Baking characteristics of gluten-free rice bread were investigated, when 20, 30, 40, 50 and 60℃ water was added during mixing. The temperature of the dough before fermentation was affected by the temperature of the water and the mixing time. When 60℃ water was added, the specific gravity of the dough was the highest before fermentation (p<0.01). The specific gravity of the dough after fermentation was 32~39% of the specific gravity of the dough before fermentation. When 50℃ water was added, the volume and the specific volume of rice bread were higher than those in addition of water at other temperatures (p<0.001). In case of adding water of 50℃, the shape of the rice bread showed the largest volume, high appearance and a round shape. After storage for 2 and 24 hours, the addition of water of 50℃ resulted in the lowest hardness and chewiness values of rice bread. The sensory descriptive analysis revealed that when 50℃ water was added, the air cell size, springiness and hardness values of gluten-free rice bread were lower than those in addition of water at other temperatures. There was a difference in the appearance and texture of gluten-free rice bread, when 20, 30, 40, 50 and 60℃ water was added during mixing.

The physical characteristics of gluten-free rice bread, commercial rice as well as wheat bread marketed in Korea were delineated, a sensory descriptive analysis performed, and a consumer acceptability study conducted. Both the specific gravity and color of gluten-free rice bread were higher than those of commercial rice and wheat bread. The sensory descriptive analysis revealed that the adhesiveness, fracturability, fermentation odor, and the powdery mouthfeel of gluten-free rice bread were higher than those of commercial rice and wheat bread. In contrast, the sweet odor, sweetness, egg taste, butter taste, and milk taste of gluten-free rice bread were lower than those of commercial rice and wheat bread. The consumer acceptability results revealed differences regarding odor, appearance, taste, texture, and overall acceptance between a blind test and an informed test of gluten-free rice bread, commercial rice, and wheat bread. The consumer acceptability findings were associated with those of the sensory descriptive analysis. In overall, the results indicated that the quality of gluten-free rice bread can be improved by controlling the decrease of adhesiveness, fracturability, and powdery mouthfeel.

The effects of mixing speed (3, 6 and 10 speed) and time (2, 5 and 10 min) on the dynamic viscoelasticity of dough and the baking properties of gluten-free rice bread were investigated. The specific gravity of the dough was not affected by the mixing speed and time before and after fermentation. The elasticity (G') and viscosity (G") of the dough increased and the tan δ (G"/G') decreased with higher mixing speeds and longer mixing times. The specific volume of the gluten-free rice bread was affected by the mixing time in response surface methodology (RSM). The hardness of the gluten-free rice bread showed a decreasing trend as the specific volume for the gluten-free rice bread increased. The appearance of the gluten-free rice bread was symmetrical at high mixing speeds and long mixing times. Overall results indicated that the quality of gluten-free rice bread could be improved by controlling the mixing speeds and mixing times for the dough.

The baking properties of gluten-free rice bread with different percentages of corn starch and waxy corn starch were investigated. The specific gravity and color (L, a, b) of the dough as well as the appearance, color (L, a, b) and texture of the rice bread were analyzed. Replacement of rice flour with 1, 2.5, 5, 7.5 and 10% corn starch did not have a significant effect on the specific gravity and color of the dough. The volume and specific volume of the rice bread showed an increasing trend as the amount of added corn starch increased. The chewiness, gumminess and hardness of the rice bread showed a decreasing trend as the amount of added corn starch increased. Replacement of rice flour with 1, 5 and 10% waxy corn starch did not have a significant effect on the specific gravity and color of the dough. The color of the rice bread showed an increasing trend as the amount of added waxy corn starch increased. These results suggest that replacement of rice flour with 7.5% corn starch or 1% waxy corn starch is effective for gluten-free rice bread.

본 연구에서는 자포니카 타입 품종 중 하나인 설갱을3가지(100, 200, 300mesh)입도크기로 나눠 제분하여 글루텐 프리 쌀 식빵을 제조하고 빵의 부피, crumb의 경도, 색도, 외관형태를 통해 제빵 적성에 가장 적합한 입도를 결정하였다. 100mesh를 통과한 쌀가루로 제조한 쌀 식빵의경우 기공이 일정하지 않고 crust의 갈라짐 현상이 발생하였고, 300mesh를 통과한 쌀가루로 제조한 쌀 식빵의 경우반죽을 형성하기 위한 물에 의해 발효과정이 적절하지 않게 진행되어 반죽이 부풀지 못해 좋지 않은 품질의 빵이제조되었다. 200mesh 체를 통과하여 제조된 쌀 식빵의 경우 가장 큰 비체적과 낮은 crumb의 경도, 균일한 기공모양등 제빵 적성에 적합한 것으로 나타났다. 쌀은 밀에 비해쌀알의 경도가 높아 미세한 입자크기를 갖도록 제분할 때전분에 손상이 과하게 발생하는 단점이 있는데, 이와 달리설갱 품종은 일반 쌀 품종에 비해 쌀알의 경도가 낮아200mesh 체를 통과하는 미세한 쌀가루를 제조하는 과정에서도 전분의 손상도가 낮게 제분할 수 있는 특징을 보였다.이러한 연구결과를 통해 글루텐 프리 쌀 식빵을 제조하는데 있어 가장 적합한 쌀가루의 입도를 결정할 수 있다.

본 연구에서는 자포니카 타입 3품종(설갱, 고아미, 백진주)의 쌀을 이용하여 글루텐 프리 쌀 식빵을 제조하고 제빵 가공적성을 빵의 부피, TPA, crust의 색도를 통해 평가하였다. 품종별 특성을 보았을 때 손상전분의 함량은 4.5% 이내, 아밀로스 함량은 20-25% 일 때 가장 적합한 것으로 확인되었는데, 3종류의 품종 중 설갱으로 식빵을 제조했을 때 부피가 가장 크고, 기공 분포 상태가 양호하며, crumb의 경도가 낮아 식빵을 제조하는데 가장 적합한 품종인 것으로 나타났다. 설갱은 쌀알의 경도가 다른 품종에 비해 낮아 분쇄가 쉽게 이루어질 수 있는데 이러한 설갱의 특징은 손상전분의 함량이 적게 미분할 수 있으며 중간 정도의 아밀로스 함량을 가지는 품종에 특성상 제빵적성에 적합한 것으로 생각된다. 이러한 결과를 통해 쌀 식빵을 제조하는데 있어 설갱이 제빵적성에 가장 부합하는 품종이며 이를 활용하여 쌀 식빵을 제조했을 때 가장 좋은 품질의 식빵을 얻을 수 있을 것으로 기대된다.