Effects of sunn pest (Eurygaster integriceps) damage ratios on rheological characteristics of wheat flour

Abstract

The effects of sunn pest (Eurygaster integriceps) damage ratios (SPDR) on flour properties and dough characteristics of wheat were investigated in this study. The flours obtained from sound (control), medium damage (2% and 4%) and high damage (from 8 to 100%) samples of 2 bread wheat cultivars (Golia and Sagittario) were analysed for rheological characteristics. As the SPDR increased, farinograph water absorption, dough development time and stability, as well as extensograph resistance, energy, and ratio values of both cultivars decreased significantly (P<0.05) probably due to deteriorative effects of sunn pest (SP) damage on gluten quality. Farinograph tolerance index and softening degree values of the damaged samples were considerably higher, while extensograph dough extensibility value was partially higher compared to those of sound samples in both wheat cultivars, due to proteolytic degradation. The strength and breaking force of the dough samples decreased significantly with increasing SPDR indicating that they were susceptible to spreading and not suitable for handling, bread making and blending application. Deterioration in gluten quality supported the significant decreases in all farinogram and extensogram values of the dough samples with increasing SPDR. Decrease in quality characteristics started at 2% SPDR and flour-dough properties reduced very obviously after 4% SPDR in both wheat varieties. This study showed that although the features of 2 wheat varieties were different from each other, dough characteristics of varieties were negatively (resistance and energy values decrease) and similarly affected by SP damage. The extensograph test also demonstrated a clear distinction between damaged and undamaged wheat samples by SP, due to increasing SP protease activity in the dough during the progress of time in the extensograph test.