Influence of hydrocolloids (galactomannan and xanthan gum) on the physicochemical and sensory characteristics of gluten-free cakes based on fava beans (Phaseolus lunatus).

Most gluten-free bakery formulations have starch sources of low nutritional value. The objective of this work was to use fava beans (Phaseolus lunatus) for the production of gluten-free sponge cakes, in addition to evaluating the effects of the partial substitution of fava bean flour by galactomannan and xanthan gum, isolated or mixed at 0.5 and 1.0% proportions, compared with a commercial reference. The properties such as viscosity, specific gravity and microscopy of the air bubbles were evaluated in the raw cakes, while the cooked cakes were analyzed according to physicochemical (chemical composition, specific volume, texture and color) and sensorial properties. Hydrocolloids increased the viscosity, specific gravity, and incorporation of air into the batters. Xanthan gum increased the cakes' firmness after cooking; in what concerns color parameters, hydrocolloids did not interfere. Cakes based on fava beans had better sensory acceptance with or without the presence of hydrocolloids and presented higher levels of moisture, proteins, lipids and ashes when compared to the commercial reference, proving to be an excellent food option without gluten and high nutritional value.

Evaluation of Caesalpinia pulcherrima endospermic gum as affinity matrices for galactose-binding lectins interaction

Lectins are proteins or glycoproteins able to bind, specifically and reversibly carbohydrates and glycoconjugates. Considering this ability, the utilization of Caesalpinia pulcherrima seeds polysaccharides as an affinity matrix was tested. The endospermic gum were solubilized in distinct concentrations of NaOH and treated with different amounts of epichlorohydrin (ECH) forming affinity gels with variable capacity for interaction with galactose- binding lectins. The gel with an ECH/gum ration of 6.0mmol/g was selected as the best affinity matrix. The matrix presented different efficiencies in terms of isolating galactose-binding lectins. C. pulcherrima endospermic galactomannans were purified by ethanol precipitation and the purified galactomannan was crosslinked with the best formulation of gel. The Artocarpus incisa, Ricinus communis and Abrus precatorius lectins showed interactions of 11.5, 17.7 and 47.2mg of retained protein in 1g of gel, respectively; the Artocarpus integrifolia lectin showed the highest affinities (79.7mg/g). The heamaglutination assays confirmed the activity and SDS-PAGE electrophoresis confirmed the isolation of the lectins in a single-step procedure.

Isolation of a lectin and a galactoxyloglucan from Mucuna sloanei seeds.

A lectin and a galactoxyloglucan were characterized from Mucuna sloanei seed cotyledons. The galactoxyloglucan, isolated by water extraction and ethanol precipitation, had Glc:Xyl:Gal proportions in a molar ratio of 1.8:1.7:1.0 and a molar mass (M(w)) of 1.6x10(6)g mol(-1). The lectin (sloanin), isolated from the same seed by affinity chromatography on cross-linked Adenanthera pavonina galactomannan, gave two protein bands by SDS-PAGE (36 and 34 kDa) and one peak by gel filtration (63.6 kDa). Its N-terminal sequence indicated approximately 69% identity with soybean agglutinin to leguminous lectins. Circular dichroism (CD) spectra established that sloanin predominantly contains beta-sheet structures. Sloanin has approximately 5.5% carbohydrate and displayed hemagglutinating activity against rabbit and enzyme treated human erythrocytes, inhibited only by D-Gal containing sugars. The interaction between sloanin and storage cell-wall galactoxyloglucan was tested by affinity chromatography and fluorescence spectroscopy.