Jianchun Xie

PREPARATIVE SEPARATION AND PURIFICATION OF ALKYLAMIDES FROM ZANTHOXYLUM BUNGEANUM MAXIM BY HIGH-SPEED COUNTER-CURRENT CHROMATOGRAPHY

High-speed counter-current chromatography (HSCCC) was successfully applied to preparative isolation and purification of alkylamides, the tingling-taste components, from pericarp extract of Zanthoxylum bungeanum Maxim (Dahongpao). With the lower phase of n-hexane-ethyl acetate-methanol-water (7:3:5:5, v/v) eluted at a flow rate of 1.5 mL · min−1, and the revolution speed at 850 rpm, 0.19 g of alkylamides in purity of 98.0% by the relative peak area of HPLC was obtained from 1.0 g of extract in one run within 2 hr. On the basis of MS, IR, and 1H NMR analysis, the product of alkylamides was confirmed to be composed of hydroxy-α -sanshool, hydroxy-β-sanshool, and hydroxy-ϵ-sanshool. Furthermore, using the HSCCC product as external standard, alkylamide in the extract was determined to be in total of 21.41%, among which hydroxy-α-sanshool, hydroxy-β-sanshool, and hydroxy-ϵ-sanshool were in 15.69%, 4.76%, and 0.96%, respectively.

Preparative Separation and Purification of β-Caryophyllene from Leaf Oil of Vitex negundo L. var. heterophylla (Franch.) Rehd. by High Speed Countercurrent Chromatography

Abstract High speed countercurrent chromatography (HSCCC) coupled with an evaporative light scatter detector (ELSD) was successfully applied to preparative isolation and purification of β-caryophyllene from essential oil of Vetix negundo L. var. heterophylla (Franch.) Rehd. Using either n-hexane-chloroform-acetonitrile (6:2:5) or n-hexane-dichloromethane-acetonitrile (10:3:7) as the two-phase solvent system, β-caryophyllene was separated in one run from the crude essential oil by HSCCC. However, the application of n-hexane-dichloromethane-acetonitrile (10:3:7) resulted in a higher purity and recovery of β-caryophyllene. About 85 mg of β-caryophyllene representing 97.3% by GC, was yielded from 600 mg crude essential oil when eluted with the lower phase at a flow rate of 1.5 mL.min−1.

Aromatic constituents from chinese traditional smoke-cured bacon of mini-pig

Volatile composition of Chinese traditional smoke-cured bacon of Mini-pig breed was first characterized. Both headspace solid phase microextraction (SPME) and simultaneous distillation and solvent extraction (SDE) were performed. SDE exhibited efficiency in the extraction of representative aromatic volatiles especially the phenolic smoky flavors from the bacon sample. In total, 104 different components were found with the major quantity and kinds of aromas being the volatile saturated and unsaturated aldehydes from lipid oxidation and the phenolic compounds from smoke. Olfactory evaluation (GC-O) of the SDE extract revealed five basic odor patterns pertaining to 53 odor active regions and 47 odorants. Some key flavors accounting for the bacon aroma were (E, E)-2, 4-decadienal, 3-(methylthio) propanal, 2-furanmethanol, guaiacol, 3-ethylphenol and 2, 5-dimethylpyrazine.

Volatile flavor constituents in the pork broth of black-pig

Pork of black-pig in China is well known for its quality and preferred by consumers. However, there is a lack of research on its flavors. By solvent assisted flavor evaporation combined with GC-MS, 104 volatile compounds in the stewed pork broth of black-pig were identified with the dominant amounts of fatty acids, alcohols, and esters. By aroma extract dilution analysis-GC-O method, 27 odor-active compounds were characterized, including 2-methyl-3-furanthiol, 3-(methylthio)propanal, 2-furfurylthiol, γ-decalactone, nonanal, (E)-2-nonenal, and (E,E)-2,4-decadienal that had high FD factors. Compared to the common white-pig, the aroma compounds in both pork broths were almost the same, but the aroma profile of potent odorants for the black-pig pork broth showed less fatty and more roasted notes, which were partially attributed to the higher monounsaturated fatty acids and lower polyunsaturated fatty acids in meat. With aid of authentic chemicals and selected reaction monitoring mode of GC-MS/MS, 19 aroma compounds were quantitated.

Roles of different initial Maillard intermediates and pathways in meat flavor formation for cysteine-xylose-glycine model reaction systems

To explore initial Maillard reaction pathways and mechanisms for maximal formation of meaty flavors in heated cysteine-xylose-glycine systems, model reactions with synthesized initial Maillard intermediates, Gly-Amadori, TTCA (2-threityl-thiazolidine-4-carboxylic acids) and Cys-Amadori, were investigated. Relative relativities were characterized by spectrophotometrically monitoring the development of colorless degradation intermediates and browning reaction products. Aroma compounds formed were determined by solid-phase microextraction combined with GC-MS and GC-olfactometry. Gly-Amadori showed the fastest reaction followed by Cys-Amadori then TTCA. Free glycine accelerated reaction of TTCA, whereas cysteine inhibited that of Gly-Amadori due to association forming relatively stable thiazolidines. Cys-Amadori/Gly had the highest reactivity in development of both meaty flavors and brown products. TTCA/Gly favored yielding meaty flavors, whereas Gly-Amadori/Cys favored generation of brown products. Conclusively, initial formation of TTCA and pathway involving TTCA with glycine were more applicable to efficiently produce processed-meat flavorings in a cysteine-xylose-glycine system.

