Examinando por Materia "pH"

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The distribution of cadmium in soil and cacao beans in Peru
(Elsevier, 2023-04-11) Thomas, Evert; Atkinson, Rachel; Zavaleta, Diego; Rodriguez, Carlos; Lastra Paucar, Sphyros Roomel-Luciano; Yovera, Fredy; Arango, Karina; Pezo, Abel; Aguilar, Javier; Tames, Miriam; Ramos, Ana; Cruz, Wilbert; Cosme, Roberto; Espinoza, Eduardo; Chavez, Carmen Rosa; Ladd, Brenton
Peru is the eighth largest producer of cacao beans globally, but high cadmium contents are constraining access to international markets which have set upper thresholds for permitted concentrations in chocolate and derivatives. Preliminary data have suggested that high cadmium concentrations in cacao beans are restricted to specific regions in the country, but to date no reliable maps exist of expected cadmium concentrations in soils and cacao beans. Drawing on >2000 representative samples of cacao beans and soils we developed multiple national and regional random forest models to develop predictive maps of cadmium in soil and cacao beans across the area suitable for cacao cultivation. Our model projections show that elevated concentrations of cadmium in cacao soils and beans are largely restricted to the northern parts of the country in the departments of Tumbes, Piura, Amazonas and Loreto, as well as some very localized pockets in the central departments of Huánuco and San Martin. Unsurprisingly, soil cadmium was the by far most important predictor of bean cadmium. Aside from the south-eastern to north-western spatial trend of increasing cadmium values in soils and beans, the most important predictors of both variables in nation-wide models were geology, rainfall seasonality, soil pH and rainfall. At regional level, alluvial deposits and mining operations were also associated with higher cadmium levels in cacao beans. Based on our predictive map of cadmium in cacao beans we estimate that while at a national level <20 % of cacao farming households might be impacted by the cadmium regulations, in the most affected department of Piura this could be as high as 89 %.
Medición del pH intramuscular del cuy (Cavia porcellus) durante las primeras 24 horas post beneficio tradicional
(Universidad Peruana Cayetano Heredia, 2015-02-10) Nakandakari, Luis; Gutiérrez, Eduardo; Chauca Francia, Lilia; Valencia, Roberto
La carne de cuy tiene un alto valor nutricional para el ser humano. Sin embargo, es un excelente medio de cultivo para microorganismos que pueden ser nocivos para el consumidor. Durante la transformación del músculo a carne se producen reacciones biológicas y químicas que ayudan a descender el pH muscular, reduciendo el crecimiento bacteriano. Objetivo: Determinar los cambios del pH intramuscular del cuy (Cavia porcellus), durante las primeras 24 horas post beneficio tradicional. Materiales y Métodos: Se emplearon 30 cuyes machos de raza Perú, de 8 a 10 semanas de edad, clinicamente sanos y con pesos vivos entre 800 y 1300 g. Luego del sacrificio, las medidas del pH se realizaron en los músculos Psoas mayor izquierdo y derecho utilizando un pH-metro digital, las medidas se tomaron a las 0, 4, 8, 12, 16, 20 y 24 horas post beneficio. Resultados y conclusiones: A las 0 horas los pH en los músculos Psoas mayor izquierdo y derecho fueron de 6.71 ± 0.27 y 6.67 ± 0.27 respectivamente, alcanzando su mínimo valor de 5.95 ± 0.08 y 5.96 ± 0.09 pH a las 12 horas. A las 24 horas post beneficio experimentaron un ligero incremento hasta 6.05 ± 0.09 y 6.06 ± 0.08 pH en el músculo Psoas mayor izquierdo y derecho. Se concluye que los valores de pH de los músculos Psoas mayor fluctuaron en un rango de 5.95 ± 0.08 pH a las 12 horas a 6.06 ± 0.08 pH a las 24 horas post beneficio.