Meat quality and Raman spectroscopic characterization of Korat hybrid chicken obtained from various rearing periods.

Meat quality attributes vary with chicken age. Understanding the relationship between poultry age and the quality of the meat would be beneficial for efficient poultry farming to meet market needs. The Korat hybrid chicken (KC) is a new crossbred chicken whose meat quality is distinct from that of commercial broiler (CB) chickens and has not been well characterized. In this study, we characterized the physico-chemical properties of KC meat and correlate the findings with Raman spectral data. The protein content of KC breast and thigh meat increased with age. The pH of thigh meat decreased, while the water-holding capacity of breast meat increased as the age of the chickens increased. The amount of cholesterol in breast meat decreased as the rearing period was extended. Inosine 5'-monophosphate and guanosine 5'-monophosphate of breast meat decreased as KC grew older. The shear force values of meat from older birds increased concomitantly with an increase in total collagen. Principle component analysis revealed that the meat quality of CB was greatly different from that of KC meat. High shear force values of KC meat at 20 wk of age were well correlated with an increase in the ß-sheet structure (amide I) and amide III of collagen. Raman spectra at 3,207 cm-1 and relative α-helical content were negatively correlated with shear force values of KC breast meat. These could be used as markers to evaluate KC meat quality.

Low-temperature and long-time heating regimes on non-volatile compound and taste traits of beef assessed by the electronic tongue system.

The influence of temperature-time combinations on non-volatile compound and taste traits of beef semitendinosus muscles tested by the electronic tongue was studied. Single-stage sous-vide at 60 and 70 °C (6 and 12 h), and two-stage sous-vide that sequentially cooked at 45 °C (3 h) and 60 °C (either 3 or 9 h) were compared with traditional cooking at 70 °C (30 min). Umami was better explained in the given model of partial least squares regression than astringency, sourness, saltiness, bitterness, and richness. Sous-vide at 70 °C for 12 h characterized the most umami, likely adenosine-5'-monophosphate (AMP) and guanosine-5'-monophosphate (GMP) as significant contributors. Two-stage sous-vide projected higher histidine, leucine, inosine, and hypoxanthine with the astringent and sour taste significant after 6 and 12 h cooking, respectively. Equivalent umami concentration (EUC) between umami amino acids and umami nucleotides showed a strong relationship to umami taste assessed by the electronic tongue.

A novel non-enzymatic sensing platform for determination of 5'-guanosine monophosphate in meat.

Graphitic carbon nitride (g-C3N4) doped carboxylated MWCNTs nanocomposite was synthesized using a simple method. The composite films containing 45 wt%, 50 wt%, 56 wt%, 67 wt% fraction of the carboxylated MWCNTs doped into g-C3N4 were fabricated and characterized. An electrochemical non-enzymatic sensor for determination of 5'-guanosine monophosphate (GMP) based on the nanocomposite was developed. The results indicate that the g-C3N4-carboxylated MWCNTs nanocomposite has highly electrocatalytic activity, good conductivity and biocompatibility, which plays an essential role in the determination of GMP. Under the optimum conditions, the linear fitting equation was I (µA) = -0.0022c (µg·mL-1) + 0.3560 (R2 = 0.9982). The linear range was from 0.5 to 100 µg·mL-1 and the detection limit (LOD, S/N = 3) was 0.109 µg·mL-1. This non-enzymatic sensor can offer a better alternative to other methods for the analysis of GMP because of cheap cost, low detection limit and good anti-jamming capability in meat quality evaluation.

An improved "ion pairing agent free" HPLC-RP method for testing cAMP Phosphodiesterase activity.

