Objective: To assess the validity of a food frequency questionnaire (FFQ) by applying it to children and adolescents living in Salvador, Bahia. Methods: The validity of this FFQ with 98 food items was investigated among 108 children and adolescents who were selected from a sample of 1445 that had been planned for a study on the risk factors for asthma and other allergic diseases. The adults responsible for these children and adolescents gave responses for a 24-hour recall (R24h) and an FFQ. The average energy and nutrient values from the FFQ were compared with those from the R24h by means of the paired t test and Pearson correlation coefficients. The concordance was evaluated using the Bland-Altman method and kappa statistics. Results: The energy and nutrient intake estimated using the FFQ was significantly higher than what was obtained using the R24h. The correlation coefficients adjusted for energy were statistically significant for protein, fat, vitamin C and zinc. The weighted kappa values ranged from 0.06 for vitamin A (p = 0.24) to 0.34 for energy (p < 0.00). The results from the Bland-Altman plots for lipid, protein and zinc showed the most significant validity parameters, and zinc was found to show the best concordance. Conclusion: The results suggest that the FFQ showed satisfactory validity for use in studies involving children and adolescents.

Objetivo: Evaluar la validez de un cuestionario de frecuencia de alimentos (QFA) aplicándolo a niños y adolescentes residentes en Salvador, Bahía. Métodos: Se investigó la validez de este QFA con 98 ítems de alimentos en 108 niños y adolescentes seleccionados a partir de una muestra de 1.445 planificados para un estudio sobre los factores de riesgo para asma y otras enfermedades alérgicas. Los adultos responsables de estos niños y adolescentes proporcionaron respuestas para un recuerdo de 24 horas (R24h) y el QFA. Los valores promedio de energía y nutrientes procedentes del QFA se compararon con los del R24h mediante una prueba t de student y los coeficientes de correlación de Pearson. La concordancia se evaluó usando el método de Bland-Altman y el estadístico kappa. Resultados: El consumo estimado de energía y nutrientes usando el QFA fue significativamente superior que el obtenido usando el R24h. Los coeficientes de correlación ajustados para la energía fueron estadísticamente significativos para proteínas, grasas, vitamina C y cinc. Los valores ponderados por kappa variaron desde 0,06 para la vitamina A (p = 0,24) hasta 0,34 para la energía (p < 0,00). Los resultados de las gráficas de Bland-Altman para los lípidos, proteínas y cinc mostraron los parámetros más significativos para la validez y se halló que el cinc tenía la mejor concordancia. Conclusión: Los resultados sugieren que el QFA mostró una validez satisfactoria para ser usado en estudios con niños y adolescentes.

The hydrodynamic behaviour of a short Kühni column was investigated under no mass transfer conditions using the binary system water (continuous phase) and Exxsol D-80 (dispersed phase). The counter-current flow pattern of the liquid phases was characterised regarding the Sauter mean drop diameter, drop size distribution and hold-up; a photographic method was used to assess drop sizes. The following operating variables were studied: rotor speed, flow rate of both liquid phases and column stage. The log-normal probability density function was found to be adequate to fit the experimental drop size distributions along the column. As expected, smaller drops and more uniform drop size distributions were obtained with the increase of rotor speed and column stage number, thus indicating the predominance of drop breakage phenomena in short columns. The total hold-up was influenced mainly by rotor speed and flow rate of the dispersed phase. Recommended correlations available in the literature were found to be inadequate for predicting experimental drop sizes and hold-up, so alternative expressions, valid only for short Kühni columns, were proposed.