Néstor Raúl Pellegrino

In vitro measurement of available iron in fortified foods

Abstract The objective of this study was to investigate the influence of base systems used to regulate pH values of digests on iron dialysability as an indicator of bioavailable iron. We studied the pertinence of measuring titratable acidity to pH 7.5 with KOH to calculate mEq of NaHCO 3 to be used for pancreatic digestion/dialysis. The pH achieved using the same mEq of each base was lower when using NaHCO 3 than when using KOH. The discrepancy between achieved and attempted pH was uneven for several iron sources. Differences in pH regulation procedure, including type and concentration of base or buffer added to the pepsin digest rendered different final digest/dialysate pH values, thus affecting dialysable iron. A modification of in vitro equilibrium dialysis method is proposed using PIPES buffer of sufficient molarity to obtain a uniform final pH of 6.5 in digest/dialysate systems. The main factors taken into account to calculate buffer concentration were buffer capacity of food matrix (HCl mEq required to reach pH 2), HCl mEq included in the aliquot of pepsin suspension, acid or base mEq generated through enzymatic hydrolysis during in vitro digestion and intrinsic food pH (HCl mEq to adjust food matrix pH to 6.5). With these data buffer molarity for each food matrix can be calculated. Modifications suggested for the equilibrium dialysis method allowed development of a uniform final pH of the digest/dialysate system in a variety of foods assayed.

DIALIZABILIDAD DE HIERRO Y ZINC EN CEREALES PARA DESAYUNOS COMERCIALES FORTIFICADOS CON HIERRO ELEMENTAL, SULFATO FERROSO O EDTA FERRICO SODICO

Se comparo la dializabilidad de Fe y Zn en 7 cereales para desayuno comercialmente fortificados o no, con Fe elemental y ZnO y se comparo la dializabilidad de Fe y Zn en tres tipos diferentes de cereales experimentalmente fortificados con ZnO y FeNa2EDTA o FeSO4 en el laboratorio. Se utilizo una metodologia in vitro que mide el porcentaje de dializabilidad (D%) del mineral en condiciones controladas de pH. Los cereales comercialmente fortificados presentaron valores de DFe% entre 0,4 y 15,0 y entre 1,0 y 5,6; sin y con leche. Para DZn% los valores fueron entre 3,3 y 16,1 y entre 3,3 y 30,8, sin y con leche. Casi todos los cereales fortificados en el laboratorio presentaron mayor DFe% (entre 19,5 y 28,6) y DZn% (entre 12,4 y 29,2) cuando fueron fortificados con FeNa2EDTA (con y sin leche). Los resultados obtenidos muestran al FeNa2EDTA como una alternativa viable para la fortificacion de cereales para desayuno.

Variation in exocrine pancreatic secretion in rats due to different commercial diets

The diet fed to laboratory animals is one of many variables that can confound research results. The authors investigated the effect of the composition of commercial standard rodent diets on exocrine pancreatic function in rats. They compared two widely used commercial animal diets and found that diet composition greatly influences pancreatic secretion. Their results indicate that commercial diets should conform to the recommended composition requirements to avoid alterations in physiological functions that would eventually affect the results of biomedical research and that investigators should be keenly aware of the composition of the diets being fed to their animals.