, old indicators of the ripening dynamics of salted fish based on amino acids are not current. Determination of free amino acids can be performed by many methods, but most are labor intensive and expensive. Therefore, a capillary electrophoresis method without derivatization (CZE) was used to determine the actual ripening rates of salted herring fillets. A group of hydrophobic and basic amino acids were determined in trichloroacetic acid (TCA) extracts of meat and brine to develop 16 indicators. Statistical regression analysis of the indicators (R2adj, RMSE, cluster analysis) followed by principal component analysis (PCA) correlation analysis of the indicators vs sensory evaluation parameters of texture and TPA-hardness of salted fillet meat allowed the choice of the most precise indicators. The best indicator in meat was Phe/Tyr-height, which value increased during salting. A more precise indicator of ripening was His/Tyr-height in brine, which value decreased during salting. Sensory evaluation parameters of salted herring texture correlated strongly with TPA-hardness and traditional indicators such as non-protein nitrogen and protein hydrolysis product fraction content. However, the most precise indicators were those obtained from amino acids determined by the CZE method. Results obtained in this study may be suitable for fast monitoring of the salted herring ripening process in industry.

Determination of Free Amino Acids in Banlangen Granule and its Fractions by Solid Phase Extraction Combined with Ion-pair Hig-h Perfor mance Liquid Chromatography using a Corona-charged Aerosol Detector (SPE-HPLC-CAD)

Background: Banlangen granules are broad-spectrum effective antiviral drugs, and have a large clinical demand in China. Free amino acid is one of the main antiviral active ingredients of Banlangen granules. The pre-processing of samples by the existing pre-column derivatization reversed- HPLC method is complicated. Therefore, the determination of free amino acids (AAs) by underivatized ion-pair HPLC-CAD is advantageous for simplifying the preparation process and improving sensitivity. Objective: To better optimize AAs analysis methods, here a sensitive SPE-HPLC-CAD method with a better resolution was established for the determination of underivatized AAs in Banlangen Granule for the first time. Method: The analytes were separated only by HPLC using a Hypercarb column with gradient elution of solvent A (20 mM nonafluorovaleric Acid in water) and solvent B (0.3% trifluoroacetic acid in acetonitrile-0.3% trifluoroacetic acid in water (1:9, v/v)) at a flow rate of 0.15 mL/min. N2 gas pressure and evaporation temperature of CAD were held at a constant 58.6 psi and 60 ℃, respectively. Results: This method was linear over the respective concentration range of six amino acids. The precision, accuracy, stability and recovery were satisfactory in all samples examined. And the method was successfully applied to determination of free amino acids in Banlangen granules and its fractions. The total contents of six amino acids in 28 batches of Banlangen Granule were between 1.36 mg/g-11.62 mg/g. Conclusion: The proposed method could be a simple, accurate and sensitive alternative approach for the determination of free AAs in Banlangen Granule.

Determination of free amino acids, saccharides, and selected microbes in biogenic atmospheric aerosols – seasonal variations, particle size distribution, chemical and microbial relations

Abstract. Primary biological aerosol particles (PBAPs) play an important role in the interaction between biosphere, atmosphere, and climate, affecting cloud and precipitation formation processes. The presence of pollen, plant fragments, spores, bacteria, algae, and viruses in PBAPs is well known. In order to explore the complex interrelationships between airborne and particulate chemical tracers (amino acids, saccharides), gene copy numbers (16S and 18S for bacteria and fungi, respectively), gas phase chemistry, and the particle size distribution, 84 size-segregated aerosol samples from four particle size fractions (&lt; 1.0, 1.0–2.5, 2.5–10, and &gt; 10 µm) were collected at the SMEAR II station, Finland, in autumn 2017. The gene copy numbers and size distributions of bacteria, Pseudomonas, and fungi in biogenic aerosols were determined by DNA extraction and amplification. In addition, free amino acids (19) and saccharides (8) were analysed in aerosol samples by hydrophilic interaction liquid chromatography–mass spectrometry (HILIC-MS). Different machine learning (ML) approaches, such as cluster analysis, discriminant analysis, neural network analysis, and multiple linear regression (MLR), were used for the clarification of several aspects related to the composition of biogenic aerosols. Clear variations in composition as a function of the particle size were observed. In most cases, the highest concentration values and gene copy numbers (in the case of microbes) were observed for 2.5–10 µm particles, followed by &gt; 10, 1–2.5, and &lt; 1.0 µm particles. In addition, different variables related to the air and soil temperature, the UV radiation, and the amount of water in the soil affected the composition of biogenic aerosols. In terms of interpreting the results, MLR provided the greatest improvement over classical statistical approaches such as Pearson correlation among the ML approaches considered. In all cases, the explained variance was over 91 %. The great variability of the samples hindered the clarification of common patterns when evaluating the relation between the presence of microbes and the chemical composition of biogenic aerosols. Finally, positive correlations were observed between gas-phase VOCs (such as acetone, toluene, methanol, and 2-methyl-3-buten-2-ol) and the gene copy numbers of microbes in biogenic aerosols.

