# Innovations in Wheat Bread: Using Food Industry By-Products for Better Quality and Nutrition
## 6 Nutritional Value of Bread
The bioavailability and bioavailability of phenolic compounds can be influenced by molecular interactions between dietary fiber and other compounds in the food matrix, such as lipids and proteins, as well as interactions between fiber and phenolic compounds [152]. In the study by [PERSON] et al. [149], a significant increase in the bioaccessibility of anthocyanins after in vitro digestion was noted in the bread with the addition of GP compared to the control sample. This increase was particularly noticeable during the transition from the gastric to the small intestine phase. An average bioaccessibility value of 24% for anthocyanins was recorded in the small intestine for both 5% and 10% GP fortification. Additionally, the authors note that the relatively high percentage bioaccessibility values observed at the end of the small intestine phase for other phenolic classes (flavones, and tyrosol equivalents) could promote an antioxidant environment in the digestive tract. The increase in bioaccessibility values observed at the end of the small intestine [149] confirms that the interactions between dietary fiber and phenolic compounds, and the resulting compounds, are key substrates for the colonic microbiota, enabling further processing of phenolics [150]. The increased inclusion of GP in bread led to reduced starch hydrolysis and a lower predicted glycemic index. At the 10% supplementation level, both of these characteristics exhibited approximately a 12-13% reduction [149]. Integrating these results with the previously discussed technological and sensory aspects implies that GP could be a beneficial ingredient for crafting enhanced wheat bread. Nevertheless, it's essential to note that fortifying with GP may influence the sensory attributes of the food, including factors like flavor, color, and texture. Similar to the supplementation of bread with grape pomace (GP), incorporating apple pomace (AP) also enhances the dietary fiber content in the final product. In [PERSON] et al. study [107], where apple pomace or skimmed apple pomace (SAP) was added at levels of 3, 6, or 9% relative to the flour mass, a notable increase in dietary fiber content was observed in the bread dough mixes. Initially, the dietary fiber content (DF) in wheat flour was 2.7% dry matter (d.m.). With 3% supplementation of AP and SAP, the DF content rose to 4.31% and 4.42% d.m., respectively, representing an increase of over 1.5 times. Incorporating 9% of AP or SAP led to respective increases of 2.78 and 2.82 times, categorizing these samples as high-fiber products (meeting the minimum requirement of 6 g/100 g) [152]. Although for the 3% supplementation, the apple raw materials were sieved through US-60 or US-100 mesh, the results showed no discernible differences in DF content resulting from this process. Dietary fiber content was also assessed in the study by [PERSON] et al. [120]. The authors applied 5, 10 or 15% additions of whole apple pomace (WAP) or milled apple pomace (MAP). The total dietary fiber (TDF) content for the control sample was 3.94% d.b., while for samples with only a 5% level of flour substitution, it rose to 8.18% d.b. (WAP) and 8.31% d.b. (MAP). Meanwhile, 15% supplementation resulted in further increases up to 12.95% d.b. and 13.35% d.b. The levels of individual fiber fractions were also determined, showing proportional increases with the supplementation level: IDF increased from 2.92% d.b. for CON to 10.15% d.b. for the 15% addition of WAP, and SDF increased from 1.02% d.b. to 3.16% d.b. for the same sample. It is noteworthy that the SDF content in the obtained bread increased over threefold, likely due to the high pectin content in the apple waste. This is a favorable development, as the positive impact of pectin consumption on health has been demonstrated, including its role in maintaining gut health and cancer therapy [153]. A similar trend was observed when supplementing apple pomace powder at levels from 5 to 25% into another bakery product, namely cookies.