Fibre replacement may create low GI breads

The study, published in LWT - Food Science and Technology​, suggests using a ten per cent replacement of larger particle, high viscoelastic, dietary fibres (DFs) may result in breads with lower GI values, and good physical and sensory properties.

“Basic investigations of the physicochemical properties of dietary fibres and their implications on food specific functional properties are crucial to exploit the added value of DFs as both a key nutritional factor and a functional ingredient in foods,” ​wrote the researchers, led by Dr. Concha Collar, from the​Institute of Agrochemistry and Food Technology (CSIC), in Spain.

Nutritional factor​

Dietary fibres are a key nutritional factor in a healthy diet, and are recognised for their beneficial physiological effects such as reducing the digestive absorption of glucose and cholesterol.

Viscous DFs – polysaccharides such as gums, pectin, psyllium, and beta-glucans – have been associated with slower gastric emptying, extended transit time through the small intestine, and modifying starch digestion – consequently altering the Glycaemic Index (GI) of starch-based foods.

Careful selection of DFs with suitable physico-chemical properties is an important factor in bread-making applications, noted the authors

The new study investigates DFs effects on bread technological functional and nutritional properties in order to better understand the effects of substitution.

Functional properties​

Researchers reported that few technological or functional properties were found to depend on dietary fibre characteristics, whilst most nutritional bread properties were affected by DFs molecular characteristics, complex viscosity, and solvent retention capacity.

Dietary fibres with larger particle size resulted in “highly sensory acceptable breads with higher amounts of resistant starch and slightly lower protein digestibility,” ​according to the researchers.

They reported DFs with a high viscoelastic profile and complex viscosity produced breads with better sensory perception, and lower digestible starch, resulting in lower GI values and reduced protein digestibility.

Strict link​

The researchers concluded the structural make up of dietary fibre, and the physiological and technological functional properties of food matrix are “strictly linked together”​.

“In bread making applications, a careful selection of DFs with suitable physicochemical properties preventing permanent disruption of the protein matrix is a pre-requisite to obtain sensorially accepted breads in highly substituted flour systems,”​ they wrote

“The development of … dietary fibre-rich cereal products exhibiting nutritional added value, safety, tasty palatability, convenience and easy handling during processing, closely depend on the proper knowledge of the physico-chemical properties of the polymeric DFs,”​ concluded the researchers

Source: LWT - Food Science and Technology​

Published online ahead of print, doi: 10.1016/j.lwt.2010.09.008

“Physicochemical and nutritional properties of reduced-caloric density high-fibre breads”​

Authors: A. Angioloni, C. Collar