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Lopez-Tobar E.,CSIC - Institute for the Structure of Matter | Blanch G.P.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic | Ruiz Del Castillo M.L.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic | Sanchez-Cortes S.,CSIC - Institute for the Structure of Matter
Vibrational Spectroscopy | Year: 2012

FT-Raman and UV-visible adsorption spectroscopy are applied for the first time in the structural study of the antioxidant, antitumoral polyphenol curcumin and its complexation with β- and γ-cyclodextrin. Additionally, high performance liquid chromatography linked to UV spectroscopy was employed to monitor the encapsulation yield of curcumin. These techniques indicate that the effectiveness of the encapsulation is higher in the case of γ-cyclodextrin (γ-CD) likely due to the better fit of the polyphenol size with the dimensions of the γ-CD cavity. Raman spectra provided specific structural information from the ligand which indicates that the encapsulation takes place at the level of the aromatic rings, through H-bonds, and that a tautomerization from the planar keto enol form to the non-planar diketo form of curcumin also occurs. These changes may lead to an increase of the chemical stability, the bioavailability and the biological activity of curcumin. © 2012 Elsevier B.V. Source


Herranz B.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic | Borderias A.J.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic | Solas M.T.,Complutense University of Madrid | Tovar C.A.,University of Vigo
Food Research International | Year: 2012

Samples of 3% glucomannan gels made with 0.6M KOH and preheated at T ht: 25°C (A), 50°C (B), 70°C (C) and 90°C (D) were studied at two measurement temperatures (T m: 50 and 70°C) and compared to T m: 25°C. Samples B and C were gels more thermo-stable at high measurement temperatures. This means that a preliminary heating at 50 and 70°C would be needed to retain their structural integrity of these gels. When the preheated gels were subjected to high deformation (puncture test), rigidity increased with increasing T m. Similarly, small deformation tests showed that at T m: 50°C and 70°C, the C sample had better gel characteristics than the others: i.e. higher elasticity and lower frequency-dependence of viscoelastic moduli. This means that there was more particle aggregation, so that when gels C were heated they would maintain a high degree of internal cohesion and connectivity. Mechanical and rheological analyses were consistent with the structures shown in SEM photographs. © 2012 Elsevier Ltd. Source


Sanchez-Alonso I.,CSIC - Institute for the Structure of Matter | Martinez I.,University of the Basque Country | Martinez I.,University of Tromso | Martinez I.,Ikerbasque | And 2 more authors.
Food Chemistry | Year: 2012

The potential of low field NMR (LF NMR) as a fast monitoring technique to estimate the quality of hake (Merluccius merluccius) frozen stored at -10 °C for up to 6 months was evaluated. LF NMR clearly detected three populations of water: water strongly bound to macromolecules (T2b), trapped water (T21) and free water (T22). As storage time increased, and concomitant with an increase in the T22 and a decrease in the T 21 water populations, the water holding capacity (WHC) and apparent viscosity values decreased and the shear strength increased, reflecting the characteristic loss of juiciness and tougher texture developed by hake during frozen storage. Two mathematical models were constructed: a simple regression using the biexponential analysis of the relaxation times (T21, T 22) and amplitudes (A21, A22) and a partial least square regression (PLS) of CONTIN analysis. Both models seemed suitable to estimate the quality of the product. © 2012 Elsevier Ltd. All rights reserved. Source


Herranz B.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic | Borderias A.J.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic | Solo-de-Zaldivar B.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic | Solas M.T.,Complutense University of Madrid | Tovar C.A.,University of Vigo
Food Hydrocolloids | Year: 2012

This paper examines the thermostability of glucomannan gels (3 and 5 %) deacetylated with 0.6 N KOH (A3, A5) and 1 N NaOH (B3, B5) at both concentrations. Gels were heated at heat treatment temperature (T ht): 25, 50, 70 and 90 °C for 20 min. Different analyses: puncture, small amplitude oscillatory shear (SAOS) and scanning electron microscopy (SEM) were made at 25 °C. All gels (irrespective of alkali and glucomannan concentration) behaved as thermo-irreversible with permanently bonded networks. Some structural differences were found depending on the alkali and glucomannan concentration and T ht range: increased T ht produced stronger networks in A3 and B3, which were more orderly in A3. At high T ht, A3 had a more elastic network, with higher water binding capacity (WBC) than B3. At 5% glucomannan, gel networks (A5-B5) were tighter and were less reinforced by temperature. Mechanical and rheological analyses were consistent with the structures shown in SEM photographs. © 2012 Elsevier Ltd. Source


Herranz B.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic | Tovar C.A.,University of Vigo | Solo-de-Zaldivar B.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic | Borderias A.J.,Institute Ciencia Y Tecnologia Of Los Alimentos Y Nutricion Ictan Csic
LWT - Food Science and Technology | Year: 2013

The effect of type and concentration of alkali on 5 g/100 mL of glucomannan gels was examined in depth by mechanical and thermo-rheological analysis. Four KGM gels were made from aqueous glucomannan solutions deacetylated with 0.6 mol/L and 1 mol/L of KOH (A0 and A1) and NaOH (B0 and B1), respectively. At 25 °C all physical networks were too tight and dense due to the large number of extended junction zones, as indicated by the high breaking force (BF), complex modulus (G*) and low strain amplitude (γmax). The influence of alkali concentration was noticeable only in KOH gels, of which A0 was significantly more elastic and time stable than A1 over both short and longer-time scales. 0.6 mol/L KOH was the most suitable alkali, producing the most stable and homogeneous gel, with the highest level of connectivity, the lowest relaxation exponent (n) and the highest gel strength (S).Increasing temperature resulted in loss of elasticity in A0, where γmax, G* and S decreased, and the loss factor (tan δ), creep and recovery compliances (J) and n increased. Thus, the networks become less flexible and more unstable at high temperatures, especially between 25 and 50 °C. © 2012 Elsevier Ltd. Source

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