Determination of copper ions in jams produced in copper vessels - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Journal Articles International Journal of Molecular and Physical Gastronomy Year : 2023

Determination of copper ions in jams produced in copper vessels

Stéphane Besançon
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Marie-Charlotte Foropon
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Abstract

Traditionally jams, jellies and marmalades have been made in copper vessels. Chefs and authors of culinary book sometimes argue that this metal makes “better” products because of its a high thermal conductivity. However copper consumption should be limited for safety reasons, some chemical forms being toxic. In view of finding best practices for the use of copper vessels, it is interesting to know how much copper moves from copper vessels towards the jam, jellies and marmalades when they are being made. After the development of an analytical procedure of copper determination applicable to jams, jams were prepared in a copper vessel that was chosen to be dirty and oxidized, in order to obtain samples with a lot of copper ions, and this was compared with jams made in the same copper pan after cleaning, and also with jams made in an enamel covered steel vessel; the analysis of a commercial jam advertised to have been made in a copper vessel was performed for comparison. For the interpretation of the measurements of the copper concentrations, model jams were prepared from water, pectin and sugar, and the influence of pH was determined through the addition of acids. For all the samples, the determination of copper concentrations was performed by atomic absorption spectrometry, after mineralization (using nitric acid) of jam samples. Dirty and oxidized copper basins did release as much as 48.41 (sd 17.80) mg of copper per kg of jam, whereas only 19.0 (sd 5.94) mg/kg of copper were found in jams prepared in the same vessel, after it had been cleaned using a traditional cleaning process (twice vinegar and salt, plus rinsing with water). However, in the cleaned vessel, the copper concentration rises to 38.3 (sd 6.01) mg/kg when the jam is stored in that same vessel for 4 hours. For comparison, the copper concentration in jams made in an enameled covered steel vessel was only 0.52 (sd 0.09) mg/kg. Analysis of the effect of pH showed that the copper concentration increases at low pH (1.3-3.0), but no chelating effect of citric acid was observed.
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Dates and versions

hal-03990131 , version 1 (15-02-2023)

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Stéphane Besançon, Marie-Charlotte Foropon, Hervé This, Vo Kientza. Determination of copper ions in jams produced in copper vessels. International Journal of Molecular and Physical Gastronomy, 2023, 1, ⟨10.17180/ijmpg-2023-art01⟩. ⟨hal-03990131⟩
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