Current HPLC methods for analyzing cAMP Phosphodiesterase activity (PDE) use salts, limiting the life of the columns. For this reason, we have developed an improved "ion pairing agent free" method, using a simple 150 mm C18-hydro column at 30 °C and two phases: (a) water with 0.1% acetic acid and (b) 85/15 w/w MeOH/tetrahydrofuran with 0.1% acetic acid. Using this method the peaks for cAMP and AMP were obtained with good resolution (R ≈ 1.35) and sensitivity (5·10-9 mols) in only 15 min. Moreover, the method was applied to the GMP/cGMP pair obtaining the same sensitivity and resolution (R ≈ 1.38). The precision and accuracy were tested and the method was verified with a Type IV Phosphodiesterase reaction, which produced AMP from cAMP. The method is cleaner and less aggressive, and represents an interesting alternative to currently used methods.

Analysis and Evaluation of the Characteristic Taste Components in Portobello Mushroom.

To identify the characteristic taste components of the common cultivated mushroom (brown; Portobello), Agaricus bisporus, taste components in the stipe and pileus of Portobello mushroom harvested at different growth stages were extracted and identified, and principal component analysis (PCA) and taste active value (TAV) were used to reveal the characteristic taste components during the each of the growth stages of Portobello mushroom. In the stipe and pileus, 20 and 14 different principal taste components were identified, respectively, and they were considered as the principal taste components of Portobello mushroom fruit bodies, which included most amino acids and 5'-nucleotides. Some taste components that were found at high levels, such as lactic acid and citric acid, were not detected as Portobello mushroom principal taste components through PCA. However, due to their high content, Portobello mushroom could be used as a source of organic acids. The PCA and TAV results revealed that 5'-GMP, glutamic acid, malic acid, alanine, proline, leucine, and aspartic acid were the characteristic taste components of Portobello mushroom fruit bodies. Portobello mushroom was also found to be rich in protein and amino acids, so it might also be useful in the formulation of nutraceuticals and functional food. PRACTICAL APPLICATION: The results in this article could provide a theoretical basis for understanding and regulating the characteristic flavor components synthesis process of Portobello mushroom.

[Determination of five nucleotides in infant formula milk powder by modified high performance liquid chromatography].

A modified high performance liquid chromatographic (HPLC) method was developed for the determination of the five nucleotides (uridine monophosphate (UMP), adenosine monophosphate (AMP), inosine monophosphate (IMP), guanosine monophosphate (GMP) and cytidine monophosphate (CMP)) in infant formula milk powder. The samples were extracted by water, deproteinized by acetic acid and purified with an HLB SPE cartridge. The analytes were separated by a Waters XBrigde Amide column (150 mm×4.6 mm, 3.5 µ m). Acetonitrile, 10 mmol/L sodium dihydrogen phosphate aqueous solution and 0.12%(v/v) phosphoric acid aqueous solution were used as mobile phases with gradient elution. The detection wavelength of photodiode array detector was set at 254 nm. Five linear calibration curves were obtained with correlation coefficients (r2) of 0.9999. The recoveries were determined at three spiked levels ranging from 86.9% to 105.7%. The limits of quantification (LOQs) were from 5.6 mg/kg to 8.0 mg/kg. The intra-day and inter-day precisions were 0.5%-1.7% (n=5) and 0.6%-1.9% (n=9), respectively. The method is simple, effective, accurate and repeatable. It is suitable for thedetermination of the five nucleotides in infant formula milk powder.

Photo-electrochemical Bioanalysis of Guanosine Monophosphate Using Coupled Enzymatic Reactions at a CdS/ZnS Quantum Dot Electrode.

A photo-electrochemical sensor for the specific detection of guanosine monophosphate (GMP) is demonstrated, based on three enzymes combined in a coupled reaction assay. The first reaction involves the adenosine triphosphate (ATP)-dependent conversion of GMP to guanosine diphosphate (GDP) by guanylate kinase, which warrants substrate specificity. The reaction products ADP and GDPare co-substrates for the enzymatic conversion of phosphoenolpyruvate to pyruvate in a second reaction mediated by pyruvate kinase. Pyruvate in turn is the co-substrate for lactate dehydrogenase that generates lactate via oxidation of nicotinamide adenine dinucleotide (reduced form) NADH to NAD(+). This third enzymatic reaction is electrochemically detected. For this purpose a CdS/ZnS quantum dot (QD) electrode is illuminated and the photocurrent response under fixed potential conditions is evaluated. The sequential enzyme reactions are first evaluated in solution. Subsequently, a sensor for GMP is constructed using polyelectrolytes for enzyme immobilization.

