The purpose of present research is to produce sourdough bread by using rice bran as the ingredient for sourdough and to analyze its physiochemical properties and organoleptic properties. The intention is to identify the optimal addition rate of rice bran based on the study results. As samples, sour starter are produced by adding rice bran to flour at the ratio of 25%, 50%, 75%, and 100% to use them for producing sourdough bread.
The study results are as follows.

Regarding the pH of sour starter, all samples show a decrease by lapse of time and addition of rice bran leads to an increase in pH. Regarding the pH right after kneading the dough and 1st fermentation, the order is B50 > B25 > CON > B75 > B100 while the pH of completed sourdough bread is the lowest at B50 and the highest at CON.

Sour starter added with rice bran have greater fermentation power whereas the fermentation power decreases when rice bran is added above certain amount.

As a result of analyzing the specific volume, the weight is not significantly different whereas the volume increases when rice bran is added, leading to decreased specific volume.

Regarding moisture content, CON is the highest and B100 is the lowest, which is caused by lower moisture content of rice bran compared to flour.

The results of chromaticity analysis are as follows. CON has the highest L-value(brightness) while the a-value(redness) and b-value(yellowness) are increased when rice bran is added.

As a result of analyzing the texture, sourdough bread produced with sour starter without rice bran has greater springiness and resilience than those of CON whereas adhesiveness and cohesiveness do not demonstrate a statistical difference. Also, the experimental group produced with sour starter containing rice bran has higher hardness, chewiness, and gumminess than those of CON.

The preservation analysis demonstrates that the hardness of all samples increases as time goes by and B100 shows the largest rate of increase, which indicates the fastest aging process among the samples. Moreover, the moisture content in all samples decreases by lapse of time.

Among the results of sensory test, the result of preference test is as follows. The flavor gets stronger when rice bran is added but it is accompanied with decreased appearance and texture thus B50 has the highest preference in overall. In the test of property difference, the volume in general decreases more than CON while the experimental group added with rice bran shows greater level of roughness, color of crust and crumb than those of CON. In common with the volume, CON has the largest size of grain whereas the uniformity of the grain shows an opposite tendency in the order of B100 > B75 > B50 > B25 > CON. The experimental group added with rice bran has greater level of hardness, chewiness, and crumbliness than those of CON. Also, the ease to tear, springiness, moistness, and stickiness show an opposite tendency where they are decreased when rice bran is added. The rice bran flavor, flour flavor, sour flavor, grain flavor, and savory flavor are increased in the sourdough bread added with rice bran, and B100 has stronger sour flavor. The sour taste is also strongest in B100 whereas sweetness is the opposite where the control group without rice bran has higher sweetness than that of the experimental group added with rice bran. The savory taste is in the order of B50 > CON > B25 > B75 > B100, which indicates that addition of rice bran leads to stronger bitter taste and interferes with the savory taste. The particles left in the mouth and the flavor after swallowing are increased when rice bran is added.

In sum, as a result of examining the quality characteristics and preference based on organoleptic properties of sourdough bread produced with sour starter added with rice bran, the sourdough bread added with 50% of rice bran has the best quality characteristics. This research may contribute to commercialization of a new product added with rice bran and to high-end strategy of bread and bakery industry.