Meat quality attributes and oxidation stability of loin chops from finishing gilts and cull sows.

The objective of this study was to compare the meat quality attributes, color stability, and lipid oxidation of loin chops from finishing gilts and cull sows in a three-way crossbreeding system: landrace × large white × duroc finishing gilts (n = 20) and landrace × large white sows (n = 20). No significant differences in pH, proximate composition, or total collagen content were found between the two pig groups. However, sow loin chops exhibited different quality characteristics for color, cooking loss, protein solubility, and shear force, in which an increased cooking loss and shear force might be associated with a lower heat-soluble collagen content compared to the gilt loin chops (p < 0.05). Moreover, more rapid changes in redness and chroma during 7 days of aerobic display were observed in the sow loin chops (p < 0.05). Therefore, the results presented here highlight the possibility of issues regarding color and tenderness in sow meat compared to retail pork produced from finishing gilts.

Nitrite scavenging impact of fermented soy sauce in vitro and in a pork sausage model.

The objective of this study was to determine nitrite scavenging activity of fermented soy sauce in vitro and in a pork sausage model. In vitro nitrite scavenging activity (pH 6.0) of fermented soy sauce (10 mg/mL) was 13.2%. Within selected concentrations (10-100 mg/mL), in vitro nitrite scavenging activity and total phenol content of fermented soy sauce were highly dose-dependent (P < 0.001). In pork sausage model containing 120 mg/kg of NaNO2, fermented soy sauce resulted in significantly lower residual nitrite content (35.28 mg/kg) compared to only NaNO2 addition (40.12 mg/kg) at initial storage. During 4 weeks of cold storage, however, fermented soy sauce showed little effect on the residual nitrite content. This study indicates that fermented soy sauce could initially contribute to reduce residual nitrite content, and the nitrite scavenging impact of fermented soy sauce was less effective in the pork sausage model than in vitro evaluation.

Determination of glyoxal, methylglyoxal, and diacetyl in red ginseng products using dispersive liquid-liquid microextraction coupled with GC-MS.

A simple and rapid dispersive liquid-liquid microextraction method coupled with gas chromatography and mass spectrometry was applied for the determination of glyoxal as quinoxaline, methylglyoxal as 2-methylquinoxaline, and diacetyl as 2,3-dimethylquinoxaline in red ginseng products. The performance of the proposed method was evaluated under optimum extraction conditions (extraction solvent: chloroform 100 µL, disperser solvent: methanol 200 µL, derivatizing agent concentration: 5 g/L, reaction time: 1 h, and no addition of salt). The limit of detection and limit of quantitation were 1.30 and 4.33 µg/L for glyoxal, 1.86 and 6.20 µg/L for methylglyoxal, and 1.45 and 4.82 µg/L for diacetyl. The intra- and interday relative standard deviations were <4.95 and 5.80%, respectively. The relative recoveries were 92.4-103.9% in red ginseng concentrate and 99.4-110.7% in juice samples. Red ginseng concentrates were found to contain 191-4274 µg/kg of glyoxal, 1336-4798 µg/kg of methylglyoxal, and 0-830 µg/kg of diacetyl, whereas for red ginseng juices, the respective concentrations were 72-865, 69-3613, and 6-344 µg/L.

Identification of volatile markers for the detection of adulterants in red ginseng (Panax ginseng) juice using headspace stir-bar sorptive extraction coupled with gas chromatography and mass spectrometry.

Red ginseng (Panax ginseng) products are frequently adulterated by manufacturers with cheaper medicinal plant products including deodeok (Codonopsis lanceolata) and doraji (Platycodon grandiflorum) to increase profits. To identify possible volatile markers for the adulteration of red ginseng juices with deodeok or doraji, a headspace stir-bar sorptive extraction method was developed. Gas chromatography with mass spectrometry and untargeted metabolomics analysis revealed that 1-hexanol, cis-3-hexen-1-ol, and trans-2-hexen-1-ol are abundantly present in deodeok and doraji but not red ginseng. The peak area ratios in gas chromatograms of these compounds in red ginseng juices mixed with deodeok or doraji indicate that these volatile chemicals can be used as markers to detect the adulteration of red ginseng juice.

Development and Method Validation of Analysis of Urushiol in Sumac and Food Ingredients in Korea.

