Effect of Ionising Irradiation on Wheat Flour

Abstract

Radiation processing suppresses the development of microorganisms and pests in food products. This method is safe and does not affect nutritional value; however, it may change the properties of starch and proteins. The research objective was to define the effect of ionization on the baking properties and safety indicators of wheat flour. The study featured wheat flour subjected to gamma irradiation at 0–47.52 kGy, as well as dough and bread made from this flour. The flour samples were tested for the radioactivity of radionuclides; a set of experiments revealed their microbiological indicators and falling-number values. The dough samples were studied on an Alveograph and a Mixolab analyzer to define their structural and mechanical properties. The quality of bread was evaluated by its specific volume, shape stability, and sensory profile. The flour proved safe in terms of residual gamma radiation after 24 and 72 h. At the maximal dose of gamma radiation, the total viable count of mesophyll aerobic and optional-anaerobic microorganisms decreased by fifteen times, whereas the amount of mold decreased by five times. The total strain energy, elastic properties, and elasticity index of the dough declined by more than 50%. The dough had a lower stability during kneading. Its gelatinization onset started earlier by 2.3–3.3°C. The falling number decreased by more than four times, probably, due to the changes in the state of wheat starch. The bread samples had a smaller specific volume and a lower dimensional stability. They also demonstrated signs of darkening, stickiness, and crumb crushing at the maximal irradiation dose (47.52 kGy). The microbiological safety indicators of wheat flour increased at the maximal irradiation dose. However, the baking properties of flour decreased. The sensory and physicochemical parameters of bread quality started to deteriorate at ≥ 23 kGy. Therefore, ionization cannot be recommended as a disinfection method for baking wheat flour production.

Keywords

• bakery
• radiation activity
• radionuclides
• protein
• starch
• technological properties
• quality
• safety