Involved in the degradation of arabinan and is a key enzyme in the complete degradation of the plant cell wall. Catalyzes the cleavage of terminal alpha-(1->5)-arabinofuranosyl bonds in different hemicellulosic homopolysaccharides (arabino-oligoxylosides, branched and debranched arabinans). It acts rapidly on the short-chain arabino-oligoxylosides from digestion of xylan with xylanases. It hydrolyzes slowly arabinan and arabinoxylan from wheat and rye flour. Hydrolysis of terminal non-reducing alpha-L-arabinofuranoside residues in alpha-L-arabinosides. Optimum pH is 6.0. Optimum temperature is 60 degrees Celsius. Glycan metabolism; L-arabinan degradation. Homohexamer; trimer of dimers. Belongs to the glycosyl hydrolase 51 family.