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oxygen presented a similar profile to permeability to water vapor. P values increased significantly with RH for both samples, in agreement with previous reports (Aucejo et al., 2000; Yamamoto et al., 2009). The incorporation of the extract improved the oxygen barrier at low humidity, an effect that can be attributed to the previously commented increase in polymer crystallinity. At high humidity, the active film presented higher values than the blank polymer as a result of increased water sensitivity, in agreement with the effect observed in the water permeability. The diffusion coefficient was also calculated by applying the analytical solution to Fick’s law for the boundary conditions of an isostatic permeation process (Gavara and Hernández, 1993). The diffusion coefficient was measured at 90% RH, and the values were 1.125·10 –13 m 2 /s and 1.63·10 –13 m 2 /s for the EVOH blank and EVOH_GT5% films, respectively. The values obtained were very similar to the value obtained from the literature, 1·10 –13 m 2 /s (Aucejo et al., 2000). The higher value obtained for the sample containing the extract revealed a faster diffusivity of oxygen in this film as a consequence of a more plasticized polymer structure. 3.5. Green tea extract release Release studies were carried out by exposure of the films developed to the food simulants included in EU regulations (UNE-EN 1186-3) for migration studies. The antioxidant activity of the GT released on food simulants was evaluated periodically by measuring the radical scavenging ability, using the ABTS •+ assay in the case of aqueous simulants and the DPPH • method in the case of 95% ethanol. Figure 3.3 presents the antioxidant activity of food simulants exposed to GTcontaining films, expressed as equivalent ascorbic acid concentration. The kinetics presented a similar profile with all of the simulants, following an “exponential growth to a maximum” type profile. The effect of the type of food was clearly noticeable, presenting around ten times higher antioxidant activity on 95% ethanol, probably owing to the better solubility of the active agents in
this liquid. Catechins, the most powerful antioxidants present in green tea extract, are slightly soluble in water and highly soluble in ethanol. The nominal antioxidant activity towards the DPPH • radical which could be provided by the film to the 95% ethanol simulant (considering 5% of green tea extract, no degradation, and full release) was 1.25 g/L ascorbic acid equivalent. According to the results of the release (Figure 3.3), the extraction of the green tea components advances towards an almost complete release after two weeks of exposure. Antioxidant activity (g/L ascorbic acid) 1.20 1.00 0.80 0.60 0.40 0.10 0.05 Water 10% EtOH 3% HAc 95% EtOH 0.00 0 100 200 300 400 time (hours) 500 600 700 800 Figure 3.3. Antioxidant activity of green tea extract found in the food simulants tested during exposure to the EVOH-based materials determined by the DPPH• method (95% ethanol) and by the ABTS•+ method for the aqueous simulants. For the aqueous simulants, the nominal antioxidant activity against ABTS •+ which could be provided by the film to the water, 3% acetic acid, and 10% ethanol simulants (considering 5% of green tea extract, no degradation, and full release) was 0.267 g/L ascorbic acid equivalent. According to the release results (Figure 3.3), the extraction of the green tea components advances
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Instituto de Agroquímica y Tecnolo
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DESARROLLO Y CARACTERIZACIÓN DE PO
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DESENVOLUPAMENT I CARACTERITZACIÓ
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DEVELOPMENT AND CHARACTERIZATION OF
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1. INTRODUCCIÓN 1.1. ENVASADO ACTI
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1.1.1. Características básicas de
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adecuadas para permitir la acción
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educción de los recuentos microbio
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1.1.2. Legislación de envases acti
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humedad y en presencia de ambientes
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Figura 2. Estructura de los monóme
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autooxidación, cuando la ranciedad
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antioxidante. Actúa como agente en
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Ambos mecanismos dependen del disol
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Figura 4. Esquema de un envase acti
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Actualmente existen pocos materiale
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Figura 6. Formación de complejos d
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y se añadieron distintos agentes e
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Dias, H., Berbicz, F., Pedrochi, F.
