The impact of freezing and toasting on the glycaemic response of white bread

• Published in: European journal of clinical nutrition Vol. 62; no. 5; pp. 594 - 599
• Main Authors: Burton, P, Lightowler, H J
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2008; Nature Publishing; Nature Publishing Group
• Subjects: Adult; Area Under Curve; Biological and medical sciences; Blood; blood glucose; Blood Glucose - analysis; Blood Glucose - metabolism; Blood sugar; Bread; breads; Clinical Nutrition; Cooking; Cooking - methods; Defrosting; Dietary Carbohydrates - pharmacokinetics; Epidemiology; Feeding. Feeding behavior; Female; Food; food composition; Food Handling - methods; food preparation; Food Preservation - methods; food storage; Freezing; Freezing points; freezing quality; Fundamental and applied biological sciences. Psychology; Glucose; Glycemic Index; Health aspects; human nutrition; Humans; Influence; Internal Medicine; Male; Medical sciences; Medicine; Medicine & Public Health; men; Metabolic Diseases; Methods; Middle Aged; Nutrition; original-article; Public Health; Storage conditions; storage quality; Thawing; toasting; Vertebrates: anatomy and physiology, studies on body, several organs or systems; women; United Kingdom; blood glucose; bread; food preparation; glycaemic response; food storage; Nutrition; Metabolic diseases; Glucose; Blood; White bread; Storage; Preparation; Glycemia; Food
• ISSN: 0954-3007; 1476-5640
• DOI: 10.1038/sj.ejcn.1602746

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 22–59 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, 2 h 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 259 mmol min/l), IAUC was significantly lower when the bread was frozen and defrosted (179 mmol min/l, P <0.05), toasted (193 mmol min/l, P <0.01) and toasted following freezing and defrosting (157 mmol min/l, P <0.01). Similarly, compared to the fresh commercial white bread (253 mmol min/l), IAUC was significantly lower when the bread was toasted (183 mmol min/l, P <0.01) and frozen, defrosted and toasted (187 mmol min/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.