The challenges of weight reduction and good strength in automotive industry have drawn considerable interest in thixocasting technologies. Joining of such components with conventional fusion welding creates voids, hot cracking, distortion in shape, and more importantly evolution of dendritic microstructure that ultimately would lead to inferior mechanical properties of the weld region. Thus, the purpose of making thixocast component is lost. The friction welding which is a solid state joining process can avoid defects associated with melting and solidification in a typical fusion weld and can be a promising alternative. This process produces a weld under compressive force at the contact of workpieces rotating or moving relative to one another to produce heat and plastically displacing material from the faying surfaces. Research on semisolid processing has its origin in the early 1970s. However, from the literature survey on semisolid processing it is clear that, till date, not much work has been done in field of joining of semisolid processed components. In the area of solid state welding, in particular, it is not at all explored. In view of this, the present work is focused on exploration of joining of Thixocast A356 Aluminium alloy component by friction welding and comparison of its performance with friction weld of conventionally cast sample of the same alloy. The study is carried out experimentally as well as numerically. Moreover, the material behaviour of thixocast component at elevated temperature in solid state is also described with the help of processing maps and constitutive modelling. The hot workability of thixocast and conventionally cast A356 alloy is evaluated with the help of processing maps developed on the basis of the dynamic materials model approach using the flow stress data obtained from the isothermal compression test in wide range of temperature (300-500℃) and strain rates (0.001s-1-10s-1). The domains of the processing map are interpreted in terms of the associated microstructural mechanism. On comparing the flow stress at elevated temperature of thixocast and conventionally cast A356 alloy samples, it is observed that the flow stress of the latter showed higher value at different strain level, temperature and strain rates. This indicates that the flow property of the thixocast alloy sample is better than that of the conventionally cast one (i.e. response to plastic flow is better for the former); while at room temperature thixocast sample has higher strength. Moreover to investigate the general nature of the influence of strain, strain rate and temperature on the compressive deformation characteristics of thixocast A356 and conventionally cast A356 aluminium alloy, a comprehensive model describing the relationship of the flow stress, strain rate and temperature of the alloys at elevated temperatures is proposed by hyperbolic-sine Arrhenius-type equation and Johnson-Cook model. The validity of descriptive results based on the proposed constitutive equation is also investigated and a comparison between two constitutive models is also made. In order to numerically model the friction welding process of a thixocast A356 aluminium alloy and conventionally cast alloy of same material using a finite element method (FEM), temperature dependent physical properties, mechanical properties as well as viscoplastic constitutive equations were used in the model. A two- dimensional axisymmetric finite element model has been developed. The modelling is based on a coupled thermomechanical approach. First, a nonlinear, transient two-dimensional heat transfer model is developed to determine the temperature fields. Later, the temperature fields are used as input for a nonlinear, two-dimensional structural model in order to predict the distortions and von Mises stress. The finite element models are parametrically built using APDL (ANSYS Parametric Design Language) provided by ANSYS. The validation of the model is carried out by comparing with the experiment. Once validated, the thermomechanical model was used to perform parametric studies in order to investigate effects of various process parameters on temperature and stress distribution in the workpieces. This helps in deciding the range of parameters for friction welding experiments in order to get good weld. Both thixocast and conventionally cast samples exhibited similar temperature distribution during the