http://hdl.handle.net/2117/6306 2013-05-22T10:10:44Z http://hdl.handle.net/2117/12486 Title: Estimation of the freezing point of concentrated fruit juices for application in freeze concentration Authors: Auleda Amorós, Josep Maria; Raventós Santamaria, Mercè; Sánchez Machado, José; Hernández Yáñez, Eduard Abstract: In freeze concentration operations the fluids remain at temperatures below 0 °C. For a good study of this concentration operation is very important to know the values of freezing point. The aim of this work was to establish a model that predicts the freezing point of fruit juices at various concentrations within the range of interest for freeze concentration (10–40 °Brix). The model proposed relates the freezing point of a juice with the concentrations of main sugars present in the juice: sucrose, glucose and fructose. The freezing point of apple juice, pear juice and peach juice was determined experimentally at various concentrations, and experimental results were well correlated with model calculations. 2011-05-05T16:36:14Z http://hdl.handle.net/2117/11248 Title: A new method to obtain information about the pore size distribution in microporous polymeric membranes Authors: Llorens, Joan; Marco, P.; Sabaté Reboll, José; Pujolà Cunill, Montserrat; Felip, I; Plumed, E Abstract: Transport measurements of selected fluids through porous membranes provide information on precise statistical moments of the membrane pore-size distribution (PSD). It is assumed that membrane porosity, ~T,is distributed on different pores sizes which are statistically distributed. Mean pore sizes are determined on the basis of statistical moment analysis. This paper focuses in the special case of determining PSD in microfiltration (MF) membranes from a collectíon of experíments that include porosity and bubble point determinations and liquid and gas permeations. 2011-02-01T15:13:00Z http://hdl.handle.net/2117/11247 Title: Un método sencillo de extracción y evaluación de la fracción aromática en chiles frutales Authors: Centelles, Enric; Pujolà Cunill, Montserrat; Cugat, I. Abstract: En este estudio se presenta una metódica de extracción sencilla. basada en métodos convencionales (extracción sólido-líquido), que combinada con un análisis por cromatografia de gases mediante el uso de columnas semicapilares, permite de forma rápida y fiable, evaluar diversos aspectos que conciernen a la fracción aromática de un chicle. En una primera fase del estudio se ha aplicado la metódica sobre un chicle formulado tal como un producto comercial, dosificando dos aromas de la familia de los frutales en una misma concentración. En una segunda etapa se ha trabajado con el mismo sustrato, dosificando en este caso cuatro dosis de un único aroma frutal: 0,25%, 0,30%, 0,35%, 0,45%. Los resultados obtenidos muestran que, tomando como referencia los porcentajes de recuperación de algunos componentes aromáticos, la metódica propuesta es capaz de diferenciar entre aromas muy similares, y semicuantificar la dosis de aromas que se haya aplicado. 2011-02-01T14:38:57Z http://hdl.handle.net/2117/11195 Title: Característiques físiques i químiques a determinar en els compostos fets amb fangs residual per tal d'ésser utilitzats com a substrats Authors: Arnó, Jaume; Burés, Oleguer; Marzà, J.; Pujolà Cunill, Montserrat Abstract: Hi ha una sèrie d'activitats humanes que comporten l'aparició de subproductes contaminants, En particular ens hem centrat en els fangs residuals de les indústries papereres i de les depuradores d'aigües urbanes. Aquests productes presenten problemes d'eliminació pel gran volum que se n'obté, i per llur contingut en substàncies nocives, D'altra banda l'horticultura ornamental és un sector en expansió amb una demanda creixent de substrats, El substrat més utilitzat en l'actualitat és la torba, que té un preu molt alt. Observem doncs la necessitat de trobar materials alternatius més barats. Aixó ens ha impulsat a estudiar la viabilitat dels fangs com a substrats. La utilització d'aquests materials requereix un condicionament previ, que és el que hom fa mitjançant el procés anomenat compostatge (fermentació aeròbica i termòfila d'un o més productes orgànics per a eliminar o minvar llur capacitat contaminant). El producte final és el compost, el qual ha de tenir unes propietats físico-químiques adients, Resulta imprescindible un seguiment de l'evolució del compostatge i saber quan aquest ja ha acabat. Aquest seguiment comporta el control d'uns paràmetres químics (concentració en macro- i micronutrients i metalls pesants, contingut i qualitat de la matèria orgànica ... ), paràmetres físico-químics (pH, CE, CBe. .. ) i físics (densitat real i aparent, capacitat de retenció d'aigua, .. ), A més, han estat fetes proves de creixement de plantes ornamentals per tal d'estudiar l'aptitud del producte com a substrat. 