Multi–layer health–aware economic predictive control of a pasteurization pilot plant

This paper proposes two different health-aware economic predictive control strategies that aim at minimizing the damage of components in a pasteurization plant. The damage is assessed with a rainflow-counting algorithm that allows estimating the components’ fatigue. By using the results obtained from this algorithm, a simplified model that characterizes the health of the system is developed and integrated into the predictive controller. The overall control objective is modified by adding an extra criterion that takes into account the accumulated damage. The first strategy is a single-layer predictive controller with an integral action to eliminate the steady-state error that appears when adding the extra criterion. In order to achieve the best minimal accumulated damage and operational costs, the single-layer approach is improved with a multi-layer control scheme, where the solution of the dynamic optimization problem is obtained from the model in two different time scales. Finally, to achieve the advisable trade-off between minimal accumulated damage and operational costs, both control strategies are compared in simulation over a utility-scale pasteurization plant.Peer ReviewedPostprint (author's final draft

Thermal processing techniques for improving protein-enriched beverage production

Growing consumer demand for convenient sources of high quality protein has led to a substantial global market for ready-to-drink, shelf-stable dairy protein beverages. These products have significant technical challenges associated with their manufacture due to the high processing temperatures required to render them microbiologically stable. Issues arise during thermal processing and storage as the high protein content leaves formulations susceptible to protein denaturation and aggregation, development of volatile compounds with associated off-flavours, increased viscosity, and sedimentation. This has driven dairy processors to seek out alternative formulation approaches and thermal processing techniques which can minimise the thermally-induced changes in the product, while still achieving the required shelf life. Relatively few studies have focused on a combined approach of investigating varied protein profiles in protein-enriched beverages with a range of thermal processing techniques. The objective of this research was to investigate the impact of composition and processing parameters on the physical behaviour of high-protein milk beverage systems across a range of thermal treatment systems. A new methodology for assessing the thermal stability, in terms of viscosity, for protein beverage formulations was also developed. Protein profile was shown to affect thermally-induced protein denaturation, with reductions in α-lactalbumin denaturation with an increasing casein proportion. Alterations in preheat treatment temperature significantly affected viscosity in protein systems upon concentration. The application of temperature-dependent viscosity models was demonstrated to be a useful, rapid tool in quantifying differences in product processing stability. Direct heating technology was applied to ESL- and UHT-treated whey protein solutions with a high protein content (4, 6 and 8% protein (w/w)) resulting in reduced protein denaturation, viscosity and less extensive changes to the volatile profile compared to tubular heating. A pilot-scale supersonic steam injection line was designed and integrated into an existing tubular heating plant with commissioning completed on skim milk. This novel heating system provided significantly greater reductions in protein denaturation than direct steam infusion and tubular heating for protein-enriched dairy beverage systems. The thesis provides new insights into interactions between milk proteins during thermal processing which influence the physical and volatile profile stability of protein beverages. The outcomes of the work have applications in such areas as high heat treatment processing of heat-sensitive milk proteins, allowing for minimised whey protein denaturation, reduced viscosity through formulation manipulation, and use of novel thermal technologies

Surface pasteurisation of food packages by the inversion method

Thermal processing is the most widely used and well established preservation method used in the food industry for ensuring food safety and extending the shelf life of food products. Besides from the food product, the package needs also to be decontaminated to achieve the required safety goals. This research is concerned with surface pasteurisation treatments in food packages by the method of inversion, primarily for hot-filled food products. Starch solutions and tomato soup, used as model fluids in the current work, were hot-filled in glass jars, were sealed and then inverted for thirty seconds at a filling temperature of 80oC for achieving a target process equivalent of 5 min at 70oC; the inversion step was used as a thermal treatment of the headspace and the lid. The inverted jars showed significantly higher process values for the headspace and the lid with the filling temperature being the most important parameter. The effectiveness of the inversion step during hot-fill treatments was quantified by the use of two monitoring techniques, the traditional temperature sensors and the alternative, enzymic based (Bacillus amyloliquefaciens α-amylase) Time Temperature Integrators (TTIs). TTIs are small devices with kinetics similar to the microorganisms, whose level of degradation is measured at the end of the thermal process. The enzyme activity obtained is integrated and the temperature history can be quantified. TTIs were tested for their reliability and accuracy under isothermal and non-isothermal conditions, and were then used for validating the hot-fill process

Improving the feedforward component for recent variants of Predictive Functional Control

