Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

In order to obtain dried films capable of encapsulating the maximum recommended daily values of fat-soluble vitamin E (α-tc), nanocomplexes between beta- lactoglobulin (β-lg), the major whey protein, and the vitamin were incorporated into sodium alginate (AS) solutions, to previously determined β-lg / AS ratio. The interaction between native and heat-treated protein with vitamin was studied by turbidimetry at different pH values. Native β-lg increased solubility α-tc in aqueous solutions at pH 6.80. Opacity and color tests to all films were carried out and no differences were found due to the incorporation of α-tc. Dry films improved the protection of α-tc structure when exposed to oxygen from the air and controlled light (measured by HPLC). This effect was attributable to the oxygen and ultraviolet light (UV) barrier exerted by the polysaccharide matrix.

Sweet potato, Ipomoea batatas L. (Lam) is a widely consumed food for its excellent nutritional characteristics.This vegetable can be considered as a functional food due to its higher mineral content (K, Mg) and antioxidant components as carotenoids, vitamin E, anthocyanins and polyphenols. In this work, the shelf life of the sweet potatoes was intending to be extended by osmodehydrofreezing. Zn and Ca were added during the process in order to increase its level in the fnal product, avoiding nutritional defciencies. The adjust of the experimental data was carried out with literature models that describe the bahaviour of the osmoticdehydration/impregnation and freezing process. Zn and Ca contents in the fresh and OD samples was determined by flame absorption spectrophotometry. Models of the OD like Page, Henderson y Pabis, Midilli et al., Azuara et al. and Crank were applied satisfactorily. Later, the samples were frozen in a tunnel of trays until the center of the sweet potatoes cubes reached -18 ºC. The freezing times of the samples with and without OD pretreatment were estimated favorably with the Salvadori-Mascheroni model without requiring the value of the thermal properties of the frozen food or the calculation of the effective enthalpy of the phase change.

In this work, the effect of the application of lactic acid on Listeria monocytogenes growth was evaluated in vacuum packed meat using strains isolated from local slaughter houses. Thirty-fve strains of Listeria were isolated and identifed: 29 L. innocua and 6 L. monocytogenes belonging to more than one serotype. All the isolates showed sensitivity to lactic acid in vitro. The minimum inhibitory concentration in TSB-YE was 0,3% and the minimum bactericidal concentration was 0,7%. Te L100A1 isolate was used in the meat study. In meat samples treated with 2,5% lactic acid, packed in vacuum and stored at 4 °C, an initial reduction of L100A1 of 1,1 log was achieved. By the end of eightweeks the reduction had reached 1,5 log showing a synergistic effect between lactic acid and vacuum packaging. When 5% lactic acid concentrations were used, no synergy was observed and the initial 1,4 log growth inhibition remained constant over time. In sum, the use of lactic acid at concentrations between 2,5 and 5% in vacuum packed meat signifcantly reduces L. monocytogenes counts and can be used as an additional hurdle in high value meat cuts.

Sofware development aiming measurement automation does not necessarily have a process modernizing purpose but, in most cases, focuses on reducing the risk associated with human errors by transcribing or reading data, as well as reducing the operating time to face the growing demand for services. This paper describes four custom sofware developments for the automation of measurements in temperature, length and pH laboratories, conducted at the National Metrology Laboratory of Uruguay (LATU). The general requirements of involved applications and instruments, the particular needs of each process studied, the difculties confronted during development stages with their different solutions, and most relevant features of final product for each application are presented here.A method to measure the impact on the reduction of time and risk in each automated process is also suggested.

In recent times, the consumption of meat products has been avoided by consumers, as it is associated with the prevalence of noncommunicable diseases and obesity. As a consequence, recent strategies have been developed in order to enhance the nutritional composition of these types of products. In this study, 100 consumers evaluated from the sensory standpoint hamburgers produced with beef, vegetables and spices against a homemade formulation (composed of beef, salt and oregano), and a frozen commercial beef burger. 9-point hedonic scales were used, as well as a check-all-that-apply (CATA) composed of 32 terms; consumers were also asked to describe an “ideal hamburger”. Results show that there is a segment of the studied population that is interested in a hamburger formulated with the addition of vegetable ingredients, having assigned a high acceptance score to the developed formula, and describing it as tender, natural, delicious, nutritious, healthy and tasty, as well as close to their concept of an ideal hamburger.

