The authors of the study, published in Food Chemistry, said that monosodium phosphate is also an effective FDA-labelled product for preventing and treating most causes of hypophosphataemia -low levels of phosphate in the blood - and hypercalcaemia - high blood calcium levels - due to its metal-chelating properties.
The researchers, who are all based at the University of Valladolid in Spain, said that no systematic studies, prior to this, have been reported on the effect of acidic substances on gluten free bread. However, vinegar, as an acidic ingredient, has been traditionally added in the dough to improve bread quality, they noted.
The objective of this study then was to determine the effect of adding acidic food additives with different properties - acetic acid, lactic acid, citric acid and monosodium phosphate – on the properties of dough and quality attributes of the free gluten system, said the Spanish team.
Rice flour (15.1% moisture, 0.32% d.b. ash, 7.25% d.b. protein and 81% d.b. starch) was used throughout the present study for all bread formulations, said the team. And a straight dough process was performed using 110 per cent water, 6 per cent oil, 5 per cent sucrose, 2 per cent salt, 2 per cent HPMC and 3 per cent yeast.
All bread samples, except the control, were supplemented with 0.4 per cent, 0.8 per cent and 1.2 per cent (flour basis) of the acid additive tested, with acetic acid added at half concentrations (0.2 per cent, 0.4 per cent and 0.6 per cent).
The authors said that they made pH measurements of dough samples at regular intervals, using a CRISON 2002 pH meter, from the moment the sample was placed in the fermentation chamber and up to 50 minutes. Bread volume, they explained, was determined after cooling to room temperature and resting for 16 hours at 20 ºC, using a laser volume analyser.
Crumb grain characteristics of bread were assessed using a digital image analysis (DIA) system, while sensory tests were conducted by 52 untrained panellists.
The researchers findings show there was a large alveolus size and consequently large volume - around 950 cm3 - obtained in the loaf of bread when phosphate was added, suggesting that “phosphate has a greater effect on the dough’s characteristics than any other organic acid tested.”
They explained that the larger volume of alveolus when phosphate is present may be due to the fact that the compound has the adequate size to fix, by hydrogen and coordinated bonds, the long chain of HPMC macromolecules, keeping them close enough to retain the carbon dioxide produced by the yeast.
The authors also report that their results indicate that monosodium phosphate yields bread producing better texture scores, associated with the higher volumes in loaves attained with the compound.
But the Spanish team concluded that the rheometric properties of the dough were not significantly altered when acids were added to the free gluten system.
“The dough’s viscoelastic properties did not differ significantly in all acidified samples when compared to the control,” they reported.
Furthermore, the researchers said that, except for the positive effect of monosodium phosphate observed on the texture, a lack of a relationship was observed between sensory properties of the loaves such as appearance, odour, taste and the different additives tested.
Source: Food Chemistry
Published online ahead of print: doi: 10.1016/j.foodchem.2011.01.127
Title: Improving gluten-free bread quality by enrichment with acidic food additives
Authors: Blanco, C.A, Ronda F, Pérez B, Pando V