Mesoporous silica particles and macrocyclic ligands as modulators of polyphenol oxidase activity in food systems

Tesis por compendio[ES] El oscurecimiento de los tejidos de frutas y verduras dañados puede provocar cambios indeseables y el rechazo por parte del consumidor. Este deterioro, conocido como pardeamiento enzimático, es causado principalmente por la enzima polifenol oxidasa (PPO), que oxida los compuestos fenólicos en pigmentos rojizos llamados melanoides. De esta forma, la prevención de la actividad de PPO en el procesamiento postcosecha tanto en frutas y verduras como en sus licuados, ha recibido desde siempre mucha atención por parte de la industria alimentaria. Sin embargo, los tratamientos actuales presentan diversos inconvenientes, entre los que podemos destacar los efectos negativos en la calidad nutricional de los productos y su elevado coste. El cometido de esta tesis doctoral se centra en el desarrollo y evaluación de nuevas estrategias no térmicas para la inhibición de la PPO con el objetivo final de detener el pardeamiento enzimático. Para esto se abordaron dos estrategias diferentes. Por un lado, se seleccionaron y evaluaron varias poliaminas macrocíclicas. Se determinó que la estructura química influye fuertemente en el poder inhibidor, existiendo dos compuestos altamente eficaces contra el pardeamiento enzimático, los cuales presentan IC50 de 10 µM y 0.30 mM. Su eficacia se validó en zumo de manzana recién licuado retrasando el pardeamiento enzimático y la pérdida de compuestos fenólicos totales. Por otro lado, se estudió el desarrollo y aplicación de partículas de sílice mesoporosas funcionalizadas con diversos grupos químicos. Los resultados mostraron que tanto la estructura del material como la funcionalización son determinantes. El soporte UVM-7 ofreció la inhibición más fuerte sobre la enzima PPO, y una vez funcionalizado con grupos tiol este aumentó notablemente su poder inhibidor, deteniendo el pardeamiento enzimático en zumo de manzana. Por el contrario, los grupos amino, aunque mostraron menor poder inhibidor, fueron capaces de inmovilizar a la enzima y eliminarla del medio. Finalmente, el soporte UVM-7 fue magnetizado para su fácil eliminación del medio, evitando así la etapa de filtración. El soporte UVM-7 magnetizado y funcionalizado con tioles logró mantener la concentración inicial de vitamina C y flavonoides en el zumo de manzana. Además, la capacidad antioxidante y el contenido de fenoles totales se mantuvieron casi sin cambios.[CA] L'enfosquiment de fruïtes i verdures provoca un alt rebuig per part del consumidor. Aquest fet genera grans pèrdues econòmiques i un gran desaprofitament d'aliments. Aquest deteriorament, conegut com enfosquiment enzimàtic, és causat principalment per l'enzim polifenol oxidasa (PPO), que oxida els compostos fenòlics en pigments vermellosos anomenats melanoïdines. D'aquesta manera, la prevenció de l'activitat de la PPO en el processament postcollita tant en fruites i verdures com en els seus liquats, ha rebut des de sempre molta atenció per part de la indústria alimentària. No obstant això, els tractaments actuals presenten diversos inconvenients, entre els quals podem destacar els efectes negatius en la qualitat nutricional dels productes o el seu elevat cost. L'objectiu d'aquesta tesi doctoral es centra en el desenvolupament i avaluació de noves estratègies no tèrmiques per a la inhibició de la PPO amb la finalitat de detindre el enfosquiment enzimàtic. Per això s'aborden dues estratègies diferents. D'una banda, es va seleccionar i avaluar diverses poliamines macrocícliques. Determinat que l'estructura química influeix fortament en el poder inhibidor, existint dos compostos altament eficaços contra el enfosquiment enzimàtic, els quals presenten IC50 de 10 µM i 0.30 mM. La seua eficàcia es va validar en el suc de poma recentment liquat retardant el enfosquiment enzimàtic i la pèrdua de compostos fenòlics totals. D'altra banda, es va estudiat el desenvolupament i aplicació de partícules de sílice mesoporoses funcionalitzades amb diversos grups químics. Els resultats van mostrar que tant l'estructura del material com la funcionalització foren determinants. El suport UVM-7 va oferir la inhibició més forta sobre l'enzim PPO, i una vegada funcionalitzat amb grups tiol aquest va augmentar notablement el seu poder inhibidor, detenint el enfosquiment enzimàtic en el suc de poma. Tot i això, els grups amina, encara que mostren menys poder inhibidor, foren capaços d'immobilitzar l'enzim i eliminar-la del medi. Finalment, el suport UVM-7 va ser magnetitzat per la seva fàcil eliminació del mig, evitant així l'etapa de filtració. El suport UVM-7 magnetitzat i funcionalitzat amb grups tiol va aconseguir mantindre la concentració inicial de vitamina C i flavonoides en el suc de poma. A més, la capacitat antioxidant i el contingut de fenols totals es van mantindre quasi sense canvis.[EN] The browning of injured fruit and vegetable tissues can cause undesirable changes and consumers' rejection resulting in high economic losses and food waste. This damage, known as enzymatic browning, is mainly caused by the polyphenol oxidase enzyme (PPO) which oxidize the phenolic compounds found in these tissues into reddish pigments named melanonids. Thus, preventing PPO activity in post-harvest processing fruits and vegetables including their juices has received a lot of attention from the food industry. Nonetheless, the current alternatives have some drawbacks such as negative effects on the nutritional quality of products or high cost. Hence, the purpose of this doctoral thesis is focused on the development and evaluation of new non-thermal strategies for PPO inhibition and prevention of the enzymatic browning. For this purpose, two different strategies were addressed; On one hand, several macrocyclic polyamine compounds were selected and evaluated. The chemical structure was found to strongly influence the inhibitor power, and two different compounds were found to be efficient against the enzymatic browning with IC50 of 10 µM and 0.30 mM. Their effectiveness was proved in cloudy apple juice resulting in a delay of the enzymatic browning and the loss of total phenolic compounds. On the other hand, the development and application of mesoporous silica particles functionalized with diverse chemical groups were studied. The results showed that both the structure of the material and the type of functionalization are decisive. The UVM-7 support offered the strongest inhibition of the PPO. The functionalisation with thiol groups enhanced the inhibitor power stopping the enzymatic browning in cloudy apple juice. Alternatively, amine groups, although showing less inhibitory power, were able to immobilise the enzyme. Finally, the UVM-7 support was magnetized for easily elimination of the medium, thus preventing the juice filtration need. Cloudy apple juice treated with magnetized UVM-7 functionalized with tiol groups maintained the initial concentration of both vitamin C and flavonoids. Moreover, the antioxidant capacity and the total phenolic content remained almost unchanged.Financial support by the Spanish Ministerio de Ciencia, Innovación y Universidades (project RTI2018-100910-B-C44 and MAT2015-64139-C4-1), Ministerio de Economía y Competitividad (projects CTQ2016-78499-C6-1-R, Unidad de Excelencia MDM 2015- 0038 and CTQ2017-90852-REDC) and Generalitat Valenciana (projects PROMETEOII2015-002 PROMETEO/2018/024 and GVA/2014/13) is gratefully acknowledged.Muñoz Pina, S. (2021). Mesoporous silica particles and macrocyclic ligands as modulators of polyphenol oxidase activity in food systems [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/174934TESISCompendi

