Effect of different life stages of rhizopertha dominica on component and edible quality of wheat

Abstract: In order to investigate the physicochemical and application quality changes of wheat damaged by Rhizopertha dominica in different growth stages, the nutritional properties, dough rheological properties, food processing properties and other relevant quality indices of wheat were determined after infestation by Rhizopertha dominica in the egg stage, larval stage, pupa stage and adult stage under the optimal growth conditions such as the temperature of (32±1)℃ and relative humidity of 75%±1%. And all data were processed by the differential analysis method. The results showed that the ash content of the wheat firstly decreased and then increased after infected by Rhizopertha dominica from the egg to the adult stage, and the ash content between the infested wheat sample in the pupal and adult stage and the control sample showed a significant difference (P<0.05). The albumin and reducing sugar content had a tendency of increasing firstly and then decreasing, and the albumin content between the infested wheat sample in all development stages and the control sample showed significant difference (P<0.05), while the reducing sugar content had not significant difference. The crude fat content and glutenin content decreased gradually, and the crude fat content between the infested wheat sample in all different development stages and the control sample showed significant difference (P<0.05), while the glutenin content between the infested wheat sample in the larval, pupa and adult stage and the control sample had significant difference (P<0.05). The globulin and gliadin content irregularly changed, and the globulin and gliadin content between the infested wheat sample in the larval, pupal and adult stage and the control sample had significant difference (P<0.05) respectively. In addition, with Rhizopertha dominica eggs growing and developing in the wheat grain kernel, the microstructure of the wheat endosperm showed the interface damaged by Rhizopertha dominica became to have hard texture and rough surface, the structure was softening, the matrix proteins had severe fracture, and the damaged starch gradually increased. The rheological properties of whole wheat flour dough changed obviously, the peak time gradually decreased, and the peak time between the infested wheat sample respectively in the pupal and adult stage and the control sample showed significant difference (P<0.05); the peak height and peak area first decreased and then increased, the peak width had an overall upward trend, and the peak height, front width and peak area between the infested wheat sample in all different development stages and the control sample showed significant difference (P<0.05). The slope of the right side of the midline peak had a tendency of first rising and then decreasing, and the slope of the right side of the midline peak between the infested wheat sample in all different development stages and the control sample had significant difference (P<0.05). The sensory evaluation scores of the steamed bread made with whole wheat flour decreased gradually, and the elasticity, adhesiveness and restorative parameters in texture analysis of the steamed bread decreased, while the hardness, chewiness, gumminess changed irregularly. The differential analysis results indicated that the infestation by Rhizopertha dominica in different growth stages had significant effects on the physicochemical and application quality of wheat (P<0.05). The physicochemical properties and application quality of wheat infested by Rhyzopertha dominica in the larval and adult stages changed more obviously, and the differences with the control sample were more significant (P<0.05). The research results show that the wheat damaged by Rhizopertha dominica in different growth stages can not only cause the change of physical and chemical properties of wheat, but also directly affect their eating quality, and therefore it should pay much attention to the prevention and control of Rhyzopertha dominica in the different growth stages during the wheat storage.