DISTRIBUTION OF CARBOHYDRATES IN GLUTEN FRACTIONS-ISOLATED FROM EUROPEAN WHEATS (TRITICUM-AESTIVUM L.) IN A BATTER SYSTEM

Glucose represented 89% of the total carbohydrate of gluten isolated i n a batter system from wheat cultivars exhibiting varying breadmaking qualities. Galactose, arabinose (Ara), and xylose (Xyl) were the remai ning carbohydrates (ca. 10% of the total carbohydrate content), while mannose was present in minor quantities (<1%). After Pronase treatment ca. 43% of the Ara and ca. 52% of the Xql originating from arabinoxyl an (AX) could be solubilized, indicating the presence of water extract able as well as water unextractable AX. Arabinogalactan-peptide (AGP) and small amounts of beta-glucan were also present. Water extractable AX with a low Ara-to-Xyl ratio (A/X) and thus a low degree of substitu tion preferentially are incorporated in the gluten network probably as a result of alignment between glutenin polymers and AX in the stirrin g direction. In gluten from cultivars exhibiting high gluten protein r ecoveries (see accompanying paper; Reels et al. J. Agric. Food Chem. 1 998, 46, 1344-1349), the levels of total gluten associated nonstarch p olysaccharides (TOTGANSP), expressed as a percentage of total flour NS P, were also high. It was postulated that the gluten proteins of such cultivars agglomerate despite the presence of NSP since the gluten fra ctions with the best agglomeration properties contained the lowest amo unt of NSP. In the aforementioned gluten fractions the AGP/AX ratio wa s also unusually high, indicating that the undocumented role of AGP in wheat gluten agglomeration may well be underestimated.