Analysis of Nucleotide 5'-Monophosphates in Infant Formulas by HPLC-UV: Collaborative Study, Final Action 2011.20.

A collaborative study was conducted on AOAC First Action Method 2011.20: 5'-Mononucleotides in Infant Formula and Adult/Pediatric Nutritional Formula. After the successful analysis of National Institute of Standards and Technology (NIST) 1849a Standard Reference Material (SRM) as a practice sample, 12 laboratories participated in the analysis of duplicate samples of six different infant formula products. The samples were dissolved in high-salt solution to inhibit protein and fat interactions, with the nucleotides [uridine 5'-monophosphate (UMP), inosine 5'-monophosphate (IMP), adenosine 5'-monophosphate (AMP), guanosine 5'-monophosphate (GMP), and cytidine 5'-monophosphate (CMP)] separated from the sample matrix by strong-anion exchange SPE, followed by chromatographic analysis using a C18 stationary phase with gradient elution, UV detection, and quantitation by an internal standard technique using thymidine 5'-monophosphate. For nucleotide-supplemented products, precision is within the Standard Method Performance RequirementsSM (SMPR) 2011.008 target reproducibility limit of ≤11%, with the reproducibility RSD (RSDR) estimated at 7.1-8.7% for CMP, 7.9-9.0% for UMP, 2.8-7.7% for GMP, 5.5-10.3% for IMP, and 2.7-6.2% for AMP, and Horwitz ratio (HorRat) values of 0.9-1.0 for CMP, 0.9-1.0 for UMP, 0.3-0.7 for GMP, 0.6-1.0 for IMP, and 0.3-0.7 for AMP.

Challenges and solutions in the bioanalysis of BMS-986094 and its metabolites including a highly polar, active nucleoside triphosphate in plasma and tissues using LC-MS/MS.

BMS-986094, a nucleotide polymerase inhibitor of the hepatitis C virus, was withdrawn from clinical trials because of a serious safety issue. To investigate a potential association between drug/metabolite exposure and toxicity in evaluations conducted after the termination of the BMS-986094 development program, it was essential to determine the levels of BMS-986094 and its major metabolites INX-08032, INX-08144 and INX-09054 in circulation and the active nucleoside triphosphate INX-09114 in target and non-target tissues. However, there were many challenges in the bioanalysis of these compounds. The chromatography challenge for the extremely polar nucleoside triphosphate was solved by applying mixed-mode chromatography which combined anion exchange and reversed-phase interactions. The LC conditions provided adequate retention and good peak shape of the analyte and showed good robustness. A strategy using simultaneous extraction but separate LC analysis of the prodrug BMS-986094 and its major circulating metabolites was used to overcome a carryover issue of the hydrophobic prodrug while still achieving good chromatography of the polar metabolites. In addition, the nucleotide analytes were not stable in the presence of endogenous enzymes. Low pH and low temperature were required for blood collection and plasma sample processing. However, the use of phosphatase inhibitor and immediate homogenization and extraction were critical for the quantitative analysis of the active triphosphate, INX-09114, in tissue samples. To alleviate the bioanalytical complexity caused by multiple analytes, different matrices, and various species, a fit-for-purpose approach to assay validation was implemented based on the needs of drug safety assessment in non-clinical (GLP or non-GLP) studies. The assay for INX-08032 was fully validated in plasma of toxicology species. The lower limit of quantification was 1.00ng/mL and the linear curve range was 1.00-500.00ng/mL using a weighted (1/x(2)) linear regression model. Intra-assay and inter-assay precision (CV, %) ranged from 2.3% to 5.5% and accuracy within ±2.2% from nominal. INX-08032 was found to be stable in acidified mouse plasma for at least 24h in wet ice bath, 125 days at -70°C and following at least three freeze-thaw cycles. No endogenous components in plasma were found to interfere with the measurement. The extraction recovery was between 90% and 95%. The assays for BMS-986094, INX-08144, INX-09054 and INX-09114 were qualified with wider acceptance criteria for accuracy and precision. Analyte stability was also evaluated to guide sample collection, storage, and processing. These assays were successfully applied to an investigative toxicokinetic and tissue metabolite profiling study described in the article.