2011-01-25T12:20:18Z http://hdl.handle.net/2117/11191 Title: Chemical properties population of nitrites oxidizers, urease and phosphatase activities in sewage sludge-amended soils Authors: Bonmati Pont, Manuel; Pujolà Cunill, Montserrat; Saña Vilaseca, Josep; Soliva Torrentó, Montserrat; Felipó, Mª Teresa; Garau, M.; Ceccanti, B.; Nannipieri, P. Abstract: The aim of this work has been to determine the effect of sterilized and non-sterilized, aerobically or anaerobically digested sewage sludges on urease and phosphatase aetivities, on populations of nitrite oxidizers and on some chemical properties in laboratory conditions and for long incubation periods. Both urease an phosphatase activities were affected when anaerobic sludges were added to the soil. The inhibitory effects on both enzyme activities attributed to the presence of heavy metals were probably masked by the additional source of organic matter both with aerobic and anaerobic sludges. The level of the NO,- oxidizer populations was higher in the aerobic than in the anaerobic sludge amended soil. Ammonia-N concentration were increased when the soil received sludges reflecting a higher mineralization rate probably due to a stimulation of the indigeneous ammonia producing microorganisms since differences between non-sterilizcd and sterilized treatments were minimal or absent. Nitrate-N concentrations increased in amended soils and care must be taken to restrict as much as possible the downward movement of nitrate in order to minimize ground-water pollution. 2011-01-25T11:33:05Z http://hdl.handle.net/2117/11189 Title: Continuous metal recovery process using polymer enhanced ultrafiltration Authors: Sabaté Reboll, José; Pujolà Cunill, Montserrat; Llorens, Joan; Marco, Pilar Abstract: The separation of metals from aqueous streams by continuous polyrner enhanced ultrafiltration (PEUF) was modelled in order to understand, evaluate and optimise the feasibility of the process. The mathematical model developed has three sections: mass balances, equilibriurn of rnetal-polymer complexation and rules for UF membrane separation. On the one hand, the modeJ allows an examination of the influence of physico-chernical variables (affinity between the metal ion and the complexing polyrner groups) and engineering parameters (rnainly expended acid and base reagents, amount of polymer used and recyc1ing strearn flow) on the quality and productivity of the treated water stream. On the other band, a' suitable representation of the simulation results has been shown to be helpful in choosing operation pararneter values that Iead to the stable output oftreated water with the desired quality and productivity. 2011-01-25T11:07:17Z http://hdl.handle.net/2117/10967 Title: Viscosidad de zumos comerciales de melocotón, manzana y pera a temperaturas cercanas a la congelación Authors: Ruiz Pardo, Yolanda; Sánchez Machado, José; Hernández Yáñez, Eduard; Auleda Amorós, Josep Maria; Raventós Santamaria, Mercè Abstract: Conèixer el comportament reològic de sucs comercials susceptibles de ser processats a baixes temperatures presenta un gran interès per el desenvolupament de noves tecnologies i equips en la indústria alimentaria. En processos de concentració de fluids alimentaris a temperatures baixes com en el cas de la crioconcentració, l’increment de la viscositat és un limitant en la eficiència del procés. En el present treball es determinen experimentalment les viscositats de sucs comercials de préssec, poma i pera a concentracions entre 40°Brix i 50°Brix, en el interval de temperatura -6 a 4 °C, sense que es presenti formació de cristalls de gel. S’ha analitzat l’efecte de la temperatura sobre la viscositat dels dos sucs. El rang de variació obtingut per a la viscositat dels tres sucs a 40 y 50 °Brix és de 11 a 22 mPa·s i de 28 a 64 mPa·s respectivament en tot l’ interval de temperatura estudiat. El suc de préssec presenta el valor més elevat de viscositat (64,0 ± 0,2 mPa·s a 50 oBrix i -6 °C). L’efecte de la temperatura sobre la viscositat dels sucs es representa de manera adient mitjançant una equació tipus Arrhenius. Els sucs estudiats presenten un comportament newtonià. 