EFFECTS OF PROCESSING ON THE OLIGOSACCHARIDES OF OILSEED AND LEGUME PROTEIN MEALS

The effects of (alkanol)-hexane, (alkanol/water)-hexane and (alkanol/ammonia/water)-hexane extraction systems on the removal of low-molecular-weight sugars from soybean, cottonseed, field pea and mung bean were studied. The total content of soluble sugars of hexane-extracted meals varied between 4.79 and 12.12%, depending on the type of seed and solvent extraction system used. The predominant sugar of cottonseed was raffinose. Sucrose and stachyose were present in smaller quantities. However, glanded cottonseed contained about four times more stachyose than glandless seeds. Seeds were extracted with methanol, ethanol and isopropanol, with or without 10% (w/w) ammonia, possibly containing 5% (v/v) water. The above extraction systems removed up to 81% of the total flatulence-causing sugars. Methanol was the most effective alkanol used, while isopropanol exhibited the poorest extraction efficiency. (Methanol/ammonia)-treated meals contained from 0.38 to 2.86% raffinose; however, all extraction systems were less effective in removing stachyose and verbascose. Results of this study imply that the removal of flatulence-causing sugars depends on their molecular weight, the seed's structural parameters, interaction within the seed components and polarity of the solvent systems used.