friction welding process, because of identical thermophysical properties. The magnitude of von Mises stress distribution during friction welding of thixocast A356 sample is found to be lower than that of the conventionally cast sample. It is because of their different constitutive behaviour at elevated temperature. Moreover, the developed FEM model can be successfully used to predict the residual stress at various locations for different set of parameters and geometry for friction welding of thixocast and conventionally cast A356 alloy. This helps in reducing time consuming and expensive experiments on residual stress measurement. The chosen experiments based on Taguchi L27 orthogonal array were conducted on the friction welding machine which works on the principles of continuous drive-mechanism. The experimental specimens were machined from thixocast A356 aluminium alloy connecting rods as well as conventionally cast A356 aluminium alloy ingot in the form of cylindrical bars of dimensions 85mm length and 20mm diameter. The parameters used for welding were friction pressure, rpm, forge pressure, burn-off, and upset pressure. The effects of welding parameters on performance characteristics (i.e. tensile strength and weld efficiency) were evaluated. Taguchi method was applied to investigate the influence of each parameter on strength of joints and evaluate the combination of parameters that leads to the highest weld strength. Accordingly optimum process parameters was identified which helps in achieving the tensile strength of more than parent material. The optimized process parameters for friction welding of thixocast A356 aluminium alloy are rpm = 500, friction pressure = 60, upset time = 5, upset pressure = 100 and burn off = 5. The empirical relationships were also developed to predict the tensile strength. The developed relationship can be effectively used to predict the tensile strength of welded joint with a correlation coefficient of 0.86, which indicates the strong positive relationship between predicted and experimental data. Friction welding of thixocast A356 aluminium alloy helps to achieve very fine eutectic silicon particles of the order of 0.4 at the interface due to severe plastic deformation taking place during welding. Obtaining such fine eutectic silicon particles is difficult to be achieved within few seconds of processing by any other method. The hardness variation of friction welded thixocast alloy shows higher value as compared to that of a conventionally cast sample in the heat affected zone, which indicates better weld strength of the former. This was also confirmed by the tensile strength studied and fatigue test. This indicates that weldability of cast alloys will get improved if the microstructure is modified to globular type.

A vida moderna tem gerado mudanças importantes nos hábitos alimentares em todo o mundo e observa-se um aumento da demanda por alimentos prontos para o consumo, tais como frutas e hortaliças minimamente processadas. As condições de embalagem e armazenamento destes produtos podem favorecer a multiplicação de bactérias psicrotróficas, destacando-se o patógeno Listeria monocytogenes. Para estudos de avaliação de riscos microbiológicos relativos a L. monocytogenes, dados quantitativos são fundamentais, mas, os métodos para enumeração disponíveis atualmente são trabalhosos e morosos. Há grande interesse no desenvolvimento de métodos rápidos para a determinação das populações de L. monocytogenes, o que pode reduzir significativamente o tempo de análise. Neste trabalho, foram analisadas 162 amostras de hortaliças minimamente processadas adquiridas no comércio varejista de Ribeirão Preto/SP, no período de setembro de 2007 a agosto de 2008. Foram realizados ensaios convencionais para enumeração de coliformes totais e termotolerantes, Escherichia coli e bactérias aeróbias psicrotróficas. Foi realizada a detecção de Listeria sp. por imunoensaio (Oxoid Listeria Rapid Test) e de Salmonella por método convencional. Alíquotas congeladas de amostras positivas para L. monocytogenes e Salmonella sp. foram também avaliadas quantitativamente empregando-se métodos convencionais. Para quantificação de L. monocytogenes foi utilizado o método da Reação de Polimerase em Cadeia (PCR) em tempo real, com primers de DNA baseados em 16S rRNA. Para a comparação do método de PCR em tempo real e método convencional de cultivo, foram inoculadas seis