The role of sodium in the salty taste of permeate.

Many food companies are trying to limit the amount of sodium in their products. Permeate, the liquid remaining after whey or milk is ultrafiltered, has been suggested as a salt substitute. The objective of this study was to determine the sensory and compositional properties of permeates and to determine if elements other than sodium contribute to the salty taste of permeate. Eighteen whey (n=14) and reduced-lactose (n=4) permeates were obtained in duplicate from commercial facilities. Proximate analyses, specific mineral content, and nonprotein nitrogen were determined. Organic acids and nucleotides were extracted followed by HPLC. Aromatic volatiles were evaluated by gas chromatography-mass spectrometry. Descriptive analysis of permeates and model solutions was conducted using a trained sensory panel. Whey permeates were characterized by cooked/milky and brothy flavors, sweet taste, and low salty taste. Permeates with lactose removed were distinctly salty. The organic acids with the highest concentration in permeates were lactic and citric acids. Volatiles included aldehydes, sulfur-containing compounds, and diacetyl. Sensory tests with sodium chloride solutions confirmed that the salty taste of reduced-lactose permeates was not solely due to the sodium present. Permeate models were created with NaCl, KCl, lactic acid, citric acid, hippuric acid, uric acid, orotic acid, and urea; in addition to NaCl, KCl, lactic acid, and orotic acid were contributors to the salty taste.

A validated method for the determination of nucleotides in infant formulas by capillary electrophoresis coupled to mass spectrometry.

In this work CE-ESI-MS is proposed for the identification and simultaneous quantification of several ribonucleotide 5'-monophosphates in infant formula (IF) samples. The target compounds were adenosine 5'-monophosphate, cytidine 5'-monophosphate, guanosine 5'-monophosphate, uridine 5'-monophosphate, and inosine 5'-monophosphate. To our knowledge, the application of CE for the determination of these bioactive compounds in IFs has not yet been described. Optimization of the composition of the electrophoretic separation buffer and -mainly- the injection medium was carried out with a view to obtaining the best sensitivity and separation efficiency for the CE-MS coupling. Different sample treatments were assayed and one based on centrifugal ultrafiltration proved to be the simplest and most compatible with CE separation of the analytes and their ionization by the electrospray source. The whole optimized method (centrifugal ultrafiltration treatment prior to CE-MS) was validated according to the 2002/657/EC decision, obtaining a reliable and robust CE-MS method to determine these compounds in IF samples, with LODs between 0.8 and 1.8 µg/g (S/N = 3) and recoveries in the 90-106% range.

Monosodium glutamate, disodium inosinate, disodium guanylate, lysine and taurine improve the sensory quality of fermented cooked sausages with 50% and 75% replacement of NaCl with KCl.

Fermented cooked sausages were produced by replacing 50% and 75% of NaCl with KCl and adding monosodium glutamate, disodium inosinate, disodium guanylate, lysine and taurine. The manufacturing process was monitored by pH and water activity measurements. The sodium and potassium contents of the resulting products were measured. The color values (L*, a* and b*), texture profiles and sensory profiles were also examined. Replacing 50% and 75% NaCl with KCl depreciated the sensory quality of the products. The reformulated sausages containing monosodium glutamate combined with lysine, taurine, disodium inosinate and disodium guanylate masked the undesirable sensory attributes associated with the replacement of 50% and 75% NaCl with KCl, allowing the production of fermented cooked sausages with good sensory acceptance and approximately 68% sodium reduction.

