Impact of flour particle size and hydrothermal treatment on dough rheology and quality of barley rusks

Abstract

Barley rusks are traditional baked products of the Cretan-Mediterranean diet, a naturally β-glucan-containing food item. The impact of flour particle size and autoclaving on dough thermomechanical properties and rusk quality features was evaluated. Rusks were made using a coarse and a fine barley flour stream without or with prior autoclaving at two different moisture levels. Calorimetry showed that autoclaving and decreased particle size of the flour reduce the gelatinization enthalpy values. Small and large deformation mechanical tests revealed that flour autoclaving increased the resistance to deformation and flow, elasticity and hardness of the barley doughs; these trends were more pronounced for coarse flours. The reduction of particle size in thermally untreated flours decreased rusk hardness and increased loaf volume and resulted in finer crumb structure; however, autoclaving of fine flour nullified these quality attribute trends. Nevertheless, these changes are not detrimental for consumer acceptability of this bakery product which traditionally is manufactured with low loaf volume, compact macrostructure and hard texture. Moreover, the hydrothermal pretreatment of barley flour can be an appropriate processing step of making naturally containing β-glucan rusks with polysaccharide molecular characteristics that are more effective in promoting the health benefits of these fibers (high molecular weight).