amostras de hortaliças minimamente processadas (alface, cheiro-verde, couve, almeirão, repolho e acelga) com três níveis de inoculação. Dentre as 162 amostras de hortaliças analisadas, L. monocytogenes foi detectada em uma amostra de couve e uma de cheiro-verde, com populações de 1,5 x 103 e 0,43 NMP/g, respectivamente. Salmonella sp. foi isolada de duas amostras de almeirão, com populações de 0,09 e 4,6 NMP/g. Contaminação por coliformes totais foi detectada em 132 (81,5%) amostras e por coliformes termotolerantes em 107 (66%) amostras. Escherichia coli foi confirmada em 86 (53,1%) amostras, enquanto que 158 (96,7%) amostras apresentaram população de bactérias psicrotróficas maior que 5 log UFC/g. Os resultados obtidos entre os dois métodos desenvolvidos apresentaram pouca variação e todos os resultados foram concordantes considerando-se o intervalo de confiança de 95% da técnica do NMP (SWANSON; PETRAN; HANLIN, 2001). A PCR em tempo real foi otimizada com a preparação comercial ABSOLUTETM QPCR SYBR® Green Mix (ABgene, Reino Unido) e os primers utilizados mostraram ser específicos para L. monocytogenes. As populações de microrganismos encontradas nestes alimentos indicaram a baixa qualidade microbiológica e evidenciaram a importância da implantação de programas para garantia da inocuidade de alimentos na cadeia produtiva das hortaliças minimamente processadas. A PCR em tempo real mostrou ser de fácil execução e diminuiu o tempo de obtenção de resultados para pouco mais que 48 horas em comparação com o tempo gasto (7 dias) quando as hortaliças foram analisadas por meio do método convencional de cultivo. / Modern lifestyles have deeply changed eating habits worldwide, with an increasing demand for ready-to-eat foods, including minimally processed fruits and leafy greens. Packaging and storage conditions of these products may favor the growth of psychrotrophic bacteria, such as the pathogen Listeria monocytogenes. For microbiological risk assessment, it is crucial to generate quantitative data on foodborne pathogens, but the enumeration methods currently available are labor and time consuming. There is great interest in the development of reliable and fast methods for enumeration of L. monocytogenes, in order to shorten the time needed to obtain quantitative results. In this study 162, samples of leafy vegetables minimally processed were acquired at retail market in Ribeirão Preto from September, 2007 to August 2008 and they were analysed by conventional enumerating methods for total and thermophilic coliforms, Escherichia coli and psychrotrophic aerobic bacteria. Presence or absence of Listeria spp. was evaluated by immunoassay (Oxoid Listeria Rapid test) and detection of Salmonella was performed by conventional methods. Frozen aliquots of Salmonella spp. and L. monocytogenes positive samples were quantitatively evaluated by conventional methods and L. monocytogenes was also enumerated by real-time Polymerase Chain Reaction (PCR) with DNA primers based on 16S rRNA. Real-time PCR method was applied to analyze six artificially contaminated vegetables and the results obtained with this methodology were similar to the ones obtained with conventional most probably number (MPN) technique with a confidence interval of 95% (SWANSON; PETRAN; HANLIN, 2001). Of the 162 samples analyzed, L. monocytogenes was detected in one sample of collard green and in one mixed bunch of parsley plus spring onion (1.5x103 and 0.43 MPN/g, respectively). Salmonella sp was detected in two samples of common chicory with populations of 0.09 and 4.6 MPN/g. One hundred and thirty two samples (81.5%) showed contamination by total coliforms and 107 (66%) by thermophilics coliforms. Escherichia coli was confirmed in 86 (53.1%) samples while 156 (96.7%) showed populations of psychrotrophic bacteria above of 5 log CFU/g. PCR was optimized with a commercial preparation ABSOLUTE TM QPCR SYBRÒ Green Mix (ABgene, UK) and the primers utilized were specific for L. monocytogenes. These results showed the low microbiologic quality of minimally processed vegetables samples studied and indicate an urge for implementation of quality programs from producer to processors of these ready-to-eat foods. Realtime In comparison with the conventional culture method, real-time PCR was more easily performed and the time required to obtain the results was reduced to ca. 48 hours, in comparison with 7 days for conventional method.

