Effect of fiber sources on fatty acids profile, glycemic index, and phenolic compound content of in vitro digested fortified wheat bread.

Key Points

There has been a decreased intake of dietary fiber (DF) in typical diets. One of the main sources of DF is bread. Because of the low-gluten content of flaxseed meal, incorporation into baked goods may result in a low-quality bread product. Therefore, there is a need to further examine and evaluate the usage of flax DF in bread production. This study examined the content of DF, fatty acid composition, and polyphenol content in bread with oat (OB), flax (FB), and apple (AB) DF. Then, an in vitro digestion was performed to assess the bioaccessibility of fatty acids, and to establish the glycemic index of bread. The highest protein content was observed in flax DF preparations (29.1%), while this preparation was the lowest in carbohydrates (0.7%). The addition of flaxseed flour was also responsible for decreasing the starch digestibility. Oat, flax and apple DF could be perceived as valuable ingredients to enrich nutritional value of fortified white bread. The obtained values estimated glycemic index were very promising because the application of oat, flax and apple DF in bread led to its lower glycemic index. In terms of phenolic compounds, the most bioaccesible phenolics were observed in the bread with flaxseed DF addition. The work could give sufficient knowledge about glycemic index, fatty acid profile and phenolic content in parallel in terms of DF application in breads. DF which are by-products of some technological processes could be introduced in many other bakery branches.

ABSTRACT

In this study, some dietary fiber (DF) sources were investigated as fortifiers of wheat bread: oat (OB), flax (FB), and apple (AB). Adding oat and flax fibers to bread significantly changed the fatty acid profiles. OB was highest in oleic acid (33.83% of lipids) and linoleic acid (24.31% of lipids). Only in FB, γ-linolenic fatty acid was present in a significant amount-18.32%. The bioaccessibility trails revealed that the DF slow down the intake of saturated fatty acids. PUFA were least bioaccessible from all fatty acids groups in the range of (72% in OB to 87% in FB). The control bread had the greatest value (80.5) and was significantly higher than values for OB, FB, and AB in terms of glycemic index. OB, FB and AB addition led to obtain low glycemic index. AB had a significant highest value of total phenolic (897.2 mg/kg) with the lowest values in FB (541.2 mg/kg). The only significant lowering of caloric values in this study was observed in AB. The study could address the gap in the area of research about taking into consideration glycemic index, fatty acid profile and phenolic content in parallel in terms of DF application in breads.