Physicochemical properties of enzyme-treated waxy rice flour and expansion properties of Gangjung (a traditional Korean oil-puffed rice snack)

Abstract

Long steeping process of waxy rice involved in Gangjung production is essential for obtaining good quality Gangjung, but it causes many related problems. The objective was to examine physiochemical properties of waxy rice flour and expansion properties of Gangjung manufactured using waxy rice flour treated with protease (P-flour), alpha-amylase (A-flour), or in combination of the two (PA-flour) over different durations. While crude protein and reducing sugar contents of P-flour and A-flour differed depending on enzyme treatment time, it was not observed for PA-flour. Gangjung made with P-flour or A-flour could show similar expansion rate to that of Gangjung made with waxy rice flour steeped under the optimal condition, however, Gangjung made with PA-flour showed lower expansion rate than of the optimal one. These findings indicate that treatment of waxy rice flour with either protease or alpha-amylase, but not both, could reduce the steeping time involved in Gangjung production.