Este trabalho teve como objetivo avaliar o efeito da utilização de película comestível, ácido ascórbico e cloreto de cálcio sobre a conservação do melão \'Amarelo\' minimamente processado. Primeiramente, visando à obtenção de um produto conveniente foram estudados os aspectos microbiológicos e os efeitos dos tratamentos sobre a taxa respiratória e a produção de etileno de produtos de melão durante o armazenamento refrigerado. Os frutos depois de selecionados, lavados e higienizados em solução de dicloroisocianurato de sódio dihidratado (200ppm) tiveram a polpa cortada em cubos (3cm de aresta), que foi imersa em solução de dicloroisocianurato de sódio dihidratado (100ppm) e drenada. A seguir, foram divididos em 4 lotes, cujos cubos foram imersos nas soluções de cloreto de cálcio a 1%, ácido ascórbico a 1% e película a base de alginato (1%) e um lote foi deixado sem tratamento, o qual serviu de testemunha. Após a segunda drenagem, os melões tratados foram acondicionados em bandejas de tereftalato de polietileno (PET) e armazenados a 5°C. Verificou-se que, em todos os tratamentos, houve redução da taxa respiratória ao longo do período de armazenamento e foi detectada baixa produção de etileno. Quanto à qualidade microbiológica, as contagens de bactérias psicrotróficas e de bolores e leveduras mantiveram-se dentro dos limites aceitáveis. Não foi detectada a presença de microrganismos do grupo coliformes e de Salmonella, mostrando que o processamento foi realizado de forma adequada. No segundo experimento estudou-se o efeito dos tratamentos químicos quanto à manutenção dos parâmetros físicos e químicos dos melões \'Amarelo\' minimamente processados. Verificou-se perda de massa de 0,34% durante todo o período de armazenamento. O ácido ascórbico fornecido pelo tratamento levou a um aumento na acidez nos frutos. O uso de película a base de alginato de sódio resultou em melões com menores teores de sólidos solúveis e de acidez titulável, menores pH e grau de solubilização da pectina, melhor sabor, além de coloração mais escura da polpa, em decorrência da cor da solução filmogênica. Os tratamentos químicos estudados pouco afetaram as características físicas e químicas dos produtos de melão e não estenderam a sua vida útil. No terceiro experimento avaliou-se a manutenção da qualidade sensorial, utilizando provadores treinados, através do método da Análise Descritiva Quantitativa (ADQ), bem como a aceitação do produto pelo consumidor. A ADQ mostrou que os tratamentos testados não apresentaram efeito no prolongamento da vida útil dos melões \'Amarelo\' minimamente processados. O teste de consumidor indicou que os melões tratados com cloreto de cálcio e com ácido ascórbico foram os melhor aceitos pelos provadores e revelou que não houve diferença quanto à intenção de compra. No quarto experimento estudaram-se alternativas para o aproveitamento das cascas e das sobras de polpa de melões minimamente processados. Da casca foram desenvolvidos três produtos, compota, doce e glaceado; e com as sobras de polpa foram elaboradas geléias. O teste sensorial indicou que todos os produtos elaborados, com exceção do doce de melão, obtiveram boa aceitabilidade por parte dos julgadores, com índice de aceitabilidade acima de 80%. / This work aims to evaluate the effect of the use of edible film, ascorbic acid and calcium chloride on the conservation of minimally processed melon. In order to obtain a convenient product, the microbiological aspects have been studied in order to evaluate the effect of the treatments on the respiratory rate and ethylene production of melons during the refrigerated storage. The fruits were selected, washed and sanitized in sodium dichloroisocianurate dehydrated solution (200ppm). The pulp of the fruits was cut in cubes (3cm of edge), immersed in sodium dichloroisocianurate dehydrated solution (100ppm) and drained and consequently it was divided in four lots. These cubes were immersed in calcium chloride (1%), ascorbic acid (1%) and alginate film (1%) and a lot was left without any treatment, which served as control. After the second drainage, the melons were placed in trays of polyethylene terephtalate (PET) and stored at 5°C. It has been verified that in all the treatments there was a reduction of the respiratory rate during the storage and the low ethylene production was detected. Concerning the microbiological quality, psychotropic bacteria, molds and yeasts counts were within acceptable limits and fecal bacteria group and Salmonella were not detected which demonstrates that the processing was