Emilio A. Cepeda

Density and viscosity of Malus floribunda juice as a function of concentration and temperature

Abstract Density for cloudy and depectinised juice of Malus floribunda was determined in a concentration range from 17 to 70 °Brix at 25°C. Density values were similar to the ones of common apple and were linearly correlated with soluble solids concentration. The influence of temperature and concentration on the rheological behaviour of depectinised juice of Malus floribunda has been studied in a temperature range from 10°C to 60°C, and concentrations between 40 and 70 °Brix. The depectinised juice has Newtonian behaviour and viscosity variation with temperature following the Arrhenius–Guzman equation, with activation energy values between 26.6 and 64.8 kJ gmol −1 . A relationship between viscosity, temperature and soluble solids concentration has been proposed.

Functional properties of faba bean (Vicia faba) protein flour dried by spray drying and freeze drying

Faba protein flour of Vicia faba was obtained by precipitation and centrifugation from peeled and milled seeds. The flour was dried by spray drying and freeze drying. The effect of both methods of drying on functional properties such as solubility, emulsification, water retention, viscosity and enzymatic hydrolysis was studied.

Solubility of anthracene and anthraquinone in acetonitrile, methyl ethyl ketone, isopropol alcohol and their mixtures

Abstract The solubilities of anthracene and anthraquinone in isopropyl alcohol, methyl ethyl ketone, acetonitrile and isopropyl alcohol-methyl ethyl ketone, isopropyl alcohol-acetonitrile mixtures, have been measured for temperatures ranging from 298 to 318 K. The solubility data have been correlated as functions of the temperature. Activity coefficients for anthracene have been estimated from the group contribution method UNIFAC and with them were calculated solubility data that were compared with the experimental ones.

Pimento (Capsicum annuum L.) purée: preparation, physicochemical properties and microscopical characterisation

Abstract The water adsorption of dehydrated pimento and the pigment loss in the maceration process was determined between 20°C and 60°C and a kinetic equation was proposed. Puree was prepared in several ways with the rehydrated pimento and their physicochemical properties were determined. A study on microscopic sections of pimento and structures of the puree was done for quality control. The puree presented pseudoplastic behaviour. The values of the behaviour index and of the shear stress at 15 s −1 were related with the length of particles of disperse phase.

The role of shape selectivity and intrinsic selectivity of acidic sites of the catalysts in the skeletal isomerization of n‐butenes

The effect upon kinetic behaviour (activity and selectivity) of the physical properties (pore volume distribution) and acidic characteristics (nature of acidic sites and acidic strength distribution) of acidic catalysts in the skeletal isomerization of n-butenes has been studied. The catalysts studied are the following: γ-alumina, alumina modified by introduction of F, Cl and Br, silica–alumina, HZSM-5 zeolite-based catalyst and SAPO-34-based catalyst. It has been proven that the selectivity of acidic catalysts towards the skeletal isomerization of n-butenes is the result of a compromise between pore shape selectivity and intrinsic selectivity of the acidic sites of different strength, this latter property being more significant. Strong acidic sites are needed for the skeletal isomerization, but sites which are too strong produce important amounts of byproducts. A chlorinated alumina is a highly active and selective catalyst for skeletal isomerization.

Selective hydrogenation of sunflower oil over Ni catalysts

This work focuses on the influence of the support and the preparation method on the activity and selectivity of nickel catalysts in the hydrogenation of sunflower oil. Catalysts were prepared over silica and alumina supports following the incipient wetness impregnation and deposition-precipitation techniques. The activation process was followed by temperature-programmed reduction (TPR). Precipitation-deposition method allowed a stronger metal-support interaction than incipient wetness impregnation. A precipitation-deposition time of 14 h (which allowed a Ni loading of about 20wt%) was deemed as the most adequate from the standpoint of high specific surface area and strong Ni-support interaction. The selectivity to oleic acid was not affected by the preparation method, but it was significantly influenced by the type of support. In this regard, the catalysts prepared on silica are more active and produce less saturated fatty acids.