This study developed an analytical method to determine the urushiol content in sap and several foods. The full process for urushiol analysis consists of extraction, trimethylsilyl silylation, analysis, and identification via GC-MS, with each step optimized to attain the required accuracy and precision. Urushiol was separated from sap via liquid-liquid extraction and was derivatized via silylation. The components were analyzed using a polar capillary column and identified using GC-MS. The deviations of relative retention times and retention time windows were within 0.001 and 0.02 min, which satisfied the criteria of 0.06 and 0.03 min, respectively. The response of the urushiol standards tested was found to be linear in the investigated concentration range, with a correlation coefficient of 0.998. The LODs were between 1.74 and 2.67 µg/mL.

The simple determination method for anthocyanidin aglycones in fruits using ultra-high-performance liquid chromatography.

The simple determination method for anthocyanidin aglycones in fruits using ultra-high-performance liquid chromatography (UHPLC) coupled with the heating-block acidic hydrolysis method was validated through the precision, accuracy and linearity. The UHPLC separation was performed on a reversed-phase C18 column (particle size 2 µm, i.d. 2 mm, length 100 mm) with a photodiode-array detector. The limits of detection and quantification of the UHPLC analyses were 0.09 and 0.29 mg/kg for delphinidin, 0.08 and 0.24 mg/kg for cyanidin, 0.09 and 0.26 mg/kg for petunidin, 0.14 and 0.42 mg/kg for pelargonidin, 0.16 and 0.48 mg/kg for peonidin and 0.30 and 0.91 mg/kg for malvidin, respectively. The intra- and inter-day precisions of individual anthocyanidin aglycones were <10.3%. All calibration curves exhibited good linearity (r = 0.999) within the tested ranges. The total run time of UHPLC was 8 min. The simple preparation method with UHPLC detection in this study presented herein significantly improved the speed and the simplicity for preparation step of delphinidin, cyanidin, petunidin, pelargonidin, peonidin and malvidin in fruits. Especially, the UHPLC detection exhibited good resolution in spite of shorter run time about four times than conventional HPLC detection.

Dealcoholized Korean Rice Wine (Makgeolli) Exerts Potent Anti-Tumor Effect in AGS Human Gastric Adenocarcinoma Cells and Tumor Xenograft Mice.

Makgeolli is a traditional wine in Korea and has been traditionally believed to exhibit health benefits. However, the inhibitory effect of dealcoholized makgeolli (MK) on cancer has never been investigated scientifically. In this study, MK exhibited an anti-angiogenic effect by inhibiting tube formation in human umbilical vein endothelial cells, without cytotoxicity. Treatment with MK reduced the proliferation of AGS human gastric adenocarcinoma cells in a dose-dependent manner and increased the sub-G1 population. Next, we evaluated whether MK could induce apoptosis in AGS cells by using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay or Annexin V method. Treatment with MK at 500 and 1,000 µg/ml increased the number of TUNEL-positive AGS cells. Under the same conditions, MK-treated (500 and 1,000 µg/ml) cells showed significant induction of early or late apoptosis, compared with untreated cells (no induction). In addition, MK also induced phosphatase and tensin homolog (PTEN) expression in AGS cells. However, p53 expression in AGS cells was not changed by MK treatment. Furthermore, MK at 500 mg/kg·d reduced the tumor size and volume in AGS tumor xenografts. Taken together, MK may be useful for the prevention of cancer cell growth.

Rapid method for the determination of 14 isoflavones in food using UHPLC coupled to photo diode array detection.

A rapid method for the determination of 14 types of isoflavones in food using ultra-high performance liquid chromatography (UHPLC) was validated in terms of precision, accuracy, sensitivity and linearity. The UHPLC separation was performed on a reverse-phase C18 column (particle size 2 µm, i.d. 2 mm, length 100 mm) using a photo diode array detector that was fixed to 260 nm. The limits of detection and quantification of the UHPLC analyses ranged from 0.03 to 0.33 mg kg(-1). The intra-day and inter-day precision of the individual isoflavones were less than 11.77% and calibration curves exhibited good linearity (r(2) = 0.99) within the tested ranges. These results suggest that the rapid method used in this study could be available to determine of 14 types of isoflavones in a variety of food such as soy bean, black bean, red bean and soybean paste.

Determination of E,E-farnesol in Makgeolli (rice wine) using dynamic headspace sampling and stir bar sorptive extraction coupled with gas chromatography-mass spectrometry.