carried out adequately. The second experiment was studied in order to evaluate the effect of the chemical treatments on the maintenance of the physical and chemical parameters of minimally processed melons. It was verified that the loss of mass was 0.34% during the storage. The ascorbic acid supplied for the treatment suffered an increase of acidity of fruits. The edible coating of sodium alginate resulted in melons with fewer contents of soluble solids and titratable acidity, lesser pH and degree of pectin solubilization, better flavor, and pulp with darker coloration, which results the color of the film solution. It was concluded that the chemical treatments affected the physical and chemical characteristics of minimally processed melons a little and they did not extend the product\'s shelf-life. In the third experiment, the maintenance of the sensorial quality, using trained panelists, through the Quantitative Descriptive Analysis Method (QDA), as well as the acceptance of the product for the consumer has been evaluated. The QDA showed that the treatments were not presented to be effective in the prolongation of the shelf-life of minimally processed melons. The consumer test indicated that the melons treated with calcium chloride and ascorbic acid were more accepted by the panelists and showed that there was no significant difference about buying intention. The fourth experiment was intended to study alternatives for the exploitation of the peels and the pulp\'s leftovers of minimally processed melons. With the peels, three products were developed: compote, candy, icing candy and jellies were made with the leftovers of the pulp. The sensorial test indicated that all the elaborated products, except for the candy made of melon peel, showed good acceptability for panelists, with rate of acceptability above of 80%.

The production of high-quality foods requires the precise control of factors influencing their quality. The aim of this doctoral thesis was to monitor the influence of sterilization heating and storage time and temperature on selected parameters of model food matrix using suitable physical, chemical and sensory methods. Sterilized processed cheese was chosen as the model matrix. Processed cheeses are milk protein concentrates, produced by melting of mixture of natural cheeses, emulsifying salts, water and other dairy and/or non dairy ingredients. Desirable transformation of this mixture to homogenous, smooth, shiny mass with desired textural, structural, rheologic and sensory properties is caused by using high temperature (about 80-100 °C) during melting. Sterilized processed cheese is subjected to additional sterilization heating (above 100 °C) after production, significantly elongating its durability. The processed cheeses (dry matter 40 % w/w, fat in dry matter 45 % w/w) were analyzed in this work, the part of them was sterilized (117 °C 20 min). Cheeses were stored at various temperatures (cold 6 ± 2 °C, laboratory 23 ± 2 °C and elevated 40 ± 2 °C), sterilized cheeses for 2 years, non sterilized for 1 year. During storage, the samples for physical (instrumental measuring of colour and texture), chemical (assessment of fatty acids and aroma compounds) and sensory (paired preference test, ranking test and evaluation using scale) analyses were taken at regular intervals. The influence of sterilization heating and for another the influence of storage conditions on mentioned parameters were investigated. Non sterilized processed cheese kept their very good quality during all the declared durability (4 months), however, then the significant worsening of most sensory properties was observed. In consequence of sterilization heating the changes of cheese colour and texture were observed, confirmed by both sensory and instrumental assessment. The impairment of taste and aroma was also found. These changes are obvious immediately after production and differences were observed during all the durability. In the case of sterilized processed cheese, the significant impairment of single sensory properties was determined, the highest in the case of texture, taste and aroma. The results of instrumental techniques confirm conclusions from sensory evaluation. The measurements of colour and texture vindicate the formation of darker colour (increasing total difference of colour delta E*) and higher hardness (increasing Fmax) of sterilized processed cheeses, continuing during storage. The worsening of taste and aroma is in accordance with lower content of aroma active compounds and selected fatty acids.

