Impact of food processing on the in vitro and in vivo glycemic response to citrus fiber-enriched dough products

Frequent consumption of processed, high-glycemic, low-fiber foods is associated with an increased risk of hyperglycemia, hyperinsulinemia, and ultimately of type-2 diabetes. This work investigated the impact of enriching high-glucose doughs with citrus fiber and various processing methods (baking and extrusion cooking) on glycemia using a novel combination of in vitro and in vivo methodology and relating to product-specific characteristics. Starch digestibility, dietary fiber composition, product structure and in vitro glucose release were determined. In vivo glycemia and insulinemia were evaluated in 11 adults at metabolic risk in a randomized, double-blind crossover study. The fiber-enriched products significantly reduced in vitro glucose release by up to 15 %. Extrusion at 180 °C increased soluble and total dietary fiber contents by 10 % and resistant starch content by 60 %, impairing in vitro glucose release. Neither fiber-enrichment nor processing methods significantly influenced postprandial glucose and insulin concentrations in study participants emphasizing the need for combined developmental approaches.