The objective of this study was to assess the effects of ultrasonic assisted cooking on the chemical profiles of spiced beef taste and flavor. Ultrasound power with 0 W, 400 W, 600 W, 800 W and 1000 W (frequency of 20 kHz) were used for cooking 120 min. The sodium chloride, sugar, free amino acids (FAAs), 5'-ribonucleotides, lipid oxidation, volatile flavor substance contents and electronic nose of spiced beef were determined. Results showed that ultrasonic treatment could significantly increase the content of sodium chloride in beef sample (P < 0.05). When the ultrasonic power lower than 1000 W, the content of sugar and 5'-ribonucleotides could be increased significantly compared with the control (P < 0.05). The essential amino acid content and the essential amino acid/non-essential ratios (E/NE) were significantly increased with the ultrasound treatment (P < 0.05). The lipid oxidation showed that ultrasound resulted in the increased of TBARS values compared with control significantly (P < 0.05), but no significant differences were shown among the different ultrasonic power groups (P > 0.05). With the ultrasonic treatment, the types and relative content of volatile flavor substances were significantly increased (P < 0.05), especially for aldehydes, alcohols and ketones. However, there was no significant variation among the different ultrasound power groups (P > 0.05). This result was consistent with the measurement of electronic nose. Data points of control samples were away from ultrasonic treatment groups, while data points of different ultrasonic treatment groups were flock together. The results indicate that the application of ultrasound during cooking has a positive effect on chemical profiles of spiced beef taste and flavor, particularly for the power of 800 W.

The traditional recipe for Chinese chicken soup creates a popular taste of particular umami and aroma. The present study investigated the effects of stewing time (1, 2, and 3 h) on the principal taste-active and volatile compounds and the overall flavor profile of traditional Chinese chicken soup by measuring the contents of free amino acids (FAAs), 5'-nucleotides, minerals and volatile compounds and by evaluating the taste and aroma profiles using an electronic nose, an electronic tongue and a human panel. Results showed that the major umami-related compounds in the chicken soup were inosine 5'-monophosphate (IMP) and chloride, both of which increased significantly (P < 0.05) during stewing. The taste active values (TAVs) of the equivalent umami concentration (EUC) increased from 4.08 to 9.93 (P < 0.05) after stewing for 3 h. Although the FAA and mineral contents increased significantly (P < 0.05), their TAVs were less than 1. The volatile compounds were mainly hexanal, heptanal, octanal, nonanal, (E)-2-nonanal, (E)-2-decenal, (E,E)-2,4-decadienal, 1-hexanol, and 2-pentyl furan. With the prolonged stewing time, the aldehydes first increased and then decreased significantly (P < 0.05), while 1-hexanol and 2-pentyl furan increased steadily (P < 0.05). The aroma scores of the chicken soup reached the maximum after stewing for 3 h. The discrepancy in overall flavor characteristics tended to stabilize after 2 h of stewing. In general, stewing time has a positive effect on improving the flavor profiles of chicken soup, especially within the first 2 h.

