title: Distinct Characteristics of Rye and Wheat Breads Impact on Their in Vitro Gastric Disintegration and in Vivo Glucose and Insulin Responses.
abstract: Disintegration of rye and wheat breads duringin vitrogastric digestion and its relation to the postprandial glucose and insulin responses of the breads was studied. Breads with distinct composition and texture characteristics were prepared with refined or wholegrain wheat and rye flour by using either straight dough or sourdough process. After chewing and gastric digestionin vitro, 100% wholemeal and refined rye breads prepared by sourdough method were disintegrated to a much lower extent than the wheat breads, having more bread digesta particles with size over 2 or 3 mm. Microstructure of the digesta particles of rye sourdough bread revealed more aggregated and less degraded starch granules when compared to refined wheat bread. The postprandial insulin responses, but not those of glucose, to the 100% rye breads made with sourdough method were lower than the responses to the refined wheat bread. Addition of gluten or bran in rye sourdough bread increased insulin response. PCA (Principal Component Analysis) analysis confirmed that the insulin response had a negative correlation with the number of larger particles afterin vitrodigestion as well as amount of soluble fiber and sourdough process. Since the high relative proportion of large sized particles after chewing andin vitrogastric digestion was associated with low postprandial insulin responses, the analysis of structural disintegrationin vitrois proposed as a complementary tool in predicting postprandial physiology.
authors.affiliation: VTT Technical Research Centre of Finland Ltd, 02150 Espoo, Finland. Emilia.nordlund@vtt.fi.
authors.forename: Emilia
authors.initials: E
authors.lastname: Nordlund
authors.affiliation: Department of Food and Environmental sciences, University of Helsinki, 00014 Helsinki, Finland. kati.katina@helsinki.fi.
authors.forename: Kati
authors.initials: K
authors.lastname: Katina
authors.affiliation: Department of Clinical Nutrition, Food and Health Research Centre, School of Public Health and Clinical Nutrition, University of Eastern Finland, 70211 Kuopio, Finland. Hannu.mykkanen@uef.fi.
authors.forename: Hannu
authors.initials: H
authors.lastname: Mykkänen
authors.affiliation: VTT Technical Research Centre of Finland Ltd, 02150 Espoo, Finland. Kaisa.Poutanen@vtt.fi.|Department of Clinical Nutrition, Food and Health Research Centre, School of Public Health and Clinical Nutrition, University of Eastern Finland, 70211 Kuopio, Finland. Kaisa.Poutanen@vtt.fi.
authors.forename: Kaisa
authors.initials: K
authors.lastname: Poutanen
keywords: bread; glucose response; in vitro digestion; insulin response; particle size; rye; sourdough; wheat