The compositions and properties of 5 Great Northern bean cultivars (Beryl-R, Coyne, Gemini, Marquis, and Orion) were investigated. Starch was isolated from each cultivar by a wet milling process. Isolated, unmodified starches were characterized for granular, molecular, thermal, and rheological properties. Smooth surfaces and essentially similar granule sizes and shapes were observed among all cultivars. Amylose contents were in the range 21.0% to 22.6%. Amylose and amylopectin molecular weights were approximately 105 and 109 Da, respectively. Typical C-type X-ray pattern was observed in all cultivars. Significant differences were observed among cultivars in percentage relative crystallinities, which were in the range 18.2% to 23.8%. The relative crystallinity was independent of amylose proportion and molecular weight. The 5 Great Northern bean cultivars differed in their thermal and rheological properties. Coyne and Gemini had low gelatinization enthalpies. In pasting profile analysis, Coyne had the lowest peak and final viscosities. Granule size, polymer proportion, and molecular weights had major influences on gelatinization and pasting properties of Great Northern bean starches.
Great Northern bean is one of the major varieties of dry-edible beans produced worldwide. Starch is the major component in Great Northern beans, which accounts for approximately 40% of its composition. Although most legume starches have been studied in detail, physicochemical and functional properties of Great Northern bean starch are largely unknown. This study investigated the properties and thermal behaviors of 5 Great Northern bean cultivars. The new information reported in this article, on starch properties, would pave ways to find new ingredient and product applications for Great Northern beans in food processing.