Effect of glycine on reaction of cysteine-xylose: Insights on initial Maillard stage intermediates to develop meat flavor

The meat-like reactions of l-cysteine and d-(+)-xylose with or without glycine were investigated. LC-MS was used to quantitatively determine the initial stage intermediates including 2-threityl-thiazolidine-4-carboxylic acid, Cys-Amadori, and Gly-Amadori in the reaction mixtures. The results showed that the addition of glycine was only in positive correlation with the browning feature of cyseine-xylose reaction. When excessive glycine was added, a high browning rate would be achieved, but it did not benefit the formation of meaty compounds. For a complex meat-like reaction system containing cysteine, reducing sugars and glycine, to overcome the low rate of reaction, and particularly, to minimize the inhibitive effect of cysteine in the generation of meaty flavors, selection of an appropriate ratio between cysteine and glycine is important in an effort to make amounts of the intermediates of Cys-Amadori and Gly-Amadori approximately equally consist in the reaction mixture.

Meat flavor generation from different composition patterns of initial Maillard stage intermediates formed in heated cysteine-xylose-glycine reaction systems

Volatile compounds formed in model reactions involving synthesized initial Maillard intermediates Gly-Amadori and [13C5]-2-threityl-thiazolidine-4-carboxylic acids ([13C5]-TTCA) in different molar ratios and free cysteine and glycine were investigated by solid-phase microextraction/gas chromatography-mass spectrometry and gas chromatography-olfactometry. The 1:1 ratio composition pattern provided the highest yields of all the sulfur-containing compounds, the potent meaty flavors or their 13C-labeled/unlabeled fractions, indicating a moderate level of glycine relative to cysteine was optimum for maximally yielding meaty flavors in complex meat-like Maillard systems containing cysteine as well as glycine. In addition, the 1:1 ratio composition led to formation of 13C-labeled molecules of some key meaty flavors e.g. 2-furanthiol representing over 70%, indicating TTCA/glycine reaction was better than Gly-Amadori/cysteine to yield meaty flavors. Formation pathways of twenty-nine flavors were elucidated based on the detected isotope distribution patterns. In particular, 2-methyltetrahydrothiophen-3-one, 3-thiophenethiol, 2-ethylthiophene, 2,5-dimethylthiophene, and 5-methylthiophene-2-carboxaldehyde involved a new formation pathway. Thiophene-2-carboxaldehyde and 2-methylthieno[3,2-b]thiophene showed two formation pathways.

Formation mechanism of aroma compounds in a glutathione-glucose reaction with fat or oxidized fat

Glutathione and glucose with or without chicken fat/oxidized chicken fat were thermally reacted for generation of stewed meat-like aroma, where 42 sulfur-containing odorants were identified by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). The observed effects or interactions on meat flavor formation due to the fats were similar to previous reports of cysteine-reducing sugar reactions. Carbohydrate module labeling approach demonstrated ten alkyl chain compounds were indeed resulted from the lipid degradation-Maillard reaction interactions, whereas the fats had little effect on formation pathways of compounds only derived from the Maillard reaction. Formation pathways of 26 potent aroma compounds were proposed, particularly, involving two benzene derivatives and seven complex thiophenes. Notably, it was found for the first time just 2-ethylthiophene could result from both an intact skeleton of glucose and the lipid degradation product of 2,4-hexadienal, and the carbohydrate modules methylglyoxal and hydroxyacetone could arise from the glutamic acid of GSH.

Rapid and sensitive detection of acrylamide in fried food using dispersive solid-phase extraction combined with surface-enhanced Raman spectroscopy

A rapid, reliable, and quantitative method to determine acrylamide content in fried food based on surface-enhanced Raman spectroscopy (SERS) by re-oxidized graphene oxide/Au nanoparticle composites and dispersive solid-phase extraction has been proposed. The peak at △v = 1478 cm-1 was selected as the characteristic peak of acrylamide for quantitation. Sufficient linearity was obtained in the concentration range of 5-100 μg·kg-1 (R2 = 0.983). The limits of detection and quantification in fried food were 2 and 5 μg·kg-1, respectively. The recovery rates for acrylamide were 73.4-92.8% with coefficients of variation less than 4.2%, and the long-term stability of the substrates was approximately 180 days at 4 °C. The results of detection using the proposed method were consistent with those obtained by LC-MS/MS, while the measurement time was reduced to 9.5 min per sample. The study also demonstrates that this method can potentially be used for acrylamide detection in the field.

Aroma Compounds in Chicken Broths of Beijing Youji and Commercial Broilers

The unique flavor of Beijing Youji (BJY) chicken broth compared with that of commercial broilers (CB) was investigated by solvent-assisted flavor evaporation combined with AEDA/GC-O (aroma extract dilution analysis of gas chromatography-olfactometry), quantitation, and aroma recombination. A total of 71 odorants with almost the same major odorants (≥10 ng/g broth) were found by GC-O in both BJY and CB broths. However, BJY broth had thirty-two more extra odorants than CB broth, indicating the rich fragrance of the former. Aroma recombination and omission experiments demonstrated that 21 versus 17 odorants (with OAV ≥ 1) contributed significantly to BJY and CB broth aromas, respectively. Those key odorants mainly included sulfur-containing compounds and aliphatic aldehydes, such as 2-methyl-3-furanthiol, 3-(methylthio)propanal, ( E, E)-2,4-decadienal, etc. Furthermore, composition analysis of the meat suggested that the better flavor, with rather more odorants, of BJY broth is probably due to higher contents of polyunsaturated fatty acids and water-soluble flavor precursor, including ribose, cysteine, thiamine, etc., present in the BJY meat.