Spirulina: A daily support to our immune system

In recent years, the various health benefits of Cyanobacteria microalgae – such as Arthrospira platensis, commonly called Spirulina, an edible blue-green algae – have attracted scientific attention including micro-level examinations of its bioactive components. As a whole food and nutritional supplement, it serves as a plant protein source, which has shown positive effects across a wide range of human health concerns, from malnutrition to metabolic syndrome. Spirulina bioactives, such as essential amino acids, phycocyanin, polysaccharides, carotenoids, and chlorophyll, and essential vitamins and trace minerals, are responsible for its holistic actions against oxidative stress and inflammation, and its antiviral, antibacterial, and immune-modulating effects. Various in vitro, in vivo, and ex vivo experiments have established Spirulina's mechanism of action and its effect on immunity as a proof of concept. The phenolic compounds and extracellular metabolites released from Spirulina whole food after digestion are postulated to strengthen the epithelial lining with antibacterial effects against pathogenic bacteria, adding to its prebiotic effect on the gut microbiota (like Bifidobacterium and Lactobacillus) due to its fiber content. In this study, the digestibility of Spirulina was assessed by the determination of free amino acids and peptide release during the each phase of digestion in a simulated static digestive model system. The hypothesis bridging poor gut health to low-level inflammation and metabolic syndrome, and the potential to address those issues with nutritional supplementation, such as with Spirulina, could also be beneficial in the long run to reduce comorbid illnesses, such as those associated with the currently prevailing coronavirus disease 2019 pandemic.

Accurate Determination of Free Amino Acids by Quadruple Isotope Dilution-Reverse Phase Liquid Chromatography-Tandem Mass Spectrometry after Derivatization with 2-Naphthoyl Chloride

Accurate Determination of Free Amino Acids by Quadruple Isotope Dilution-Reverse Phase Liquid Chromatography-Tandem Mass Spectrometry after Derivatization with 2-Naphthoyl Chloride

A novel fluorescent labeling reagent, 2-(9-acridone)-ethyl chloroformate, and its application to the analysis of free amino acids in honey samples by HPLC with fluorescence detection and identification with online ESI-MS.

In this study, a novel fluorescent labeling reagent 2-(9-acridone)-ethyl chloroformate (AEC-Cl) was designed, synthesized and applied for the determination of free amino acids by high-performance liquid chromatography with a fluorescence detector (HPLC-FLD). The free amino acids were rapidly and efficiently labeled by AEC-Cl in the presence of basic catalyst (pH9.0) within 5min at room temperature (25°C). The derivatives exhibited excellent stability and fluorescence properties, with maximum excitation and emission wavelengths at 268nm and 438nm, respectively. Derivatives of 22 kinds of natural amino acids were completely separated by gradient elution on a Hypersil ODS C18 column. Under the optimal conditions, the calibration curves exhibited excellent linear responses, with correlation coefficients of R2 > 0.9994. The detection and quantification limits were in the range of 0.61-2.67μgkg-1 and 2.07-8.35μgkg-1, respectively. Therefore, AEC-Cl was successfully applied for the detection of trace levels of free amino acids in honey samples. Graphical abstract A novel fluorescent labeling reagent was applied for the determination of free amino acids in honey by high-performance liquid chromatography with a fluorescence detector.