Background: With an estimated number of 1.2 billion in the world, adolescents represent a major transformative force in global health. Optimum adolescent nutrition is increasingly important for scaling up population health gains in low- and middle-income countries (LMICs) of South Asia. Nevertheless, little is known about the gender and socio-economic stratification of diets consumed by rural adolescents in these countries. The aim of this project was to understand the gender and socio-economic stratification of their diet with a dual, descriptive-analytic focus on dietary diversity (DD) and consumption of ultra-processed and deep-fried foods. Methods: This thesis builds upon cross-sectional analyses of data collected during 15-year follow-up of the MINIMat (Maternal and Infant Nutrition Interventions in Matlab) trial, from September 2017 to June 2019. Data on dietary and socio-demographic variables were collected through household survey; using a pre-tested, structured questionnaire. A single, 24-hour recall was employed to assess consumption of staples and non-staples arranged in 10 groups, ultra-processed foods (UPF) in four groups, and of one group of deep-fried foods. Data were analyzed using logistic regression models. The analytic sample comprised 2463 adolescents. Results: The prevalence of inadequate DD was 42.3% (40.3-44.2). Consumption of dark green leafy vegetables, vitamin A-rich fruits and vegetables, and animal-source foods–except fish–appeared low. The proportions of adolescents consuming meat, egg and dairy were higher among those from the richest households than those from the poorest households, and among boys than girls. Belonging to the poorest households (adjusted odds ratio (aOR): 1.59; 95% confidence interval (CI): 1.27-2.00) and the food insecure households (aOR: 1.34; 95% CI: 1.13-1.59), and attaining secondary education (aOR: 1.38; 95% CI: 1.11-1.71) were positively associated with inadequate DD. Adolescents having mothers with secondary education or above had lower odds of inadequate DD (aOR: 0.76; 95% CI: 0.60-0.96). Gender was not an independent predictor of inadequate DD.Approximately 83% (81.5-84.4) adolescents reportedly consumed at least one ultra-processed or deep-fried food in the 24 hours preceding the survey. Packaged confectioneries were the most consumed and sugar-sweetened beverages (SSB) the least consumed UPF group. Boys had greater odds of consumption than girls for all UPF groups and deep-fried foods. The association was strongest for SSB (aOR: 2.57; 95% CI: 1.97, 3.37), followed by deep-fried foods (aOR 1.96; 95% CI: 1.66, 2.32). Belonging to the richest households was associated with consumption of ready-to-eat foods (aOR 1.55; 95% CI: 1.12-2.16) and of SSB (aOR: 1.44; 95% CI: 1.02-2.03). Adolescents with higher educational attainment had lower odds of consuming SSB (aOR 0.73; 95% CI: 0.54-0.98). Conclusion: The studies presented compelling evidence of limited DD concurrent with emergent consumption of ultra-processed and deep-fried foods in a rural cohort of adolescents. Inadequate DD was more likely among those from the poorest and the food insecure households. For ultra-processed and deep-fried foods, gender association persisted across the food groups with boys having a greater likelihood of consumption than girls. Wealth status influenced consumption of “instant” foods and SSB only. This suboptimal dietary pattern may place the adolescents at heightened risk of different forms of malnutrition.

