Raffinose, stachyose and verbascose are non-digestible short-chain carbohydrates or oligosaccharides. Humans do not have enzymes to digest them, so they pass unchanged to the colon where the normal intestinal bacteria ferment them to gases (methane, carbon dioxide, hydrogen), which can cause abdominal bloating . The enzyme alpha-galactosidase that can break them down and thus prevent gas after eating beans is available as an over-the-counter supplement.
Function in the Human Body
In the large intestine, raffinose, stachyose and verbascose act as a soluble dietary fiber, which means they can make stools softer
Raffinose, stachyose and verbascose may promote the growth of beneficial intestinal bacteria, but are currently not considered prebiotics.
Raffinose, also called melitose, is composed of 3 sugars: galactose, glucose and fructose . Examples of foods naturally high in raffinose are beans, asparagus, cotton seeds, sugar beet molasses, cabbage, broccoli, Brussel’s sprouts, sweet potatoes and whole grains [3,5]. Raffinose as a sweetener is extracted from sugar beet molasses.
Calories per gram = 2 [producer]
Sweetness, relative to sucrose = 22% [4-p.95]
Melting point = 176 °F (80 °C)
Boiling point (decomposition) = 244.4 °F (118 °C)
Raffinose is not a reducing sugar so it does not undergo thee Maillard browning reaction .
Stachyose is composed of 4 sugar molecules: 2 galactoses, glucose and fructose. It is found mainly in beans and peas .
Calories per gram = probably ~2
Sweetness, relative to sucrose = 20% [producer]
Melting point = 343.4 °F (173 °C)
Verbascose is composed of five sugar molecules: 3 galactoses, glucose and fructose.
Effects of Soaking and Cooking
In one study, soaking red kidney beans at room temperature for 12 hours reduced their raffinose content by about 80% and additional boiling for 14 minutes by 96%; soaking had about the same effect on stachyose
Raffinose, stachyose and verbascose are used as bulk sweeteners.
Raffinose, stachyose and verbascose are examples of FODMAPs (Fermentable Oligo-, Di- and Monosaccharides and Polyols), which, when consumed in excess, can trigger abdominal bloating, excessive gas and diarrhea.