Zinc accumulation in phosphate granules of Ucides cordatus hepatopancreas

Amorphous phosphate granules are present in vertebrate and invertebrate organisms. The functions attributed to these structures depend on their mineral contents and organic matrix composition. In the present study we have determined zinc concentrations in the hepatopancreas of the crab Ucides cordatus from regions contaminated with zinc, and the elemental composition of hepatopancreal phosphate granules. Organisms were collected from the contaminated areas of Sepetiba Bay (SB) and Guanabara Bay (GB), and from a non-contaminated area, Ribeira Bay (RB). The first two sites are located near the metropolitan region of Rio de Janeiro city, Brazil. Atomic absorption spectroscopy (AAS) showed a significant difference (P<0.05) for zinc concentration in the hepatopancreas from organisms collected at the contaminated sites GB (210 ± 20 µg/g dry weight) and SB (181 ± 16 µg/g dry weight) compared to the non-contaminated site RB (76 ± 14 µg/g dry weight). Phosphate granules isolated from hepatopancreatic tissue were studied by electron diffraction (ED), energy dispersive X-ray analysis (EDX) and electron spectroscopic imaging (ESI). ED of granules presented no diffraction spots, indicating that these structures are in an amorphous state, while EDX of granules isolated from a contaminated area contained P, Ca and Zn. Mg, Cl and Fe were also found in some of the spectra. ESI showed that O, P and Ca were colocalized in the mineralized layers of most granules observed. The correlation between the results obtained by AAS and those obtained by microanalytical techniques suggests that the hepatopancreatic granules of U. cordatus may be related to the phenomenon of heavy metal retention.

Daños tóxicos en tejidos vegetales, producidos por aguas contaminadas con arsénico en Zimapán, Hidalgo, México

Según estudios realizados en el periodo de 1992-1998 en las aguas de los pozos, norias y manantiales, del municipio de Zimapán, Estado de Hidalgo, México, se corroboró que existía un incremento en el contenido de arsénico rebasando los límites máximos permisibles por la Norma Oficial Mexicana. La determinación de arsénico en las muestras de aguas se realizó por absorción atómica (AAS), mediante generador de hidruros (GH). En este estudio se utilizó el Vicia faba como un bioensayo para evaluar el daño genotóxico con la prueba de inducción de micronúcleos por exposición al agua de Zimapán, contaminada con As en células de raíces. Se utilizó como ensayo de control un agua de pozo de similares características del municipio de Pachuca, pero con contenidos de As por debajo de los límites de detección. Los resultados mostraron que el agua de esta región presenta altas concentraciones de arsénico y que puede provocar efectos genotóxicos que se manifiestan por la inducción de micronúcleos en las células meristemáticas de raíces de tejidos vegetales sensible.

Physicochemical and sensory characteristics of pan bread samples available in the Brazilian market

Pan bread samples available in the Brazilian market were evaluated for their physicochemical and sensory characteristics. Twelve pan breads, seven white and five whole grain breads, were evaluated. Moisture, water activity (Aw), firmness, and color (L*, a*, b*) of the crumb were evaluated on the first, fourth, seventh, and tenth days after purchasing the breads. Specific volume was evaluated on the first day of analysis with averages of 4.72 and 4.70 mL/g for the white and whole grain breads, respectively. The average results on the first day of analysis were: 37.03% and 41.23% moisture, 0.954 and 0.966 Aw, 276.27 and 267.83 gf firmness, 74.73 and 64.45 L* values, 0.37 and 3.85 a* values, and 15.51 and 18.98 b* values for the white and whole grain breads, respectively. The samples showed an increase in firmness, reduction in moisture and Aw, and no color changes over time. A survey conducted prior to the acceptance test showed that the three most important factors influencing purchase were taste (19.6%), tenderness (16.8%), and expiration date of the product (14.3%). The results showed that 37.2% of the panelists preferred white bread, 62.8% preferred bread with fibers, and 82.6% would probably or definitely buy white bread with fibers.