Full steam ahead for low-GI bread

Asian-style steamed bread has a lower glycaemic index (GI) than western-style baked bread, researchers have found, suggesting the preparation method could be more widely adopted as a weapon in the battle against diseases such as obesity, heart disease and diabetes.

Carbohydrates typically contribute up to 70% of total energy intake, but not all carbohydrates are created equal. The glycaemic index is used to measure how rapidly carbohydrates are converted to blood glucose. High-GI foods cause a rapid spike in blood glucose, while low-GI foods, considered ‘healthier’, increase blood glucose gradually and sustain it for longer.

A team from the A*STAR Institute for Clinical Sciences examined the GI of bread, a carbohydrate-rich staple usually made from wheat flour. The GI of bread can vary significantly based on several factors, including the way in which it is cooked.

The team compared bread baked in an oven, the traditional method in western countries, with Asian-style bread, which is usually steamed. To assess the impact of both the ingredients and manufacturing methods, they also compared bread made with western ingredients but prepared using Asian methods (including steaming) and bread made with Asian ingredients processed with western methods (including baking).

The researchers tested the four types of bread in the laboratory and by measuring the glycaemic response of volunteer consumers.

Both lab analysis and consumer blood tests revealed that the highest GI was found in bread made with Asian ingredients under western methods, while the lowest GI was found in bread made with western ingredients under Asian methods.

Processing, including cooking method, had a greater impact on GI than ingredients. Thus, the A*STAR team concluded, steaming is a healthier way of making bread than baking.

Team leader Jeyakumar Henry believes the implications may be far-reaching: “Given the worldwide interest in international cuisine, it may not be long before western consumers take to steamed bread, particularly when they know it has additional health benefits.”