Relative efficiency of ethanol and pyridine as extractants of low molecular weight carbohydrates from soybean seed axes

Conventional methods of soluble carbohydrate determination in soybean (Glyc ine max [L.] Merr.) seeds involve time consuming and labour intensive extra ction using organic solvents. In this study, a conventional plant tissue so luble carbohydrate extraction method using 75% ethanol was compared with a simultaneous extraction-derivatization in a pyridine-based reagent (pure py ridine and stox) for recovery of sugars and cyclitols in developing soybean seed axes. The comparison was performed in lyophilized or oven-dried tissu e to determine the effect of oven drying on soluble carbohydrate recovery. The degree of polymerization and/or position in the oligosaccharide biosynt hesis pathway was important in the response of sugars and cyclitols to both extraction methods. Pyridine was superior to ethanol extraction for reduci ng sugars, sucrose and free cyclitols. Ethanol was superior to pyridine ext raction for sucrosyl oligosaccharides and galactosyl cyclitols. Pyridine is a more rapid, less costly, and convenient method for extraction of low mol ecular weight soluble carbohydrates in soybean seeds. For soluble carbohydr ate quantification, this study suggests that the size of the soluble carboh ydrate may determine whether pyridine or ethanol extraction is used. The be tter recovery of galactosyl cyclitols in oven-dried than lyophilized tissue has important implications for their determination in studies where heat d rying or roasting is mandatory.