Determination of free amino acids, organic acids, and nucleotides in 29 elegant spices.

Spices can be used in cooking to enhance the flavor of food. In order to systematically summarize and discuss the flavor components of 29 elegant spices, the free amino acids, nucleotides, and organic acids in these spices were detected by high‐performance liquid chromatography. Cluster analysis was carried out to classify the 29 elegant spices based on similar data. The results showed considerable variations in the total free amino acids (1.12‒31.59 g/kg), organic acids (9.63‒71.90 g/kg), and nucleotides (0.03‒2.72 g/kg) in the elegant spices. Nine of the amino acids, especially glutamic acid and arginine, were found to have a taste active value (TAV) greater than 1. The TAVs of the 5′‐nucleotides, succinic acid, oxalic acid, tartaric acid, and ascorbic acid were all >1. The equivalent umami concentration (EUC) of sweet marjoram was 83.69 g MSG/100 g. The 29 elegant spices were divided into two categories according to cluster analysis of the EUC. Oregano fell into one category, and the remaining 28 spices fell into the other category.

UPLC-UV Method for the Quantification of Free Amino Acids, Bioactive Amines, and Ammonia in Fresh, Cooked, and Canned Mushrooms

Mushrooms are valued due to health-promoting properties and small environmental footprint. The simultaneous determination of free amino acids (17), amines (10), and ammonia in fresh, cooked, and canned Agaricus bisporus was investigated. An AQC-derivatization method was developed and validated. Norvaline was an adequate internal standard. The method was green, fast, and fit for the purpose (quantification limits, 0.14–1.92 mg/100 g; recoveries, 80–110%; repeatability, < 10%; reproducibility, < 15%). Fifteen amino acids were detected in fresh mushroom: alanine and glutamic acid were prevalent (~ 20%) followed by proline. Spermidine was the only amine detected (6.4–8.5 mg/100 g). Ammonia was present at low levels (2.8–5.5 mg/100 g). High amounts of these amino acids and spermidine warrant important health-promoting properties. The levels of amino acids, amines, and ammonia varied among lots from the same source, suggesting the influence of production conditions. During thermal processing, changes were observed: cooking affected the least (losses mainly of glutamic acid, arginine, glycine, serine, threonine, proline, and alanine, ~ 50%). Spermidine and ammonia were not affected. During canning, the losses were higher (~ 70%) for glutamic acid, serine, valine, proline, arginine, glycine, and aspartic acid. There were losses of ammonia (39%) and spermidine (24%). A two principal component model explained 97.8% of the variance and it was able to separate fresh from processed mushroom. Hierarchical cluster analysis confirmed the potential of using amines and amino acids to separate fresh from processed mushroom.

Determination of free amino acids in five commercial sweetpotato cultivars by hydrophilic interaction liquid chromatography-mass spectrometry

A sensitive and rapid method was developed for the determination of free amino acid profiles in sweetpotatoes. The method utilized an ultra-high-performance liquid chromatography system with hydrophilic interaction liquid chromatography (HILIC) separation coupled with tandem mass-spectrometry (MS/MS) detection without the need for chemical derivatization. Separation of 36 amino acid standards was achieved on a silica HILIC column in a single MS/MS run of 19 min. This validated method was applied for the analysis of the free amino acid composition of five commercial sweetpotato cultivars (Covington, Beauregard, Hatteras, Murasaki-29 and O’ Henry) from two planting lots grown in experimental fields. Analysis of variance with Tukey’s test was used to determine the differences in individual free amino acid content among the analyzed samples, and principle component analysis (PCA) was implemented to evaluate the variation in amino acid profiles of different sweetpotato cultivars. Asparagine was the most abundant free amino acid and its content varied significantly among the cultivars (p < 0.05). Fifteen additional amino acids also varied among cultivars and contributed to the differentiation of the genotypes by PCA based on their complete amino acid profiles. The efficient, reliable, sensitive method described herein could be used in quantifying amino acids in food matrices similar to sweetpotatoes.