In this paper, we analysed the volatile and semi-volatile compounds, including E,E-farnesol in Makgeolli which is a traditional type of Korean fermented rice wines. Forty-one compounds including alcohols, 1-butanol-3-methyl acetate, E,E-farnesol, stearol, and phytane, were separated and quantified by dynamic headspace sampling (DHS) and stir bar sorptive extraction (SBSE) coupled with gas chromatography-mass spectrometry. SBSE has been found to be an effective method for analysing E,E-farnesol levels in Makgeolli. The experimental parameters related to the extraction efficiency of the SBSE method, such as ethanol concentration and filtration, were studied and optimised. The linear dynamic range of the SBSE method for E,E-farnesol ranged from 0.02 to 200ngml(-1) with R(2)=0.9974. The limit of detection and limit of quantification of the SBSE method were 0.02 and 0.05ngml(-1), respectively. The relative standard deviation of intra- and inter-day reproducibility was less than 6.2% and 9.9%, respectively.

Rapid method for determination of anthocyanin glucosides and free delphinidin in grapes using u-HPLC.

A rapid method for the determination of anthocyanin glucosides and free delphinidin in food using ultra-high-performance liquid chromatography (u-HPLC) was validated through tests of precision, accuracy and linearity. The u-HPLC separation was performed on a reversed-phase C18 column (particle size 2 µm, i.d. 2 mm, length 100 mm) with a photodiode array detector. The limits of detection and quantification of the u-HPLC analyses ranged from 0.07 to 0.65 mg/kg for nine types of anthocyanin glucosides and from 0.08 to 0.26 mg/kg for delphinidin aglycone. The intra-day and inter-day precision of individual anthocyanin glucosides and delphinidin aglycone were less than 9.42%. All calibration curves showed good linearity (coefficient of determination = 0.99) within the tested ranges. The rapid and simultaneous u-HPLC method presented in this study significantly improved the speed, sensitivity and resolution of the analyses of nine types of anthocyanin glucosides and free delphidinin aglycone in grapes.

Rapid method for the simultaneous determination of flavonol aglycones in food using u-HPLC coupled with heating block acidic hydrolysis.

A rapid method for the simultaneous determination of flavonol aglycones in food using ultra-high-performance LC (u-HPLC) coupled with a heating-block acidic hydrolysis method was validated in terms of precision, accuracy, and linearity. The u-HPLC separation was performed on an RP C18 column (particle size 2 micro m id, 2 mm, length 100 mm) with a photodiode array detector. The LOD and LOQ of the u-HPLC analyses were 0.15 and 0.47 mg/kg for myricetin, 0.09 and 0.28 mg/kg for quercetin, 0.16 and 0.49 mg/kg for kaempferol, and 0.08 and 0.25 mg/kg for isorhamnetin. The intraday and interday precisions of the individual flavonol aglycones were less than 9.31%. All calibration curves exhibited good linearity (r2 = 0.99) within the tested ranges. Total run time of u-HPLC was 13 min. The rapid u-HPLC method presented herein significantly improved the speed, sensitivity, and resolution of the analyses of myricetin, quercetin, kaempferol, and isorhamnetin in food.

Simultaneous determination of free capsorubin and capsanthin in red pepper powder using u-HPLC.

A simultaneous ultra-HPLC (u-HPLC) method for the determination of free capsorubin and capsanthin in red pepper powder was validated in terms of its precision, accuracy, and linearity. The u-HPLC separation was performed on an RP C18 column (particle size 2 pm, id 2 mm length 100 mm) and with a photodiode-array detector. The recoveries of capsorubin were greater than 83.8 +/- 1.7%; the LOD and LOQ of the u-HPLC analyses were 0.043 and 0.129 mg/kg, respectively. The intraday and interday precisions for capsorubin were less than 9.01%. The recoveries of capsanthin were greater than 87.7 +/- 1.5%, and the LOD and LOQ were 0.101 and 0.306 mglkg, respectively. The intraday and interday precisions for capsanthin were less than 12.66%. All calibration curves for capsorubin and capsanthin exhibited good linearity (r2 = 0.99) within the tested ranges.

Determination of 22 ginsenosides in ginseng products using ultra-high-performance liquid chromatography.

A reverse-phase ultra-high-performance liquid chromatography (u-HPLC) method was developed for the rapid quantification of 22 ginsenosides in ginseng products. The proposed method for the analysis of ginsenosides is based on a heating-block method without further treatment. The u-HPLC separation was performed on a reversed C18 column (100 × 2 mm id, particle size 2 µm) followed by ultraviolet detection at 203 nm. Aqueous 50% methanol was used as the extraction solvent. The optimum amount of extraction solvent and the optimum extraction time were 20 mL and 20 min (extracted twice with 10 mL), respectively. The method validation parameters yielded good results for linearity, precision, accuracy and recovery. The recovery of ginsenosides from ginseng powder was greater than 98.1% and the limits of detection and quantification of the u-HPLC analysis were >0.6 and >1.8 mg/kg for ginsenosides. The calibration graphs for ginsenosides were linear from approximately 2.6 to 40.4 mg/kg for u-HPLC. The inter-day and intra-day precisions (relative standard deviation values) were <14.6 and 14.7%, except for Rg2(R) + Rh1(R).

