Document Detail


Quantitation of S-methylmethionine in raw vegetables and green malt by a stable isotope dilution assay using LC-MS/MS: comparison with dimethyl sulfide formation after heat treatment.
MedLine Citation:
PMID:  19754146     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The potent odorant dimethyl sulfide (1), showing a low odor threshold of 0.12 microg/L in water, is known to contribute to the aromas of various foods. Its cabbage-like odor plays an important role, particularly, in cooked vegetables, such as cabbage, celery, or asparagus. On the other hand, in fruit juices or beer, 1 may generate off-flavors. S-Methylmethionine (2) has previously been characterized as precursor of 1 during thermal processing, and several methods for its quantitation have been proposed. Using deuterium-labeled 2 as the internal standard, a stable isotope dilution assay (SIDA) using LC-MS/MS was developed for the fast quantitation of 2 in vegetables and malt. Application of the method to different foods revealed amounts between 2.8 mg (fresh tomatoes) and 176 mg (celery) of 2 per kilogram. To correlate the amount of 1 formed upon processing with the amounts of 2 present in the raw material, 1 was quantified before and after a thermal treatment of the same raw materials by a SIDA. Concentrations between 1.1 mg/kg (fresh tomatoes) and 26 mg/kg (celery) were determined in the processed samples. The quantitation of 2 during steeping, germination, and malting of barley, and a correlation of the data with the amounts of 1 formed after thermal treatment of the malt, resulted in yields between 24 and 27 mol % calculated on the basis of the amounts of 2. The results suggested that the extent of the formation of 1 can be predicted, for example, in plant materials, from the amount of 2 present in the raw foods.
Authors:
Julia Scherb; Johanna Kreissl; Sonja Haupt; Peter Schieberle
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Journal of agricultural and food chemistry     Volume:  57     ISSN:  1520-5118     ISO Abbreviation:  J. Agric. Food Chem.     Publication Date:  2009 Oct 
Date Detail:
Created Date:  2009-10-07     Completed Date:  2010-01-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0374755     Medline TA:  J Agric Food Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  9091-6     Citation Subset:  IM    
Affiliation:
Lehrstuhl fuer Lebensmittelchemie, Technische Universitaet Muenchen, Garching, Germany.
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MeSH Terms
Descriptor/Qualifier:
Cereals / chemistry*
Chromatography, High Pressure Liquid / methods*
Deuterium
Dimethyl Sulfoxide / analysis*
Drug Stability
Hordeum
Hot Temperature
Indicator Dilution Techniques
Tandem Mass Spectrometry / methods*
Vegetables / chemistry*
Vitamin U / analysis*
Chemical
Reg. No./Substance:
1115-84-0/Vitamin U; 67-68-5/Dimethyl Sulfoxide; 7782-39-0/Deuterium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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