Synthesis of quaternary ammonium chitosan and its application to fruit coating

Abstract

Quaternary ammonium salts of V-butyl and V-benzyl chitosan were synthesized by, first, reductive alkylation of chitosan and, second, methylation of N-alkyl chitosan. The reaction condition was studied by varying the amounts of aldehydes in the first step and methyl iodide in the second step to obtain products that are soluble in water. It is also found that when the degree of N-alkylation is high, the degree of quaternization is low. Only the quaternized derivatives of N-butyl chitosan can dissolve in water. Fruit-coating study was performed by applying solutions of chitosan and its quaternized derivatives on the peel of green bananas. Appearance and weight change were monitored throughout the period of 10 days at ambient atmosphere. Black spots and browning of the peel and fruit texture of the banana coated with chitosan and quaternized derivatives took place at a slower rate than those of the non-coated ones. This study therefore shows that chitosan and its quaternized derivatives can be considered suitable for use to delay browning of ripe banana.