Thermally Induced Degradation of Aliphatic Glucosinolates: Identification of Intermediary Breakdown Products and Proposed Degradation Pathways

In Brassica vegetables, heating processes lead to thermally induced degradation of glucosinolates (GSLs), resulting in the formation of nitriles and isothiocyanates (ITCs). To date, the mechanism is not yet satisfyingly elucidated. Thermally induced degradation of the model GSL sinigrin was studied...

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Bibliographic Details
Published in:Journal of agricultural and food chemistry 2012-10, Vol.60 (39), p.9890-9899
Main Authors: Hanschen, Franziska S, Bauer, Anna, Mewis, Inga, Keil, Claudia, Schreiner, Monika, Rohn, Sascha, Kroh, Lothar W
Format: Article
Language:English
Subjects:
Biological and medical sciences
Brassica
Brassica - chemistry
broccoli
Cooking
Food industries
Fruit and vegetable industries
Fundamental and applied biological sciences. Psychology
Glucosinolates - chemistry
heat treatment
Hot Temperature
hydrolysis
ions
Isothiocyanates - chemistry
nitriles
Nitriles - chemistry
sinigrin
sugars
temperature
thermal stability
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Summary:In Brassica vegetables, heating processes lead to thermally induced degradation of glucosinolates (GSLs), resulting in the formation of nitriles and isothiocyanates (ITCs). To date, the mechanism is not yet satisfyingly elucidated. Thermally induced degradation of the model GSL sinigrin was studied in dry as well as aqueous medium at different pH values and temperatures. The influence of the presence of iron ions and plant matrix (broccoli sprouts powder) on the degradation was studied as well. Next to the degradation of the GSL, the formation of nitrile and ITC and the release of sugar derivatives were investigated. Because d-glucose and ITC are main thermal breakdown products under aqueous conditions, hydrolysis seems to be the initial step in the degradation pathway during cooking. In contrast, under dry conditions, the desulfo-sinigrin was identified as a main intermediary thermal breakdown product for the first time. Further, degradation of the desulfo-GSL results in the release of d-thioglucose and the corresponding nitrile. Iron(II) ions and plant matrix influence the thermal stability of the GSL and favor the formation of nitriles.
ISSN:0021-8561
1520-5118
DOI:10.1021/jf302744y