O arroz (Oryza sativa L.), principal alimento para cerca de metade da população mundial, é consumido principalmente na forma polida. Contudo, o arroz integral vem se destacando, devido principalmente aos compostos bioativos presentes nas camadas mais externas do grão. Os benefícios à saúde são atribuídos, em parte, à sua capacidade de combater radicais livres e exercer atividades biológicas, tais como a inibição de determinadas enzimas. Neste trabalho foram analisados os teores de compostos fenólicos totais (FT), solúveis (FS) e insolúveis (FI) e avaliado o efeito do cozimento de 17 genótipos de arroz integral, sete com pericarpo pigmentado e dez genótipos não-pigmentados. Ainda foi avaliada a inibição da enzima conversora de angiotensina I (ECA) e da -amilase por esses compostos, no arroz cru e cozido. O arroz pigmentado se mostrou rico em compostos fenólicos, em média da ordem de 4200 µg eq. ácido ferúlico/g, devido aos seus altos teores de FS, constituídos principalmente por antocianinas e proantocianidinas. Os FI, representados principalmente pelos ácidos fenólicos contribuíram com apenas 20% dos compostos fenólicos totais. O arroz não-pigmentado contém, em média, ao redor de 1000 µg eq. ácido ferúlico/g, distribuídos quase equitativamente entre a fração solúvel e insolúvel. O cozimento do arroz provocou redução nos teores de FT e alteração na proporção entre FS e FI. Essas alterações foram mais pronunciadas no arroz com pericarpo vermelho, afetando principalmente a fração solúvel. O arroz preto, contudo, manteve a proporção entre FS e FI após o cozimento. A -amilase não foi inibida de forma significativa pelos fenólicos das amostras de arroz cozido. O arroz pigmentado inibiu mais fortemente a ECA do que o arroz não-pigmentado, levando a crer que a pigmentação seja um fator importante. No entanto, entre os diferentes genótipos pigmentados, o perfil de fenólicos parece ser o fator determinante para a maior ou menor atividade inibitória. O cozimento do arroz reduziu significativamente a inibição da ECA pelos fenólicos, fato observado principalmente nos genótipos vermelhos, devido à diminuição dos teores de FS e da capacidade inibitória dos fenólicos presentes. O arroz preto se destacou por ter o maior teor de fenólicos solúveis e a maior ação inibidora da ECA, após o cozimento. / Rice (Oryza sativa L.) sustains at present about half of the world´s population. Consumption is mainly in its milled form, but brown rice has prompted further research due to bioactive compounds present in the pericarp of the grain. Some of the positive health effects have been attributed to radical scavenging activity and other biological effects such as inhibition of certain enzymes. In this study it was analyzed the contents of total, soluble and insoluble phenolic compounds of 17 different genotypes of brown rice as well as the effect of cooking. Seven genotypes had pigmented pericarp and ten were non-pigmented. In addition, the extracts from crude and cooked rice were tested for their capacity to inhibit the angiotensin I (ACE) converting enzyme and -amylase activities. Pigmented rice genotypes were highest in phenolic compounds, with an average of about 4200 µg ferulic acid eq./g, due to their high contents of soluble phenolics, mostly represented by anthocyanins and proanthocyanidins. Insoluble phenolics, represented mainly by phenolic acids, contributed with only 20% of total phenolics. Non-pigmented rice showed overall lower levels of phenolics. The mean content was about 1000 µg ferulic acid eq./g, almost equally distributed between the soluble and insoluble fractions. Levels of total phenolics were significantly reduced by rice cooking and proportions between soluble and insoluble fractions were altered. These alterations were more pronounced for pigmented rice, and soluble phenolics were the most affected. However, after cooking, black rice was the only that maintained the original proportion between soluble and insoluble phenolics. Alpha-amylase was not significantly inhibited by phenolics after cooking. Pigmented rice showed a potent inhibition of ACE, much higher than of non-pigmented rice, which seems to indicate that color of the pericarp is an important factor. Nevertheless, different profiles of phenolic compounds may explain why individual pigmented genotypes with similar phenolic levels can have different ACE inhibiting capacities. Rice cooking reduced significantly the inhibition of ACE by phenolics, which feature was more pronounced in pigmented rice due to the reduction of soluble phenolics and the activity of individual phenolics. Among pigmented rice, the highest soluble phenolic content and the most potent ACE inhibition after cooking was observed for black rice turning it the most distinguished notable.

Objetivo: Este estudio tuvo como finalidad determinar la cantidad de arsénico total (Ast) presente en el arroz integral comercializado en los supermercados y mercados de Lima Metropolitana, enero-febrero, 2020. Metodología: Se recolectaron nueve muestras de granos de arroz integral que representaron a la totalidad de las marcas expendidas al momento de realizar el muestreo, 8 de ellas se encontraron embolsadas y 1 a granel. Se empleó la técnica de espectrometría de masas con plasma inductivamente acoplado (ICP-MS) para la determinación de metales pesados en alimentos. Resultados: Ninguna de las muestras analizadas sobrepasó el contenido de Ast pues presentaron un promedio de 0,147 mg/kg con una desviación estándar de 0,021. Discusión: Los resultados del estudio indican que en general, el valor de Ast en el arroz integral que se comercializa en Lima Metropolitana se encuentra por debajo de los niveles máximos establecidos por diferentes entidades nacionales e internacionales que vigilan la inocuidad de los alimentos. Sin embargo, debido al alto impacto que este contaminante puede tener en la salud de las personas, los profesionales de la nutrición deberían estar expectantes a que las autoridades competentes realicen un adecuado control y monitoreo de este cereal, y de esta manera tener mayor seguridad en la recomendación de su consumo, ya que este se ha incrementado en los últimos años por sus diversos beneficios en la salud. Conclusión: En las muestras de arroz integral la cantidad de Ast no superó los límites máximos recomendados para As en el arroz según el Codex Alimentarius, MERCOSUR/GMC Resolución Nº 12/11 y la NTP 205.011:2014. / Objective: This study aimed to determine the amount of total arsenic (Ast) in brown rice sold in the supermarkets and markets of Metropolitan Lima, January-February, 2020. Methodology: Nine samples of brown rice grains were collected, representing all the brands found at the time of sampling, 8 of them were packed and 1 in bulk. The inductively coupled plasma mass spectrometry (ICP-MS) technique was used for the determination of heavy metals in food. Results: None of the samples analyzed exceeded the Ast content as they presented an average of 0,15 mg/kg with a standard deviation of 0,021. Discussion: The results of the study indicate that, in general, the value of Ast in brown rice that is sold in Metropolitan Lima is below the maximum levels established by different national and international entities that monitor food safety. However, due to the high impact that this pollutant can have on people's health, nutrition professionals should expect for the competent authorities to carry out an adequate control and surveillance of this cereal, and thus have greater reassurance in the recommendation of its consumption, since it has increased in the past years for its various health benefits. Conclusion: In the brown rice samples the amount of Ast did not exceed the maximum recommended limits for As in rice according to the Codex Alimentarius, MERCOSUR/GMC Resolution Nº 12/11 and NTP 205.011: 2014. / Tesis