A Chromatographic Study of the Influence...

Published: Journal of Chromatographic Science, Volume 34, Number 1, January 1996, pp. 1-6

A Chromatographic Study of the Influence of Ion Concentrations and pH on the Yield of Volatile Materials from Heat-Treated Natural Product Extracts
W.M. Coleman, III

The effect of inorganic ion concentrations and pH on the yields of volatile materials from aqueous pressure-cooked solutions of green coffee beans, green tea leaves, and green peanuts as measured by purge and trap–gas chromatography (P&T–GC) with mass spectrometric (MS) detection and flame-ionization detection (FID) is described. Through the use of an internal standard, quantitative descriptions of the effects of these two parameters on the volatile compounds associated with pressure-cooked aqueous extracts of selected natural products are presented. The magnitude of the effect of ion concentration on the amount of material in the headspace is a function of the inorganic compound employed. The higher molecular weight components in the headspace are found to be the most affected by pH and salt concentration. As the concentration of certain inorganic species increases, more of the higher molecular weight components relative to the internal standard are found in the headspace above the pressure-cooked aqueous extracts. Variations in the pH produce similar changes. However, the effect is not universal for the extracts as a group. Increasing the pH results in both increases and decreases in the total amount of volatile material as a function of the aqueous extract type. The ability to exercise control over the release of volatile material from these aqueous extracts by varying the ion concentration and pH of the solutions would seem to provide flexibility in the design of aroma formulations.

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