A robust multi-model predictive controller for distributed parameter systems

12 páginas, 6 figurasIn this work a robust nonlinear model predictive controller for nonlinear convection–diffusion-reaction systems is presented. The controller makes use of a collection of reduced order approximations of the plant (models) reconstructed on-line by projection methods on proper orthogonal decomposition (POD) basis functions. The model selection and model update step is based on a sufficient condition that determines the maximum allowable process-model mismatch to guarantee stable control performance despite process uncertainty and disturbances. Proofs on the existence of a sequence of feasible approximations and control stability are given. Since plant approximations are built on-line based on actual measurements, the proposed controller can be interpreted as a multi-model nonlinear predictive control (MMPC). The performance of the MMPC strategy is illustrated by simulation experiments on a problem that involves reactant concentration control of a tubular reactor with recycle.This work has been also partially founded by the Spanish Ministry of Science and Innovation (SMART-QC, AGL2008-05267-C03-01), the FP7 CAFE project (KBBE-2007-1-212754), the Project PTDC/EQU-ESI/73458/2006 from the Portuguese Foundation for Science and Technology and PI grant 07/IN.1/I1838 by Science Foundation Ireland. Also, the authors acknowledge financial support received by a collaborative grant GRICES-CSIC.Peer reviewe

A robust multi-model predictive controller for distributed parameter systems

12 páginas, 6 figurasIn this work a robust nonlinear model predictive controller for nonlinear convection–diffusion-reaction systems is presented. The controller makes use of a collection of reduced order approximations of the plant (models) reconstructed on-line by projection methods on proper orthogonal decomposition (POD) basis functions. The model selection and model update step is based on a sufficient condition that determines the maximum allowable process-model mismatch to guarantee stable control performance despite process uncertainty and disturbances. Proofs on the existence of a sequence of feasible approximations and control stability are given. Since plant approximations are built on-line based on actual measurements, the proposed controller can be interpreted as a multi-model nonlinear predictive control (MMPC). The performance of the MMPC strategy is illustrated by simulation experiments on a problem that involves reactant concentration control of a tubular reactor with recycle.This work has been also partially founded by the Spanish Ministry of Science and Innovation (SMART-QC, AGL2008-05267-C03-01), the FP7 CAFE project (KBBE-2007-1-212754), the Project PTDC/EQU-ESI/73458/2006 from the Portuguese Foundation for Science and Technology and PI grant 07/IN.1/I1838 by Science Foundation Ireland. Also, the authors acknowledge financial support received by a collaborative grant GRICES-CSIC.Peer reviewe

Health Effects of Phenolic Compounds Found in Extra-Virgin Olive Oil, By-Products, and Leaf of Olea europaea L.

Olea europaea L. fruit is a peculiar vegetal matrix containing high levels of fatty acids (98-99% of the total weight of extra-virgin olive oil, EVOO) and low quantities (1-2%) of phenolics, phytosterols, tocopherols, and squalene. Among these minor components, phenolics are relevant molecules for human health. This review is focused on their beneficial activity, in particular of hydroxytyrosol (HT), oleuropein (OLE), oleocanthal (OLC), and lignans found in EVOO, olive oil by-products and leaves. Specifically, the cardioprotective properties of the Mediterranean diet (MD) related to olive oil consumption, and the biological activities of polyphenols recovered from olive oil by-products and leaves were described. Recent European projects such as EPIC (European Prospective Investigation into Cancer and Nutrition) and EPICOR (long-term follow-up of antithrombotic management patterns in acute coronary syndrome patients) have demonstrated the functional and preventive activities of EVOO showing the relation both between cancer and nutrition and between consumption of EVOO, vegetables, and fruit and the incidence of coronary heart disease. The data reported in this review demonstrate that EVOO, one of the pillars of the MD, is the main product of Olea europaea L. fruits; leaves and by-products are secondary but precious products from which bioactive compounds can be recovered by green technologies and reused for food, agronomic, nutraceutical, and biomedical applications according to the circular economy strategy

