Digestibility, biochemical changes and Kafirin polymerization analysis during sorghum grain development

International audienc

Avaliação dos tióis proteicos ao longo da maturação de grãos de trigo em genótipos de diferentes aptidões tecnológicas

O trigo é considerado a matéria-prima mais adequada para a fabricação de pães e massas devido à sua viscoelasticidade, determinada pela qualidade do glúten. Apesar do conhecido impacto dos polímeros de glúten na qualidade do trigo, a dinâmica da formação das pontes dissulfeto, por meio da oxidação dos tióis das cisteínas (PSH), não está completamente elucidada. Este trabalho objetivou o estudo da evolução do estado redox dos PSH de 8 genótipos de trigo (Triticum aestivum) brasileiro ao longo da maturação do grão (estádios leitoso, pastoso, maturação fisiológica, maduro e farinha). Os grãos foram caracterizados quanto ao peso médio, umidade, proteínas totais e PSH pelo método de DTNB. Os grãos maduros apresentaram em média 12% de umidade, 15% de proteína e peso seco de 34,0±2,1 mg/grão. Os teores de PSH variaram de 2,2-8,6 μmol/g (leitoso), 1,7-7,2 μmol/g (pastoso) a 1,0-3,4 μmol/g (maturação fisiológica). Em grãos maduros e farinhas, o teor de PSH foi similar para todas as amostras (2,3±0,6 µmol/g; <2 µmol/g, respectivamente). Três genótipos apresentaram oxidação excessiva nos estádios imaturos. As demais amostras apresentaram um declínio progressivo no teor de PSH, corroborando a literatura e confirmando o envolvimento destes nas pontes dissulfetos intermoleculares de acordo com o desenvolvimento do grão

Foodomics in wheat flour reveals phenolic profile of different genotypes and technological qualities

International audiencePhenolic compounds (PC) strongly contribute to the beneficial health effects of wheat, but their interactions can affect the quality of end-use wheat products. Free and bound PC were comprehensively characterized in 14 wheat flours (Triticum aestivum) from different Brazilian genotypes and technological qualities by using a metabolomics approach (UPLC-ESI-QTOF-MSE) combined with classical characterizations: colorimetry, ash, protein, starch and total phenolic content (TPC). Globally, 43 PC were identified: 33 (bound, 28 (free) and 15 in all flours, regardless of extract. Ferulic acid isomers were the most abundant PC, representing 25–50% of ion abundance depending on genotype. Campeiro, Sossego and Topázio genotypes showed a distinguished profile, with the highest total relative abundance of PC. TPC was significantly higher in flours with higher gluten strength (66.5–58.0 mg GAE/100 g flour). The ratio free-to-bound of PC averaged 1.15 between the flours of different technological qualities. Although PCA highlighted specific PC related to technological qualities, the genotype effect was very pronounced. This study correlates the phenolic profile and technological quality of wheat flours and provides the most recent data on the secondary metabolites profile, especially PC in refined flour, attesting to its significant nutritional importance due to its large consumption in refined forms

Effect of extrusion and turmeric addition on phenolic compounds and kafirin properties in tannin and tannin-free sorghum

International audienceSorghum is a potential substitute for corn/wheat in cereal-based extruded products. Despite agronomic advantages and its rich diversity of phenolic compounds, sorghum kafirins group together and form complex with tannins, leading to a low digestibility. Phenolic content/profile by UPLC-ESI-QTOF-MSE and kafirins polymerization by SE-HPLC were evaluated in wholemeal sorghum extrudates; tannin-rich (#SC319) and tannin-free (#BRS330) genotypes with/without turmeric powder. Total phenolic, proantocyanidin and flavonoid contents were strongly correlated with antioxidant capacity (r > 0.9, p < 0.05). Extrusion increased free (+60%) and decreased bound phenolics (−40%) in #SC319, but reduced both (−40%; −90%, respectively) in #BRS330, which presented lower abundance after extrusion. Turmeric addition did not significantly impact antioxidant activity, phenolic content and profile and kafirins profile. Tannins presence/absence impacted phenolic profiles and polymerization of kafirins which appears related to the thermoplastic process. The extrusion improved proteins solubility and can positively enhance their digestibility (phenolic compounds-proteins interactions), making more accessible to proteolysis in sorghum extrudates

Phenolic composition and kafirin digestibility of Sorghum bicolor is impacted by food processing and by germination

International audienc