Gluten-free bakery in general lacks the binding ability and structural support that gluten imparts to the dough during the foaming process as well as the normal springiness and toughness of the breadcrumb structure. To support the development of delicious and gluten-free bakery products Jungbunzlauer published a new study showing the importance of hydrocolloids as stabilisers of the sequential foaming process during proofing and baking. In this study, four different hydrocolloids, xanthan gum, guar gum, hydroxypropyl methyl cellulose (HPMC) and psyllium husk, were tested individually at different levels of use in a gluten-free sandwich bread.
Already during the dough preparation and proofing significant differences between the before mentioned hydrocolloids became visible. Jungbunzlauer’s xanthan gum imparts favourable characteristics to the dough, making it easier to rise and handle. During proofing xanthan gum built a stable foam that continued to rise as fermentation continued and was accelerated by increasing temperature and expanding gases in the foam. The measurement of loaf rise showed that xanthan gum was the best stabiliser for the cold foam during proofing and hot foam during baking, resulting in a lower-density loaf.
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Figure 1: Loaf raise after baking for different hydrocolloid concentrations.
There is a good correlation between foam stability and level of use of xanthan gum, as shown in Figure 2.
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Figure 2: Baked sandwich breads with 0–3.6 wt% xanthan gum.
Texture analysis results proved that xanthan gum imparted a softer, more cohesive (less crumbly), elastic texture that resembles a gluten bread. This is because xanthan gum was able to properly stabilise the foam in a cold and hot environment as well as keep viscosity high enough to bind the breadcrumb.
To explore potential synergies in texture, two binary blends of xanthan gum with HPMC and with psyllium husks at different ratios were tested. Although no synergy was found, these results show how loaf raise and crumb texture are mainly supported by the addition of xanthan gum. The more xanthan was used in the blend the more expanded the loaf of bread was, and so the softer the texture became. In contrast, the more HPMC or psyllium husk was used in the blend, the less expanded the bread was, and a denser and harder texture was obtained. Compared to the HPMC, the psyllium husk at least can improves the taste by adding bread-like and cereal flavours.
Finally, xanthan gum was tested in two further bread types, a gluten-free baguette and an ancient grains gluten-free bread, where the correlation between the xanthan gum content and foaming stability was corroborated. By adding 1.0 wt% of Jungbunzlauer’s xanthan gum to a gluten-free base that contains a higher amount of fibres and protein but lower starch content, like the ancient grain bread, an aerated texture and bread-like crumb was achieved. Furthermore, this type of bread also contains inclusions of legumes and grains like quinoa, sprouted lentils and millet. The viscosity produced by xanthan gum guaranteed the homogeneous suspension of such particles. With doubling the xanthan gum concentration, even the open crumb texture and large air cells of traditional baguette could replicated in the gluten-free alternative. These experiments demonstrate the stabilising potential of xanthan gum for cold and hot bakery foams across different types of baked goods.
Based on this study, xanthan gum is the best-performing hydrocolloid of those tested, as it better stabilises the foam through different thermal processes and formulations, imparting high viscosity in low shear (foaming). Junbunzlauer’s study is intended to help product designers towards a more focused approach when developing gluten-free bakery products, for more details and background information read the full article.
"Creating texture in gluten-free bread with Xanthan Gum"