## 3 Results
### Baking Loss and Specific Volume  
Baking loss and specific volume are important quality parameters of bread and are shown in Figure 1b and 1c, respectively. The lowest baking loss of the enriched breads  
Figure 1: Moisture content (**a**), baking loss (**b**), specific volume (**c**), total phenolic content (**d**), and antioxidant activity (**e**) of control and enriched breads. Values of each parameter with the same letters were not significantly different (\(p\) > 0.05).  
(10.11%) was found for the bread with the 3.13% addition of PHP, and the highest baking loss (14.87%) was found for the bread with the 4% addition of FGS. The baking loss values were lower for all the enriched breads (except for the breads with FGS) than for the control bread. This may be attributed to the fact that flours with fat, fiber, and gluten have free proteins that can bind free water in the dough, which prevents water evaporation and reduces baking loss [3; 32]. The baking loss was influenced by the type and level of the additives (\(p<0.05\)), and the control bread was significantly different from the enriched breads, except for the breads with FGS (Figure 1b). Furthermore, the baking loss values did not increase or decrease uniformly as a function of the level of additive; as the FGS content increased from 0.5% to 4%, the baking loss of the breads first decreased and then increased, with only the breads with FGS showing a statistically nonsignificant difference as a function of the change in additive level (Figure 1b). As mentioned above, the change in the other enriched breads was statistically significant (\(p<0.05\)). The comparison of the type and level of additives showed that PHP was the most effective at reducing baking loss. Thus, pistachio hulls can be used to reduce baking loss. This result can be explained by the higher moisture content of the bread samples enriched with pistachio hulls.  
The values of the specific volume of the breads enriched with different additives varied between 2.91-3.58 cm\({}^{3}\)/g for PHP, 3.19-3.56 cm\({}^{3}\)/g for FPH, 3.30-3.67 cm\({}^{3}\)/g for GSP, and 3.32-3.76 cm\({}^{3}\)/g for FGS. When comparing the specific volume of each enriched bread with that of the control bread (3.59 cm\({}^{3}\)/g), it was found that the addition of pistachio hulls (both fresh and dry) resulted in a decrease in the specific volumes of the breads, while the addition of grape seeds in small amounts increased the specific volumes. There were also significant differences in the specific volume between the control bread and the enriched breads (except for the breads with the 0.5% additions of PHP and FPH) (Figure 1c, \(p<0.05\)). The FGS breads had the highest specific volume, and the PHP breads had the lowest specific volume. Due to the higher water-holding capacity of the pistachio hull, which is a source of polysaccharides and dietary fiber [17], the water requirement of the dough increased, and the achievable volume was limited. In this process, the interaction between gluten and fiber resulted in a decrease in gas retention ability and a decrease in bread volume [33]. The specific volume always decreased as a result of fiber addition, which was previously reported by [PERSON] et al. [27]. In addition, the results of the ANOVA showed that the type and level of additives had a significant effect on the specific volume, and it was clear that the specific volumes of all enriched breads decreased with an increasing level of additive (Figure 1c), and thus, low amounts of additives could be beneficial, while higher amounts could have negative effects on the specific volume.