Wolrd Grains Summit: Food and Beverages location:San Fransisco, California, USA date:17-20 September 2006
Arabinoxylans (AX), non starch polysaccharides that constitute a significant part of cereal cell walls, have a significant impact on cereal processes, including breadmaking and brewing. Their functionality is largely determined by their degree of polymerization (DP). The analysis of the latter against the complex background of glucose polymers, such as in bread or beer, is difficult. In contrast, AX content of samples can be easily measured by gas liquid chromatography (GLC) by the following steps: (i) acid hydrolysis, (ii) conversion of monosaccharides to alditols with sodium borohydride, and (iii) acetylation of the free hydroxyl groups to yield peracetates. We here developed an analytical procedure to analyze reducing end sugar content and composition which, when combined with the above method allows to estimate the average DP of AX populations. This procedure differs from the above method as it consists of the following subsequent steps: (i) reduction of reducing end sugars, (ii) acid hydrolysis, (iii) acetylation, and (iv) analysis of the derivatised sugars by GLC. By doing so, only the reducing end sugars are analyzed as peracetates. Accuracy and repeatability of the method were verified using dextrin and xylooligosaccharide samples of known composition and DP. Results deviated less than 10% from those listed and had a coefficient of variation of less than 3%. Reducing end xylose concentrations down to 1 microgram per ml could be measured, allowing determination of DP of AX up to 5000. In conclusion, the developed method provides a unique tool for determining reducing end sugar content and composition in complex systems. It can be used for the determination of AX DP in e.g. beer and bread and in situ follow-up of xylanase activity in dough, batters and worts.