Starch and by-products from a laboratory-scale barley starch isolation procedure

Starch was isolated from three different barleys with normal, high-amylose, or high-amylopectin (waxy) starch. The laboratory-scale starch isolation p rocedure included crushing of grains, steeping, wet milling, and sequential filtration and washing with water and alkali, respectively. Yield and cont ent of starch, protein, and dietary fiber, including beta -glucan, were ana lyzed in isolated starch and in the by-products obtained. Starch yield was 25-34%, and this fraction contained 96% starch, 0.2-0.3% protein, and 0.1% ash. Most of the remaining starch was found in the coarse material removed by filtration after wet milling, especially for the high-amylose barley, an d in the starch tailings. Microscopy studies showed that isolated starch co ntained mostly A-granules and the starch tailings contained mostly B-granul es. Protein concentration was highest in the alkali-soluble fraction (54%), whereas dietary fiber concentration was highest in the material removed by filtration after alkali treatment for the normal and waxy barleys (55%). T he beta -glucan content was especially high for the waxy barley in this fra ction (26%). The study thus showed that it was possible to enrich chemical constituents in the by-products but that there were large differences betwe en barleys. This result indicates a need for modifications in the isolation procedures for different barleys to obtain high yields of starch and diffe rent by-products. Valuable by-products enriched in beta -glucan or protein, for example, may render starch production more profitable.