Nutritional potential and inhibitory activity of bread fortified with green coffee beans against enzymes involved in metabolic syndrome pathogenesis

The nutritional potential and selected enzyme inhibitory properties of wheat bread fortified with coffee beans (1, 2, 3, 4, and 5 g/100 g, B1-B5, respectively) were investigated. Replacement of wheat flour with powdered green coffee beans (GCB) significantly decreased the total protein content only in the case of B4. The characteristic starch parameters such as the total starch content, resistant starch, and starch digestibility did not differ significantly between the control bread (C) and the enriched bread samples. Only potentially bioavailable starch was significantly lower in B4 and B5 (311.84 and 325.34 mg/g d.w., respectively), compared with C (392.67 mg/g d.w.). The bread with GCB was characterized by a higher hydrolysis index and expected glycemic index than C but these changes had no significant effect. Moreover, the EC50 value of ACE inhibition noted for bread B2-B5 was significantly lower (in the range of 1.6-7.77 mg/mL) than in C (17.96 mg/mL). The fortification with GCB had an influence on lipase inhibitory activity, whereas this property was not detected for C. The lowest EC50 value was noted for bread B3 and B5 (3.00 and 2.02 mg/mL, respectively). The addition of GCB to bread had no significant effect on alpha-amylase and alpha-glucosidase inhibitory activity.