Impact of elderly gastrointestinal alterations on in vitro digestion of salmon, sardine, sea bass and hake: proteolysis, lipolysis and bioaccessibility of calcium and vitamins

[EN] This study aimed to analyze the effect of elderly gastrointestinal (GI) conditions on proteolysis, lipolysis and calcium and vitamins A and D3 bioaccessibility in salmon, sardine, sea bass and hake. For this purpose, cooked fishes were in vitro subjected to three elderly in vitro digestion models: E1 (oral elderly conditions), E2 (oral and gastric elderly conditions) and E3 (oral, gastric and intestinal elderly conditions)). In parallel, samples were digested under standardized GI conditions of a healthy adult as a control. Proteolysis was highly affected by elderly GI alterations (p < 0.05) (50% of reduction compared to control), being salmon and sea bass proteolysis extent (40 and 33%, respectively) the most affected with an important descend in leucine release. Calcium and vitamins bioaccessibility seemed to be also compromised for elders; however, the extent of the reduction highly depends on the fish type. Finally, these GI disorders did not negatively influence the bioabsorbable lipids of the fishesThe authors gratefully acknowledge the financial support from the Generalitat Valenciana AICO/2018/289. Also, Ever Hernandez-Olivas is recipient of a pre-doctoral grant from CONACYT (MEX/Ref. 306682)Hernández-Olivas, E.; Muñoz-Pina, S.; Andrés Grau, AM.; Heredia Gutiérrez, AB. (2020). Impact of elderly gastrointestinal alterations on in vitro digestion of salmon, sardine, sea bass and hake: proteolysis, lipolysis and bioaccessibility of calcium and vitamins. Food Chemistry. 326:1-9. https://doi.org/10.1016/j.foodchem.2020.127024S1932

Understanding the role of food matrix on the digestibility of dairy products under elderly gastrointestinal conditions