The ion-exchange resins are mainly constituted by synthetic organic polimers, with reticulated structure which form porous granules with ion charges. This charges are neutralized by their counterions available in solution, which are exchangeable, leading to a charge exchange process. The resins are very used in water deionizers, which have acid and basics groups in its structure, changeable by the cations and anions contaminants that are disposed in a resin and ions dynamic, in a process called demineralization. The comparative tests proposed to evaluate the recovery efficiency of polyfunctional resin was the conductivity test and the adsorptive capacity of the methylene blue (MB) and methyl orange (MO) dye. The conductivity obtained in the recovered resins was 0,880 μS cm-1, the value contained in the band ideal for deionized water (0,5-3,0 μS cm-1). Compared to the commercial resin, the recovered one presented a superior adsorptive capacity; the anionic recovered resin (R-) adsorb 22% more than the anionic commercial (C-). Regarding the adsorption capacity of the cationic recovered resin (R+) and the cationic commercial (C+), both are practically alike. Applying the adsorption mathematical models, it was found that the recovery process applied did not modify the adsorption pattern (remaining homogenic, Langmuir), while in the C+ and R+ resin there were modification in the adsorption pattern, from homogeneous to heterogeneous (Freundlich), respectively. The FTIR tests showed the recovery modifies the morphology of the resin, but not its chemical structure.

Moringa stenopetala is a good source of nutrients intended for human and animal consumption. This fact inspired the study of its minerals and vitamin C contents. Metals were analyzed by flame atomic absorption spectrometry. Vitamin C was determined by liquid chromatography equipped with a diode array detector. The nutrients availability in infusions was evaluated by calculating transfer factors from the solid matrices. After analyzing several commercial brands, a greater variability in the content of elements such as iron, magnesium and sodium was observed. The high calcium content found in the samples was highlighted, but with a low transfer factor to the infusions. In the case of vitamin C, a great loss was detected during the preparation of the infusions due to thermal decomposition. Moringa stenopetala would be an interesting natural supplement beneficial to health, especially consumed on a fresh basis, rich in calcium, potassium, magnesium and vitamin C, in quantities like those present in foods recommended as a source of these nutrients.

A prototype of a low-cost automated analyser capable of in situ operation next to a water body is described. The analyser can determine levels of phosphorus (orthophosphate) and nitrogen (nitrate+nitrite), along with pH and temperature, transmitting the results to a remote station via wireless internet. Phosphorus and nitrogen determinations are carried out by means of photometric methods, implemented in a pulsed-flow system. For control and data acquisition the open-source Arduino platform of microcontrollers was used. The system runs on rechargeable batteries, with the possible support of a solar panel. Preliminary evaluation of the analytical methods carried out in the laboratory showed figures of merit fit for the purpose. A field evaluation is foreseen in the near future, where the analyser will be tested under real conditions. This type of instruments is considered to be potentially useful in environmental analysis.

Honey as a natural food has a high quality standard. Nevertheless, honey production is performed together with agricultural activities. Pesticide residues have been detected in honey samples from various countries including Uruguay, sometimes exceeding their maximum residue limits (MRL). The implementation of a modern methodology for the analysis of glyphosate in honey is presented. The sample preparation method named QuPPe, involves extraction with methanol and was specifically developed for the analysis of polar pesticides, by ionic liquid chromatography coupled to a mass spectrometer (LC–MS/MS). Due to the particularities of the glyphosate molecule it can not be included in a multiresidue method. The evaluated and validated methodology was developed by the European Union Reference Laboratory for Single Residue Methods (EURL–SRM). In order to perform its validation, SANTE guidelines were followed, obtaining good results even at the European MRL in honey (0.050 mg kg-1). Real Uruguayan samples were analyzed finding glyphosate residues in some cases. The methodology is useful for quality control and safety assurance of honey regarding glyphosate residues.

Water temperature is a fundamental parameter to understand the dynamics of continental waters. Surface water temperature trend and variability of the large reservoirs of the Río Negro river, Rincón del Bonete and Baygorria, using 16 years of satellite data (MUR-GHRSST) with a spatial resolution of 0.01º between 2002 and 2018 was studied. The average temperature was 18.8 ºC, with a minimum of 12.1 ºC and maximum of 25.2 ºC, in July and January, respectively. Spring and autumn showed the highest intraseasonal variability, and winter the highest interannual variability. The surface temperature of the reservoirs showed a signifcant trend towards warming of 1.3 °C per decade for spring-summer, while the seasons of autumn and winter did not exhibited a signifcant trend. The warming trend increased towards downstream. The satellite information was correlated with opportunistic observed data (n = 67), with a correlation of 0.94 and a root mean square error of 1.92 ºC. Generating time series of continuous measurements in situ would allow an evaluation of the product and viability for operational usage. These results demonstrate the utility of remote sensing of water temperature as a monitoring tool based on freely accessible information. In addition, the seasonal cycle, trend and variability of the reservoirs of the Río Negro river were described for the first time. It is expected that these results contribute to the environmental management measures of the Río Negro river reservoirs.