Abstract
Objective:
To investigate the impact of freezing and toasting on the glycaemic response of white bread.
Subjects/methods:
Ten healthy subjects (three male, seven female), aged 22â59 years, recruited from Oxford Brookes University and the local community. A homemade white bread and a commercial white bread were administered following four different storage and preparation conditions: (1) fresh; (2) frozen and defrosted; (3) toasted; (4) toasted following freezing and defrosting. They were administered randomized repeated measures design. Incremental blood glucose, peak glucose response, 2âh incremental area under the glucose response curve (IAUC).
Results:
The different storage and preparation conditions resulted in lower blood glucose IAUC values compared to both types of fresh white bread. In particular, compared to the fresh homemade bread (IAUC 259âmmolâmin/l), IAUC was significantly lower when the bread was frozen and defrosted (179âmmolâmin/l, P<0.05), toasted (193âmmolâmin/l, P<0.01) and toasted following freezing and defrosting (157âmmolâmin/l, P<0.01). Similarly, compared to the fresh commercial white bread (253âmmolâmin/l), IAUC was significantly lower when the bread was toasted (183âmmolâmin/l, P<0.01) and frozen, defrosted and toasted (187âmmolâmin/l, P<0.01).
Conclusions:
All three procedures investigated, freezing and defrosting, toasting from fresh and toasting following freezing and defrosting, favourably altered the glucose response of the breads. This is the first study known to the authors to show reductions in glycaemic response as a result of changes in storage conditions and the preparation of white bread before consumption. In addition, the study highlights a need to define and maintain storage conditions of white bread if used as a reference food in the determination of the glycaemic index of foods.
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Acknowledgements
Sponsorship: This study was supported by a Biotechnology and Biological Sciences Research Council studentship.
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Contributors: PB planned and designed the study and was responsible for the collection of data and writing the manuscript. HJL advised on the study design and contributed to the preparation of the manuscript.
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Burton, P., Lightowler, H. The impact of freezing and toasting on the glycaemic response of white bread. Eur J Clin Nutr 62, 594â599 (2008). https://doi.org/10.1038/sj.ejcn.1602746
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DOI: https://doi.org/10.1038/sj.ejcn.1602746