Carbohydrates with three to nine degrees of polymerization (i.e. three to nine monosaccharide units) are classified as oligosaccharides. Some oligosaccharides occur naturally in plants: stachyose and raffi nose in soybeans and other legumes and fructooligosaccharides in fruits, vegetables, and grains. However, because of their usefulness as food ingredients and their possible health benefits, an increasing number of oligosaccharides are now synthesized from sugars or obtained through extraction and/or partial hydrolysis of longer - chain plant polysaccharides.