Hydrothermal treatment of sprout-damaged grain: II. Effects on the technological quality of rye

Authors

• Christina Westermarck-Rosendahl Department of Food Chemistry and Technology, University of Helsinki, 00710 Helsinki 71, Finland

DOI: https://doi.org/10.23986/afsci.71978

Abstract

Sprout-damaged rye with the falling number of 87 was heat-treated by immersing the grain in water having temperatures of 80, 90 and 100°C. The treatment lasted at the most 60 sec and was followed by an immediate chilling process. The aim of the treatment was to suppress the excess of a-amylase activity in the outer layers of the kernels. The changes in the quality of the rye were determined by the falling number test, amylograph test and baking tests in which yeast and no acid was added. All the performed treatments affected the results of the quality determinations. Treatment at 80, 90 and 100°C lasting 30 sec raised the falling number values to 102, 117 and 155, respectively. After treatment for 60 sec the values were 101, 142 and 223. In the amylograms the peak viscosity increased markedly. Processing at 100 and 90°C for more than 20 sec resulted in an increase of the peak viscosity beyond 1000 B.U. The peak temperature of all the samples was rather low and some decrease in the peak temperature was indicated at the processing temperatures of 80 and 90° C. The loaf volumes of loaf made from the treated samples were all lower than the volume of the loaf from the untreated sample. The samples treated for 30 and 60 sec at 100°C gave lowest volumes. Stickiness of the doughs was diminished by the more severe processing conditions, as also were dampness and elasticity of the crumb. All loaves except the ones made of grain heated at 100“C for 30 and 60 sec had a rather large cavity beneath the crust. The samples processed at 90 and 100°C for 30 and 60 sec gave a lighter brown crust colour than the rest of the samples.