Antioxidative Characteristics and Sensory Acceptability of Bread Substituted with Purple Yam (Dioscorea alata L.)

Abstract

In this study, plain bread was made by substituting wheat flour with purple yam flour (Dioscorea alata, L). The addition of 0, 10, 15, 20, and 30% purple yam flour aims to increase the functional value of plain bread as a source of natural antioxidants. The bread produced with two baking temperatures (170°C and 180°C) was tested for anthocyanin levels, total phenol, antioxidant activity (DPPH free radical scavenging), volume expansion, color, and preference test. The results showed that the temperatures of the bread baking did not affect anthocyanin levels, total phenol, antioxidant activity, volume expansion, and bread color ( p > 0.05 ). The substitution of purple yam flour had a significant effect on anthocyanin levels, total phenol, antioxidant activity, volume, and bread color ( p < 0.05 ). The levels of anthocyanins, total phenol, antioxidant activity, and darker color increased with the addition of purple yam flower whereas the rate of expansion reduced. However, the addition of purple yam flour did not affect the level of preference for the bread produced. Purple yam flour can be added to the manufacture of bread made from wheat flour as much as 30% with a baking temperature of 180°C. The resulting bread contained total anthocyanins 54.62 mg/100 g db, total phenol 391.14 mg EAG/100 g db, antioxidant activity 48.53% and volume expansion 64.85%, color L ∗ = 53.06 , a ∗ = 6.52 , b ∗ = 13.32 , C = 14.87 , H = 64.06 , and sensory score = 3.24 (preferred).

Antioxidative properties and sensory evaluation of white bread containing pre-treated cowpea (Vigna unguiculata L) flour

“…Making plain bread containing cowpea flour refers to [16] with slight modifications. The addition of cowpea flour is 0, 5.2, 7.8, and 10.4% (w/w).…”

“…The addition of ingredients other than wheat flour in making bread changes the color of the product. For example, [16] added purple yam flour to white bread, resulting in a color change pattern.…”

“…In wheat flour, the gluten component affects how much bread expands in volume. The bread's hollow interior shape causes the gluten to coagulate during baking, firming it and preventing the bread's volume from dropping [16]. The impact of pretreatment cowpea flour on the bread sample's expansion volume can be seen in Figure 1.…”

“…The higher the portion of cowpea flour added, the amount of gluten also decreases, this may have an impact on the capacity of the dough to hold produced throughout the process for making bread. The amount of bread development decreased due to the of purple yam flour [16].…”

Physical, Chemical, and Preference Levels of Macaroni, formulated with wheat flour, mocaf flour, and purple yam flour

“…Purple yam flour can be used as a substitute for wheat-based products. Purple yam flour has the potential as an alternative source of carbohydrates, with a starch content of 60.3-74.4% db, protein content of 4.3-8.7% db, ash of 2.9-4.1% db, and total dietary fiber of 4.1 -110% db [3]. The advantage of purple yam flour is the anthocyanin component, which functions as a natural antioxidant.…”