Isomaltooligosaccharide

Isomaltooligosaccharide (IMO) is a mixture of short-chain carbohydrates which may have a digestion-resistant property. IMO is found naturally in some foods, as well as being manufactured commercially. Although isomaltose is found in some foods, such as honey, as a disaccharide, it behaves like all other disaccharides and is easily digested. Because of a confusion over nomenclature, such disaccharides have frequently been described as IMO, however to truly be called an 'oligosaccharide' the molecules must have a degree of polymerization (DP) of three or more. Historically, the best documented source of IMO was found in sourdough breads wherein proper oligosaccharides are produced. IMO is currently produce by two distinctly different methods. One is based on a conversion of starch using enzymes. The raw material used for manufacturing IMO is starch, which is enzymatically converted into a mixture of isomaltooligosaccharides. However, IMOs produced via this method result in a very high proportion of isomaltose disaccharides (approximately 50%) and a majority of panose (IMO DP3) as the end product. These IMO preparations have been shown to be highly digestible and generally do not exhibit much if any, digestion resistance. The second method uses bacterial fermentation and bio-conversion of sugar and starch to create an IMO variant maltosyl-isomaltooligosaccharide (MIMO). Typically the end product ranges in molecular complexity from DP3 (<10%) to DP9 with an average molecular weight near DP5. MIMO preparations exhibit very good digestion resistance and also intestinal microbiota selectivity. Isomaltooligosaccharide (IMO) is a mixture of short-chain carbohydrates which may have a digestion-resistant property. IMO is found naturally in some foods, as well as being manufactured commercially. Although isomaltose is found in some foods, such as honey, as a disaccharide, it behaves like all other disaccharides and is easily digested. Because of a confusion over nomenclature, such disaccharides have frequently been described as IMO, however to truly be called an 'oligosaccharide' the molecules must have a degree of polymerization (DP) of three or more. Historically, the best documented source of IMO was found in sourdough breads wherein proper oligosaccharides are produced. IMO is currently produce by two distinctly different methods. One is based on a conversion of starch using enzymes. The raw material used for manufacturing IMO is starch, which is enzymatically converted into a mixture of isomaltooligosaccharides. However, IMOs produced via this method result in a very high proportion of isomaltose disaccharides (approximately 50%) and a majority of panose (IMO DP3) as the end product. These IMO preparations have been shown to be highly digestible and generally do not exhibit much if any, digestion resistance. The second method uses bacterial fermentation and bio-conversion of sugar and starch to create an IMO variant maltosyl-isomaltooligosaccharide (MIMO). Typically the end product ranges in molecular complexity from DP3 (<10%) to DP9 with an average molecular weight near DP5. MIMO preparations exhibit very good digestion resistance and also intestinal microbiota selectivity. The term 'oligosaccharide' encompasses carbohydrates that are larger than simple di- or tri-saccharides, but smaller than polysaccharides (greater than 10 units). Isomalto-oligosaccharides (IMO) are glucose oligomers with α-D-(1,6)-linkages, including isomaltose, panose, isomaltotriose, isomaltotetraose, isomaltopentaose, nigerose, kojibiose, and higher branched oligosaccharides. Depending on production method, the structure of the IMO molecules can vary significantly. While human intestinal enzymes readily digest α(1,4)-glycosidic bonds, longer change IMO (e.g. >= DP4) with α(1,6)-linkages are not easily hydrolyzed and exhibit a digestion-resistant property. Therefore, some IMO preparations are only partially digested in the upper gastrointestinal tract. Isomalto-oligosaccharides are a normal part of the human diet and occur naturally in fermented foods, such as fermented sourdough breads and kimchi. The disaccharide isomaltose is also present in rice miso, soy sauce, and sake. Isomaltose, one of the α(1,6)-linked disaccharide components of IMO, has been identified as a natural constituent of honey and although chemically related, it is not and IMO . IMO is a sweet-tasting, high-density syrup which could be spray-dried into powder form. For manufacturing IMO on a commercial scale, food industries use starch processed from cereal crops like wheat, barley, pulses (peas, beans, lentils), oats, tapioca, rice, potato and others. This variety in sources could benefit consumers who have allergies or hypersensitivity to certain cereal crops. The manufacturing process controls the degree of polymerization (dp) and the α(1,6)-linkages to ensure a consistent quality of IMO from different starch sources. The starch is first converted, by means of simple enzymatic hydrolysis, into high maltose syrup with di-, tri and oligosaccharides (2, 3 or more glucose units) having α(1,4)-glycosidic linkages which are readily digestible in the human intestine. These α(1,4)-glycosidic linkages are further converted into digestion-resistant α(1,6)-glycosidic linkages, creating 'iso' linkages between glucose moieties and forming Isomalto-oligosaccharide (IMO). The majority of oligosaccharides found in IMO consist of three to six monosaccharide (glucose) units linked together. However, disaccharides, as well as longer polysaccharides (up to nine glucose units), are also present. The disaccharide fraction of IMO consists mainly of α(1,6)-linked isomaltose, while maltotriose, panose, and isomaltotriose make up the trisaccharide fraction. A mixture of isomaltotetraose, isomaltopentaose, maltohexaose, maltoheptaose, and small amounts of oligomers with 8 or more degrees of polymerization, comprise the remaining oligomers in IMO. Longer oligomers do not have 100% α(1,6)-linkages; the ratio of α(1,4)- to α(1,6)-linkages is variable. Health claims for the various classes of oligosaccharides have been investigated by the European Food Safety Authority (EFSA) and found to be insufficiently substantiated. Therefore, health claims for oligosaccharides and prebiotics are prohibited in the European Union. IMO is a multifunctional molecule which exerts positive effects on human digestive health; it acts as a prebiotic, decreases flatulence , has a low glycemic index , and prevents dental caries in animals. Prebiotics are defined as 'non-digestible food ingredients that may beneficially affect the host by selectively stimulating the growth and/or activity of a limited number of bacteria in the colon'. Oligosaccharides that are not digested and absorbed in the small intestine, pass through to the colon where they are fermented by Bifidobacteria, thus enhancing the proliferation of the bacteria. In this respect, fermentable oligosaccharides may be considered prebiotics. The oligosaccharides in IMO mixtures are, at least partially, fermented by bacteria in the colon and may, therefore, stimulate the growth of bacterial subpopulations. Short chain oligosaccharides which confer prebiotic properties also produce short-chain fatty acids (like acetate, propionate and butyrate) as end-products of fermentation. These molecules decrease the intra-luminal pH, directly inhibiting the growth and activity of harmful micro-organisms (enteropathogens). This stimulates the growth of Bifidobacteria, which compete with the enteropathogens for nutrients and epithelial adhesion sites. The beneficial effects of IMO have been found in infants, children, and the elderly.