Prolonged frozen storage of partially-baked wheat bread increases in vitro slowly digestible starch after final bake

Abstract

We have studied the effect of the frozen storage time of industrially produced partially-baked wheat bread 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 the effects of frozen storage on in vitro starch digestibility of partially-baked bread after final bake, with the Englyst analytical method. The rapidly digestible starch, expressed as percentage of dry matter ± 95% confidence interval, fell significantly at 63 days, from 51.9 ± 2.9 to 42.7 ± 2.9 whereas the slowly digestible starch increased over this period, from 18.8 ± 5.5 to 29.9 ± 2.7 (P < 0.05). During the frozen storage, changes occur in the composition and structure of partially-baked bread, modifying the in vitro starch digestibility, with a significant reduction in rapidly digestible starch, which is associated with a lower glycaemic response.

Keywords::

• Starch digestibility, partially-baked bread, glycaemic response

Acknowledgements

The guidance of Dr Klaus Englyst is most gratefully acknowledged. The authors would like to thank Novozymes Spain for providing a large part of the enzymes used in the analyses.

Declaration of interest: The present work has been supported by Europastry S.A. and by the Junta de Castilla y León (Ref: VA087A08). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.