Physicohemical Properties of Extruded Rice Flours and a Wheat Flour Substitute for Cookie Application

압출쌀가루의 이화학적 특성 및 밀가루 대체 쿠키 특성

  • We, Gyoung Jin (Department of Food Science and Technology, Sejong University) ;
  • Lee, Inae (Department of Food Science and Technology, Sejong University) ;
  • Kang, Tae-Young (Department of Food Science and Technology, Sejong University) ;
  • Min, Joo-Hong (Department of Bio-Health Technology, Kangwon National University) ;
  • Kang, Wie-Soo (Department of Bio-Health Technology, Kangwon National University) ;
  • Ko, Sanghoon (Department of Food Science and Technology, Sejong University)
  • 위경진 (세종대학교 식품공학과) ;
  • 이인애 (세종대학교 식품공학과) ;
  • 강태영 (세종대학교 식품공학과) ;
  • 민주홍 (강원대학교 생명건강공학과) ;
  • 강위수 (강원대학교 생명건강공학과) ;
  • 고상훈 (세종대학교 식품공학과)
  • Received : 2011.11.01
  • Accepted : 2011.11.15
  • Published : 2011.11.30

Abstract

The purpose of this study is to prepare extruded rice flours suitable for baking rice cookies. The extruded rice flours were prepared at 100 and 130$^{\circ}C$ temperature and 25 and 27% moisture content in a co-rotating twin screw extruder. The rice extrudates were dried at 100$^{\circ}C$ for 18 hr and subsequently ground into the fine flour. Characteristics of the extruded rice flours were examined by rapid visco analysis, hydration property analysis, differential scanning calorimetry (DSC), and in vitro digestion test. Water absorption, solubility, and swelling power of all extruded rice flours were higher than those of native rice flour. DSC analysis showed that native rice flour had a peak at about 65$^{\circ}C$ while all extruded rice flours did not show any peaks since they were already gelatinized during the extrusion proess. Viscosity of the extruded rice flours decreased with increasing temperature and lowering moisture content in the extrusion proess. The extruded rice flours prepared at 130$^{\circ}C$ exhibited lower viscosity than those prepared at 100$^{\circ}C$. The operating temperature of the extrusion proess was critical for the starch digestion in vitro. The extruded rice flours prepared at 130$^{\circ}C$ showed a rapid decrease in digestible starch content while an increased level of slowly digestible starch content was observed compared to those treated at 100$^{\circ}C$ in the extruder. Cookies were prepared with a mixture of wheat flour and extruded rice flours at the ratio of 7 to 3. The cookies made with the extruded rice flours had lower spread factor and darker yellow color than those prepared with wheat flour only. Hardness of the extruded rice flour-added cookies was similar to that of the wheat flour cookie whereas their overall acceptance was better. Therefore the rice cookies partially supplemented with extruded rice flours may have a potential as early childhood foods which require soft texture and allergy reduction.

Acknowledgement

Grant : 쌀가루 이용성 증진 연구 및 실용화 기술 개발

Supported by : 농촌진흥청