ENHANCING THE QUALITY ATTRIBUTES OF RICE BREAD FORTIFIED WITH OKRA MUCILAGE VIA SWEET POTATO (Ipomoea batatas) FLOUR

Abstract

Functional foods (e.g., gluten-free (GF)) products need continuous improvements in quality characteristics. Generally, GF foods like rice bread (RB) are found to be nutritionally poor when compared to gluten-containing ones. Moreover, due to the absence of gluten, technological properties of RB are different from those of wheat bread (WB). This study was conducted on gluten free rice bread (GFRB) for improving its chemical, physical, textural, sensorial properties, as well as staling rate (SR) with adding of sweet potato flour (SPF) and okra mucilage (OM) used as novel hydrocolloid. Hence, the results revealed that as the replacement levels of rice flour (RF) by orange sweet potato flour (OSPF) and/or white sweet potato flour (WSPF) increased, the RB content from ash (0.82-2.13%) and crude fibers (CF) (1.43-5.17%) increased, while the values for crude protein (CP) (5.97-4.20%), total carbohydrates (TC) (86.42-81.43%), and total calories (412-381kcal/100g) decreased comparing to RB prepared from 100% RF. Concerning physical properties, the bread volume (BV) and specific volume (SV) increased, while the baking loss (BL) and bread density (BD) decreased when replacement levels were up to 30% for both types of SPF and vice versa when the ratios were more than 30% for BV,SV, and BD. In terms of texture profile analysis (TPA), the RB samples made from RF replaced by OSPF and/or WSPF at 30% exhibited minimum values of hardness (2.97 and 3.66 N), chewiness (10.95 and 11.22 mJ), and gumminess (2.94 and 3.05 N), and the maximum values of resilience (0.96 and 0.91) and springiness (3.72 and 3.67 mm) for OSPF and WSPF, respectively. However, the superiority was in favor of OSPF. Regarding bread SR, it is clear that increasing substitution levels of RF with OSPF and/or WSPF caused a decreasing trend in the SR until it reached the best ratio at 30% (0.080 and 0.087, respectively). Accordingly, the current study suggested that the substitution of RF by OSPF at 30% was the ideal ratio to produce a high-quality GFRB, where the produced loaves had the same sensory qualities as wheat bread.