Prebiotic fiber inulin as enhancer of calcium bioavailability in wheat breads. Quality improvement through desirability function

SALINAS MV; ZULETA A; RONAYNE DE FERRER P; PUPPO MC

Paris

Congreso; 6th Dietary Fibre Conference 2015. From fibre functionality to health; 2015

INRA-ICC

During milling a high proportion of minerals and vitamins are lost in wheat grains, resulting in a reduction in the nutritional value of the flour. In Argentina, the fortification of wheat flour with iron, thiamine, riboflavin, niacin and folic acid is required by law. Therefore, deficiencies of some essential nutrients are covered, but not all, such as calcium. According to the National Survey on Nutrition and Health (NSNH, 2007) of Argentina, calcium was one of the most critical nutrients; this mineral was deficient in 45.6% of children (2-5 years old) and in 94.3% of women (10-49 years old). A diet with adequate calcium supplements could help to control diseases caused by deficiency of this element such as osteopenia and osteoporosis. Because the calcium content of white flour, and hence breads made with them, is very low, the contribution to the diet is negligible. Bread is an adequate food for providing calcium to people because it is widely consumed throughout the world. Not only the calcium quantity but also its bioavailability is important. For this reason, it is recommended to include prebiotic together with calcium in bread formulation. Therefore, the objective of this work was to study the effect of calcium citrate and inulin enriched with fructo-oligosacharides (Synergy1, Beneo Orafti) on bread making quality of wheat flour and to optimize a formulation of wheat bread fortified with these high quality nutrients. A factorial design (central composite design, CCD) with two factors (calcium and Inulin) was utilized. Levels of calcium (Ca) from 1.08 to 2.52 g/kg, and inulin (In) from 0 to 13% were analyzed. Control bread (C) without calcium and inulin was studied. Browning Index (BI), specific volume (Vs), moisture and texture properties of crumb were analyzed. BI and Vs were dependent on inulin content. Breads showed higher crust colour and lower volume with increasing prebiotic content. Control crumb bread was the wettest. Calcium citrate in the absence of inulin caused a decrease in moisture, consistent with lower water absorption. The crumb moisture decreased with the increment of prebiotic. Generally, textural parameters mainly varied with the prebiotic. Inulin increased firmness and chewiness but lowered cohesiveness. On the other hand, an increase of calcium content caused a decrease in bread firmness at equal concentration of prebiotic (≤ 12%). Cohesiveness is a parameter related to forces that bind together the components of the matrix; a low value of cohesiveness is generally associated with a low integration of crumb structure.  The model obtained for cohesiveness prediction was: 0.488 - 0.025 In (R2 = 0.93, RMSE = 0.01), showing a significant negative dependency with inulin. Chewiness, calculated as the product of springiness, cohesiveness and firmness, is generally associated to mastication work. With less than 12% inulin, high levels of calcium would facilitate bread mastication (low firmness and chewiness) leading to softer crumbs; nevertheless, chewiness was only inulin dependent (5.596 + 1.073 In ,R2 = 0.84, RMSE = 0.57). Based on the response surface of multiple variables (Vs, moisture, cohesiveness, chewiness) bread formulation was optimized using a desirability function. The best quality bread fortified with calcium and prebiotic was the one that contained 2.4 g/kg Ca and 7.49% In.