Caracterização microbiológica e nutricional, aceitação sensorial e estabilidade de ácido fólico e tiamina em arroz fortificado (Ultra Rice®) após diferentes técnicas de cocção

• Ano de defesa: 2012
• Autor(a) principal: Silveira, Carlos Mário Martins
• Orientador(a): Sant ana, Helena Maria Pinheiro
• Banca de defesa: Duarte, Maria Sônia Lopes , Chaves, José Benício Paes , Pirozi, Mônica Ribeiro
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso embargado
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Ciência da Nutrição
• Departamento: Valor nutricional de alimentos e de dietas; Nutrição nas enfermidades agudas e crônicas não transmis
• País: BR
• Palavras-chave em Português: Caracterização microbiológica e nutricional; Grãos de UR; CLAE-DAD; Cocção; Ferro; Zinco
• Palavras-chave em Inglês: Characterize microbiologically and nutritionally; Raw grains of Ultra Rice (UR); HPLC-DAD; Iron; Zinc
• Área do conhecimento CNPq: CNPQ::CIENCIAS DA SAUDE::NUTRICAO
• Link de acesso: http://locus.ufv.br/handle/123456789/2764

This study aimed to characterize microbiologically and nutritionally raw grains of Ultra Rice® (UR®) fortified with iron, zinc, thiamine and folic acid and evaluate the sensory acceptance, content and stability of acid folic and thiamine in preparations of UR® added to polished rice after different cooking techniques. Microbiological analysis were performed in raw grains of UR® for coliforms enumeration at 45ºC, Salmonella spp, Bacillus cereus, fungi and yeasts. The nutritional composition analysis of raw grains of UR® was made by the recommended techniques of AOAC (2002). Methods for analysis of acid folic and thiamine content were optimized by Reverse Phase High Performance Liquid Chromatography coupled to a photodiode array detector (RP-HPLC-DAD) in raw grains of UR® and in UR® added to polished rice, before and after cooking. Iron and zinc contents were determined by atomic absorption spectrometry. The content and stability of thiamine and folic acid were evaluated after cooking at laboratory scale (stir-frying before boiling, boiling, and boiling in a microwave oven) and in food service (boiling), using UR® added to polished rice following the proportion of 1:100, totalizing 4 treatments, with 5 repetitions for extraction and analysis of thiamine and folic acid. The statistical analysis was performed with the treatments arranged in a completely randomized design, using the Duncan s test ( = 5%) for comparison among treatment means. To analyze the sensory acceptance of the preparations, the nine-point hedonic scale was used, with the following attributes: odor, flavor, texture and overall impression. Acceptance data were evaluated by analysis of variance (ANOVA), followed by Tukey s test ( = 5%), for comparison among means. Also, the technique of internal preference map, based on the model of analysis of main components, was used. Raw UR® showed micro-organisms count absent or lower than allowed by health legislation. Regarding the raw UR® nutritional composition, it was found (in 100 g) 0.12 g of lipids; 7.26 g of proteins; 0.96 g of total dietary fiber; 79.75 g of carbohydrates; 821.24 mg of iron; 142.15 mg of zinc, 161.72 mg of thiamine and 20.95 mg of folic acid. The optimized methods showed good resolution of peaks of the searched vitamins and excellent recovery for folic acid and thiamine (82 to 104% for thiamine and 87 to 96% for folic acid), repeatability with relative standard deviation of peak areas and of retention times lower than 10% and high coefficients of determination (0.9998 for thiamine and 0.9997 for folic acid). The detection and quantification limits were low (0.00193 μg and 0.0193 μg for thiamine and 0.000934 μg and 0.00934 μg for folic acid, respectively), demonstrating high sensibility to the optimized methods. Preparation cooked in microwave oven showed significantly higher thiamine content (0.3627 mg/100g) than the other preparations, while for folic acid, there was no significant difference among cooking techniques (average content of 0.07592 mg/100g). After the different cooking techniques, preparations of UR® added to polished rice showed higher retention of folic acid (75.69 96.11%) compared to that obtained for thiamine (49.66 - 65.41%). Thiamine retention was higher when microwave oven cooking method was used (65.4%), while for the other cooking techniques, retention was statistically equal (average of 52.1%). For folic acid, the highest retention was obtained when the technique of stir-frying before boiling was used (96.1%), while the other cooking techniques did not show significant difference (p > 0.05). Considering one portion of rice, the microwave cooked preparation may contribute from 37.5 to 64.2% of thiamine diary recommendations and 32.5 to 52.8% of the recommendations of folic acid for different age groups. Sensory acceptance of the preparations was satisfactory and, in average, 83.9% of the scores were located between 6 and 9 (liked slightly to liked extremely) for all evaluated attributes. In conclusion, UR® grains presented adequate microbiological standard and centesimal composition similar to polished rice for proteins, lipids and carbohydrates, besides high content of iron, zinc, thiamine and folic acid. The optimized methods demonstrated reliability and sensitivity in the detection and quantification of thiamine and folic acid in raw grains of UR® and in the mixture of UR® grains with polished rice before and after different cooking techniques. Sensory acceptance was satisfactory and high stability of folic acid in the preparations was found. Cooking in a microwave oven and stir-frying before boiling stood out, allowing higher vitamins stability. Preparations containing UR® and polished rice showed good content of folic acid and thiamine, and a portion may contribute in an important way for the attendance of daily vitamins recommendations.