Tesis por compendio / [EN] In the present Doctoral Thesis, antimicrobial active packaging materials, at lab and at semi-industrial scale, have been developed with the aim to reduce the natural flora of peeled and cut fruit and extend its shelf life. Packaging prototypes have been developed for their further application. Prior to developing the active materials, the most suitable active agents were selected. To that end, the antimicrobial properties of the volatile active agents citral, hexanal and linalool and mixtures thereof were evaluated against typical microorganisms related to fruit spoilage, molds and yeast, concluding that the effectiveness of the mixture is higher than the sum of the effectiveness of the individual agents. Likewise, non-volatile antimicrobial agents such as potassium sorbate and sodium benzoate were selected, which are widely used in the food industry due to their antifungal properties. With the selected active agents, monolayer polypropylene (PP) films with different concentration of the active mixture citral, hexanal and linalool, at lab scale by means of extrusion, and bilayer films at semi-industrial scale with different active layer thickness by means of coextrusion were prepared. Besides, active packaging trays were developed at semi-industrial scale by thermoforming active sheets obtained by coextrusion of PP and ethyl vinyl acetate (EVA) compounds containing potassium sorbate and sodium benzoate as active agents. Mechanical, barrier and thermal properties of the developed active packaging materials, as well as their sealability and transparency were evaluated. In general, the materials' properties were not affected in a significant manner. However, active trays decreased in transparency due to the incorporation of non-volatile active agents. The release kinetics of the volatile and non-volatile active agents were studied at different temperatures, defining their diffusion coefficients by the adjustment to mathematic models based on Second's Law Fick. Among the volatile active agents, hexanal showed a higher diffusion coefficient, followed by citral and linalool. On the other hand, very small differences were observed between potassium sorbate and sodium benzoate diffusion coefficients, being of the same order of magnitude. In vitro tests were also performed at different temperatures to evaluate the antimicrobial properties of the developed materials. In general, the active packaging materials showed high antimicrobial properties which were enhanced with the increment of temperature. Once the properties of the developed materials were evaluated, in vivo tests with peeled and cut orange and pineapple were performed by packing these fruits with the active film, active tray and their combination (active packaging system). In general, the active packaging system improved the microbiological preservation of the fruit for longer times, between 2 and 7 days for orange and pineapple, respectively, and maintained quality parameters of the fruit at stable levels for longer times. Lastly, the safety of the active packaging materials was evaluated according to the European food contact materials and food legislation, and it was concluded that these materials were not of any safety concern for the consumers. / [ES] En la presente Tesis Doctoral se han desarrollado materiales de envase activo antimicrobiano, a escala laboratorio y a escala semi-industrial, con el objetivo de reducir la proliferación de la flora natural de la fruta pelada y cortada y extender su vida útil. Se han desarrollo distintos prototipos para su posterior aplicación industrial Previo al desarrollo de los materiales de envase, se ha realizado una selección de agentes activos más idóneos. Para ello se han estudiado mediante ensayos in vitro las propiedades antimicrobianas de agentes activos volátiles, citral, hexanal y linalool y diferentes mezclas de los mismos, frente a distintos microorganismos típicos del deterioro de las frutas, mohos y levaduras, concluyendo que la efectividad de la mezcla de los tres es superior a la suma de la efectividad de los activos de forma individual. Así mismo, también se han seleccionado antimicrobianos no volátiles como el sorbato potásico y benzoato sódico, los cuáles son ampliamente empleados en la industria alimentaria debido principalmente a sus propiedades antifúngicas. Con los agentes activos seleccionados, se han desarrollado películas monocapa de polipropileno (PP) con distintas concentraciones de la mezcla activa, citral, hexanal y linalool, a escala laboratorio, mediante técnicas de extrusión, y películas bicapa a escala