# Innovations in Wheat Bread: Using Food Industry By-Products for Better Quality and Nutrition
## 6 Nutritional Value of Bread
The increase in dietary fiber content ranged from 250 to 621% compared to the control sample [103]. Literature data suggest that by-products from apple processing are not significant sources of protein. Their addition resulted in either no differences [120] or a decrease in the protein content in bread [141]. Concerning fat content, a decrease was also observed: from 2.12% d.m. for control bread to 1.53% d.m. for 15% WAP [120] and from 6.72% d.m. for control to 5.82% d.m. for 10% APP [141]. As for the mineral component content in the form of ash, a significant increase was noted in studies on the addition of APP, from 0.54% d.m. to 0.95% for 10% APP. A similar trend was observed in [PERSON] et al. [120] research, but only for samples with 5% MAP addition and 10% WAP addition. In other trials, no statistically significant changes were noted, which the author attributes to randomness. The same author indicates a decrease in sugar content in bread with increasing proportions of apple components, from 2.03% d.m. for control to 1.32% d.m. for 15% MAP. However, [PERSON] et al. [141] reported opposite results: their study showed a significant increase in carbohydrate content in bread after enrichment with APP, from 1.91% for 1% APP to 9.24% for 10% APP, which may result from the high carbohydrate content in the raw material [32]. The findings reveal a significant increase in both total polyphenol content (expressed as grams of gallic acid equivalents per kilogram dry weight) and AA (antioxidant activity expressed as grams of Trolox equivalents per kilogram dry weight) levels in wheat bread following the supplementation of APP, demonstrating a statistically significant (\(p<0.05\)) surge compared to the control sample [141]. Furthermore, notable differences (\(p<0.05\)) emerged among the experimental variants with incremental incorporations of APP. Particularly, bread loaves fortified with 10% APP exhibited a remarkable 4.27-fold increase in total polyphenols (from 0.6 g/kg for CON to 2.65 g/kg for APP 10%) and a significant 1.7-fold surge in AA levels (from 1.65 g/kg for CON to 2.79 g/kg), highlighting the robust impact of this supplementation strategy. In the study conducted by [PERSON] et al. [120], the analysis of polyphenol content revealed a significant increase in breads enriched with apple pomace compared to the control. The total polyphenol content showed a notable increase, ranging from 0.29 mg catechin equivalent per gram dry matter (d.m.) for the control to 0.68 mg catechin equivalent per gram d.m. for 15% WAP (a 155-234% increase with all supplementations compared to the control). Additionally, polyphenol levels were, on average, 16% higher in loaves made with WAP than those made with MAP. While baking typically leads to polyphenol loss, the extent of degradation may vary depending on the form of introduction into the bread formulation. Thermal degradation was more pronounced when polyphenols were added in MAP, likely due to increased exposure to hot air [154]. Conversely, flavonoid fractions, specifically flavonoids and anthocyanins, increased, especially in breads made with MAP. However, breads with WAP showed a higher flavonoid content compared to those with MAP and the control. This discrepancy may be attributed to the labeling of only flavonoids and anthocyanins as markers of the entire range of flavonoids in this study. The remaining flavonoid fractions may have been more abundant in breads with WAP, resulting in higher total flavonoid and polyphenol levels compared to those with MAP. Additionally, WAP acts as a protective barrier for bioactive substances, preventing excessive losses during baking. This observation aligns with similar studies involving grape pomace and pomegranate peel powder, which also demonstrated increased phenolic content in enriched bread [121]. The antioxidant activity, measured in Trolox equivalent antioxidant capacity, varied between 7.80 uM Trolox equivalent per kilogram d.m. for the control sample and 25.37 uM Trolox equivalent per kilogram d.m.