The researchers in the new study, which has been accepted for publication in the journal Food Hydrocolloids, say composite breads, made from mixtures of wheat and/or other grains, are gaining in popularity. One driver is people turning towards gluten-free diets, whether because they suffer from coeliac disease or because they perceive gluten-free to be a healthier way of eating.
In African, however, research is being conducted on the partial substitution of wheat flour in bread to reduce the expense associated with wheat importation and to foster use of locally available crops.
Indeed, last year the FAO emphasised the role of cassava in food security in African producing countries, providing the equipment is available to process it.
Nigerian cassava production was estimated by the FAO to be 34 million tonnes in 2002.
Wheat and cassava
The researchers, from Nigeria’s University of Agriculture in Abeokuta, carried out their experiments using a composite bread that was not totally gluten free but made using 90 per cent wheat flour and ten per cent cassava flour.
In general, as substitution of wheat increases, quality and gas retention capacity tends to decrease.
Since previous studies have shown that hydrocolloids can build back some of the functionality lost with reduced gluten, the aim of the study was to see how xanthan gum affects the rheology of the dough and the freshness and shelf-life of the bread. They used xanthan gum at levels of between 0 and 2 per cent of the composite flour weight.
The team tested the gas retention characteristics of the dough and the dough rheology. After baking the packaged breads were stored at ambient temperatures for up to 96 hours. Bred size and softness were analysed and images were taken of the bread crumb and crust for analysis. The sensory acceptability was assessed by panellists.
Overall, the researchers reported that the addition of xanthan gum “significantly affected all the dough handling properties and some bread quality”. Dough handling actually became more difficult.
However higher xanthan gum content was seen to increase springiness, loaf volume, crumb softness, per cent cell area and overall sensory acceptability.
To stop the bread drying out too fast and to keep the bread crumb firm, they saw that a maximum of 1 per cent xanthan gum was required.
Journal: Food Hydrolloids (2009). Published online ahead of print.
Functional effects of xanthan gum on composite cassava-wheat dough and bread
Authors: Shittu, TA; Aminu RA; Abulude EO.