[Métodos] Extract preparation: Coffee by-product extracts were obtained as described in WO2013004873A1 and were added in the milk base prior to fermentation. Yogurt design: Yogurts formulations were made using UHT cow milk, a commercial soluble dietary fiber and CSE and/or CAE. As a result, 8 yogurt formulations were designed where coffee by-product extracts were included in regular yogurt or yogurts complying with the nutritional claim “high in fiber”. Antioxidant capacity: The antioxidant capacity of CSE, CE and formulated yogurts was measured by the ABTS•+ decolourisation assay. Trolox (0.02-0.25mM) and clorogenic acid (CGA) (0.02-0.25mM) were used as references compounds for quantification. Enzymatic inhibition assay: The study of the inhibition of α-glucosidase was performed using acarbose as inhibitor of reference.

[Conclusiones] The addition of coffee byproduct extracts as novel ingredients in yogurt formulations improved the antioxidant capacity and inhibition of the enzymatic activity of α-glucosidase. Moreover, yogurts containing soluble dietary fiber showed similar results to their homologous formulation without fiber, suggesting that fiber addition did not interfere with the product’s functional properties. Therefore, yogurts high in dietary fiber containing bioactive compounds from coffee byproduct extracts open a new market segment of functional foods involved in the regulation of postprandial glucose response.

[Resultados] Antioxidant capacity: The antioxidant capacity of CSE (135.68mg eq. CGA/g extract, 117.97mg eq. Trolox/g extract) was significantly greater than that of CAE (46.39mg eq. CGA/g extract, 41.25mg eq. Trolox/g extract) (p0.05). Yogurts containing both extracts showed a synergistic effect, increasing the antioxidant capacity of the yogurts by 177% compared to the control. Enzymatic inhibition: CSE and CAE inhibited the activity of α-glucosidase, showing IC50 values of 140μg/mL and 270μg/mL. Yogurts containing CAE and CSE showed significantly higher inhibition of α-glucosidase than the control.

[Introducción] Coffee processing byproducts, such as coffe silverskin (tegument of the coffee bean) and cascara (outer skin of the coffee berry), have potential health promoting properties due to the presence of bioactive compounds. Their use as novel ingredients in the development of functional yogurts is a means of valorizing these fractions and incorporating bioactive compounds in the human diet. Dairy products are one of the biggest market segment among functional foods. We selected yogurt, as it is one of the food products most preferred by consumers as a carrier for functional ingredients.

[Objetivos] The present research aimed to study the antioxidant capacity and inhibitory effect on α-glucosidase of coffee-silverskin-extract (CSE) and cascara-extract (CAE). We also studied the feasibility of using yogurt for vehiculization of bioactive compounds involved in the regulation of carbohydrate metabolism.

[Discusión] To our knowledge, it is the first time that the inhibitory effect of CAE on α-glucosidase is described. As shown for CSE, this effect may be due to the presence of intrinsic polyphenolic compounds.

Este trabajo ha sido financiado por el proyecto SUSCOFFEE (AGL2014EE (AGL2014-57239 -R). M. Iriondo-DeHond agradece al IMIDRA su beca predoctoral.

Trabajo presentado al XII Congreso Internacional Nutrición, Alimentación y Dietética, celebrado en Madrid el 11 y 12 de abril de 2018.

Peer reviewed