Nutritional Quality and glycemic index evaluation of whole grain flours and breads

MOIRAGHI, MALENA; BUSTOS, MARIELA C.; PAESANI, CANDELA; PEREZ, GABRIELA T.

Rennes

Congreso; 5th International Conference on Food Digestion; 2017

INFOGEST and INRA

The increasing demand for high-fiber products has favored the design of numerous bakery products rich in fiber such as bread, cookies, and cakes. We aim to study the physicochemical properties of whole-grain flour from different commercial wheat cultivars, their performance in breadmaking and the estimated glycemic index (eGI) of breads. We worked with nine wheat grain cultivars corresponding to the 2013/2014 crop grown in INTA Marcos Juárez (32°42' S, 62°07' W), Córdoba, Argentine. Whole grain flours were analyzed for protein, lipids, gluten, soluble (SP) and insoluble pentosans (IP), soluble (SDF) and insoluble dietary fiber (IDF). Bread quality was assessed by specific volume (SV), color and texture. Bread were screened for total and resistant starch fraction and eGI by utilizing an in vitro starch hydrolysis method. Starch digestion were measured by adding α amylase and pepsin to bread. Samples were collected every 30 minutes, up to 180 minutes, and reducing sugars release was measured. Whole-grain flours showed significant differences in the protein content (between 13.4 and 16.8%), gluten (between 30.7 and 41.2%) and pentosans (SP: between 0.44 and 1.07%; IP: between 5.48 and 16.33%), while fiber values were similar in all samples (SDF: 1.48%; IDF: 12.58). Bread quality parameters also showed significant variations between cultivars, showing differences on SV (between 1.79 and 2,0 cm3/g), crumb texture (between 18.1 and 25.8 N) and color. Total starch content from bread varied significantly between wheat varieties (from 21.81 to 33.44%) while resistant starch undetectable which means that all samples present less than 2% w/w (detection limit). Whole-grain breads showed significant different eGI, ranged from 79.9 to 97.19 with an average value of 88.91. Results indicate that besides the effect on technological quality, the cultivar of wheat flour selected highly influence the rate and extent of starch hydrolysis, affecting eGI.