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Lopez, P., Sanchez, C., Batlle, R.,
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Seppanen, C.M., Song, Q.H., Csallan
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2. OBJETIVOS
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) Materiales activos para el contro
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3. RESULTADOS Y DISCUSIÓN En esta
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contacto directo con el alimento, c
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Para comprobar la actividad en un c
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intención de estudiar el efecto so
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RH 50 RH 75 RH 100 RH 50 RH 90 Blan
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“CASTING” 100% H2O 10% EtOH 95%
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ciclodextrinas, βCD, en el ímero
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inferiores de permeabilidad se obtu
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Artículo 1 IMPROVING THE ANTIOXIDA
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1. INTRODUCTION Oxidation processes
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are still released into the atmosph
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analysis. Their thermal properties,
Page 71 and 72: aluminum foil to protect the conten
Page 73 and 74: Heat Flow (J/g) 2 0 -2 -4 -6 -8 -10
Page 75 and 76: Figure 1.2. Derivative of the weigh
Page 77 and 78: Table 1.2. Water Vapor and Oxygen P
Page 79 and 80: A second important factor was the f
Page 81 and 82: Figure 1.4. Partition (K) and diffu
Page 83 and 84: The reason for this effect is the a
Page 85 and 86: Lopez-Rubio, A., Almenar, E., Herna
Page 87 and 88: Artículo 2 REDUCING OXIDATION OF F
Page 89 and 90: 1. INTRODUCTION Lipids are found na
Page 91 and 92: donate hydrogen atoms or electrons
Page 93 and 94: ml. A gas stream containing hydroxy
Page 95 and 96: where V is the volume of sodium thi
Page 97 and 98: To monitor the antioxidant activity
Page 99 and 100: u. A. (hexanal) 60000 50000 40000 3
Page 101 and 102: Peroxide index (meq O 2 /Kg) 100 80
Page 103 and 104: Han, J. H., Hwang, H. M., Min, S.,
Page 105 and 106: Williams, J. P., Duncan, S. E., Wil
Page 107 and 108: ABSTRACT Ethylene vinyl alcohol cop
Page 109 and 110: (EGC), (-)-gallocatechin gallate (G
Page 111 and 112: wavelength in the presence of the s
Page 113 and 114: were measured. All of the samples w
Page 115 and 116: DPPH • method in the case of the
Page 117 and 118: of them identified as gallic acid (
Page 119 and 120: TGA of the two polymeric samples sh
Page 121: The addition of the green tea extra
Page 125 and 126: Table 3.4. Concentration of four id
Page 127 and 128: matrices. Kinetically, the release
Page 129 and 130: values (shown in Figure 3.6). As ca
Page 131 and 132: ACKNOWLEDGEMENTS The authors acknow
Page 133 and 134: Contaminants Part a-Chemistry Analy
Page 135 and 136: Artículo 4 ACTIVE ANTIOXIDANT PACK
Page 137 and 138: 1. INTRODUCTION Active packaging wi
Page 139 and 140: groups. Catechins are the principal
Page 141 and 142: aluminum cups were filled with 7 g
Page 143 and 144: was performed by immersion in brine
Page 145 and 146: Table 4.1. Concentration of antioxi
Page 147 and 148: The second and biggest process for
Page 149 and 150: incorporating antioxidants although
Page 151 and 152: and the hydroxyl groups of the poly
Page 153 and 154: Figure 4.4. Experimental data and t
Page 155 and 156: Figure 4.6. Partition (K) and diffu
Page 157 and 158: process. No reliable D values could
Page 159 and 160: was more efficient in the initial a
Page 161 and 162: ACKNOWLEDGEMENTS The authors acknow
Page 163 and 164: López-de-Dicastillo, C., Catalá,
Page 165 and 166: 3.2. DESARROLLO DE MATERIALES PARA
Page 167 and 168: ABSTRACT Current developments in ac
Page 169 and 170: complexes, entrapping all or part o
Page 171 and 172: 2. MATERIALS AND METHODS 2.1. Chemi
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applicable EC directives (European
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Orangeburg, USA). The concentration
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2.8. Statistical analysis One-way a
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from the films was carried out by d
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literature on this material (Aucejo
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depression differed, being wider wi
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presence of glycerol in the sample
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addition of βCD increased the diff
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Aproximately 90% of the α-pinene a
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EVOH with glycerol is highly plasti
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Grob, K., Biedermann, M., Scherbaum
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Artículo 6 FOOD APPLICATIONS OF AC
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1. INTRODUCTION Active packaging is
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The aim of this work was to use the
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The transparency of the films was d
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2.4. Monitoring oxidation by-produc
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Figure 6.1 shows the profile of K/S
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within the active matrix has a prot
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of peanuts (Han et al., 2008). In t
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generated by oxidation of frying oi
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factors of the compounds were simil
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Analysis, and Packaging Influences,
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Artículo 7 DEVELOPMENT OF ACTIVE P
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1. INTRODUCTION The development of
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2. MATERIALS AND METHODS 2.1. Chemi
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column (4.6 x 150 mm, 5 µm particl
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To simulate the conditions of a con
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matches the case of a migration pro
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was higher and PVOH sensitivity to
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PVOH*.CD and PVOH.CD*, indicating a
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As can be seen, the spectra of the
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Table 7.2 Thermal properties of the
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degradation band of the pure βCD (
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(PVOH.CD)* 9.6 ± 1.1 b,x 38.3 ± 2
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4. CONCLUSIONS Water resistant poly
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Lopez-de-Dicastillo, C., Gallur, M.
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4. CONCLUSIONES 1. Se han obtenido
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8. Según los resultados derivados
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