M. Failure of the Ipsogen MutaScreen kit to detect the JAK2 617VϾF mutation in samples with additional rare exon 14 mutations: implications for clinical testing and report of a novel 618CϾF mutation in addition to 617VϾF [letter]. Blood. 2010;115(15) To the editor: Beta 2 glycoprotein I is a substrate of thiol oxidoreductasesBeta 2 glycoprotein I (␤2GPI) is an abundant plasma protein recognized as the major autoantigen in the antiphospholipid syndrome. Although the crystal structure of ␤2GPI has been resolved, 1,2 its normal function remains unknown. We have been intrigued by the presence of a C-terminal cysteine (Cys326), which forms a loop-back disulfide link in the fifth domain of ␤2GPI. In the current study we examined ␤2GPI's potential to participate in thiol exchange reactions with the thiol oxidoreductases thioredoxin-1 (TRX-1) and protein disulfide isomerase (PDI). The incorporation of free thiols into ␤2GPI after reaction with TRX-1 or PDI was shown by labeling the products of this reaction with the selective sulfhydryl probe N a -(3-maleimidylpropionyl) biocytin (MPB). The biotinylated proteins were visualized by Western blotting with streptavidin-horseradish peroxidase. Because ␤2GPI does not contain unpaired cysteines, no labeling was observed after incubation with MPB ( Figure 1A). Free thiols could not be introduced into ␤2GPI by incubation with the reducing agent dithiothreitol (DTT) alone. However, free thiols could be introduced into ␤2GPI after incubation with the reduced forms of the thiol oxidoreductases TRX-1 and PDI, identifying ␤2GPI as a thiol oxidoreductase substrate ( Figure 1A-C). An interesting effect caused by the reduction of ␤2GPI by TRX-1 was a marked decrease in the affinity of anti-␤2GPI monoclonal and polyclonal antibodies as noted on the immunoblots.To determine the cysteine residue(s) in the ␤2GPI molecule involved in thiol exchange reactions, ␤2GPI treated with the TRX-1/TRX-1 reductase/NADPH system and labeled with MPB was resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE; Figure 1B). Gel bands were excised, digested, and analyzed by liquid chromatography-tandem mass spectrometry. Mass spectral data were searched using Mascot (Version 2.2; Matrix Science) or converted to MzXML file format using ReAdW (Version 4.0.2) 3 and submitted to the database search program X!Tandem (Release 2008.12.01). 4 The analysis revealed Cys326 to be predominantly labeled with biotin (F.H.P., S.R., M.Q., M.J.R., J.W.H.W., K.T., Y.I., J.Y.Z., R.G., J.C.Q., B.G., W.E.H., P.J.H., S.A.K., manuscript submitted). The structural features of the disulfide bond containing Cys326 and all disulfide bonds of the 2 structures of ␤2GPI (PDB 1C1Z and 1QUB) were determined using the disulfide bond analysis tool available at www.cancerresearch.unsw.edu.au/CRCWeb. nsf/page/DisulfideϩBondϩAnalysis. 5 The analysis showed that the Cys288-Cys326 disulfide is a Ϫ/ϩ right-handed hook (Ϫ/ϩRHHook) configuration in both crystal structures of the protein. 1,2 Although there is no other structu...

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Effects of stewing time (1, 2, and 3 h) on the levels of taste-active and volatile compounds were measured. The flavor characteristics of the stewed yellow-feather chicken meat were assessed with sensory evaluation and electronic nose. Results showed that increasing stewing time significantly decreased the contents of taste components such as free amino acids, 5′-nucleotides, minerals. Inosine 5′-monophosphate and chloride were the major umami-related compounds in stewed meat and decreased significantly during stewing. The taste-active values of the equivalent umami concentration decreased from 283.2 to 38.7 after 3 h of stewing. In contrast, increasing stewing time improved aroma levels. The volatile compounds mainly included pentanal, hexanal, heptanal, octanal, (E)-2-octenal, nonanal, (Z)-4-decenal, decanal, (E,E)-2,4-decadienal, 1-pentanol, and 1-octen-3-ol. With increased stewing time, aldehydes significantly decreased (P < 0.05), whereas alcohols significantly increased (P < 0.05). The high-intensity aroma after 2 h of stewing could be attributed to 1-pentanol and 1-octen-3-ol. The aroma scores of the chicken meat were at maximum after stewing for 3 h. The overall flavor characteristics tended to stabilize after 2 h of stewing. In general, stewing improved the aroma but decreased the taste components in the chicken meat, especially within the first 2 h. The data herein not only provides insight into the changes in odor and taste of chicken meat during cooking, but also guidelines for improving the stewing process.ARTICLE HISTORY

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Summary Three classes (normal, PSE‐like and woody, thirty for per class) of fresh chicken breast meats were selected from a Chinese processing plant. Then, three classes of chicken breast meats were used to prepare meat batters and meatballs. This study investigated the effects of three classes of chicken breast meat on the physicochemical properties, water distribution, protein secondary structures and microstructures of meatballs. PSE‐like and woody meatballs both had lower water holding capacity and textural properties than normal meatballs. Furthermore, the free water mobility and proportion in PSE‐like and woody meatballs were increased (P < 0.05). According to near‐infrared spectroscopy results, the intensity of the 1940‐nm bands of PSE‐like and woody classes both increased. Both PSE‐like and woody meatballs formed more aggregated gel matrices than normal class. PSE‐like and woody classes had higher α‐helix and lower β‐structure contents (P < 0.05). Overall, compared with normal meatballs, PSE‐like and woody meatballs showed inferior functional properties.