LAKTOZA (lot. lac, lactis – shir), qandi shir, C12H22O11, karbogidrat az guruhi disakharidho. Dar shiri hayvonoti shirmak (2 – 8,5%) mavjud ast; dar gardnaychai baze rastaniho niz oshkor karda shudaast. L. moddai berang buda, se shakli kristalli dorad; az jihati optiki faol ast. Dar ob, spirti etil va piridin hal meshavad, dar efir halnashavanda ast. L.-ro dar dorusozi kor mefarmoyand.