Characterization of Key Odorants in Scallion Pancake and Investigation on Their Changes during Storage

To characterize key odorants in scallion pancake (SP), volatiles were extracted by solvent extraction-solvent assisted flavor evaporation. A total of 51 odor-active compounds were identified by gas chromatography-olfactometry (GC-O) and chromatography–mass spectrometry (GC-MS). (Z/E)-3,6-Diethyl-1,2,4,5-tetrathiane was detected for the first time in scallion food. Application of aroma extract dilution analysis to extracts showed maltol, methyl propyl disulfide, dipropyl disulfide and 2-pentylfuran had the highest flavor dilution (FD) factor of 4096. Twenty-three odorants with FD factors ≥ 8 were quantitated, and their odor active values (OAVs) were calculated. Ten compounds with OAVs ≥ 1 were determined as the key odorants; a recombinate model prepared from the key odorants, including (E,E)-2,4-decadienal, dimethyl trisulfide, methyl propyl disulfide, hexanal, dipropyl trisulfide, maltol, acetoin, 2-methylnaphthalene, 2-pentylfuran and 2(5H)-furanone, successfully simulated the overall aroma profile of SP. The changes in odorants during storage were investigated further. With increasing concentrations and OAVs during storage, hexanal became an off-flavor compound.

Galactooligosaccharides and Xylo-oligosaccharides Altering the Caecal Microbiome, Metabolome, and Transcriptome of Chickens Revealed by a Multi-Omics Analysis

Backgroud Studies have shown that prebiotics could affect meat quality, but the underlying mechanism are poorly understood. This study aimed to investigate whether prebiotics affect chicken’s meat quality through gut microbiome and metabolome. Methods The gut content were collected from chickens fed with or without prebiotics (galactooligosaccharides or xylo-oligosaccharides) and subjected to microbiome and metabolome analyses, and chicken breast was performed transcriptome sequencing. Results The prebiotics altered proportions of microbiota in gut contents at different levels, especially microbiota in the phylum of Bacteroidetes and Firmicutes, such as genus of Alistipes, Bacteroides, and Faecalibacterium. The prebiotics also altered contents of caecal metabolites such as lysophosphatidylcholine (lysoPC), intramuscular fat and flavor compound (Benzaldehyde and myristic acid). Differentially expressed genes (DEGs) induced by prebiotics were significantly involved in regulation of lipolysis inadipocytes and adipocytokine signaling pathway. Changes in gut microbiota and metabolites were remarkably correlated such as Bacteroidetes and Firmicutes was respectively positively and negatively correlated with lysoPC. DEGs were also interacted with caecal metabolites. Conclusion These findings integrated and incorporated link among gut microbiota, metabolites and transcriptome, which proposed prebiotics may affect meat quality and flavor of chickens.

Isolation and characterization of yeast for the production of rice wine with low fusel alcohol content

Fusel alcohols (FAs) are a type of flavor compound found in rice wine. An overly high FA content not only leads to spicy, bitter, and astringent taste but also has side effects. Therefore, screening for yeast that produce low FA contents has attracted much attention. Thirty-two yeast strains were isolated from fermenting material during Luzhou-flavor liquor production in this study. Strain YB-12 was selected as a suitable candidate for rice wine production. The strain was identified as a member of the genus Meyerozyma based on phylogenetic analysis using 26S rDNA gene sequences. The ability of strain YB-12 to produce ethanol was similar to that of Saccharomyces cerevisiae NRRL Y-567, while isobutanol and isoamyl alcohol production was only 53.96% and 50.23%, respectively, of that of NRRL Y-567. The FA yield of rice wine produced with strain YB-12 was reduced to 51.85% in a 20 L fermenter. These results demonstrate that strain YB-12 presents promising characteristics for use in the production of rice wine with a potentially low content of FAs.

Data Statistics in Volatile Analysis by Accurate HS-SPME-GC/MS Measurement and Calculation

The volatile flavor compound in oil is an important indicator of quality which is widely used in the industry to assess the commercial value of oil. The volatile compounds of moringa seed oil were investigated by HS-SPME-GC/MS. The results showed that 52 volatile compounds were identified in moringa seed oil, including 12 hydrocarbons (20.66%),3 acids (23.99%),8 alcohols (8.28%),2 esters (2.61%),8 aldehydes (14.58%),2 ketones (0.82%),7 phenols (6.25%) and 10 heterocyclics (8.74%). Due to the low sensory threshold and high relatively content of aldehydes, aldehydes is one of the mainly factors to affect the flavor of moringa seed oil.

Evaluation of Roasting Effect on Selected Green Tea Volatile Flavor Compound and Pyrazine Content by HS-SPME GC-MS

The present study aims at the development and validation of a quali-quantitative headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME GC-MS) method for the analysis of odorants in different Chinese and Japanese green teas. A 65 µm PDMS/DVB fiber was used, and GC-MS was performed on a ZB-5 (30 m × 0.25 mm ID, 0.25 μm film) column. The main odorants in green tea samples were identified and the method was fully validated. Linearity (r2 0.981–0.999), sensitivity (LOQ 0.005–0.04 µg/mL), reproducibility (CV% 3.12–10.37), accuracy (recovery% 79.08–99.17) and matrix effect (ME% −9.5 to +4.5) were determined. Quantitation of 2,4-heptadienal, β-damascenone, β-ionone, linalool, indole, 2-ethyl-6-methyl-pyrazine, 2-ethyl-5-methyl-pyrazine, 2-ethyl-3,6-dimethylpirazine, 2-ethyl-3,5-dimethyl-pyrazine and 2-acetyl-pyrazine was carried out in the presence of isotopically labeled compounds as the internal standards. The proposed method was applied to the comparison of the profile of the volatile flavor compounds (VFCs) of green tea subjected to roasting treatment at three different temperatures (160, 180 and 200 °C for 30 min). In particular, the roasting process was monitored by following the quantitative variations of the selected odorant content, considered as the most important contributory components to the Hojicha or black tea (roasted tea) flavor. A temperature of 160 °C was found to be the best roasting temperature.

Volatile Flavor Compounds Composition of Steamed Marble Goby (Oxyeleotris marmorata)

The identification and composition of volatile flavor compounds was carried out for steamed marble goby (Oxyeleotris marmorata). This study was carried out in Fishery Processing Laboratory at Faculty of Fishery and Marine Science, Universitas Padjadjaran, Jatinangor; Flavor Laboratory, Indonesian Center of Rice Research, Sukamandi, Subang; Inter-University Center Laboratory of Bogor Agricultural Institute. The study were carried out on steamed marble goby (at 100oC, for period of ±30 minutes). The Solid Phase Microextraction (SPME) method was used to extract volatile flavor compound and identified by using Gas Chromatography-Mass Spectrometry (GC / MS). Steamed marble goby has 27 compounds. The major volatile compound in steamed marble goby is naphthalene. Proximate analysis shows that steamed marble goby has 79.70% water content, 1.48% ash, 0.36% lipid, and 16.65% protein.