Naphthyridine-based lanthanide complexes worked as magnetic resonance imaging contrast for guanosine 5'-monophosphate in vivo.

New lanthanide complex Gd-ANAMD containing 2-amino-7-methyl-1,8-naphthyridine was achieved for selective magnetic resonance imaging towards guanosine 5'-monophosphate over other ribonucleotide polyphosphates in aqueous media and in vivo. The formation of strong multi-hydrogen bonds between naphthyridine and guanosine made the phosphate in guanosine 5'-monophosphate positioned on a suitable site to coordinate with the lanthanide ion. The substitution of the coordination naphthyridine by the phosphate oxygen atoms caused obvious relaxivity decrease. The negligible cytotoxicity and appropriate blood circulation time of Gd-ANAMD allow potential application of Magnetic Resonance Imaging in vivo. (1)H NMR confirmed that the selectivity of these lanthanide complexes towards guanosine was attributed to the formation of hydrogen bonds between the guanine moeity and the naphthyridine. The fluorescence detection and lifetime measurement of Tb-ANAMD and Eu-ANAMD suggested that the decrease of the relaxivity is not attributed to the change of the q value, but caused by the prolonging of the residence lifetime of inner-sphere water.

Analysis of 5'-mononucleotides in infant formula and adult/pediatric nutritional formula by liquid chromatography: First Action 2011.20.

A method for the routine determination of 5'-mononucleotides (uridine 5'-monophosphate, inosine 5'-monophosphate, adenosine 5'-monophosphate, guanosine 5'-monophosphate, and cytidine 5'-monophosphate) in infant formula and adult nutritionals is described. After sample dissolution and addition of internal standard, potential interferences were removed by anion-exchange SPE followed by HPLC-UV analysis. Single-laboratory validation performance parameters include recovery (92-101%) and repeatability (1.0-2.3% RSD). The method was approved for Official First Action status by an AOAC expert review panel.

HILIC-MS/MS method for the quantitation of nucleotides in infant formula and adult nutritional formula: First Action 2011.21.

Official Method 2011.21 is for the quantitation of the following nucleotides: adenosine 5'-monophosphate (AMP), guanosine 5'-monophosphate (GMP), uridine 5'-monophosphate (UMP), cytidine 5'-monophosphate (CMP), and inosine 5'-monophosphate (IMP) in infant formula and adult/pediatric nutritional formula. It uses hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS). Preparation of the internal standards was conducted using centrifugal ultrafiltration and the standards are AMP- (13)C10, (15)N5; GMP-(13)C10, (15)N5; UMP-(13)C9, (15)N2; and15 CMP- (13)C9, (15)N3. Data were collected by using multiple reaction monitoring of the product ions of protonated molecules of the five nucleotides generated by positive-electrospray ionization. The HILIC conditions were conducted with ammonium formate (30 mmol/L) in water (pH 2.5, adjusted with formic acid) and methanol. The LOD and LOQ of the standard solution were 0.005-0.01 and 0.01-0.03 microg/mL, respectively. Recovery data were collected for intraday and interday testing and ranged from 98.1 to 108.9% with an RSD of 0.7-5.4%. The analytical range of the method is between 0.04 to 5 microg/mL for standard solution.

LC-MS based quantification of 2'-ribosylated nucleosides Ar(p) and Gr(p) in tRNA.

RNA nucleosides are often naturally modified into complex non-canonical structures with key biological functions. Here we report LC-MS quantification of the Ar(p) and Gr(p) 2'-ribosylated nucleosides in tRNA using deuterium labelled standards, and the first detection of Gr(p) in complex fungi.

