## 3 Results and Discussion
### Effects of Waxy Barley Bran Blend Ratio  
#### 3.3.1 Appearance and Color  
Figure 3 displays images of the bread cross-sections. The highest bread height was observed in the bread with 10% IBLP replacement group, surpassing that of the control. However, with an increase in IBLP replacement proportions to 30% and 50%, the height decreased. The height of the bread with 30% OBLP replacement group was lower than those in the control, 10%, and 30% IBLP replacement groups but was comparable to that in those with a 50% IBLP replacement group. The color of the bread was comparable in the control and 10% IBLP replacement groups, but it shifted from cream to a slightly brown hue in the other two IBLP replacement groups. Bread with 30% OBLP replacement group exhibited a brown color. Cross-sectional observations under a stereomicroscope revealed that the crumb structure of the breads in the control and 10% IBLP replacement groups were finer, characterized by smaller and more uniform bubbles with thinner dough surrounding them. In contrast, the breads in the 30% and 50% IBLP and 30% OBLP replacement groups had an increased number of larger bubbles and a thicker dough around the bubbles. Color measurements are shown in Figure 3. The highest L* value (lightness) was observed in the control (73.59), with progressively darker shades in the 10% IBLP replacement group (72.22), 30% IBLP replacement group (66.01), 50% IBLP replacement group (59.12), and 30% OBLP replacement group (56.41), respectively. Compared to that in the control group, the L values differed significantly in the 30% and 50% IBLP and 30% OBLP replacement groups (\(p<0.05\)), but not in the 10% IBLP replacement group. Furthermore, no significant difference was observed between the 50% IBLP and 30% OBLP replacement groups. Figure 3: Comparison of digital camera images, stereomicroscope images and color differences of bread with different waxy barley bran content. The values are presented as means and standard errors (\(n=10\)). Different letters (a–e) indicate significant differences (\(p<0.05\)). IBLP—inner bran layer powder; OBLP—outer bran layer powder. The a* value (red-green) was the highest and most intense in the 30% OBLP replacement group (5.42). The other replacement groups also showed significantly higher a* values (3.65, 1.12, \(-\)0.07 in 50%, 30%, and 10% IBLP, respectively) than the control group (\(-\)0.64; \(p\) < 0.05). The b* value (yellow-blue) was highest in the 30% OBLP replacement group (22.71), indicating a strong yellow tone, though this was not significantly different from that in the 50% IBLP replacement group (22.14). The 30% and 10% IBLP replacement groups exhibited significantly higher b* values of 16.92 and 12.67, respectively, than the control group (11.18; \(p\) < 0.05). In powdered form, both IBLP and OBLP were cream-colored. However, when incorporated into bread dough and baked, the crumb color turned brown as the substitution percentage increased. OBLP, in particular, produced a noticeably browner crumb color even with 30% substitution, evidenced by lower L* values and significantly higher a* and b* values. This trend was consistent with the appearance in photographs. Darker colors, typical of whole-grain products, may be less attractive to consumers [25]. Nonetheless, a proportion of 30% IBLP is considered acceptable for the production of whole-grain bread. IBLP and OBLP contain many polyphenols [26]. Specifically, catechins (14-41 mg/g), the main proanthocyanidins, include the dimeric prodelphinidinB3 (48-106 mg/g) and procyanidinB3 (63-126 mg/g), the trimeric prodelphinidinC2 (40-105 mg/g) and procyanidinC2 (31-81 mg/g) [27]. For example, it has been reported that catechins, when oxidized, produce dark-colored substances such as theaflavins, thearubigins and theabrownins, which turn bread brown [28]. Catechins significantly accelerated the browning of barley water extract and barley paste by heating [29]. Procyanidins cause the red color of rice with added red beans due to oxidation [30].