1.Quantitative analysis of fragrance and odorants released from fresh and decaying strawberries.
Kim YH1, Kim KH, Szulejko JE, Parker D. Sensors (Basel). 2013 Jun 20;13(6):7939-78. doi: 10.3390/s130607939.
The classes and concentrations of volatile organic compounds (VOC) released from fresh and decaying strawberries were investigated and compared. In this study, a total of 147 strawberry volatiles were quantified before and after nine days of storage to explore differences in the aroma profile between fresh strawberries (storage days (SRD) of 0, 1, and 3) and those that had started to decay (SRD = 6 and 9). In terms of concentration, seven compounds dominated the aroma profile of fresh strawberries (relative composition (RC) up to 97.4% by mass, sum concentration): (1) ethyl acetate = 518 mg∙m⁻³, (2) methyl acetate = 239 mg∙m⁻³, (3) ethyl butyrate = 13.5 mg∙m⁻³, (4) methyl butyrate = 11.1 mg∙m⁻³, (5) acetaldehyde = 24.9 mg∙m⁻³, (6) acetic acid = 15.2 mg∙m⁻³, and (7) acetone = 13.9 mg∙m⁻³. In contrast, two alcohols dominated the aroma profile of decayed samples (RC up to 98.6%): (1) ethyl alcohol = 94.2 mg∙m⁻³ and (2) isobutyl alcohol = 289 mg∙m⁻³.
2.Main odorants in Jura flor-sherry wines. Relative contributions of sotolon, abhexon, and theaspirane-derived compounds.
Collin S1, Nizet S, Claeys Bouuaert T, Despatures PM. J Agric Food Chem. 2012 Jan 11;60(1):380-7. doi: 10.1021/jf203832c. Epub 2011 Dec 12.
The aromatic profile of Jura flor-sherry wines (also called "yellow wines") has been little studied. Only acetaldehyde, diethoxy-1,1-ethane, and sotolon have been described as key odorants. In the present work, three wines (vintages 2002 and 2003) were investigated by gas chromatography-mass spectrometry and gas chromatography-olfactometry (GC-O) aroma extract dilution analysis. The goal was to assess the relative impact of varietal, fermentation, and oak-barrel compounds by using two complementary extraction procedures. No grape terpenoids were found after the long barrel aging (6 years and 3 months). On the other hand, two candy/fruity esters issued from yeast exhibited high flavor dilution factor (FD) values: ethyl isobutyrate (64-1024) and ethyl isovalerate (128-1024). As expected, many oak-related odorants were found in the XAD 2 flavor extracts, mainly homofuraneol [2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone] (cotton candy, FD = 16-256) and cis-β-methyloctalactone (butter, woody, FD = 256).
3.Draft genome sequence of Mesotoga strain PhosAC3, a mesophilic member of the bacterial order Thermotogales, isolated from a digestor treating phosphogypsum in Tunisia.
Ben Hania W1, Fadhlaoui K1, Brochier-Armanet C2, Persillon C3, Postec A4, Hamdi M5, Dolla A6, Ollivier B4, Fardeau ML4, Le Mer J4, Erauso G4. Stand Genomic Sci. 2015 May 1;10:12. doi: 10.1186/1944-3277-10-12. eCollection 2015.
Mesotoga strain PhosAc3 was the first mesophilic cultivated member of the order Thermotogales. This genus currently contain two described species, M. prima and M. infera. Strain PhosAc3, isolated from a Tunisian digestor treating phosphogypsum, is phylogenetically closely related to M. prima strain MesG1.Ag.4.2(T). Strain PhosAc3 has a genome of 3.1 Mb with a G+C content of 45.2%. It contains 3,051 protein-coding genes of which 74.6% have their best reciprocal BLAST hit in the genome of the type species, strain MesG1.Ag.4.2(T). For this reason we propose to assign strain PhosAc3 as a novel ecotype of the Mesotoga prima species. However, in contrast with the M. prima type strain, (i) it does not ferment sugars but uses them only in the presence of elemental sulfur as terminal electron acceptor, (ii) it produces only acetate and CO2 from sugars, whereas strain MesG1.Ag.4.2(T) produces acetate, butyrate, isobutyrate, isovalerate, 2-methyl-butyrate and (iii) sulfides are also end products of the elemental sulfur reduction in theses growth conditions.
4.RP-HPLC/MS-APCI analysis of branched chain TAG prepared by precursor-directed biosynthesis with Rhodococcus erythropolis.
Schreiberová O1, Krulikovská T, Sigler K, Cejková A, Rezanka T. Lipids. 2010 Aug;45(8):743-56. doi: 10.1007/s11745-010-3447-7. Epub 2010 Jul 16.
Reversed phase liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/MS-APCI) was used to analyze both synthetic triacylglycerols (TAG) having 1-3 branched fatty acids (FA) in the molecule, and natural TAG prepared by precursor directed biosynthesis from valine, leucine and isoleucine and the corresponding branched short-chain acids in cultivations of Rhodococcus erythropolis. The technique made it possible to identify and quantify TAG differing in a single branched-chain FA. Altogether 11 TAG were synthesized, out of which 8 were synthesized stereospecifically. Branched- and straight-chain-TAG were separated and identified while TAG differing only in iso or anteiso FA could not be separated. The APCI mass spectra of iso-, anteiso- and straight-chain TAG were completely identical. The natural material was found to contain 19 TAG having at least one branched FA. Cultivation on six different substrates showed, apart from the presumed and common incorporation of precursors to iso-even, iso-odd and anteiso FA, also some unusual features such as an increase in the content of odd-FA after the addition of Val (attributed to catabolism of Val to propionate) or the appearance of branched monounsaturated FA.