2011-01-11T18:41:32Z http://hdl.handle.net/2117/10297 Title: Freeze concentration of whey in a falling-film based pilot plant: process and characterization Authors: Sánchez Machado, José; Hernández Yáñez, Eduard; Auleda Amorós, Josep Maria; Raventós Santamaria, Mercè Abstract: Falling-film freeze concentration is a technique for concentration of liquids by freezing the available water in the form of a layer of ice on a refrigerated surface. Processing at low temperatures keeps the organoleptic properties of the initial product. In this study the freeze concentration of whey was investigated as an technological alternative for the use of this byproduct of the dairy industry. Freeze concentration tests were carried out in pilot-scale equipment and the increase in soluble solids content of the whey and the amount and purity of the ice formed were analysed. Electrical conductivity, viscosity and freezing point of the concentrated whey were determined. The concentrate obtained had a solid concentration of up to 21.8 ºBrix. The ice formed in the last stage of the freeze-concentration process had a lactose content of 11.3 g/L and protein content of 3.45%. The electrical conductivity of the ice formed increased exponentially to a value of 29.40 mS/cm. Freeze-concentrated whey of 10, 15, and 20 ºBrix behaves as a Newtonian fluid in the temperature range of -4 ºC – 4 ºC. 2010-11-15T17:24:02Z http://hdl.handle.net/2117/9819 Title: Concentration of apple and pear juices in a multi-plate freeze concentrator Authors: Hernández Yáñez, Eduard; Raventós Santamaria, Mercè; Auleda Amorós, Josep Maria; Ibarz, Albert Abstract: In this article we will examine the process for concentration of apple and pear juices as well as concentration of sugar solutions modelling pear juice (simulation fluid) using a descending film multi-plate freeze concentrator. It has been determined in advance the freezing point of those fluids in the working concentration and temperature intervals. In addition, different parameters were studied to allow tracking of the process of freeze concentration, such as ice accumulation, variation of the content of soluble solids in the solution and in the ice removed, ice production and energy consumption. The apple and pear juices tested showed similar behaviour, while the mixture of sugars used for simulation showed better behaviour, due perhaps to the absence of foam in the process and to the quicker formation of ice. It has been obtained concentrations of 30.2 and 30.8 °Bx with the apple and pear juices, respectively, and up to 32.7 °Bx with the simulation fluid. Industrial relevance: The clarified juices usually are concentrated on an evaporation stage. In this stage the juice is subjected to high temperatures that cause undesirable reactions, such as non enzymatic browning and destruction of nutritive compounds. The freeze concentration is a technology that allows eliminatingwater from the juices at temperatures below the water’s freezing point, what allows obtaining products of better quality. In this work has been applied this technology to concentrate apple and pear juices, obtaining promissory results. 2010-10-19T13:59:37Z http://hdl.handle.net/2117/9611 Title: Reflexiones sobre la brucelosis de la oveja Authors: Durán Ferrer, Manuel; Gutiérrez Repiso, Carolina; Álvarez del Castillo, Lorenzo; Latre Cequiel, María Victoria; Garrido, Fulgencio; Yustes, C.; Vendrell, J.; Gómez, Belén; García López, María Jesús; Ruiz Villamor, Eduardo 2010-10-11T08:43:26Z http://hdl.handle.net/2117/9512 Title: Aplicación de HPLC en la determinación de ácidos orgánicos no volátiles : estudio de su evolución en frutas frigoconservadas Authors: Rico, C; Centelles, Enric; Pujolà Cunill, Montserrat 2010-10-07T10:01:57Z http://hdl.handle.net/2117/9502 Title: Genetic and environmental effects on chemical composition related to sensory traits in common beans (Phaseolus vulgaris L.) Authors: Flórez Vergara, Alexis; Pujolà Cunill, Montserrat; Valero Baya, Jordi; Centelles, Enric; Almirall Malivern, Antonio Rafael; Casañas Artigas, Francesc 2010-10-07T09:04:06Z http://hdl.handle.net/2117/9447 Title: Aplicación del gluten índex para la determinación de la degradación del trigo Authors: Bolaño, Ana; Pujolà Cunill, Montserrat; Monleón Getino, Antonio; Gordún Quiles, Elena 2010-10-06T11:46:50Z http://hdl.handle.net/2117/9089 Title: Contribució a l'estudi sobre la utilització de compost de residus sòlids urbans com a substrat per a conreus hortícoles Authors: Jiménez de Ridder, Patrícia; Pujolà Cunill, Montserrat; Soliva Torrentó, Montserrat 2010-09-25T19:25:51Z http://hdl.handle.net/2117/8708 Title: Progressive freeze concentration of orange in a pilot plant falling film Authors: Sánchez, J.; Ruiz, Y.; Raventós Santamaria, Mercè; Auleda Amorós, Josep Maria; Hernández Yáñez, Eduard 2010-09-01T10:57:38Z