Pão de forma sem glúten a base de farinha de arroz / Gluten free pan bread based on rice flour

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

24/02/2011

RESUMO

It is being a challenge for researchers in the food field to make available to the celiac the variety of foods that they are not allowed to consume. The bread has been studied as deep in it, especially the replacement of the technological functionality of gluten, which is particularly nontrivial. The objective of this work was to develop gluten-free bread based on rice flour, with similar characteristics of a traditional loaf. The technological intent of research was divided in five parts: literature review, general mapping and basic formulation development, screening of significant variables via Plackett and Burman design, once determined the significant variables, central composite rotational design 24 including eight star points and four replicates at the central point, followed by central composite rotational design 22 including four star points and four replicates at the central point. In the initial stage 50 formulations were examined, involving 32 ingredients and 12 process variables. At the end, gluten-free pan bread was developed, whose formulation can be obtained by replacing the wheat flour by a mix of rice flour, tapioca starch and modified egg albumen acidified and dehydrated. The rice flour was found to be a good working basis, acting as agent of the body. The modified tapioca starch provided consistency and cohesiveness to the dough. The egg albumen acidified and dehydrated replaced the gluten being responsible for the growth of the dough. Hydrocolloid (carboxymethyl) cellulose was also added, acting as a thickener, contributing to the dough viscosity and water absorption. The other ingredients acted similarly to a traditional formulation of pan bread prepared with wheat flour. The production process has shown that using an mixer with paddle, dough ratio of 3.71 mL/g in a pan 21 x 10 x 10 cm (l x w x h), fermentation of 60 minutes at 40°C held at 85% of relative humidity, followed by baking temperature of 180°C during 23 minutes and cooling during 60 minutes promoted the best results. All samples after 24 hours of its preparation presented an excessive firmness. The experimental design of Plackett and Burman was applied in sequence to determine which variables had significant effect (p <0.10) on the average height of the central slice and firmness on days 01, 03, 07 and 10 after produced of loaves of gluten-free bread based on rice flour. The firmness was influenced by modified cassava starch, maltogenic amylase and water, while the protease, powdered and acidified egg albumen and water had effect on the average height of the center slice The lack of pan flow affected the bread¿s crust color, due to lower heat contact on the surface. The dough consistency influenced the characteristic of the crust. Dough with water in excess and consequently with less structure, had collapsed compromising the symmetry. The crumb color was whiter as the average height of the central slice of the pieces was above 100 mm. The crumb structure followed the trend of color, except PB11, where the levels of powdered and acidified egg albumen and water were maximum and modified cassava starch was minimum, that aside from presenting good height, had a more closed crumb structure. The formulation PB11 presented similar chewing to traditional pan bread. The aroma and flavor ranged from the light of rice flourish to neutral, with remark for formulas PB02 and PB05, where the levels of modified cassava starch and powdered and acidified egg albumen were maximum and water was minimum, whose flavors were unpleasant. Once determined the significant variables the central composite rotational design 24 including eight star points and four replicates at the central point was used to determine which independent variables - dried and acidified egg albumen, water, enzyme maltogenic amylase and modified cassava starch ¿ had a significant effect on the average height of central slice and crumb firmness on days 01, 03, 07 and 10 of gluten-free loaves based on rice flour. As a result of this work, it was found that the average height of the central slice was positively and significantly impacted (p<0.05) by water in the form of a parabolic shape with a maximum at the level 1.1. Regarding the firmness, it was significantly, linear and positively affected (p <0.10 on day 01 and p <0.05 on the other days) by the modified cassava starch, dried and acidified egg albumen. The quadratic and linear terms of the water on the firmness were significantly positive and negative, respectively (p <0.10 on day 01 and p <0.05 on the other days). On the contrary expected, the enzyme maltogenic amylase showed no effect on firmness. All formulations showed good proofing and visual aspects, lacking the flavor that ranged from slightly rice flour to bitter. Once the fungal protease was not studied in the previous step, and it was noted as significant by the Plackett and Burman planning, the central composite rotational design 22 trials including 4 star points and 4 replicates at the central point was employed to determine which independent variables - (carboxymethyl) cellulose (cmc) and fungal protease (eprt) - had a significant effect on the height of the central slice, the crumb firmness on days 01, 03, 07 and 10, specific volume and proofing time of gluten-free loaves based on rice flour. As a result of this work, it was found that the average height of the center slice was positively and significantly impacted (p <0.05) by eprt in the form of a parabolic shape by cmc in linear way, with a maximum at the level 2.0 and 0.8, respectively; and also the linear relationship of eprt and cmc. Regarding the firmness, it was significant and positively affected by the cmc linear and quadratic term for days 01, 03 and 07 after produced (p <0.05, p<0.05 and p<0.10), while the firmness of 10 days was affected negatively only by the linear term of the cmc (p <0.10). The specific volume was positively affected (p <0.10) by cmc linearly, while the quadratic term of cmc positively affected the fermentation (p <0.10). All formulations showed good bread development and good chewing characteristics. The taste remained neutral, with the exception of the experiment with the lowest level of cmc which collapsed and presented bitterness. From these results mathematical models for firmness on days 01, 03, 07 and 10, shelf life, the average height of the center slice, bulk and fermentation time were created. The models were tested and validated at optimum firmness in 01 days of shelf life and average height of the center slice, cmc = 0.8 and eprt = 1.41 (encoded variables). The sensorial analysis has shown that the gluten-free pan bread has presented characteristics very close to regular wheat loaf (p<0.01). It was concluded that it is possible to produce sliced bread based on recipe of rice flour with typical features of a traditional loaf, but that still presents opportunities of improvement in the texture and flavor

ASSUNTO(S)

glúten bread pão farinha de arroz doença celiaca gluten rice flour coeliac disease

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