A comparative analysis of cutin monomers from cereal brans and fruit peels: Isolation and characterization

Plant cuticles contain mainly lipid polymers (cutin), protecting them against desiccation and environmental stresses. The monomeric composition of the cuticular polymer fractions of three cereal fibers: maize bran, wheat bran and sorghum bran, as well as hemicellulose/cellulose fractions isolated from sorghum bran were investigated and compared with cuticular content isolated from apple and tomato peel samples. Total cuticular contents in apple and tomato peels were the highest, ranging from 54.5 % to 54.8 %, when compared with the total cuticular content of maize, wheat and sorghum brans. Among three cereal samples, the cuticular material content in sorghum bran (7.14%) was higher than the maize bran and wheat bran (3.92% and 5.92% respectively). The hexadecanoic acid (C16), octadecanoic acid (C18), omega-hydroxy fatty acids, with medium chain functional groups such as enoic, epoxy and hydroxyl groups were identified in each cutin sample. The percentage of p-coumaric acid in apple and tomato peel samples were 84.0% and 78.7% respectively of the total phenolic acids present. The ferulic acid content in maize, sorghum and wheat brans were 94.1%, 92.8% and 88.0% respectively, indicating that ferulic acid was the major phenolic compound in these brans.