semi-industrial con distintos espesores de capa activa mediante coextrusión. Por otra parte, se desarrollaron bandejas activas a escala semi-industrial mediante termoconformado de láminas obtenidas por coextrusión de compuestos de PP y etilvinilaceteto (EVA) con sorbato potásico o benzoato sódico como agentes antimicrobianos. Se han evaluado las propiedades mecánicas, barrera y térmicas de los materiales activos desarrollados, así como su sellabilidad y transparencia. En general, las propiedades de los polímeros no se vieron afectadas de manera relevante. Sin embargo, las bandejas activas perdieron su carácter transparente debido a la incorporación de los agentes activos no volátiles. Se ha estudiado la cinética de liberación de los compuestos activos volátiles y no volátiles a distintas temperaturas, determinando los coeficientes de difusión de los agentes activos mediante el ajuste a modelos matemáticos de difusión basados en la Segunda Ley de Fick. Entre los agentes volátiles, el hexanal mostró un mayor coeficiente de difusión seguido de citral y linalool. Por otra parte, no hubo apenas diferencia en los coeficientes de difusión del sorbato potásico y benzoato sódico, siendo éstos del mismo orden de magnitud. Igualmente, se han realizado diferentes experimentos in vitro a distintas temperaturas para determinar las propiedades antimicrobianas de los materiales desarrollados. En general, los materiales activos presentan una elevada capacidad antimicrobiana que se ve potenciada al aumentar la temperatura de exposición. Una vez evaluadas las características de los materiales desarrollados, se han efectuado ensayos de envasado de naranja y piña pelada y cortada con las películas y las bandejas activas y con la combinación del sistema de envase bandeja activa termosellada con la película activa. En general, el sistema de envase activo mejoró la conservación de la fruta por un mayor tiempo, entre 2 y 7 días para la naranja y piña, respectivamente, presentando una gran capacidad antimicrobiana y manteniendo los parámetros de calidad de la fruta en niveles estables por un mayor tiempo. Por último, se ha estudiado la seguridad de estos materiales de acuerdo a la legislación de materiales en contacto con alimentos y la legislación alimentaria europea, concluyendo que los materiales activos desarrollados no presentan preocupación para la seguridad de los consumidores. / [CA] En la present Tesi Doctoral s'han desenvolupat materials d'envasament actiu antimicrobià, a escala de laboratori i a escala semi-industrial amb l'objectiu de reduir la proliferació de la flora natural de la fruita pelada i tallada i estendre la seua vida útil. S'han desenvolupament diferents prototips per a la seua posterior aplicació industrial. Previ al desenvolupament dels materials actius, s'han seleccionat els agents actius mes idonis estudiant mitjançant assajos in vitro les propietats antimicrobianes d'agents actius volàtils, citral, hexanal i linalool i diferents mescles dels mateixos, enfront de diferents microorganismes típics de la deterioració de les fruites -floridures i llevats- concloent que l'efectivitat de la mescla dels tres és superior a la suma de l'efectivitat dels actius de forma individual. Així mateix, s'han seleccionat antimicrobians no volàtils, sorbat potàssic i benzoat sòdic, els quals son àmpliament empleats a l'industria alimentaria per les seues propietats antifúngiques. Amb els agents actius seleccionats, s'han desenvolupat pel·lícules monocapa de polipropilè (PP) amb diferents concentracions de la mescla activa, citral, hexanal i linalool, a escala laboratori, mitjançant tècniques d'extrusió, i pel·lícules bicapa a escala semi-industrial amb diferents espessors de capa activa mitjançant coextrusió. D'altra banda, s'han desenvolupat safates actives a escala semi-industrial mitjançant termoconformació de làmines obtingudes per coextrusió de compostos de PP i etil vinil acetat (EVA) amb sorbat potàssic o benzoat sòdic com a agents antimicrobians. S'han avaluat les propietats mecàniques, barrera i tèrmiques dels materials actius desenvolupats, així com la seua sellabilidad i transparència. En general, les propietats dels polímers no es van veure afectades de manera rellevant. No obstant això, les safates actives van perdre el seu caràcter transparent a causa de la incorporació dels agents actius no volàtils. S'ha estudiat la cinètica d'alliberament dels compostos actius volàtils i no volàtils a diferents temperatures, determinant els coeficients de difusió dels agents actius mitjançant l'ajust a models matemàtics de difusió basats en la Segona Llei de Fick. Entre