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The use of antibiotics is not permitted in Switzerland; moreover, no other medication exists to combat European foul brood. Hives with symptoms must therefore be destroyed in order to limit the outbreak, and the contaminated material must be sanitised. Since prevention is the best cure, early detection is desirable. Numerous studies have been undertaken and documents have been created at the Swiss Bee Research Centre and elsewhere to draw the attention of beekeepers to these problems and inform them about the causes and the control measures to be implemented.

Merkblatt zur erkennung von Bienenbrutkrankheiten (German (PDF, 357 kB, 18.10.2017) and French (PDF, 226 kB, 02.02.2017))
M. Tschumi (2011)

Advantages and limitations of a high-throughput analytical method using an automated enzymatic assay to quantify the glutathione in grape juice.

Institutional Repository Agroscope

Dienesné Nagy A., Vuichard F., Belcher S., Blackford M., Rösti J., Lorenzini F.

Advantages and limitations of a high-throughput analytical method using an automated enzymatic assay to quantify the glutathione in grape juice.

Journal of Food Composition and Analysis, 122, 2023, 1-6.

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Résumé:

Glutathione is a tripeptide, present in plants and other organisms in free (GSH) and dimer (GSSG) forms, known for its antioxidant activity. A high-throughput, economical method was developed to measure the total glutathione (TG) concentration in grape juice, using an enzymatic assay (EA), based on the reaction of thiol with 5,5′-dithio-(2-nitrobenzoic acid) (DTNB) in the presence of glutathione reductase enzyme. This method was automatised to allow high-throughput measurements in the concentration range of 1–100 mg L−1. GSH and GSSG were also quantified separately using the UHPLC-MS/MS method. The two methods (EA and UHPLC-MS/MS) gave comparable results in grape juice (R2 =0.97), where the concentrations of SO2 were low (<100 mg L−1). The sample preparation is a critical step in the quantitative analysis of glutathione given the high reactivity of GSH. In this work, ascorbic acid and SO2, commonly used in oenology, were tested as protecting agents at different concentration. The results given by the EA method could be altered by the reaction of SO2 and DTNB, however this effect was observed only at high concentration of SO2 (1 g L−1). Ascorbic acid at a 2.5 mg L−1 concentration protected the sample well, without interfering with the analysis, and allowed for storage for up to four months at − 20 °C.

ISSN Print 0889-1575
ISSN en ligne: 0889-1575
Digital Object Identifier (DOI): https://doi.org/10.1016/j.jfca.2023.105440
ID publication (Code web): 53353 Envoyer par e-mail

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Advantages and limitations of a high-throughput analytical method using an automated enzymatic assay to quantify the glutathione in grape juice.