Chlorogenic acid (CGA) is a natural phenol present in several vegetable food and it can directly affect the organoleptic characteristics, colour, nutritional and antioxidant properties. it is well known that CGA is involved in enzymatic browning of vegetable food but there isn't much known about the chemical changes occurring during food processing. In this article, some changes of the chlorogenic acid observed in different alkaline solutions are reported. Two alkaline solutions were made at pH 12, one consisting of 10 mM buffer and one of a NaOH 1.25 N solution. It emerged that the chlorogenic acid, pure or contained in phenol extracts of natural raw material, changes radically in respect to its original form by treatment with a strongly alkaline solution. These changes were repeatable and constant and produced new compounds not well identified, with exception of the caffeic acid. Probably, the high value of the pH causes only an immediate and irreversible isomerisation of the chlorogenic acid. if the high pH is due to NaOH, in addition to the above-said isomerisation, a subsequent hydrolytic process happens that generates not only caffeic acid but also a new unknown compound. This new compound is chemically stable, easily measurable and separable by different chromatographic techniques; it has an absorption spectrum similar to that of phenol matrix and shows antioxidant properties. Neither caffeic acid nor original chlorogenic acid form themselves by the alkaline hydrolysis of this new unknown compound. The real chemical structure of all the compounds forming when the chlorogenic acid is in a medium strongly alkaline is not still clear. Nevertheless, even if the results of the observations made are still incomplete, we have retained right to reveal them considering the strong interest in chlorogenic acid and its derivatives in several sectors.
Chemical changes of the chlorogenic acid observed in different alkaline solutions
DE LEONARDIS, Antonella
;
2005-01-01
Abstract
Chlorogenic acid (CGA) is a natural phenol present in several vegetable food and it can directly affect the organoleptic characteristics, colour, nutritional and antioxidant properties. it is well known that CGA is involved in enzymatic browning of vegetable food but there isn't much known about the chemical changes occurring during food processing. In this article, some changes of the chlorogenic acid observed in different alkaline solutions are reported. Two alkaline solutions were made at pH 12, one consisting of 10 mM buffer and one of a NaOH 1.25 N solution. It emerged that the chlorogenic acid, pure or contained in phenol extracts of natural raw material, changes radically in respect to its original form by treatment with a strongly alkaline solution. These changes were repeatable and constant and produced new compounds not well identified, with exception of the caffeic acid. Probably, the high value of the pH causes only an immediate and irreversible isomerisation of the chlorogenic acid. if the high pH is due to NaOH, in addition to the above-said isomerisation, a subsequent hydrolytic process happens that generates not only caffeic acid but also a new unknown compound. This new compound is chemically stable, easily measurable and separable by different chromatographic techniques; it has an absorption spectrum similar to that of phenol matrix and shows antioxidant properties. Neither caffeic acid nor original chlorogenic acid form themselves by the alkaline hydrolysis of this new unknown compound. The real chemical structure of all the compounds forming when the chlorogenic acid is in a medium strongly alkaline is not still clear. Nevertheless, even if the results of the observations made are still incomplete, we have retained right to reveal them considering the strong interest in chlorogenic acid and its derivatives in several sectors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