els agents volàtils, l' hexanal va mostrar un major coeficient de difusió seguit de citral i linalool. D'altra banda, no va haver-hi a penes diferències en els coeficients de difusió del sorbat potàssic i benzoat sòdic, sent aquests del mateix ordre de magnitud. Igualment, s'han realitzat diferents experiments in vitro a diferents temperatures per determinar les propietats antimicrobianes dels materials desenvolupats. En general, els materials actius presenten una elevada capacitat antimicrobiana que es veu potenciada en augmentar la temperatura d'exposició. Una vegada avaluades les característiques dels materials desenvolupats s'han efectuat assajos d'envasament de taronja i pinya pelada i tallada amb la safata, la pel·lícula activa i la seva combinació (sistema d'envàs actiu). En general, el sistema d'envàs actiu va millorar la conservació de la fruita per un major temps, entre 2 i 7 dies per a la taronja i pinya respectivament, presentant una gran capacitat antimicrobiana i mantenint els paràmetres de qualitat de la fruita en nivells estables per un major temps. Finalment, s'ha estudiat la seguretat d'aquests materials d'acord a la legislació de materials en contacte amb aliments i la legislació alimentària europea, concloent que els materials actius desenvolupats no presenten preocupació per a la seguretat dels consumidors. / Lara Lledó, MI. (2016). Antimicrobial packaging system for minimally processed fruit [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/61388 / Premios Extraordinarios de tesis doctorales / Compendio

Made available in DSpace on 2014-12-17T15:01:14Z (GMT). No. of bitstreams: 1 AndreiaSS.pdf: 675563 bytes, checksum: 8fb6ac6948a845dc7f3157989cb415a1 (MD5) Previous issue date: 2008-02-08 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This work deals with the kinetics assay of Caj? (Spondias mombin L.) bagasse drying by an experimental design using a tray dryer. In order to add-value to this product a kinetic study has been carried out. A central composite experimental design has been carried out to evaluate the influence of the operational variables: input air temperature (55; 65 e 75?C); the drying air velocity (3.2; 4.6 e 6.0 m/s) and the fixed bed thickness (0.8; 1.2 e 1.6 cm) and as response variable the the moisture content (dry basis). The results showed that the diffusional Fick model fitted quite well the experimental data. The best condition found has been input air temperature of 75?C, drying air velocity of 6.0 m/s as well as fixed bed thickness of 0.8 cm. The experimental design assay showed that the main effects as well as the second ones were significant at 95% confindance level. The best operational condition according to statistical planning was 75 oC input air temperature, 6.0 m.s-1 drying air velocity and 0.8 cm fixed bed thickness. In this case, the equilibrium moisture content (1.3% dry basis) occured at 220 minutes / O presente trabalho teve como objetivo estudar a cin?tica de secagem do baga?o de caj? (mat?ria prima proveniente da ind?stria de processamento de polpa de frutas), em um secador convectivo de bandejas com leito fixo, em que se determinou o coeficiente de difusividade efetiva atrav?s do modelo difusional de Fick. Foi utilizado um planejamento fatorial composto central no qual foram avaliados os seguintes fatores: temperatura do ar de entrada no secador (55; 65 e 75?C); velocidade do ar de entrada (3,2; 4,6 e 6,0 m/s) e espessura da torta na bandeja (0,8; 1,2 e 1,6 cm). Os resultados mostraram que o modelo difusional de Fick descreve bem o processo de secagem e que a melhor condi??o foi com a temperatura de 75?C, velocidade do ar de secagem de 6,0 m/s e espessura da torta de 0,8 cm onde a difusividade efetiva calculada foi de 6,772 x 10-9 m2/s no tempo de 220 minutos. A an?lise do planejamento mostrou que todos os fatores e suas intera??es foram significativos, com n?vel de confian?a de 95%

Made available in DSpace on 2014-12-17T15:01:29Z (GMT). No. of bitstreams: 1 ErlyMMAN_DISSERT.pdf: 2763165 bytes, checksum: 02d0a064f93f95db42ddc7fc2c52410e (MD5) Previous issue date: 2012-03-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Brazil, one of the largest agricultural producers in the world, has managed in recent years to significantly improve its production. However, in response to this advance in the agro-industrial sector, the generation of agro-industrial residues has also increased. New technological alternatives have to be implemented in order to bring economic and rational use of this material and drying is one of the possible choices. Considering the great importance that