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Santa Fe de la Vera Cruz, Argentina

Sanchez V.,Pontifical Catholic University of Argentina | Baeza R.,Pontifical Catholic University of Argentina | Ciappini C.,University of Latinamerican Education Centre | Zamora M.C.,Pontifical Catholic University of Argentina | And 2 more authors.
Food Control | Year: 2010

The aim of this work was to compare refractometric index (RI) and Karl Fischer (KF) titration methods for water content measurement in honeys. In addition, the effectiveness of two different solvents (methanol (M) and methanol:formamide in the ratio 1:1 (M + F)) was evaluated. Results indicated that RI and KF methods yielded similar results for water content determination in honeys; mainly, when the solvent M + F was used. This solvent mixture (M + F) also allowed a reduction in titration time which may be a potential advantage for measuring water content in honey. © 2009 Elsevier Ltd. All rights reserved. Source


Zandron O.P.,CONICET | Abecasis C.L.,University of Latinamerican Education Centre
Advanced Studies in Theoretical Physics | Year: 2010

From our family of first-order Lagrangian and applying the super-symmetric version of the Faddeev-Jackiw symplectic formalism for a t-J model, the constrained structure for triangular lattice antiferromagnetic is found. In this context, the Hubbard operators are used as field variables. In this approach the Hubbard X-operators are used as field variables, and they satisfy the commutation rules of the graded algebra spl(2,1). This model is also analyzed by using the path-integral formalism, and so the correlation generating functional and the effective Lagrangian are constructed. On the other hand, we must introduce appropiate ghost field in order to obtain a renormalizable model. It is shown how propagators and vertices can be renormalized to each order. In particular, the renormalized antiferromagnetic magnon propagator coming from our formalism is studied. As an example the thermal softening of the magnon frecuency is computed. Source


Cespedes M.,University of Latinamerican Education Centre | Cardenas P.,University of Latinamerican Education Centre | Staffolani M.,University of Latinamerican Education Centre | Ciappini M.C.,University of Latinamerican Education Centre | Vinderola G.,CONICET
Journal of Food Science | Year: 2013

The increase in vegetarianism as dietary habit and the increased allergy episodes against dairy proteins fuel the demand for probiotics in nondairy products. Lactose intolerance and the cholesterol content of dairy products can also be considered two additional reasons why some consumers are looking for probiotics in other foods. We aimed at determining cell viability in nondairy drinks and resistance to simulated gastric digestion of commercial probiotic lactobacilli commonly used in dairy products. Lactobacillus casei LC-01 and L. casei BGP 93 were added to different commercial nondairy drinks and viability and resistance to simulated gastric digestion (pH 2.5, 90 min, 37 °C) were monitored along storage (5 and 20 °C). For both strains, at least one nondairy drink was found to offer cell counts around 7 log orders until the end of the storage period. Changes in resistance to simulated gastric digestion were observed as well. Commercial probiotic cultures of L. casei can be added to commercial fruit juices after a carefull selection of the product that warrants cell viability. The resistance to simulated gastric digestion is an easy-to-apply in vitro tool that may contribute to product characterization and may help in the choice of the food matrix when no changes in cell viability are observed along storage. Sensorial evaluation is mandatory before marketing since the product type and storage conditions might influence the sensorial properties of the product due to the possibility of growth and lactic acid production by probiotic bacteria. Practical Application: Many probiotic cultures are available for application in dairy products. However, care must be taken before applying them to different foods and the necessary control of viable cells must be carried out in order to diversify the market of probiotic products with the present available commercial strains. © 2013 Institute of Food Technologists®. Source


Aimaretti N.R.,National University of Santa | Aimaretti N.R.,University of Latinamerican Education Centre | Ybalo C.V.,University of Latinamerican Education Centre | Rojas M.L.,Spanish University for Distance Education (UNED) | And 2 more authors.
Bioresource Technology | Year: 2012

A revalorization of discarded carrots as substrate for the production of second-generation ethanol is proposed. In order to increase the fermentable sugar concentration of the musts two strategies were studied: Strategy 1 consisted in the enzymatic hydrolysis of bagasse must and Strategy 2 by which carrots were milled, dropped into distilled water and hydrolyzed with different enzymes prior to compressing and filtering to obtain carrot must. By applying Strategy 2 using 0.05% (v/v) of the enzyme Optimase CX255 at 70 °C and pH 5.5 during 2.5 h, the fermentable sugars extracted increased 3.5 times. In this way, the production of 77.5 L of ethanol for each ton of discarded carrots was achieved. This process yielded bagasse as byproduct, which could be used for animal feed. © 2012 Elsevier Ltd. Source


Clementz A.L.,CONICET | Aimaretti N.R.,CONICET | Aimaretti N.R.,University of Latinamerican Education Centre | Manuale D.,CONICET | And 2 more authors.
International Journal of Energy and Environmental Engineering | Year: 2015

Discarded carrots are a valuable source of biomass amenable for valorization. Their use as raw material for ethanol production by fermentation, using yeasts immobilized in Calcium alginate, was proposed. The biocatalyst immobilization method, the existence of internal and external mass transfer limitations, the effect of the initial pH and the reuse of immobilized yeasts were particularly evaluated. Results indicate that beads made with a 2 % solution of Sodium alginate and a 30 % solution of Saccharomyces cerevisiae were strong enough to allow an efficient nutrient transfer into the matrix and to prevent cell leaking. A stirring rate of 200 rpm was needed to avoid external mass transfer limitations. These beads were used in three successive fermentations. An initial pH of 5.5 reached the best fermentation parameters. Non-enriched, non-sterile carrot must was fermented through immobilized yeasts; and values of ethanol concentration (29.9 g L−1), Yp/s (0.409 g g−1), and productivity (7.45 g L−1 h−1) were obtained. These values were similar to those registered when free cells were used. © 2014, The Author(s). Source

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