Possesses beta-amylase activity in vitro (PubMed:21512221). May be involved in cold resistance by mediating the accumulation of maltose upon freezing stress, thus contributing to the protection of membranes (Probable). Hydrolysis of (1->4)-alpha-D-glucosidic linkages in polysaccharides so as to remove successive maltose units from the non-reducing ends of the chains. Optimum pH is 5.5-6.0. Optimum temperature is 35 degrees Celsius. Belongs to the glycosyl hydrolase 14 family. Truncated N-terminus.