Chemical compounds of grape (Vitis vinifera L.) and its interaetion with cyanide salts

Claudio Ciudad B.1 y Regina Ite D.1

The possible grape berry contamination with cyanide salts, caused a study to elucidate the conduct and persistence of these compounds in the fruit which· was carried out at the Central Laboratory of Contaminants and Foods (La Platina Experimental Station, INIA).
It was proved that the persistence of poison by law of mass action, depend on the cyanide initial concentration chemical activity of reagents and mainly the environmental temperature.
Also was possible to validate that in grapes, organic acids participates in an acid-base reaction giving proton and produce hydrogen cyanide, that should be easily scattered. Other compound like glucose and fructose contain electrophilic carbonyl groups, that react with cyanide to give cyanohydrin.
Both potentialities were submitted to studies, forcing cyanide ion to manifest kinetic decay in: berries, juice, glucose solution 22% and water. AII of them at pH 3.7 and 4°C.
The objective was to analyse residual cyanide by the Merck method, in different times, from 0 to 150 minutes. The result showed that the cyanide behaviour is similar in berries, juice and glucose solutions, going through a pseudo first-order reaction, exponential type, as:

Ct = Coe-kt

In a cyanide acid solution, this falled off following a linear regression, as:

C = 948 - O,665t

Key words:

1 Estación Experimental La Platina (INlA), Casilla 439, Correo 3, Santiago, Chile.

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