In vitro methods for the analysis of starch digestibility are good predictors of the glycaemic response to foods derived from cereals. As frozen part-baked bread (PBB) is consumed widely in Europe, we have studied the effect of the frozen storage time of industrially produced PBB on starch digestibility, as the conventional production process is substantially modified for this type of bread, and alterations in its nutritional characteristics are therefore possible. The objective of the present study was to determine changes occurred in in vitro starch digestibility PBB (baguette-type) after frozen storage for different periods (0, 7, 21, and 63 days), after final cooking.
The Englyst analytical method (n=6) was used to evaluate the following parameters: rapidly digestible starch (RDS), slowly digestible starch (SDS), rapidly available glucose (RAG), resistant starch (RS), and starch digestion rate index (SDRI). The RDS expressed as % of dry matter ± 95% CI, fell significantly at 63 days, from 51.9 ± 2.9 to 42.7 ± 2.9 whereas the SDS increased over this period, from 18.8 ± 5.5 to 29.9 ± 2.7 (P<0.05). In contrast, changes in the RS were not significant. Based on the above results, the SDRI at 63 days significantly fell from 67.3 ± 3.7 to 55.4% ± 3.8 and the RAG from 57.8 ± 3.7 to 47.6 ± 3.3.
During the frozen storage, changes occur in the composition and structure of PBB, modifying the in vitro starch digestibility, with a significant reduction in RDS and RAG, which is associated with a lower glycaemic response.
More info: Ronda F, Gómez M, Quílez J. (2010). Prolonged frozen storage of partially-baked bread increases in vitro slowly digestible starch after final bake. International Journal of Food Sciences and Nutrition, 61(6), 624-629.
