Antioxidant activity of defatted wheat germ affected by hot air and microwaves

MERILES, SILVINA PATRICIA; BORDÓN, MARÍA GABRIELA; PENCI, M.C.; BOILLEREAUX, LIONEL; CURET, SEBASTIEN; RIBOTTA, PABLO DANIEL

Lisboa

Conferencia; 13th International Data Cconference; 2019

The effect of hot air (HA) and microwaves (MW) on the antioxidant activity of wheat germ was evaluated. Processing conditions were: 150, 180 and 200 ºC for HA (air temperature) and 50, 60 y 70 ºC for MW treatments (sample temperature) with 4 intermediate times in each case. Total phenolic content (TPC), radical scavenging activity (ABTS) and reducing power (FRAP) were measured. HA treatment was performed on a convective oven. MW system had a monochromatic wave (2.45 GHz, 300W). Irradiated power varied as a function of surface sample temperature. Deffated raw wheat germ (not thermally treated) had 34.15 ± 0.46 mg GAE/g, 9.76 ± 0.40 mg Trolox/100 g (FRAP) and 10.53 ± 0.44% inhibition (ABTS). In MW processing a significant decrease of TPC was observed, with reductions of 30, 15 and 29% with respect to raw sample at 50, 60 and 70 ºC, respectively. In HA, small variations of TPC as a function of time were observed but there was not a general tendency, which could be attributed to the simultaneous degradation of native compounds and the formation of unstable Maillard reaction products. An increase of the reducing power was observed at 200 and 150 ºC (p