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 / TESIS / Premios Extraordinarios de tesis doctorales / Compendio

Tener un acertado pronóstico de ventas es un tema indispensable en empresas productoras y distribuidoras, ya que impacta positivamente en la toma de decisiones relacionadas a la demanda, gestión de inventario, abastecimiento, distribución y surtido de productos, así como otras áreas del negocio como finanzas, marketing, operaciones y servicio al cliente. Sin embargo, actualmente, en la mayoría de los casos, las predicciones de las ventas se basan en análisis individuales de los productos, mas no en técnicas de clustering, las cuales permitirían reducir el error y ser más acertados en sus pronósticos. Por ello, el presente trabajo propone evaluar y comparar el impacto de la precisión de los pronósticos de ventas del método tradicional, regresión lineal simple con series de tiempo, con los métodos de clustering k-means y Ward. El alcance de la investigación será a los cinco principales productos de una importante empresa productora y distribuidora de alimentos procesados en el Perú. Los indicadores que se utilizarán para identificar el método más preciso serán los errores medios absolutos (MAD) y errores cuadráticos medios (MSE) resultantes. / Having a successful sales forecast is an essential issue in manufacturing and distributing companies, since this impacts the decision-making related to demand, inventory management, supply, distribution and product assortment, as well as other areas of the business such as finance, marketing, operations and customer service. However, currently, in most cases, sales forecast are based on individual product analyzes, but not on clustering techniques, which would reduce error and be more accurate in their forecasts. Therefore, the present work proposes to evaluate and compare the impact of the precision of the sales forecasts between the traditional method, simple linear regression with time series, and the clustering methods such as k-means and Ward. The investigation scope will be the five main products of an important manufacturer and distributor of processed foods in Peru. The indicators that will be used to identify the most accurate method will be the mean absolute deviation (MAD) and mean square errors (MSE). / Tesis

The Institute of Medicine (IOM) and National Research Council (NRC) established guidelines for weight gain during pregnancy to maximize positive health outcomes for mothers and their offspring. However, in the US, about half of all pregnant women exceed these recommendations. Excessive weight gain during pregnancy is associated with various negative outcome for mothers and their children. Research in recent years has begun to explore the relationship between both diet quality and ultra-processed food (UPF) intake during pregnancy with gestational weight gain (GWG). However, research is scarce, especially pertaining to UPF intake and GWG. Additionally, there is no research which explores these relationships among Latina women living within the US. The purpose of this study is to explore the relationships between prenatal diet quality, measured with the Healthy Eating Index-2020 (HEI), and intake of UPF, based on the Nova classification system, with the adequacy of GWG among a predominantly Latina sample of adult pregnant women living within the US. Additionally, the association between social determinants of health with diet quality and with UPF intake were also explored. The study is a secondary-data analysis of data from a longitudinal study. The sample analyzed includes 118 pregnant women between the ages of 18-45 years old (mean = 29.9, SD = 6.1). Mean pre-pregnancy body mass index (pBMI) for the total sample was 25.8 kg/m2 (overweight). 67% of the sample identified as Hispanic/Latina. Overall, 22% of the sample were classified with inadequate GWG; 17% with adequate GWG; and 61% with excessive GWG. The mean total HEI score for the sample was 54.1 out of 100, where higher scores reflect higher diet quality and adherence to the Dietary Guidelines for Americans. There was a statistically significant difference across GWG groups (inadequate/adequate/excessive) in mean total HEI scores (p < .05). The adequate GWG group had the highest total HEI scores and the excessive GWG group had the lowest total HEI scores. Variables that were found to be univariately associated with excessive gestational weight gain included: average total HEI score, pBMI, ethnicity; education; and income (p < .05). A 1-point increase in mean total HEI scores was associated with a 5% lower chance of excessive GWG (p = .02). However, after adjustment for covariates (maternal age; pBMI; income; education; race and ethnicity), the association between average total HEI score and excessive gestational weight gain was attenuated and no longer statistically significant. There was a statistically significant difference across GWG groups (inadequate, adequate, or excessive) in their scores of two HEI components: Greens and Beans (p < .01); and Seafood and Plant Proteins (p < .01). The adequate GWG group had the highest scores and the excessive GWG group had the lowest scores in these HEI components. In simple logistic regressions of excessive GWG versus adequate GWG on HEI components, the Greens and Beans scores and the Seafood and Plant Protein scores were significantly associated with excessive GWG. After adjustment, the Greens and Beans scores and Seafood and Plant Proteins scores indicated strong estimated negative associations with excessive GWG, OR = 0.61, 〖 χ〗_1^2= 8.07, p < 0.01 and OR = 0.60, 〖 χ〗_1^2= 7.84, p < 0.01, respectively. A higher score on these components was associated with a lower risk of excessive GWG. The mean percentage of energy intake from ultra-processed foods (PEI-UPF) was 51.2%. There was no statistically significant difference in the PEI-UPF across GWG groups (inadequate, adequate, or excessive) and the PEI-UPF was not associated with odds of excessive GWG. However, the adequate GWG group had the lowest intake of PEI-UPF (49.2%) and the excessive GWG group had the highest intake of PEI-UPF (52.1%). Social determinants of health were not associated with the mean PEI-UPF, but results suggested a positive relationship between social support and total HEI scores (p = .08). Deeper analysis of the social support measure revealed a statistically significant relationship between the appraisal subscale of social support and HEI scores, Β = 0.13, F(1, 102) = 7.11 (p = 0.009). Overall, dietary intake during pregnancy may influence the adequacy of gestational weight gain. Achieving recommended intake of greens and beans, as well as seafood and plant proteins, may play a particularly important role in reducing the risk for excessive gestational weight gain. In addition, greater levels of social support, particularly access to another person who can offer advice and guidance with personal problems, may enhance diet quality during pregnancy.

