Superheated steam treatment on wheat bran: Enzymes inactivation and nutritional attributes retention

Abstract

Superheated steam (SS) was used to inactivate peroxidase and lipolytic enzymes of wheat bran (WB) in this study. Meanwhile, the effects of SS on nutritional attributes of WB were also evaluated. Compared with conventional hot air (HA) treatment (16 min), SS processing could inactivate enzymes of WB within a much shorter time (7 min). SS processing did not cause the loss of non-starch nutrients (lipid, protein, ash and dietary fiber) or promote the oxidation of lipids in WB. Superheated steam-stabilized wheat bran (SS-WB) also showed comparable antioxidant activities to that of native WB. However, compared with hot air-stabilized wheat bran (HA-WB), SS-WB exhibited a brighter color (L* value, 69.96 and 64.65, respectivly), higher extractable phenolic compounds contents (3736.7 and 2952.1 μg GAE/g WB d.b., respectivly) and stronger antioxidant activities (13.76 and 11.95 μmol Trolox equivalent/g WB d.b., respectivly) as well as lower peroxide value (1.27 and 1.81 meq O2/kg d.b., respectivly), higher unsaturated fatty acid contents (64.05% and 58.11%, respectivly) and sensory evaluation scores. Therefore, SS treatment should be a new efficient technology that could stabilize WB while maintain its nutritional attributes at the same time. The resultant SS-WB may be a potential alternative to native WB and HA-WB.