Baking quality of bread wheat cultivars damaged by nysius simulans

Abstract

Wheat grain may be attacked by different insect species. Among them, some Heteroptera species (e.g. Aelia spp., Eurygaster spp.) reduce wheat breadmaking quality; others such as Nysius simulans commonly extract water and nutrients from soy plants. The aim of this study was to assess the effect of N. simulans infestation on breadmaking quality of different bread wheat cultivars. Twelve wheat cultivars (damaged and undamaged by N. simulans) were studied. Infested grain percentage varied between 51-78% depending on cultivar. Protein and gluten quantity and quality were significantly reduced in damaged flours as shown by gluten index, solvent retention capacity and SDS-sedimentation index. SDS-PAGE from water-extractable proteins evidenced an important proteolytic activity in damaged samples. Dough rheological properties showed a reduced dough viscoelasticity in damaged samples. Micro-bread specific volume changed from 3.26 cm3/g for samples made with undamaged flour to 2.77 cm3/g for bread made with damaged ones. No evidence for modification in starch properties was found. The infestation by N. simulans reduced wheat breadmaking quality in all cultivars studied, as a result of proteolytic activity occurring after dough hydration. Results suggest that the presence of N. simulans should be considered as a factor affecting wheat crops, mainly those located next to soy crop areas which is the usual host for this insect.