Desenvolvimento de pão sem glúten com farinha de arroz e de batata-doce

Abstract

Celiac disease (CD) is a permanent intolerance to gluten, characterized by atrophy of the small intestine and consequent malabsorption of nutrients. Treatment of DC consists in the introduction gluten free diet permanently. The gluten-free bread is the product that celiac would like to find more easily in the market, allowing wider distribution of products with low cost, and convenience. This research aimed to characterize the flours of rice and sweet potatoes flour, formulate gluten-free bread for celiacs, applying different hydrocolloids (carboxymethyl cellulose and xanthan gum) and verify the effect of substitution of rice flour (RF) for sweet potatoes flour (SPF) on technological and sensory quality of bread. First, it determined the chemical composition of flour performing moisture analysis, water activity, acidity, pH, lipids, protein, ash, dietary fiber, carbohydrates, amylose content, grain size and color. Were also made microbiological analysis (Salmonella sp., Bacillus cereus, coliforms, molds and yeasts). Starch paste property was determined for RF, and their mixtures (25% and 75% RF, 50% and 50% RF, 75% SPF and 25% RF). At the second stage, the processing of breads occurred using the hydrocolloids carboxymethylcellulose (CMC) and xanthan gum (XG) in a farinaceous-based rice flour to develop gluten-free bread. Then, it was found the best results in respect to texture (hardness, elasticity, cohesiveness and chewiness), color (of the crust and crumb) and specific volume. Thus, it was held the replacement of rice flour by sweet potato flour and assessed their effects on textural parameters, color and specific volume, such as the acceptability of using sweet potatoes flour in bread formulation without gluten. For the production of bread were used rice flour (100%), granulated sugar (12%), water (150%), albumin (10%), margarine (10%), dried yeast (6%), salt (2%) and different concentrations of CMC and XG (in the values of 0%, 0,5%, 1,0%, 1,5% and 2%). The data were submitted to analysis of variance (ANOVA) and the averages compared by Tukey test (p ˂ 0,05). Yet, it was held microbiological analysis of the loaves and ordering preference test with consumers of bread. Flours differed significantly (p <0,05) according to L*, a* and b* color coordinates. The sweet potato flour presented itself darker than the rice one. In the characterization were obtained the following standards: sweet potatoes flour (moisture 9,18%, 9,92% protein, lipid 1,72%, 1,51% ash, 3,77% fiber and carbohydrates 77,81 %) and rice flour (13,31% moisture, 10,34% protein, 1,41% lipid, ash 0,31%, fiber 0,76%, carbohydrates 75,03%). In the assessment of paste properties of the flours and their mixtures, it was observed that RF paste temperature (88,65°C) was superior compared to the other samples. The maximum viscosity decreased with the increase of SPF in the blend. The values of final viscosity and retrogradation tendency decreased as increased SPF content in the mix. The paste properties of the mixtures of RF and SPF should be seen in a joint manner because they affect the texture in gluten-free breads. In gluten-free bread with rice flour processing it was discovered that for all the analyzes the control sample (without hydrocolloid) differed significantly (p <0,05) of others. It was found that with the use of 2% of CMC, there was obtained best results in relation to the set of analyzes, and sensorially there was no significant difference (p <0,05) between samples containing hydrocolloids. With the use of hydrocolloid CMC and replacement of RF for SPF, it was found that the higher the ratio of SPF, the lower the specific volume and the higher the hardness of the samples. However, the sample with 25% SPF was not significantly different compared to control hardness, chewiness, 10 cohesiveness and elasticity sample. The addition of SPF in the breads gave a darker color to the samples. The microbiological evaluation of the sample with 25% SPF resulted in a bread with a shelf life of 07 days. This same sample achieved a 80,3% acceptance rate, considered high for being a new product developed,. The analysis of only 2% purchase intent of tasters certainly would not buy the product, showing that the use of hydrocolloids combined with the use of sweet potato flour in gluten-free bread formulations, is an option for celiac public to obtain Products with sensorial quality.