Encapsulación de flavonoles en ciclodextrinas. Efectos en su actividad antioxidante

1. Los tres flavonoles estudiados, miricetina, quercetina y kaempferol, pueden ser complejados en CDs, aumentando su solubilidad acuosa por la formación de complejos 1:1. 2. La complejación de miricetina, quercetina y kaempferol en CDs, provoca una variación en la intensidad de fluorescencia de los 3 flavonoles. En el caso de miricetina y quercetina, la fluorescencia aumenta con la complejación en CDs, mientras que, en el caso de kaempferol, la fluorescencia disminuye como consecuencia de la complejación. 3. La oxidación de miricetina, quercetina y kaempferol por HPR en presencia de H2O2 es inhibida en la medida en que estos compuestos son complejados por CDs, indicando que el flavonol libre, es el único sustrato disponible para la enzima. 4. La variación en la solubilidad, velocidad de oxidación enzimática y espectro de fluorescencia, permite calcular el valor de las constantes de complejación (KC) de los tres flavonoles objeto de estudio con diferentes tipos de CDs. 5. El método enzimático y los estudios de solubilidad nos proporcionan valores reales de las constantes de complejación entre flavonoles y CDs. Sin embargo, el método fluorimétrico infravalora el valor de dichas constantes en los tres flavonoles estudiados. 6. De las CDs estudiadas, HP-β-CDs son las más efectivas en la complejación de miricetina, quercetina y kaempferol, ya que presentan mayor valor de KC, independientemente del método utilizado para el cálculo de la misma. 7. La capacidad antioxidante de miricetina, quercetina y kaempferol aumenta tras su complejación en HP-β-CDs. Cada flavonol complejado presenta aproximadamente el doble de actividad antioxidante que cuando está libre en el medio, indicando que la complejación lo protege frente al ataque por radicales libres.Ciencias de la Alimentació

Effects of Cyclodextrin Type on Vitamin C, Antioxidant Activity, and Sensory Attributes of a Mandarin Juice Enriched with Pomegranate and Goji Berries

The effects of the addition of cyclodextrins (CDs), β-CD, or HP-β-CD (1%), on the protection of antioxidant compounds of mandarin juices enriched with pomegranate extract and goji berries juice, was studied. Juices were prepared and after their thermal treatment (98 ◦C, 30 s) they were stored at 4 ◦C during 75 d. Vitamin C content, CIE L∗a∗b∗ color, antioxidant capacity, retinol equivalents, and sensory properties were studied. Losses on vitamin C were higher (6%) for juices with β-CD than juices with HP-β-CD. Retinol equivalents degradation was lower (3.4%) in juices with HP-β-cyclodextrins than in those treated with β-CD. Lower losses were observed for the instrumental and sensory color intensity in juices with HP-β-CD addition. Finally, the antioxidant capacity was also higher in juices treated with HP-β-CD. Finally, the overall sensory quality of juices with HP-β-CD was the best one after 30 d of cold storage. Even though β-CD addition did not cause any improvement compared with control juice (without CD addition), the benefits of adding HP-β-CD to this particular juice were shown in almost all parameters under study.Ciencias de la Alimentació

Comparative study of different methods to measure antioxidant activity of resveratrol in the presence of cyclodextrins

The antioxidant activity of resveratrol in the absence and presence of increasing concentrations of HPb- CDs was determined using three different methods: ORAC, ABTS and DPPH. The three methods were validated and compared for their linearity, precision and accuracy in measuring resveratrol antioxidant activity. The results indicated that the most sensitive method is the ORAC assay, which can measure the lowest resveratrol concentration (0.15–2 lM) with the highest precision. In the presence of increasing concentrations of HP-b-CDs, the antioxidant activity of resveratrol was seen to increase when it was measured by the ORAC and ABTS assays. However, no increase was observed when the DPPH assay was used. With the ORAC assay, the antioxidant activity increased until all the resveratrol had been included in HP-b-CDs (0.4 mM CDs), whereas in the case of ABTS assay the plateau in antioxidant activity was reached after 2 mM HP-b-CDs, suggesting that the CDs interferences in the measurement method. When the DPPH assay was used, no effect was observed when increasing concentrations of HP-b-CDs, indicating that in a methanolic medium resveratrol is free. Therefore, so this method cannot be used to measure the effect of resveratrol complexation with CDs on its antioxidant activity.Ciencias de la Alimentació