Discovery of N(2)-(1-carboxyethyl)guanosine 5'-monophosphate as an umami-enhancing maillard-modified nucleotide in yeast extracts.

Sensory-guided fractionation of a commercial yeast extract involving medium-pressure RP-18 chromatography and ion-pair chromatography, followed by LC-MS/MS, LC-TOF-MS, 1D/2D-NMR, and CD spectroscopy, led to the discovery of the previously not reported umami-enhancing nucleotide diastereomers (R)- and (S)-N(2)-(1-carboxyethyl)guanosine 5'-monophosphate. Model experiments confirmed the formation of these diastereomers by a Maillard-type glycation of guanosine 5'-monophosphate with dihydroxyacetone and glyceraldehyde, respectively. Sensory studies revealed umami recognition threshold concentrations of 0.19 and 0.85 mmol/L for the (S)- and (R)-configured diastereomers, respectively, and demonstrated the taste-enhancing activity of these nucleotides on monosodium l-glutamate solutions.

Ion-pair high-performance liquid chromatography with diode array detection coupled to dual electrospray atmospheric pressure chemical ionization time-of-flight mass spectrometry for the determination of nucleotides in baby foods.

A liquid chromatography with diode array detection coupled to dual electrospray atmospheric pressure chemical ionization time-of-flight mass spectrometry (HPLC/ESI-APCI-TOF-MS) method is described for the rapid determination of five monophosphate nucleotides (cytidine 5'-monophosphate, uridine 5'-monophosphate, adenosine 5'-monophosphate, inosine 5'-monophosphate and guanosine 5'-monophosphate) in baby foods. The method is based on the deproteinisation of foods and direct analysis of nucleotides by ion-pair HPLC using isocratic elution with a mobile phase of 5% (v/v) methanol and 95% (v/v) 0.1 M formate buffer (pH 5.5) containing 0.01 M N,N-dimethylhexylamine (DMHA) at a flow-rate of 0.7 mL min(-1). The HPLC was hyphenated with two different detection systems, photodiode-array (DAD) and ESI-APCI-TOF-MS in negative mode. The method was validated for linearity, detection and quantitation limits, selectivity, accuracy and precision. The recoveries obtained for spiked samples were satisfactory for all the analytes. The method was successfully applied to the analysis of nucleotides in different baby and/or functional food samples, as cereals, purees and dairy products. A study was also carried out on the stability of nucleotides in acidified dairy infant food with pasteurized yoghourt and follow-on formulae samples stored at room temperature and at 30 degrees C.

Glutamate: from discovery as a food flavor to role as a basic taste (umami).

In 1908 Kikunae Ikeda identified the unique taste component of konbu (kelp) as the salt of glutamic acid and coined the term umami to describe this taste. After Ikeda's discovery, other umami taste substances, such as inosinate and guanylate, were identified. Over the past several decades, the properties of these umami substances have been characterized. Recently, umami has been shown to be the fifth basic taste, in addition to sweet, sour, salty, and bitter.

The possible role of human milk nucleotides as sleep inducers.

Breast-milk contains a potent mixture of diverse components, such as the non-protein nitrogen fraction which includes nucleotides, whose variation in levels is evident throughout lactation. In addition, these substances play an important role in sleep homeostasis. In the present study, human milk samples were analyzed using a capillary electrophoresis system. The rhythmicity of each nucleotide was studied by cosinor analysis. It was found that the nucleotides 5'AMP, 5'GMP, 5'CMP, and 5'IMP have significant (P < 0.05) circadian rhythms, the acrophases of the first two being during the night, and of the latter two during the day. While 5'UMP did not show a clear circadian rhythm, there was an increase in its levels at night. In conclusion, the rise in nocturnal levels of 5'AMP, 5'GMP, and 5'UMP could be involved in inducing the 'hypnotic' action of breast-milk at night in the infant.