Determination of hexanal in rice using an automated dynamic headspace sampler coupled to a gas chromatograph-mass spectrometer.

The aim of this study was to establish a method for the determination of hexanal as a lipid oxidation marker in rice. For the sample preparation, ground rice exhibited better sensitivity and reproducibility for the analysis of hexanal than whole rice. A total flow of purge gas of 300 mL at 20 mL/min of purge was sufficient to obtain the necessary sensitivity for the analysis of hexanal in rice. The total time for sample preparation and analysis for individual samples was approximately 15 min. A low incubation temperature of 30°C was chosen, not only to reduce the effect of water, but also to avoid excess lipid oxidation and loss of hexanal during the analysis. The limits of detection and quantification were 3.7 and 5.1 ng/g, respectively. Good linearity was obtained in the range from 5.1-500.0 ng/g. The recoveries of hexanal in rice were greater than 97.0 and 107.0% at the spiked levels of 5 and 50 ng/g, respectively, with relative standard deviations of 3.3 and 6.1%, respectively.

Rapid method for the determination of vitamins A and E in foods using ultra-high-performance liquid chromatography.

A rapid and novel ultra-HPLC (u-HPLC) method for the determination of vitamins A (retinol) and E (alpha-, gamma-, and delta-tocopherol) in foods was validated in terms of its precision, accuracy, and linearity. The u-HPLC separation was performed on an RP C18 column (particle size 2 microm, id 2 mm, and length 75 mm), followed by fluorescence detection. The recovery of retinol was more than 84.58%; the LOD and LOQ of the u-HPLC analysis were 0.015 and 0.045 mg/kg, respectively. The intraday and interday precision was less than 9.12%. The recoveries of alpha-, gamma-, and delta-tocopherol were more than 81.37%; the LOD and the LOQ were 0.014, 0.002, and 0.001 mg/kg and 0.042, 0.005, and 0.004 mg/kg, respectively. All calibration curves had good linearity (r2 = 0.99) within the test ranges. The novel, rapid method coupled to u-HPLC can provide significant improvements in the speed, sensitivity, and resolution compared with a conventional HPLC method.

Determination of hexanal as an oxidative marker in vegetable oils using an automated dynamic headspace sampler coupled to a gas chromatograph/mass spectrometer.

An automated dynamic headspace sampler coupled to a gas chromatograph/mass spectrometer was evaluated as an oxidative marker to determine hexanal content in vegetable oils. For the effective analysis, a cooled injection system (CIS) was used to focus and to introduce the hexanal desorbed from the Tenax TA. The temperature of the CIS was maintained at -60 °C for 12 min before desorbing the hexanal. Hexanal was separated on a capillary column (DB-5, 0.25 mm × 60 m, 0.25 µm in film thickness) from 50 to 230 °C, followed by mass spectrometer-selected ion monitoring analysis at m/z 56. The instrumental response to hexanal was highly linear from 10 ng mL(-1) to 1 µg mL(-1) (r(2) = 0.9999). The relative standard deviation (RSD) of intra- and inter-day repeatability was acceptable, with values of less than 3.88 and 4.25%, respectively. The LOD and LOQ of hexanal were determined by gas chromatograph/mass spectrometer-selected ion monitoring to be 3.3 and 9.8 ng mL(-1), respectively. The acid value, peroxide value and fatty acid composition revealed a good correlation with the hexanal concentration.

Determination of elaidic and vaccenic acids in foods using GC×GC-FID and GC×GC-TOFMS.

Trans fatty acids (TFAs) are present in meat and dairy products as m ruminant animals and in vegetable fats due to partial hydrogenation. This study aimed to discriminate between natural (N-TFA) and hydrogenated trans fatty (H-TFA) acids by GC×GC-flame ionization detection (GC×GC-FID) and comprehensive GC×GC-time-of-flight mass spectrometry (GC×GC-TOFMS). The separation of two kinds of trans fats, vaccenic acid (18:1 trans-11) and elaidic acid (18:1 trans-9), was performed using GC×GC-FID and GC×GC-TOFMS. A 100 m×0.25 mm I.D.×0.2 µm (film thickness) SP-2560 (bis-cyanopropyl polysiloxane) fused capillary column (first separation dimension, 1D) was coupled to a 1.5 m×0.18 mm I.D.×0.18 µm (film thickness) RTX-5 (5% diphenyl/95% dimethyl polysiloxane) fused capillary column (second separation dimension, 2D). The RSD of the intra-day repeatability by both GC×GC-FID and GC×GC-TOFMS for elaidic and vaccenic acids was ≤9.56% and ≤9.97%, and the RSD of the inter-day repeatability was ≤8.49 and ≤9.06%, respectively. It was found that the V/E value (vaccenic acid to elaidic acid ratio) could be used to distinguish H-TFA from N-TFA and to evaluate the quality of the fatty foods.