Effect of HP-b-cyclodextrins complexation on the antioxidant activity of flavonols

The beneficial effects from phenolic compounds have been attributed to their antioxidant activity. Differences in the chemical structure of flavonols and their degree of substitution will influence phenoxyl radical stability and, thereby, their antioxidant properties. Cyclodextrins (CDs) can be used as a flavonol complexation agent, since they act as a substrate reservoir in a dose-controlled manner. In the present paper, the effect of complexing flavonols, kaempferol, quercetin and myricetin with HP-b-CDs on their antioxidant capacity is studied by means of the oxygen radical absorbance capacity-fluorescein (ORAC-FL) assay. This complexation phenomenon increased the antioxidant activity of the three flavonols, which reached a maximum level when each flavonol had been complexed in the hydrophobic cavity of CDs. The antioxidant activity increased because of the flavonol was protected against rapid oxidation by free radicals.Ciencias de la Alimentació

Antioxidant Activity, Color, Carotenoids Composition, Minerals, Vitamin C and Sensory Quality of Organic and Conventional Mandarin Juice, cv. Orogrande

The effects of organic farming on antioxidant activity, CIE L*a*b* color, carotenoids composition, minerals contents, vitamin C and sensory quality of Orogrande mandarin juices were studied. Independent of the farming type, mandarin juices can be considered as good source of some important nutrients, such as potassium and antioxidant chemicals, for example, b-cryptoxanthin. Organic farming of mandarins resulted in juices with higher antioxidant activity, total carotenoids concentrations, minerals (Ca, K and Fe) contents, vitamin C content, more appealing and intense orange color and better sensory quality. For instance, organic Orogrande juice contained significantly (p<0.001) higher total carotenoids content (22.7±0.3 mg/L) than conventional juice (15.7±0.4 mg/L); a similar pattern was observed for the antioxidant activity, with values being 0.076±0.004 and 0.053±0.003mM Trolox m/L in organic and convectional juices, respectively. A trained panel stated that organic Orogrande juices had higher intensities of orange color, fresh mandarin and floral aromas than conventional juices.Ciencias de la Alimentació

Effect of temperature, pH, β- and HP-β-CDs on the solubility and stability of flavanones: naringenin and hesperetin

Naringenin and hesperetin are two of the most abundant flavanones found in citrus with beneficial effects on human health. However, their poor water solubility imposes considerable limitations to their use in functional foods or nutraceuticals development. In order to increase their aqueous solubility and find a new stable system, the effect of different factors as temperature, pH or complexation agents as cyclodextrins has been studied. The solubility of both flavanones increased exponentially with temperature (25-90 ºC): 10-fold in the case of naringenin and 20-fold for hesperetin. The solubility of both flavanones also increased with the media pH (3.5-8.5): 314-fold in the case of naringenin and 3.5-fold for hesperetin. Flavanones solubility also increased with β- or HP-β-CDs concentration. By the addition of β-CDs 13 mM naringenin solubility increased 9.3-fold and hesperetin solubility 30-fold. Using HP-β-CDs 100 mM naringenin solubility increased 143-fold and hesperetin 467-fold. In summary, the higher increase in naringenin solubility was reached by increasing pH up 8.5. However, in the case of hesperetin, the higher increase was obtained by complexation with HP-β-CDs 100 mM. Moreover, the presence of CDs, not only increased the aqueous solubility of flavanones, but also improved the stability of hesperetin at pHs 3.5 and 6.5.Ciencias de la Alimentació

Protective effect of cyclodextrins on the quality parameters of roast preserved pepper

Total phenolics (TP), vitamin C, antioxidant activity and colour of preserved peppers were evaluated at 4, 25 and 50 C storage during 30-day intervals. Except for 4 C, TP decreased during storage at 25 C and 50 C, being softer for fortified samples with b-CDs. The protective effect was evident, since 50 C samples containing b-CDs exhibited lower TP loss (19%) than control samples (38%) for 5 months storage. A decrease in the vitamin C content was observed for both samples as time and temperature progressed. In samples stored at 50 C the protective effect of b-CD only was evident at the first month, since fortified samples showed lower vitamin C loss (10%) than control samples. The fortified samples with b-CDs exhibited lowest antioxidant activity loss (40%) during 90-day storage at 50 C, than control samples (64%). The colour changes were in line with those observed for total phenolics and at the end of study, the presence of 1% b-CDs delayed the darkening of samples at both (25 and 50 C) storage conditions.Ciencias de la Alimentació

