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Changes in microbial diversity and volatile metabolites during the fermentation of Bulang pickled tea

Zhou J, Chen L, Foo HL, Cao Z, Lin Q

Food Chem, 2024 Nov 15;458:140293.
PMID: 38970959 DOI: 10.1016/j.foodchem.2024.140293

The present study aimed to determine microbial community, short-chain fatty acids (SCFAs), and volatilome of Bulang pickled tea during fermentation. Sequencing of 16S rRNA and ITS revealed that Bualng pickled tea was dominated by Lactobacillus plantarum, unclassified Enterobacteriaceae, unclassified Debaryomyces, Candida metapsilosis, Cladosporium sphaerospermum, and unclassified Aspergillus. The overall contents of SCFAs increased, with acetic acid showing the highest content. A total of 398 differential volatile metabolites were detected using differential metabolomics analysis. Out of these different volatile compounds, ten key volatile compounds including (Z)-4-heptenal, 1-(2-thienyl)-ethanone, 5-methyl-(E)-2-hepten-4-one, 2-ethoxy-3-methylpyrazine, p-cresol, 2-methoxy-phenol, ethy-4-methylvalerate, 3-ethyl-phenol, p-menthene-8-thiol, and 2-s-butyl-3-methoxypyrazinewere were screened based on odor activity value (OAV). The Spearman correlation analysis showed a high correlation of SCFAs and volatile compounds with microorganisms, especially L. plantarum and C. sphaerospermum. This study provided a theoretical basis for elucidating the flavor quality formation mechanism of Bulang pickled tea.

Matched MeSH terms: Odors/analysis
Headspace solid-phase microextraction gas chromatography-mass spectrometry determination of volatile compounds in different varieties of African star apple fruit (Chrysophillum albidum)

Lasekan O, Khatib A, Juhari H, Patiram P, Lasekan S

Food Chem, 2013 Dec 1;141(3):2089-97.
PMID: 23870932 DOI: 10.1016/j.foodchem.2013.05.081

The volatile compounds in four selected African star apple fruit (Chrysophyllum albidum) varieties were isolated and identified using the headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). A total of 59 compounds were identified. Application of the aroma extract dilution analysis (AEDA) to the aroma distillates from the fruits revealed 45 odour-active compounds in the flavour dilution (FD) factor range of 4-128. Among them, the highest odour activities (FD factors) were determined for methylhexanoate, acetophenone and ethyl dodecanoate. Moreover, aroma lipophilicity appears to reflect molecular conformation. Further analysis of the similarities and differences between the fruit varieties in terms of the key odourants by the application of PLS-DA and PLS-regression coefficient showed strong positive correlation between the very sweet/sweet varieties and 10 key odourants. The odourants included ethyl acetate, acetyl methyl carbinol, methylhexanoate, sabinene, p-cymene, methylbenzoate, ethylbenzoate, geraniol, cis-α-bergomotene, acetophenone, and ethyl dodecanoate.

Matched MeSH terms: Odors/analysis
Fulltext In-vitro diagnosis of single and poly microbial species targeted for diabetic foot infection using e-nose technology

Yusuf N, Zakaria A, Omar MI, Shakaff AY, Masnan MJ, Kamarudin LM, et al.

BMC Bioinformatics, 2015;16:158.
PMID: 25971258 DOI: 10.1186/s12859-015-0601-5

Effective management of patients with diabetic foot infection is a crucial concern. A delay in prescribing appropriate antimicrobial agent can lead to amputation or life threatening complications. Thus, this electronic nose (e-nose) technique will provide a diagnostic tool that will allow for rapid and accurate identification of a pathogen.

Matched MeSH terms: Odors/analysis*
Fulltext Changes in Physicochemical Properties and Volatile Compounds of Roselle (Hibiscus sabdariffa L.) Calyx during Different Drying Methods

Juhari NH, Martens HJ, Petersen MA

Molecules, 2021 Oct 16;26(20).
PMID: 34684840 DOI: 10.3390/molecules26206260

Fresh roselle are high in moisture and deteriorate easily, which makes drying important for extending shelf-life and increasing availability. This study investigated the influence of different drying methods (oven-drying, freeze-drying, vacuum-drying, and sun-drying) on the quality of roselle calyx expressed as physicochemical properties (moisture content, water activity, soluble solids, color), volatile compounds, and microstructure. Oven-drying and freeze-drying reduced moisture content most while vacuum-drying and sun-drying were not as efficient. All drying methods except sun-drying resulted in water activities low enough to ensure safety and quality. Vacuum-drying had no impact on color of the dry calyx and only small impact on color of water extract of calyx. Drying reduced terpenes, aldehydes, and esters but increased furans. This is expected to reduce fruity, floral, spicy, and green odors and increase caramel-like aroma. Sun-drying produced more ketones, alcohols, and esters. Scanning electron microscopy revealed that freeze-drying preserved the cell structure better, and freeze-dried samples resembled fresh samples most compared to other drying techniques. The study concludes that freeze-drying should be considered as a suitable drying method, especially with respect to preservation of structure.

