The change in antioxidant activity characteristics of buckwheat flour after microwave supported heat-moisture treatment

The use of microwaves for the physical modification of flours and starches is a fast and more effective alternative to conventional hydrothermal treatments that is still poorly studied. In this study, microwave treatments were carried out with buckwheat flour, which is a gluten-free pseudocereal flour notable for its high protein content and its phenolic and antioxidant compounds. Hydrothermal treatments (HMT) can be applied to food through a wide variety of procedures. The application of microwave radiation (MW) has been increasing. MW energy has the characteristic of being a non-ionizing energy whose foundation lies in the rapid alternation of high-frequency electromagnetic fields within the products, producing temperature increase, due to the friction between the molecules, which quickly orient themselves towards these electromagnetic fields. The studied factors were buckwheat flour origin, humidity of the samples before the treatment and exposure time to microwaves. Taking two types of Polish buckwheat flours (controlled variety and commercial flour), their initial moisture was adjusted to 20% and 30% and then two microwave treatment times were tested. The microwave treatment also had a significant effect on the functional (viscometric profile) and technological properties (water absorption capacity, oil absorption capacity, water absorption index, and swelling power) of flours but negative on the total content of polyphenols, soluble polyphenols and antioxidant activity. However, the effect was positive on the insoluble polyphenols, getting a greater extraction of them, if compared with samples of untreated flour.