No description available.

Introduction : Il existe peu de données sur l’alimentation des Canadiens issus de la diversité culturelle, y compris des immigrants, particulièrement sur la consommation d’aliments ultra-transformés (AUT) associée à une faible qualité nutritionnelle et à un risque accru de maladies chroniques. Objectif : Cette étude vise à estimer les niveaux de consommation d’AUT parmi les adultes issus de la diversité culturelle au Canada et selon certains marqueurs d’acculturation. Méthode : Les données de rappel de 24 h (n= 13 697) issues de l’Enquête sur la santé dans les collectivités canadiennes (ESCC 2015) ont été utilisées afin d’estimer les niveaux d’apport en AUT (pourcentage calorique quotidien) parmi la diversité culturelle. Des analyses ont permis d’estimer la consommation en AUT selon certains marqueurs culturels (statut d’immigration, groupe ethnoculturel) et d’acculturation (pays de naissance, temps depuis l’immigration, langues parlées). Des analyses ANOVA ont permis de comparer la consommation d’AUT avec les groupes de référence sélectionnés. Résultats : La consommation d’AUT était moindre parmi les immigrants canadiens que les non-immigrants et présentait des variations parmi les communautés ethnoculturelles. Celle-ci était significativement plus élevée parmi les immigrants « blancs », ceux d’origine latino-américaine et ceux résidant au Canada depuis plus longtemps. Elle variait aussi selon les groupes ethnoculturels. La consommation d’AUT ne semblait pas associée aux langues parlées. Conclusion : L’apport calorique provenant des AUT varie en fonction de la diversité culturelle et devrait être considéré dans les interventions destinées à ces groupes au Canada. / Background: There is little data on the diet of culturally diverse Canadians, including immigrants, particularly on the consumption of ultra-processed foods (UPF) which is associated with poor nutritional quality and an increased risk of chronic disease. Objective: The aim of this study is to estimate the levels of UPF consumption among culturally diverse adults in Canada and according to selected acculturation markers. Methods: 24h recall data (n=13,697) from the Canadian Community Health Survey (CCHS 2015) was used to estimate the mean of the usual UPF intake levels (daily caloric percentage) among cultural diversity. Statistics helped estimate UPF intake according to certain cultural markers (immigration status, ethnocultural group) and acculturation markers (country of birth, time since immigration, languages spoken). ANOVA analyses were used to compare UPF consumption with selected reference groups. Results: UPF consumption was lower among Canadian immigrants than non-immigrants, and there were variations of consumption between ethnocultural communities. UPF consumption was significantly higher among "white" immigrants, those of Latin American origin and those who had been in Canada for longer. UPF consumption did not appear to be associated with variables of languages spoken. Conclusion: Caloric intake coming from UPF consumption varies according to cultural diversity, and this needs to be considered in interventions targeting ethnocultural groups in Canada.