The Volatile Sulphur Compounds of Oysters

1964 ◽  
Vol 21 (6) ◽  
pp. 1481-1487 ◽  
Author(s):  
A. P. Ronald ◽  
W. A. B. Thomson
Keyword(s):  
Gas Chromatography ◽  
Crassostrea Gigas ◽  
Infrared Analysis ◽  
Dimethyl Sulphide ◽  
Sulphur Compounds ◽  
Pacific Oysters ◽  
Volatile Sulphur Compounds ◽  
Bacterial Action ◽  
Mercury Salts ◽  
Characteristic Odour

The compound responsible for the characteristic odour of fresh Pacific oysters, Crassostrea gigas (Thunberg), has been identified as dimethyl sulphide [(CH3)2S], by the formation of mercury salts, and by infrared analysis and gas chromatography. The effect of bacterial action on the oysters has been observed and a number of the volatile organo-sulphur decomposition compounds, produced during room storage at 20–21 °C, have been identified by gas chromatography and by the formation of their lead and mercury salts.

Flavour sulphides are produced from methionine by two different pathways by Geotrichum candidum

2000 ◽  
Vol 67 (3) ◽  
pp. 371-380 ◽  
Author(s):  
YANN DEMARIGNY ◽  
CÉLINE BERGER ◽  
NATHALIE DESMASURES ◽  
MICHELINE GUEGUEN ◽  
HENRY E. SPINNLER
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Geotrichum Candidum ◽  
Gas Chromatography Mass Spectrometry ◽  
Specific Production ◽  
Dimethyl Sulphide ◽  
Sulphur Compounds ◽  
Nitrobenzoic Acid ◽  
Dimethyl Disulphide ◽  
Chromatography Mass Spectrometry

We have investigated the capacities of Geotrichum candidum strains to produce sulphides from methionine. This attribute is very important in cheese technology because of the flavouring potential of sulphur compounds. A spectrophotometric procedure using 5,5′-dithiobis(2-nitrobenzoic acid) to determine sulphides was tested on a collection of G. candidum strains, and confirmed by gas chromatography–mass spectrometry. The strains were distinguished on the basis of their ability to produce methanethiol. Gas chromatography–mass spectrometry also made it possible to identify other sulphides, such as dimethyl disulphide, dimethyl trisulphide and dimethyl sulphide. Using sonicated cells, the specific production of these four sulphides was studied in presence of L-[S-methyl-2H]methionine. Both methanethiol and dimethyl sulphide were produced from methionine, but two different pathways were used by G. candidum.

scholarly journals Electrophysiological Evaluation of Pacific Oyster (Crassostrea gigas) Sensitivity to Saxitoxin and Tetrodotoxin

Marine Drugs ◽  
2021 ◽  
Vol 19 (7) ◽  
pp. 380
Author(s):  
Floriane Boullot ◽  
Caroline Fabioux ◽  
Hélène Hégaret ◽  
Pierre Boudry ◽  
Philippe Soudant ◽  
...  
Keyword(s):  
Crassostrea Gigas ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Alexandrium Minutum ◽  
Paralytic Shellfish Toxins ◽  
Pacific Oysters ◽  
Paralytic Shellfish ◽  
Good Potential ◽  
First Time ◽  
Micromolar Range

Pacific oysters (Crassostrea gigas) may bio-accumulate high levels of paralytic shellfish toxins (PST) during harmful algal blooms of the genus Alexandrium. These blooms regularly occur in coastal waters, affecting oyster health and marketability. The aim of our study was to analyse the PST-sensitivity of nerves of Pacific oysters in relation with toxin bio-accumulation. The results show that C. gigas nerves have micromolar range of saxitoxin (STX) sensitivity, thus providing intermediate STX sensitivity compared to other bivalve species. However, theses nerves were much less sensitive to tetrodotoxin. The STX-sensitivity of compound nerve action potential (CNAP) recorded from oysters experimentally fed with Alexandrium minutum (toxic-alga-exposed oysters), or Tisochrysis lutea, a non-toxic microalga (control oysters), revealed that oysters could be separated into STX-resistant and STX-sensitive categories, regardless of the diet. Moreover, the percentage of toxin-sensitive nerves was lower, and the STX concentration necessary to inhibit 50% of CNAP higher, in recently toxic-alga-exposed oysters than in control bivalves. However, no obvious correlation was observed between nerve sensitivity to STX and the STX content in oyster digestive glands. None of the nerves isolated from wild and farmed oysters was detected to be sensitive to tetrodotoxin. In conclusion, this study highlights the good potential of cerebrovisceral nerves of Pacific oysters for electrophysiological and pharmacological studies. In addition, this study shows, for the first time, that C. gigas nerves have micromolar range of STX sensitivity. The STX sensitivity decreases, at least temporary, upon recent oyster exposure to dinoflagellates producing PST under natural, but not experimental environment.

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