Flavonoids and total phenolic content in extruded buckwheat products with sweet and salty taste
¹Latvia University of Agriculture, Faculty of Food Technology, Department of Nutrition, Riga street 22, LV–3004, Jelgava, Latvia
²Latvia University of Agriculture, Faculty of Food Technology, Department of Chemistry, Liela street 2, LV–3001, Jelgava, Latvia
The aim of research was to evaluate the effect of added ingredients used for taste improvement on flavonoids and total phenolic content in extruded buckwheat products. The added ingredients were – sugar, vanilla sugar, stevia, agave syrup, cinnamon, caraway, garlic powder, sweet pepper powder and salt. Six extruded buckwheat products were analysed, where an extruded buckwheat product without added ingredients was a control sample, two extruded buckwheat products were with sweet taste and three products with salty taste. Total phenolic content was determined using the modified Folin–Ciocalteu method but flavonoid content according to LC-TOF-MS method.
The highest total phenolic content (p < 0.05) was determined in extruded buckwheat product with vanilla sugar + stevia (91.17 ± 0.67 GAE mg 100g-1DW). It was almost three times higher than in the control sample. The significant differences were observed in extruded buckwheat products with caraway + salt + agave syrup (41.5 ± 0.12 GAE mg 100g-1DW) and sweet pepper powder + salt + agave syrup (42.39 ± 0.80 GAE mg 100g-1DW) comparing to other extruded products (p < 0.05). The highest content of rutin and quercetin (p < 0.05) was established in extruded buckwheat product with garlic powder + salt + agave syrup, whereas the highest content of catechin and epicatechin – in extruded buckwheat product with vanilla sugar + stevia. The extruded buckwheat product with caraway + salt + agave syrup in addition contained luteolin, kaempferol and isoquercitrin. The results of research showed that some added ingredients used for taste improvement can significantly influence the total phenolic content and flavonoid content.