[Mineral composition of milk from the State of Mérida, Venezuela]. / Composición mineral de la leche del Estado Mérida, Venezuela.

The main mineral components were measured on 132 composite raw milk samples collected in the low and high zones of Mérida State, located in the Venezuelan Andes, by spectrophotometric and atomic absorption methods. The results were grouped to evaluate the effect of the zone (low vs. high) breed (hybred vs. Holstein) and season (dry vs. rain). The mean values and standard deviations (mg/L) were: sodium, 537.0 +/- 143.05; potassium, 1327.9 +/- 133.84; calcium, 952.4 +/- 118.67, phosphorous, 739.2 +/- 97.9; iron, 0.397 +/- 0.1549; magnesium, 82.4 +/- 10.40; copper, 0.589 +/- 0.340; zinc, 7.95 +/- 1.737. These values were higher for the low zones due probably to differences in the production systems. Significant high concentration of iron and copper were obtained which could result in milks susceptible to oxidative rancidity.

[Microflora in pasteurized fruit juices in Venezuela]. / Microflora en jugos de frutas pasteurizados venezolanos.

A total of 96 pasteurized fruit juice samples obtained at retail level and packed in pure-pak containers were analyzed, to determine their pH and mould yeasts counts. The isolated microflora were identified by macroscopic and microscopic techniques besides biochemical reactions. The pH rate values were the following: cocktail fruit, pH 2.3-4.3; orange, pH 2.8-3.7; passion fruit, pH 2.3-3.7; and tamarind, pH 2.5-3.7. The yeast and mould counts per ml were: cocktail fruit, 0-8.0 x 10(3), orange, 1.0 x 10(2)-4.5 x 10(3); passion fruit, 0-7.7 x 10(3), and tamarind, 0-6.0 x 10(2). The predominance of yeasts over the fungi in almost all the juices is evident; the only exception was tamarind juice. The genera of the yeasts commonly isolated were: Candida, Rhodotorula, Saccharomyces and Pichia, and among the fungi: Aspergillus, Penicillium and Cladosporium. Yeasts are probably the main cause of spoilage in these pasteurized fruit juices.

[Thermal resistance of Candida tropicalis and Rhodotorula rubra in orange juice]. / Resistenica térmica de Candida tro picalis y Rhodotorula rubra en jugo de naranja.

The thermal resistance of two yeasts (Candida tropicalis and Rhodotorula rubra) was studied. The yeasts were isolated from Venezuelan pasteurized orange juice obtained at retail level. The flask method was utilized, applying temperatures which ranged from 49.5 to 53.5 degrees C to initial populations of 1x10(5) cells/ml of orange juice. Values of D50C=3.4 min and z=4.1 degrees C were found for C. tropicalis, and D50C=2.6 min and z=9.8 degrees C for R. rubra. Linear correlation coefficients of r=0.99 and r=0.98 wee obtained, respectively, for the experimental data.

Resistencia termica de Candida tropicalis y Rhodotorula rubra en jugo de naranja. / Thermal resistance of Candida tropicalis and Rhodotorula rubra in orange juice

El presente trabajo constituye un estudio sobre la resistencia termica de dos levaduras (Candida tropicalis y Rhodotorula rubra) que frecuentemente se aislan de muestras de jugo de naranja pasteurizados comerciales, recolectadas en el mercado venezolano. El experimento se desarrollo siguiendo el metodo del frasco, y aplicando temperaturas comprendidas entre 49.5 y 53.5 grados C, a poblaciones iniciales de 1 x 10 a quinta celulas/ml de jugo. Se encontraron valores de D50C = 3.4 min y z = 4.1 grados C para C. tropicalis y de D50C = 2.6 min y z = 9.8 grados C para R.rubra, obteniendose coeficientes de correlacion lineal r = 0.99 yr = 0.98, respectivamente, para los datos experimentales