A recent study demonstrated that the use of feedforward information with conventional Predictive Functional Control (PFC) leads to unexpected inconsistencies, with subsequent negative impacts on tuning and behaviour. A proposal was made to define the coincident point differently and shown to reduce the lag in the closed-loop PFC responses and applied to some systems with benign dynamics. Other recent work has looked at parameterisations of the future input to deal with challenging open-loop dynamics and significantly extended the range of problems for which PFC can be effective. This paper combines the two concepts, and thus proposes an algorithm that has both more effective and simple tuning than original PFC as well as being applicable to a range of challenging dynamics

Pyrococcus furiosus α-amylase as a candidate sterilisation time-temperature integrator

Thermal treatment is the most common method used by industry to ensure food is safe for consumption and to increase storage life. To ensure safety, food is often over processed, which can significantly affect its nutritional value as well as taste and flavour attributes. In this study a candidate sterilisation time-temperature integrator (TTI) from the hyperthermophilic Pyrococcus furiosus α-amylase is investigated. Reliability and accuracy of the TTIs was determined by exposure to various isothermal and non-isothermal industrially relevant temperature profiles. The integrated temperature history obtained by the TTIs correlated generally well with the data obtained from thermocouples installed, although the error increased with hold time of heat treatment. The work showed that the TTIs can be used reliably over a range (3-25 minutes at 121°C) which is relevant for conditions of thermal sterilisation. This was measured by developing a new assay technique for assaying the activity of hyperthermophilic α-amylase within the food industry. The assay was calibrated against more laboratory relevant assays and computational models. The kinetics and mechanism of thermal denaturation of Pyrococcus furiosus α-amylase was determined through FT-IR, DSC and CD techniques. It was found that through thermal denaturation after the melting temperature (Tm), the enzyme unfolded by first order kinetics from a α-helical structure, through α-sheet structure to aggregation of the enzyme.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Study of short-wave ultraviolet treatments (UV-C) as a non-thermal preservation process for liquid egg products

La viabilidad de los tratamientos con radiación ultravioleta (UV-C) a 254 nm como proceso no térmico para la conservación de ovoproductos líquidos fue evaluada desde el punto de vista de la eficiencia en la descontaminación y sus efectos en los atributos de calidad. Los estudios cinéticos sobre la inactivación de microorganismos inoculados y de los principales grupos de microorganismos alterantes sirvieron para discriminar los parámetros más relevantes del tratamiento con UV-C. Los estudios de vida útil sirvieron para evaluar las ventajas aportadas por esta tecnología frente a tratamientos térmicos tradicionales. Las fracciones de huevo (clara, yema y huevo entero) tratadas con UV-C fueron analizadas en cuanto a los cambios de pH, color, estabilidad de lípidos (TBARS, colesterol y valor de peróxidos), efectos en las proteínas (oxidación proteica, DSC, SDS-PAGE), propiedades reológicas (viscosidad dinámica, comportamiento de flujo, viscosidad en función de la temperatura), propiedades funcionales (emulsionantes y espumantes), composición nutricional (vitaminas y minerales), composición de componentes saludables (carotenoides), y cito-genotoxicologia. Finalmente, la aceptación sensorial de los ovoproductos líquidos tratados por UV-C y de productos preparados con ovoproductos líquidos tratados por UV-C (mayonesa, bizcocho y pudin) fueron evaluadas por medio de pruebas triangulares y afectivas. El tratamiento con UV-C demostró ser una excelente alternativa a la pasteurización térmica. En microorganismos inoculados, se demostró una reducción de 5 Log tanto para Gram(+) como para Gram(-) en un equipo comercial para tratamientos en régimen continuo (UVivatec�). En tandas, los resultados también mostraron decrecimientos importantes en el recuento de microorganismos inoculados, aunque serían necesarios tiempos largos de tratamiento para producir una descontaminación comparable a la pasteurización térmica. Los ovoproductos líquidos tratados con UV-C fueron estables durante 8Mendes De Souza, P. (2012). Study of short-wave ultraviolet treatments (UV-C) as a non-thermal preservation process for liquid egg products [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16696Palanci

Soybean

Soybean is an agricultural crop of tremendous economic importance. Soybean and food items derived from it form dietary components of numerous people, especially those living in the Orient. The health benefits of soybean have attracted the attention of nutritionists as well as common people

