Reaction solutions are disclosed herein comprising water, incompletely refined sucrose, and a glucosyltransferase enzyme that synthesizes insoluble poly alpha-1,3-glucan having at least 50% alpha-1,3 glycosidic linkages and a weight average degree of polymerization (DPw) of at least 100. The yield of poly alpha-1,3-glucan by a reaction solution herein is at least 7% of the weight of sucrose that was converted in the reaction solution. Further disclosed are methods of producing poly alpha-1,3-glucan using incompletely refined sucrose, and poly alpha-1,3-glucan produced by these methods.