Changes in physico-chemical properties of native and toasted defatted soy flour on submission to electron beam radiation

Abstract

Ionizing radiations are increasingly being used to disinfest raw material for several food products. Toasted and native soy flour, the major food ingredients in bread and bakery industries, can be disinfested prior to use through electron beam. However, this can induce changes in the nutritional and functional properties, which can ultimately affect the quality and the nutritional value of the final products. In the present study, toasted and native soy flour were submitted to electron beam (EB) irradiation at 4.8, 9.2, 15.3 and 21.2 kGy; and assessed for water absorption capacity (WAC), protein dispersibility index (PDI), protein solubility, trypsin inhibitor (TI) content, isoflavones content, in vitro protein digestibility (IVPD), glycinin (11S) to -conglycinin (7S) ratio, and lipoxygenase. WAC declined slightly (P < 0.05) in toasted soy flour, but increased significantly (P < 0.05) at low doses in native soy flour. In both toasted and native soy flour, slight decline was noted in protein solubility while TI and lipoxygenase declined significantly (P < 0.05). However, the decline noted in TI content was not proportionate to the increase in IVPD. PDI remained unchanged in toasted soy flour but declined significantly (P < 0.05) in native soy flour. 11S to 7S ratio increased significantly (P < 0.05) in toasted flour at all the doses. In general, significant (P < 0.05) decline in isoflavones was noted in both toasted and native soy flour. In conclusion, the results showed that EB irradiation could induce desirable changes in the nutritional/functional properties of toasted and native soy flour, though at the expense of some of the physical properties.