Belagbildung durch Milchkomponenten und Reinigung modifizierter Oberflächen

This work seeks to identify and quantify the influence of surface energetic and topographic properties on the fouling and cleaning of milk constituents. Amorphous hydrogen containing carbon coatings diamond-like carbon DLC and Si doped DLC coatings were used for the investigations. Batch-wise fouling experiments were performed with whey protein WPI, calcium phosphate SMUF and both components combined as well as raw milk at low and high initial surface temperatures of 80°C and 120°C on coated standard and electropolished stainless steel surfaces. Continuous fouling experiments were carried out in a pilot scale plate heat exchanger, which was operated at a product side flow velocity of 0.1 m/s (Re = 870), heating the solution from 62°C to 85°C. The cleaning kinetics of WPI plus SMUF soils on the coated surfaces was monitored in a flow cell using NaOH. The fouling layer formation, composition and structure, as well as its adhesion and cohesion strengths and thus its removal were affected by the surface free energy, surface roughness, the initial surface temperature, the solution composition and the flow conditions. The main surface property influencing the interactions at deposit/surface interface was the polar contribution to surface free energy, particularly the electron donor component Gamma-. A quadratic relationship between Gamma- and the final fouling resistance, deposit dry mass or protein and mineral contents could be found. Slightly more fouling built up on electropolished coated surfaces, which were also more difficult to clean, compared to unpolished coated surfaces. The influence of the Gamma- on deposition was stronger at 80°C than at 120°C. The formation of different calcium phosphate aggregates in the first fouling layers could be related to Gamma-, which possibly also contributed for deposits with different structures from the protein and SMUF-rich protein solutions. On low Gamma- surfaces, calcium phosphate will prevail, while protein will attach preferentially to high Gamma- surfaces. Crystallization and particulate fouling were more pronounced than protein fouling in the experiments under flow conditions. Cleaning profiles were dependent on the surface properties. On high Gamma- surfaces, the soil was almost completely removed and the highest cleaning rate as well as the fastest reduction of the thermal resistance could be measured. Optimum Gamma- values for minimal fouling and maximal cleaning effort were suggested.Die Effekte der energetischen und topographischen Oberflächeneigenschaften auf die Belagbildung und Reinigung von Milchkomponenten wurden identifiziert und quantifiziert. Diamond-like Carbon DLC und Si dotiertes DLC wurden für die Untersuchungen verwendet. Beläge aus drei Modellstoffsystemen: Molkeproteinisolat WPI, Calciumphosphat SMUF und beide kombiniert sowie Rohmilch, wurden bei initialen Oberflächentemperaturen T_o von 80°C bzw. 120°C auf beschichteten unbehandelten und elektropolierten Edelstahlsubstrakten in einer Batchanlage sowie in einem Plattenwärmeübertrager erzeugt. Die Reinigungskinetik von den Belägen wurde in einem Strömungskanal untersucht. Die Belagbildung, die Belagzusammensetzung und -struktur sowie die Adhäsions– und Kohäsionsfestigkeiten und damit die Entfernung des Belages wurden durch die freie Oberflächenenergie und –rauhheit sowie durch T_o, Lösungszusammensetzung und die Strömungsverhältnisse beeinflusst. Der polare Anteil der freien Oberflächenenergie, insbesondere die Elektronendonorkomponente Gamma-, hat wesentlich die Wechselwirkungen zwischen Belag und Oberfläche beeinflusst. Eine quadratische Beziehung zwischen Gamma- und dem Endwert des Foulingwiderstands, Belagmasse oder Protein– und Mineralgehalte im Belag wurde gefunden. Etwas mehr Verschmutzung auf beschichteten elektropolierten Oberflächen, die auch schwieriger zu reinigen waren, wurde im Vergleich zu beschichteten unbehandelten Oberflächen festgestellt. Der Einfluss von Gamma- an der Belagbildung war stärker bei T_o von 80°C als bei 120°C. In der proteinfreien Lösung hing die Bildung von Salzaggregaten in ersten Foulingschichten mit Gamma- zusammen, die auch für Ablagerungen aus Protein sowie aus Protein plus SMUF mit unterschiedlichen Strukturen beigetragen hat. Auf niedrigen Gamma- Oberflächen wuchs ein Belag überwiegend aus Calciumphosphat, während sich auf hohen E Oberflächen Protein bevorzugt ablagerte. Die Beläge unter kontinuierlichen Strömungsbedingungen entstanden mehr aus Kristallisations- und partikulärem Fouling als aus Proteinfouling. Reinigungsprofile waren abhängig von den Oberflächeneigenschaften. Auf hohen Gamma- Oberflächen konnte der Belag nahezu vollständig entfernt werden und die höchste Reinigungsrate sowie die schnellste Abnahme des thermischen Foulingwiderstands wurden gemessen. Optimale Gamma- Werte für minimales Fouling und maximale Reinigungswirkung wurden daraus abgeleitet