CONTROL PREDICTIVO MULTIVARIABLE CON LINEALIZACIÓN SUCESIVA Y TARGETS DE ENTRADA

Dos propuestas de MPC multivariable con linealización sucesiva fuerondesarrolladas para controlar un proceso de fangos activados no cuadrado (más entradas que salidas). La primera propuesta utiliza una función objetivo estándar en la que son penalizadas las desviaciones de las salidas y los cambios en las variables manipuladas. En la segunda, se adiciona un término a la estándar que penaliza las desviaciones de las variables manipuladas de su valor en estado estacionario (targets de entrada). El objetivo principal fue evaluar el efecto del uso de targets de entrada sobre el desempeño del sistema controlado. Los resultados mostraron una reducción del 50% de las variaciones de la concentración de sustrato del efluente, una disminución del 85% en el consumo de energía de bombeo y menor carga de contaminación en el efluente, con el uso de targets de entrada, lo que demostró la utilidad de estos para mejorar el rendimiento del proceso

Understanding the impact of different cheese-making strategies on Mozzarella cheese properties

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2016-2017Le fromage Mozzarella entre dans la composition de plusieurs mets populaires d’Amérique du Nord. L’aptitude de ce fromage à être râpé et ses propriétés caractéristiques de cuisson en font un ingrédient idéal. Ces qualités sont attribuées principalement aux propriétés physiques particulières de ce fromage sous certaines conditions de cisaillement et de température. Le but de ce projet était d’évaluer l’impact de différentes stratégies couramment mises en oeuvre dans l’industrie fromagère sur la composition, la microstructure et les propriétés physiques du fromage. Diverses stratégies ont été étudiées : les conditions de filage du caillé lors du procédé de « pasta filata », l’addition de protéines sériques dénaturées, le contrôle de la minéralisation et le vieillissement du fromage. Les résultats ont démontré que le contrôle de l’intensité mécanique et thermique fournie lors du filage permettait respectivement de réduire les pertes de solides et d’améliorer la répartition de la phase aqueuse dans la matrice fromagère. L’aptitude au râpage du fromage peut être optimisée en combinant l’utilisation de plusieurs stratégies dont la réduction du calcium colloïdal, un temps de vieillissement adéquat et un râpage à basse température. Par ailleurs, des changements aux facteurs mentionnés précédemment sont apportés lors de l’ajout de protéines sériques dénaturées, ces dernières ayant un impact sur la composition et la structure du fromage. Des modèles prédictifs de l’aptitude au râpage ont été développés en sélectionnant uniquement les descripteurs de composition et de texture pertinents. La perception sensorielle du fromage cuit sur pizza et les propriétés physiques du fromage fondu ont été considérablement influencées par l'évolution physico-chimique du fromage au cours du vieillissement. L’utilisation d’une nouvelle approche pour la caractérisation des propriétés rhéologiques du fromage fondu sous fortes contraintes a permis d’établir de bonnes relations avec les descripteurs sensoriels de texture. Ce travail a permis de valider l’hypothèse que l’utilisation d’une ou plusieurs stratégies simples et accessibles pouvait être mise de l’avant afin d’optimiser les propriétés physiques du fromage Mozzarella. Cela contribue à une meilleure compréhension des facteurs pouvant être contrôlés afin de développer des fromages avec des attributs spécifiques, lorsqu’utilisés comme ingrédient.Mozzarella cheese is expected to perform various key attributes when used as a food ingredient. The shreddability and the melting properties of cheese during and after baking are mainly governed by the physical properties of cheese when subjected to external factors such as shear and temperature. Therefore, the goal of this project was to evaluate the impact of cheese-making strategies commonly used in the dairy processing industry on the cheese composition, microstructure, and physical properties. Various strategies were studied: pasta filata process conditions, addition of denatured whey protein (WP-D) to milk, control of curd mineralization, and cheese aging. Results showed that controlling the mechanical and thermal intensity during the pasta filata process can lead to reduced cheese solid losses and a better distribution of water within cheese microstructure, respectively. The ability of cheese to be shredded can be increased using a combination of multiple factors such as lowering colloidal calcium phosphate associated with casein, proper aging, and by reducing cheese temperature before shredding. However, an optimisation of the previous factors should be done if WP-D is added because of its impact on cheese composition and structure. Predictive models to assess cheese shreddability were built using only few relevant compositional and textural descriptors. Sensory perception of baked cheese texture and physical properties of melted cheese were dramatically influenced by the physico-chemical evolution of cheese during aging. Melted cheese texture was satisfactorily related to different sensory attributes using a novel approach to determine the rheological properties under the large stress experienced during mastication. This work validated the hypothesis that simple cheese-making strategies, alone or combined, can be used to optimize the cheese physical properties. This contributes to a better understanding of the factors that can be controlled to improve or develop cheese ingredient with specific attributes