A new strategy for basic drug extraction in aqueous medium using electrochemically enhanced solid-phase microextraction.

This work describes an electrochemically enhanced solid-phase microextraction (EE-SPME) method using a mild negative potential (-0.6 V) for the enhanced extraction of the selected basic drugs in a pure aqueous matrix and urine samples. The EE-SPME method gave a more effective extraction of drugs (primarily via electrophoresis and complementary charge interaction) compared to that obtained with SPME (without applying a potential, and which is based on passive partitioning). The EE-SPME method eliminated the need for alkalizing, derivatizing the drugs, or modifying the fiber coating before extraction. The analysis of methamphetamine (MA) and amphetamine (AM) was selected as a typical example to demonstrate in detail the advantages of EE-SPME over SPME. Based on the results obtained, 3-min extraction efficiency for both the amphetamines using EE-SPME was better than that of 30-min using SPME. The developed EE-SPME-GC method exhibited wide linear ranges (2-1000 ng mL(-1)) for both the amphetamines with R(2) larger than 0.99, and the method detection limits (MDLs) for AM and MA were 0.26 and 0.12 ng mL(-1), respectively. In addition, the EE-SPME method developed was also successfully applied to enhance the extraction of several other basic drugs (ephedrine, 3,4-methylenedioxyamphetamine (MDA), atropine, methadone, cocaine, codeine, acetylcodeine and papaverine) with preconcentration factors from 157 to 2199, indicating the potential applicability of this method in the field of forensic, clinical and pharmaceutical analysis.

Preparation and evaluation of graphene-coated solid-phase microextraction fiber.

In this paper, a novel graphene (G) based solid-phase microextraction (SPME) fiber was firstly prepared by immobilizing the synthesized G on stainless steel wire as coating. The new fiber possessed a homogeneous, porous and wrinkled surface and showed excellent thermal (over 330°C), chemical and mechanical stability, and long lifespan (over 250 extractions). The SPME performance of the G-coated fiber was evaluated in detail through extraction of six pyrethroid pesticides. Although the thickness of G-coated fiber was only 6-8 µm, its extraction efficiencies were higher than those of two commercial fibers (PDMS, 100 µm; PDMS/DVB, 65 µm). This high extraction efficiency may be mainly attributed to huge delocalized π-electron system of G, which shows strong π-stacking interaction with pyrethroid pesticide. The G-coated fiber was applied in the gas chromatographic determination of six pyrethroids, and their limits of detection were found to be ranged from 3.69 to 69.4 ng L(-1). The reproducibility for each single fiber was evaluated and the relative standard deviations (RSDs) were calculated to be in the range from 1.9% to 6.5%. The repeatability of fiber-to-fiber and batch-to-batch was 4.3-9.2% and 4.1-9.9%. The method developed was successfully applied to three pond water samples, and the recoveries were 83-110% at a spiking of 1 µg L(-1).

An electrochemically enhanced solid-phase microextraction approach based on a multi-walled carbon nanotubes/Nafion composite coating.

In this paper, we proposed an approach using a multi-walled carbon nanotubes (MWCNTs)/Nafion composite coating as a working electrode for the electrochemically enhanced solid-phase microextraction (EE-SPME) of charged compounds. Suitable negative and positive potentials were applied to enhance the extraction of cationic (protonated amines) and anionic compounds (deprotonated carboxylic acids) in aqueous solutions, respectively. Compared to the direct SPME mode (DI-SPME) (without applying potential), the EE-SPME presented more effective and selective extraction of charged analytes primarily via electrophoresis and complementary charge interaction. The experimental parameters relating to extraction efficiency of the EE-SPME such as applied potentials, extraction time, ionic strength, sample pH were studied and optimized. The linear dynamic range of developed EE-SPME-GC for the selected amines spanned three orders of magnitude (0.005-1mugmL(-1)) with R(2) larger than 0.9933, and the limits of detection were in the range of 0.048-0.070ngmL(-1). All of these characteristics demonstrate that the proposed MWCNTs/Nafion EE-SPME is an efficient, flexible and versatile sampling and extraction tool which is ideally suited for use with chromatographic methods.