Postprandial Responses to Hydroxytyrosol-enriched Bread

The amelioration of postprandial glucose and insulin responses to bread is of great importance since it may have significant beneficial effects on health. A number of studies have shown that hydroxytyrosol may have positive metabolic effects. However, this compound presents high hydrophilicity which constitutes the major barrier to its potential application in foods. Microencapsulation arises as a technological strategy to protect it and increase its stability. Alpha-cyclodextrin besides being a great carrier molecule, seems to also be beneficial to postprandial glucose levels. Enrichment of bread with encapsulated hydroxytyrosol could examine potential postprandial benefits.

Ten healthy normoglycemic subjects will participate in the study and will be provided with either a solution of glucose (reference food) or white wheat bread or wheat bread enriched with a-cyclodextrin or wheat bread enriched with hydroxytyrosol encapsulated in a-cyclodextrin, with 1-week intervals in amounts that yielded 50 g of available carbohydrates. Venous blood samples will be collected before consumption and at 30, 45, 60, 90, 120 and 180 min postprandially. Postprandial glucose, insulin and appetite-related hormone responses as well as glycemic index (GI) and subjective appetite ratings will be evaluated.