[EN] This study aimed to evaluate the effect of some elderly in vitro gastrointestinal (GI) conditions on proteolysis and lipolysis extent, calcium, vitamins A and D bioaccessibility and lactose release in milk, yogurt, fresh and aged cheeses. To evaluate the impact of the some oral, gastric and intestinal disorders appearing with ageing on dairy digestion, three in-vitro elderly models were applied (E1 (oral altered conditions), E2 (oral and gastric altered conditions) and E3 (oral, gastric and intestinal altered conditions)) plus a healthy adult one as control. Proteolysis extent was significantly affected by elderly GI alterations (p < 0.05) (around 40% of reduction compared to control), being fresh and aged cheese proteolysis the most affected with an important descrease in leucine release (18 and 25%, respectively). Calcium, vitamins A and D3 bioaccesibility and lactose release seemed not to be highly compromised in these models of elderly conditions; however, the micronutrients bioaccessibility was very dependent on dairy matrix¿s structure. Finally, the amount of the lipid hydrolyzed fraction of cheeses is not influenced in the investigated models.The authors gratefully acknowledge the financial support from the Generalitat Valenciana AICO/2018/289. Ever Hernández-Olivas is recipient of a pre-doctoral grant from the Mexican Government through the CONACYT (MEX/Ref. 306682) and Janaina Sanchez-García of a master s degree scholarship funded by the Ecuadorian Government through the SENESCYT (contract CZ05-000716-2018)Hernández-Olivas, E.; Muñoz-Pina, S.; Sánchez-García, J.; Andrés Grau, AM.; Heredia Gutiérrez, AB. (2020). Understanding the role of food matrix on the digestibility of dairy products under elderly gastrointestinal conditions. Food Research International. 137:1-10. https://doi.org/10.1016/j.foodres.2020.109454S11013

A tetraazahydroxypyridinone derivative as inhibitor of apple juice enzymatic browning and oxidation

[EN] Enzymatic browning in fruits and vegetables can produce undesirable colour changes and adversely affect the taste, flavour, and nutritional value. This fact poses a challenge to the food industry to apply appropriate inhibitors to control enzymatic browning to maintain food quality. Accordingly, this study aims to evaluate the effect of small mazamacrocyclic compounds modified with a hydroxypyridinone similar to kojic acid on enzymatic browning, total polyphenols and antioxidant activity in apple juice. The results showed how these compounds interact with the tyrosinase enzyme in a complex interaction inhibiting its activity. The hydroxypyridinone attached to the macrocycle (I1) was crucial to induce the greatest inhibition, being the most powerful inhibitor. The kinetic studies of I1 reveal mixed-type inhibition over tyrosinase with an IC50 of 0.30 mM, which was much higher than the calculated IC50 for I2 and I3. Furthermore, I1 at a concentration of 2.25 mM, significantly reduced the enzymatic browning in fresh apple juice by more than 50% after 1 h under stirring. Also, it completely stops the decrease in the total phenolic content and delays loss of antioxidant capacity during the first 30 min.Grant RTI2018-100910-B-C44 funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe" and the Spanish Ministerio de Economia y Competitividad (Projects CTQ2016-78499C6-1-R, CTQ2017-90852-REDC, RED2018-102331-T, PID 2019110751RB-I00 and Unidad de Excelencia CEX2019-000919-M).Muñoz-Pina, S.; Duch-Calabuig, A.; Ros-Lis, JV.; Verdejo, B.; García-España, E.; Argüelles Foix, AL.; Andrés Grau, AM. (2022). A tetraazahydroxypyridinone derivative as inhibitor of apple juice enzymatic browning and oxidation. LWT - Food Science and Technology. 154:1-7. https://doi.org/10.1016/j.lwt.2021.1127781715

Influence of the functionalisation of mesoporous silica material UVM-7 on polyphenol oxidase enzyme capture and enzymatic browning

The authors are grateful to the Spanish Government (Projects RTI2018-100910-B-C44 and MAT2015-64139-C4-1) and the Generalitat Valencia (Project PROMETEO/2018/024) for supportMuñoz-Pina, S.; Ros-Lis, JV.; Argüelles Foix, AL.; Martínez-Máñez, R.; Andrés Grau, AM. (2020). Influence of the functionalisation of mesoporous silica material UVM-7 on polyphenol oxidase enzyme capture and enzymatic browning. Food Chemistry. 310:1-8. https://doi.org/10.1016/j.foodchem.2019.125741S1831

Impacto de la implementación del aprendizaje basado en problemas en combinación con las prácticas de laboratorio clínico y virtual de Fisiopatología para el desarrollo de competencias profesionales

Sección Deptal. de Fisiología (Farmacia)Fac. de FarmaciaFALSEsubmitte

Implementación del aprendizaje basado en problemas (ABP) en la enseñanza práctica de la fisiología del sistema digestivo

Sección Deptal. de Fisiología (Farmacia)Fac. de FarmaciaFALSEsubmitte