Kafirins are the sorghum storage proteins, considered safe for celiac patients. Due to its potential use in gluten-free systems, kafirins have been extracted from several types of sorghum fractions, especially those obtained from dry-milling. Nevertheless, the extraction of these proteins from sorghum gluten meal (SGM) obtained from wet-milling has not yet been explored. In this study, we investigated the differences in composition, color, molecular structures, functionality and <i>in vitro</i> protein digestibility of kafirin extracts obtained from dry-milled flour or SGM obtained from decorticated white sorghum treated with and without endopeptidic protease. Kafirins were extracted using aqueous ethanol and metabisulfite. Kafirin extracts from SGM presented higher protein purity (94.87 vs 85.56%), lower fat content (0.72 vs 2.03%), <i>in vitro</i> protein digestibility (89.46% vs 84.77%), and better water holding (2.82 vs 1.85 g/g) and fat absorption capacities (2.39 vs 1.57 g/g) compared to extracts from ground decorticated sorghum. Color was not affected by treatments. SDS-PAGE showed differences in the low molecular weight patterns of kafirin extracts obtained from SGM whereas FTIR analyses showed reduction of a-helical and β-turn percentages and β-sheet increment after extraction. The proposed protease treatment increased free amino nitrogen and emulsifying index of kafirins, but did not affect other functional properties. Thus, SGM represents a potential and profitable new feedstock for the extraction of food-grade kafirins.

Differences in the functionality and characterization of kafirins extracted from decorticated sorghum flour or gluten meal treated with protease

253rd National Meeting (2017)

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