RESUMO
Gluten-free batters, in general, require the incorporation of agents to control their rheology; this role is commonly played by hydrocolloids. New natural sources of hydrocolloids are under permanent research. In this regard, the functional properties of the galactomannan extracted from the seed of Gleditsia triacanthos (Gledi) have been studied. In this work, we evaluated the incorporation of this hydrocolloid, alone and in combination with Xanthan gum, in gluten-free batters and bread and compared it with Guar gum. The incorporation of hydrocolloids increased the viscoelastic profile of the batters. Gledi addition at 0.5% and 1.25% increased the elastic modulus (G') by 200% and 1500%, respectively, and similar trends were observed when Gledi-Xanthan was used. These increases were more pronounced when Guar and Guar-Xanthan were used. The batters became firmer and more elastically resistant because of the addition of hydrocolloids; batters containing Gledi had lower values of these parameters than batters containing Gledi-Xanthan. The addition of Gledi at both doses significantly increased the volume of the bread compared to the control by about 12%, while when Xanthan gum was included, a decrease was observed, especially at higher doses (by about 12%). The increase in specific volume was accompanied by a decrease in initial crumb firmness and chewiness, and during storage, they were significantly reduced. Bread prepared with Guar gum and Guar-Xanthan gum combinations was also evaluated, and the trends observed were comparable to that of bread with Gledi gum and Gledi-Xanthan gum. The results showed that Gledi addition favors the production of bread of high technological quality.
RESUMO
Anthropogenic activities have increased disturbances and alien woody invasion in mountain ecosystems worldwide. Whether disturbances promote or counteract upward movement of woody aliens is poorly understood. We assessed if the most successful woody invader of low mountains of central Argentina (Gleditsia triacanthos) might expand its elevational distribution in response to the principal disturbances of these ecosystems (fire and livestock browsing) across increasing climatic severity. We assessed seedling emergence, growth and mycorrhizal colonization on sown plots distributed in burned and unburned sites, with and without browsing at the lower and upper elevation belts (i.e. 1000 and 2400 m a.s.l.). Additionally, several abiotic variables were measured to relate their influence on the seedling establishment. Disturbances reduced seedling emergence at both elevations. Burned conditions increased seedling growth and arbuscular colonization only in the lower belt. Seedling success (total seedling biomass per plot) was not modified by disturbances at the upper elevation, but was reduced by browsing and enhanced by fire in the lower elevation. The overall reduction in seedling emergence and growth in the upper elevation despite the higher soil nutrient content places climate as the strongest regulator of G. triacanthos seedling establishment. Accordingly, climate rather than disturbances would be the main limiting factor of upward expansion of this woody alien. Our findings differ from general patterns described for mountain invasion by herbaceous species, highlighting that mountain invasibility is highly growth-form dependent, and that upper range expansion by woody aliens interacting with multiple disturbances should be assessed worldwide.