bioactive compounds present for food science and technology, this research aims to evaluate the air-drying process of acerola residue in a tray convective drier under controlled temperature (60, 70 e 80?C), air velocity (4.0, 5.0 e 6.0 m/s) and material width (0.5, 0.62 e 0.75 cm) by applying an experimental planning 23 + 3. Based on that, the impact on physical-chemical characteristics, color, bioactive compounds concentration and antioxidant activity of dried acerola waste was evaluated, having the in natura and freeze dried waste as control groups. Dried acerola residue presented natural pigments, mainly carotenoids (143.68 - 68.29 mg/g) and anthocyanins (290.92 - 90.11 mg/100 g), which explain the red and yellow instrumental color parameters observed. The acerola residue powder is also rich in phenolic compounds (3261.11 -2692.60 mgGAEeq/100g), proanthocyanidins (61.33-58.46 eq/100g), ascorbic acid (389.44 739.29 mg/100 g) and DPPH antioxidant activity (20.91 24.72 ?g Trolox eq/g). Results show decreased concentration of phenolic compounds, anthocyanins, carotenoids, proanthocyanidins and ascorbic acid caused by the air-drying process. However, even after the observed drying losses, the acerola residue powder can be considered a high value food ingredient, considering the high bioactive compounds concentration found in the final product, as well as the colorimetric characterization and microbiological stability of the dried powder / O Brasil, um dos maiores produtores agr?colas atuais, tem conseguido aumentar sua produ??o agroindustrial nos ?ltimos anos. Em conseq??ncia a isso a gera??o de res?duos tamb?m aumentou. Dessa forma, torna-se relevante a pesquisa de alternativas de uso racional e econ?mico para esse tipo de mat?ria prima, incluindo opera??es unit?rias de transforma??o como a secagem. Diante da import?ncia que os compostos bioativos apresentam para a ?rea de ci?ncia e tecnologia de alimentos, esta pesquisa objetivou avaliar a secagem do res?duo agroindustrial da acerola em secador convectivo de bandejas sob condi??es controladas de temperatura de trabalho (60; 70 e 80?C), velocidade do ar (4,0; 5,0 e 6,0 m/s) e espessura do material (0,5; 0,62 e 0,75 cm), mediante aplica??o de planejamento experimental do tipo fatorial 23 + 3 pontos centrais. A partir disso, o impacto da secagem sobre as caracter?sticas f?sico-qu?micas, cor, concentra??o de compostos bioativos selecionados e atividade antioxidante do res?duo da acerola s?o abordados, tomando os res?duos in natura e liofilizado como grupos-controle. Os p?s do res?duo desidratado de acerola apresentaram presen?a de pigmentos naturais, com colora??o vermelha e amarela, sobretudo caroten?ides (143,68 a 68,29 mg/g), antocianinas (290,92 a 90,11 mg/100 g), al?m de elevado teor de compostos fen?licos (3261,11 a 2692,60 mg GAE eq/100 g amostra), proantocianidinas (61,33 a 58,46 eq/100 g amostra) e ?cido asc?rbico (389,44 a 739,29 mg/100 g), bem como expressiva atividade antioxidante obtida pelo m?todo DPPH (20,91 a 24,72 ?g Trolox eq/g amostra). Os dados experimentais mostraram diminui??o da concentra??o de compostos fen?licos, antocianinas, caroten?ides, proantocianidinas e ?cido asc?rbico ocasionada pela secagem nas condi??es estudadas. No entanto, a concentra??o final desses compostos detectada no produto desidratado, bem como a caracteriza??o colorim?trica e a estabilidade microbiol?gica alcan?ada, caracteriza o p? do res?duo de acerola como ingrediente com elevado potencial bioativo

This thesis deals with mechanical design of tool turret for CNC lathe. The first part of the thesis is dedicated to research of automatic tool exchange and current trends in design of tool turrets with drive of rotary tools. The second part is focused to design of tool turret, which is based on the findings of the research part of the thesis. The design includes calculations of machining loads, spindle deformation, bearings, gears and spindle startup. Furthermore, 3D models and selected drawings are included.

The thesis contains information about the design of pressure vessels and describes their individual parts. It is mentioned production of individual parts and the process including assembly parts in one unit. The thesis includes options of control and testing of pressure vessels. It is described kinds of built-ins of distillation column and the basic principles and types of distillation. It is created stress analysis of pressure vessels parts according to ČSN EN 13 445 – 3, and also stress analysis of the selected part of column by using FEM. Mechanical drawing of distillation column is part of the thesis.