AIR Contents and Activity of α-L-arabinofuranosidase in Banana (Musa sp.) Fruits during Ripening and Softening

alpha-L-arabinofuranosidase (alpha-Arab, EC 3.2.1.55, alpha-AF) is a plant enzyme that has the capacity to release terminal arabinofuranosyl residues from pectic and hemicellulosic polymers, as well as different glycoconjugates. To find out whether alpha-AF plays important roles in banana fruit softening, alcohol-insoluble residue (AIR) contents in banana pulp, the enzyme activities in peel and pulp, fruit firmness, respiration rate and ethylene release rate were assayed during banana softening. The results showed that AIS changes and alpha-AF activity increased suddenly synchronic to the appearance of the ethylene production peak at later stage, while at the early stage remained steady, so we thought that alpha-AF induced the decrease of fruit firmness and played an important role in banana fruit softening, and its activity is regulated by ethylene.