Entrapment of 5‐aminolevulinic acid under edible composite film of konjac glucomannan and chitosan

Abstract

5‐Aminolevulinic acid (5‐ALA) is a known plant regulator and growth promoter. It is a very sensitive and highly unstable compound that is easy to deteriorate. Here we propose a novel approach to stabilize 5‐ALA into a film. Films from konjac glucomannan (KGM), KGM treated with alkali solution (KGOH), chitosan (CHI) as well as blends between KGOH and CHI were fabricated for 5‐ALA entrapment. It was found that the efficiency of KGM film, KGOH film and CHI film for 5‐ALA entrapment was 55.7 ± 0.73%, 58.3 ± 0.36% and 60.3 ± 0.18 %, respectively. A 25:75 (%w/w) blended film (KGOH/CHI) showed the highest entrapment efficiency of 5‐ALA (65.9 ± 0.37%) versus other films. The possible mechanism for entrapment of 5‐ALA in blended film was postulated under two mechanisms. A secondary amide that leads to the interaction between the amino group of CHI and carboxyl group of 5‐ALA is proposed as the first mechanism. The fact that the 5‐ALA molecule was entrapped within the complexity of KGOH structure is proposed as the second mechanism. Therefore, stabilizing 5‐ALA in a film may be an alternative way to use and preserve 5‐ALA for further applications.

Keywords

• 5‐Aminolevulinic acid
• Konjac glucomannan
• Chitosan
• Edible film
• Plant growth regulator