Effect of water soaking pretreatment on the quality of glutinous rice cookies

In this study, we aimed to improve the quality of rice cookies by investigating the preparation of the principal ingredient, glutinous rice (Oryza sativa var. glutinosa 'Dongjin'). The effects of pre-milling water soaking on the quality characteristics of the rice flour and resultant rice cookies were investigated; in particular, the characteristics of cookies made from water-soaked and untreated rice flours were compared. Rice flour, sugar, butter, salt, egg, and baking powder were mixed together to from a dough, which was then cut (thickness 3 mm and diameter 35 mm), baked for 9 min at 170-180°C, cooled, and packaged in plastic bags. In glutinous rice cookies prepared from water-soaked rice flour, the moisture content, water activity, and hue and red-green (h^o and -a∗) color values were significantly higher but the yield, spread ratio, bulk density, hardness, lightness, yellow-blue and chroma (L∗, b∗ and C∗) color values, phenolic compound contents, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity were significantly lower than those prepared from untreated rice flour. These results suggest that the treatment of glutinous rice grain by water soaking before milling affects the quality properties of the resultant cookies, and the pretreatment of glutinous rice results in cookies with a darker color, softer texture, and lower antioxidant ability.