Matched MeSH terms: Odors/analysis*
Mimicking the biological olfactory system: a Portable electronic Mucosa

Che Harun FK, Covington JA, Gardner JW

IET Nanobiotechnol, 2012 Jun;6(2):45-51.
PMID: 22559706 DOI: 10.1049/iet-nbt.2010.0032

In this study the authors report on the development of a new type of electronic nose (e-nose) instrument, which the authors refer to as the Portable electronic Mucosa (PeM) as a continuation of previous research. It is designed to mimic the human nose by taking significant biological features and replicating them electronically. The term electronic mucosa or simply e-mucosa was used because our e-nose emulates the nasal chromatographic effect discovered in the olfactory epithelium, located within the upper turbinate. The e-mucosa generates spatio-temporal information that the authors believe could lead to improved odour discrimination. The PeM comprises three large sensor arrays each containing a total of 576 sensors, with 24 different coatings, to increase the odour selectivity. The nasal chromatographic effect provides temporal information in the human olfactory system, and is mimicked here using two-coated retentive channels. These channels are coated with polar and non-polar compounds to enhance the selectivity of the instrument. Thus, for an unknown sample, the authors have both the spatial information (as with a traditional e-nose) and the temporal information. The authors believe that this PeM may offer a way forward in developing a new range of low-cost e-noses with superior odour specificity.

Matched MeSH terms: Odors/analysis*
Efficacy and role of inulin in mitigation of enteric sulfur-containing odor in pigs

Deng YF, Liu YY, Zhang YT, Wang Y, Liang JB, Tufarelli V, et al.

J Sci Food Agric, 2017 Jun;97(8):2382-2391.
PMID: 27664398 DOI: 10.1002/jsfa.8050

BACKGROUND: The efficacy and role of inulin in the mitigation of enteric sulfur-containing odor gases hydrogen sulfide (H2 S) and methyl mercaptan (CH3 SH) in pigs were examined in this study. Twelve Duroc × Landrace × Yorkshire male finisher pigs (60.7 ± 1.9 kg), housed individually in open-circuit respiration chambers, were randomly assigned to two dietary groups, namely basal diet (control) and basal diet supplemented with 1% (w/w) inulin. At the end of the 45 day experiment, pigs were slaughtered and volatile fatty acid (VFA) concentration, sulfate radical (SO42- ) concentration, population of sulfate-reducing bacteria (SRB) and expression of methionine gamma-lyase (MGL) gene were determined in contents from the caecum, colon (two segments) and rectum. Metabonomic analysis was used to compare differences in biochemical composition, and the Illumina MiSeq procedure to investigate differences in bacterial components, in the different parts of the large intestine between inulin-supplemented and inulin-free (control) groups.
RESULTS: Inulin decreased (P < 0.05) the average daily enteric H2 S and CH3 SH production by 12.4 and 12.1% respectively. The concentrations of acetate, propionate and butyrate in the large intestinal content were significantly increased (P < 0.05) with inulin treatment, whereas valerate concentration and MGL mRNA expression decreased (P < 0.05). The growth of Lactobacillus, Butyrivibrio, Pseudobutyrivibrio, Bifidobacterium and Clostridium butyricum was stimulated, while that of Desulfovibrio, the dominant SRB, was inhibited, and there was an accumulation of SO42- in the large intestinal content of the inulin-supplemented pigs, suggesting that inulin mitigates H2 S generation from the SO42- reduction pathway by reducing the growth of SRB.
CONCLUSION: The results showed that inulin mitigates CH3 SH generation via three methionine degradation metabolic pathways and H2 S generation from two cysteine degradation metabolic pathways, thus resulting in increased synthesis of these two sulfur-containing amino acids in the pig large intestine. © 2016 Society of Chemical Industry.

Matched MeSH terms: Odors/analysis*