Thorough characterization and stability of HP-beta-cyclodextrin thymol inclusion complexes prepared by microwave technology: A required approach to a successful application in food

BACKGROUND The aim of the present study was to obtain a stable dry powder formulation of cyclodextrins (CDs) encapsulating thymol, for a successful application as an ingredient at industrial scale, as well as, to characterize the thymol-CDs complexes by different techniques. RESULTS Thymol was successfully solubilized in aqueous solutions and the Kc value increased with the pH of the media until neutral pH, obtaining the highest values (2583 ± 176 L mol-1) for HP-β-cyclodextrins (HP-β-CDs). The best encapsulation efficiency of thymol in solid complexes was obtained using the microwave (MWI) encapsulation method. The different characterization techniques have demonstrated the affinity of HP-β-CDs to thymol molecules, forming stable complexes. CONCLUSIONS The results obtained support the use of the MWI method in the preparation of solid HP- β-CD-thymol complexes, due to the greater encapsulation efficiency and technological and economic advantages for industrial applications.RTC-2015-3321-2, 18946/JLI/13, 012-ABEL CM-2014ACiencias de la Alimentació

Comprehensive Characterization of Linalool-HP-beta-Cyclodextrin Inclusion Complexes

The objective of the present study is to obtain linalool- cyclodextrin (CDs) solid complexes for possible applications in the food industry. For this purpose, a detailed study of linalool complexation was carried out at different pH values, to optimize the type of CDs and reaction medium that support the highest quantity of encapsulated linalool. Once demonstrated the ability of hydroxypropyl- -cyclodextrin (HP-beta -CDs), to form inclusion complexes with linalool (KC = 921 +/- 21 L/mol) and given their greater complexation efficacy (6.788) at neutral pH, HP-beta -CDs were selected to produce solid inclusion complexes by using two different energy sources, ultrasounds and microwave irradiation, subsequently spraying the solutions obtained in the Spray Dryer. To provide scientific solidity to the experimental results, the complexes obtained were characterized by using different instrumental techniques in order to confirm the inclusion of linalool in the HP-beta -CDs hydrophobic cavity. The linalool solid complexes obtained were characterized by using 1H nuclear magnetic resonance (1H-NMR) and 2D nuclear magnetic resonance (ROSEY), differential scanning calorimetry, thermogravimetry and Fourier transform infrared spectrometry. Moreover, the structure of the complex obtained were also characterized by molecular modeling.Ciencias de la Alimentació

Pulsed light for a cleaner dyeing industry: azo dye degradation by an advanced oxidation process driven by pulsed light

Water pollution by wastewater containing dyes is an environmental issue that can be mitigated by the use of advanced oxidation processes (AOP). Pulsed light (PL) is an emerging food processing technology that uses eco-friendly lamps and can potentially be adapted as light source of an UV-based AOP. In the present work, a PL/H2O2 process was tested for the decolourization of two azo dyes, and a pulsed light/H2O2/ferrioxalate process was tested for the decolourization of one azo dye. The efficiency of the PL/H2O2 process in a batch reactor under different parametric values: dye concentration, pH, H2O2 and salt doses was followed by spectrophotometry and fitted to first-order kinetics; and several degradation products were detected. In the PL/H2O2 process, decolourization rates increased at low dye concentrations and high H2O2 doses, were pH-dependent and were inhibited by the addition of NaCl, Na2SO3 or Na2CO3. More than 50 % decolouration was achieved with the PL/H2O2 process for both dyes after applying 54 J/cm2 (25 light pulses). The PL/H2O2/ferrioxalate process achieved > 95 % decolouration for Methyl orange when applying 21 J/cm2 (10 pulses); that level of energy can be supplied by PL commercial systems in nine and four seconds respectively. No known toxic degradation products were detected. Results show that a PL/H2O2 process has potential to be used for the efficient degradation of dyes from wastewater. Furthermore, the efficacy of this process can be improved by the use of ferrioxalate. PL technology could become an alternative light source to contribute to decrease the environmental impact of wastewater produced by the dyeing industry.Ciencias de la Alimentació