Alternative approaches to improve the processing and quality of under-utlized fish

Due to the global issues related to climate change and population growth, more sustainable use of existing food resources is required. Fish and other aquatic organisms are rich in health beneficial polyunsaturated fatty acids, protein, and several vitamins and minerals. Fish and other aquatic resources are estimated to play an even more vital role in the future. While many popular fish stocks have already been overexploited, several species are currently not utilized at all or are directed to low-value, non-human uses, such as feed. One example of such species is Baltic herring (Clupea harengus membras). Baltic herring is the most important commercial capture species in Finland, based on both value and quantity. However, only a small fraction of the total catch is used as food. Some factors limiting the food use of Baltic herring include the decreasing size of the caught fish, its high susceptibility to oxidation and other degradation leading to quality loss, as well as its distinct odor and flavor that are not preferred by some consumers. Roach (Rutilus rutilus) along with other cyprinid fish, are not commercially important fish species, and are utilized for human consumption even less than Baltic herring. In addition to providing a valuable source of proteins, lipids and other nutriens, increasing the capture of roach and other cyprinid fish could result in beneficial effects in reducing eutrophication. This thesis focused on alternative ways of increasing utilization of underutilized fish, with a focus on Baltic herring and roach. The two processing methods studied were the pH shift and enzymatic hydrolysis, both of which have been widely studied for other fish species but not Baltic herring or roach. Both processes have the advantage that whole fish or fish side streams without any pre-processing can be used as raw materials. Further, the addition of natural antioxidants was investigated as a means of inhibiting lipid oxidation and degradation of sensory quality during frozen and refrigerated storage of minced Baltic herring. Lingonberry juice press residue, sea buckthorn juice press residue, sea buckthorn juice press residue after supercritical CO2 extraction of lipids, and a commercial extract mixture as natural additions were compared to conventional antioxidants ethylenediaminetetraacetic acid (EDTA) and combination of α-tocopherol and ascorbic acid. The composition of proteins and lipids in Baltic herring and roach protein isolates and hydrolysates was significantly affected by the processing type (pH shift or enzymatic hydrolysis). Compared to enzymatic hydrolysis, the pH shift led to enrichment of essential amino acids, phospholipids, and in case of acid extraction, also polyunsaturated fatty acids such as docosahexaenoic acid (DHA). The pH shift, especially alkaline pH shift, however, induced considerable lipid and protein oxidation. The fish protein hydrolysates (prepared using enzymatic hydrolysis) showed more moderate formation of hydroperoxides, secondary volatile oxidation products, and protein carbonyls. The incomplete elimination of fishy odors and flavors during preparation of fish protein isolates and hydrolysates is a major factor limiting their use. Based on this research, while not completely eliminating these odors, the alkaline pH shift reduced the total intensity of odor and intensity of the fishy odor in Baltic herring, which was reflected in the quantity and quality of odor-active compounds. The natural antioxidants, lingonberry juice press residue (3%), sea buckthorn juice press residue (3% w/w), and commercial extract mixture (0.1%) retarded lipid oxidation in Baltic herring mince stored at –20 °C more effectively than EDTA or combination of α-tocopherol and ascorbic acid, as indicated by lower loss of polyunsaturated fatty acids, lower PV, and/or lower formation of secondary oxidation related volatiles, such as 1-penten-3-ol and hexanal. During refrigerated storage (1 °C), sea buckthorn juice press residue after supercritical CO2 oil extraction and lingonberry juice press residue were effective antioxidants also at the lower concentrations (1.5%, 1%). Based on the odor and flavor profile of Baltic herring minces, particularly sea buckthorn juice press residue after supercritical oil extraction (1.5%), also prevented changes in sensory quality during a 3-day storage. This was further reflected in the odoractive compounds of raw minces. Berry press residues are side streams of berry juice and oil production, and their use as antioxidantive materials would provide added value for these currently under-utilized materials as well. This thesis provided valuable insights related to increasing utilization of Baltic herring and other under-utilized fish. The results showed that pH-shift processing and enzymatic hydrolysis of Baltic herring and roach produced fish protein isolates and hydrolysates with high nutritional quality. However, lipid and protein oxidation during these processes and storage of Baltic herring poses a challenge for preservation of quality. Use of antioxidants may improve preservation of the nutritional and sensory quality of Baltic herring during processing and storage