# Innovations in Wheat Bread: Using Food Industry By-Products for Better Quality and Nutrition
## 4 Head Quality
### Baking Properties
Crumb porosity of flathead changes from 24% for the control bread to 18% for bread with 15% olive pomace supplementation. In contrast, [PERSON] et al. [26] did not demonstrate a negative impact of adding olive pomace on the volume of traditional bread, even with 20% supplementation. This difference may partially result from variations in the baking methods of flat and traditional bread. Moreover, the conducted research showed that the time (up to 6 months) and temperature of storing olive pomace (4 \({}^{\circ}\)C or \(-20\)\({}^{\circ}\)C), as well as the type of wheat flour used (all-purpose white or whole wheat flour), do not cause significant changes in the volume of wheat bread. One of the crucial physical characteristics of bread is its crumb moisture. An appropriately moist crumb is a guarantee of good-quality bread that retains freshness and does not crumble when sliced. Literature data also indicate that an increase in crumb moisture is negatively correlated with its energy density [17]. Literature reports on the influence of both grape and apple processing by-products on the moisture of fresh crumb are varied. While [PERSON] et al. [20] and [PERSON] et al. [123] observed a slight reduction in crumb moisture for bread with a 10% addition of grape pomace, [PERSON] and [PERSON] [121] observed a significant increase in crumb moisture due to the introduction of 5% and 10% grape pomace. This increase in moisture was observed across four different grape varieties (Muscadine (Noble and Scuppernong) and Cabernet (Franc and Sauvignons)). Similarly, [PERSON] et al. [120] showed that the addition of apple pomace also leads to a significant increase in the moisture content of fresh crumb compared to wheat bread. Their research indicated that, in addition to the supplementation level, the degree of pomace fragmentation plays a significant role in crumb moisture. At a 15% supplementation level, there was a 12% and 19% increase in moisture compared to the control for bread supplemented with whole and milled pomace, respectively. Crumb taken from loaves containing milled pomace contained more hydrated parts of the pomace, while those from loaves with whole pomace contained less hydrated pomace. An increase in bread crumb moisture was also observed in studies on wheat bread with the addition of micronized dietary fiber obtained from apple pomace up to 20% [114]. Introducing olive pomace into bread at a 10% level results in a significant increase in bread moisture compared to wheat bread [18]. Both 24 and 72 h post-baking, bread supplemented with olive by-products exhibited significantly higher moisture content than the control sample. Hydroxyl groups within the dietary fiber structure form hydrogen bonds with water, leading to increased moisture levels in doughs with elevated fiber content. Some water molecules bind to the hydrophilic groups of fibers, forming bound water that resists evaporation during baking. Similarly, bread supplemented with flaxseed by-products behaves in the same way. The use of by-products from flaxseed, at a level up 15% in bread production resulted in a significant increase in the moisture of fresh crumb compared to wheat bread [17; 126]. Authors suggest that the higher crumb moisture content of bread may result from the increased water retention ability of the soluble dietary fiber fraction, which, as a hydrocolloid, has high water-holding capacity [127]. Additionally, hydrocolloids could form a network that acts as a barrier to gas diffusion during baking, reducing vapor losses and leading to higher moisture content in bread crumb [128]. The increase in moisture content in breads with by-products is mostly attributed to the high water-binding capacity of dietary fiber. The hydration capacity of fiber depends mainly on its botanical origin and composition [129]. However, many studies lack information regarding both the origin of the raw materials and the fractional composition of dietary fiber.