O caldo de cana adicionado de polpa ou suco de fruta é uma bebida bastante apreciada no Brasil. O presente trabalho consistiu na elaboração, no processamento em escala piloto e no estudo da vida de prateleira de caldo de cana com polpa de maracujá. Processaram-se nove lotes de caldo de cana adicionado de 4% (m/m) de polpa de maracujá, a 85, 90 e 95 °C/30 s, em triplicata. A bebida pasteurizada foi envasada assepticamente em garrafas de polietileno tereftalato (PET) e estocada a 7 °C, na ausência de luz. Testes físico-químicos foram empregados na caracterização da bebida. Procedeu-se à análise do teor de vitamina C no caldo in natura e na bebida processada. Determinaram-se as atividades das enzimas polifenoloxidase (PPO) e peroxidase (POD) antes e após o processamento. A estimativa da vida útil do produto foi fundamentada em testes microbiológicos e sensoriais. A avaliação da estabilidade microbiológica baseou-se na enumeração de bactérias e fungos psicrotróficos. Testes de escala hedônica de sete pontos para avaliação da aparência, aroma, sabor e aceitação global foram empregados na análise da estabilidade sensorial. As médias dos valores de pH, sólidos solúveis e acidez titulável variaram entre 3,9 e 4,0; 17 e 23 °Brix; e 0,15 e 0,19% de ácido cítrico, respectivamente. A polpa de maracujá não incrementou o teor de ácido ascórbico da bebida que ficou entre 2,6 a 2,8 mg/ 100 mL de bebida. A atividade da PPO variou entre 3,1 e 40,3 U/mL para os nove lotes do caldo acidificado, antes da pasteurização. Os três binômios empregados no processamento foram efetivos na inativação da enzima. A atividade da POD oscilou entre 69,8 e 220,4 U/mL; contudo, apenas o processamento a 95 °C atingiu 100% de inativação. As contagens de bactérias e fungos em todos os nove lotes processados foram inferiores a 2 log UFC/mL ao longo de 90 dias de estocagem. A bebida atingiu médias de notas entre 5 e 6 para todos os atributos avaliados após 30 dias de estocagem. As médias dos tempos de vida útil da bebida processada a 85, 90 e 95 °C/30 s atingiram 31, 39 e 52 dias, respectivamente. Concluiu-se que o aumento da temperatura de pasteurização afetou positivamente a estabilidade da bebida. Contudo, o decréscimo da aceitação sensorial limitou a sua vida útil, no qual o sabor foi o principal atributo limitante. / Sugarcane juice, either pure or with fruit pulp addition, is an appreciated beverage in Brazil. The aim of this research was to evaluate the shelf-life of sugarcane juice mixed with passion fruit pulp (4% w/w). Nine batches were processed at 85, 90 and 95 °C/30 s, in three replicates. The pasteurized beverage was aseptically filled into polyethylene terephthalate (PET) bottles and stored at 7 °C without light exposure. pH, soluble solids and titrable acidity were measured during storage. The content of vitamin C was analyzed both in fresh sugar cane juice and pasteurized beverage. Polyphenoloxidase (PPO) and peroxidase (POD) activities were determined both before and after processing. Microbiological stability evaluation was based on psychrotrophic bacteria and fungi counts. Sensory acceptance was estimated by assigning a liking score on a 7-point hedonic scale to the attributes appearance, flavor, taste and overall appreciation. The mean values for pH, soluble solids and titratable acidity ranged from 3.8 to 4.3, 15 to 24 °Brix, and 0.13 to 0.17% of citric acid, respectively, for all processed batches. The passion fruit pulp did not increase the ascorbic acid content in the pasteurized product which ranged from 2.6 to 2.8 mg / 100 mL of beverage. The PPO activity varied from 3.1 to 40.3 U/mL for the nine acidified sugarcane juice batches before pasteurization. The three pasteurization binomials were effective for enzyme inactivation. The POD activity ranged from 69.8 to 220.4 U/mL. However, only processing at 95 °C achieved complete inactivation. The bacteria and fungi counts in all nine pasteurized batches were lower than 2 log CFU/mL up to 90 days of storage. The product achieved scores between 5 and 6 for all sensory attributes evaluated after 30 days of storage. The estimated shelf-life for beverage processed at 85, 90 and 95 °C/30 s was 31, 39 and 52 days, respectively. It was concluded that pasteurization temperature had a positive effect on beverage stability. Nevertheless, the decrease in flavor acceptance was the main limiting factor for the product\'s shelf-life.

Linguiças cozidas defumadas armazenadas a temperatura ambiente, é um produto tipicamente brasileiro, no qual são empregadas algumas barreiras para a extensão do shelf life: cozimento, defumação e embalagem à vácuo. Estudos de durabilidade comprovaram que muitas não atendem ao shelf life esperado. Na empresa estudada, somente 23% dos lotes das linguiças em estudo atenderam a 90 dias de armazenamento desejados para a indústria de alimentos e 17% dos lotes não chegaram à 45 dias. Foram realizadas avaliações microbiológicas antes do cozimento (média de 5,03 log UFC/g), após cozimento (média de 1,56 log UFC/g) e após resfriamento (média 1,54 log UFC/g) para os gomos com calibre de 40-44mm; comprimento 23-26cm; com peso variando de 260-300 gramas onde foram submetidos ao processo de cozimento e defumação por, no mínimo, 5 horas, atendendo no mínimo 71,1°C no centro térmico do gomo. Os parâmetros físico-químicos também foram avaliados e atendem a legislação, com valores de aw 0,938 e pH 6,33, favoráveis ao desenvolvimento microbiológico. Também foram realizadas análises sensoriais para avaliação dos atributos sensoriais ao longo do armazenamento a temperatura ambiente. / Smoked sausages stored at room temperature, is a typical Brazilian product, in which some hurdles are used to extend shelf life: cooking, smoking and vacuum packing. Durability studies have proven that many do not achieve the expected shelf life. In the studied company, only 23% of the lots of the sausages under study attended the 90 days of storage desired for the food industry and 17% of the lots did not reach 45 days. Microbiological evaluations were performed before cooking (average of 5.03 log CFU/g) after cooking (mean of 1.56 log CFU/g) and after cooling (mean 1.54 log CFU/g) for the caliber 40-44mm; length 23-26cm; with weight varying from 260-300 grams where they were submitted to the cooking and smoking process for at least 5 hours, attending at least 71.1°C in the thermal center of the oven. The physico-chemical parameters were also evaluated and comply with the legislation, with values of aw 0.938 and pH 6.33, favorable to the microbiological development. Sensory analyzes were also performed to evaluate the sensory attributes along the storage at room temperature.

A number of articles only present hurdle models for count data. we are motivated to present hurdle models for semi-continuous data. Because semi- continuous data is also commonly seen in non-life insurance. The thesis deals with the parameterization of various hurdle models for semi-continuous data besides for count data in non-life insurance. Two components of a hurdle model are modeled separately. A hurdle component is modeled by a logistic regression. For a semi-continuous data, a continuous component is modeled by several various regressions. Parameters of each component are estimated through maximum likelihood estimation. Model selection is mentioned before theoretical approaches are applied on the vehicle insurance data. Finally, we get some predicted values based on the fitted models. The prediction gives insurance companies a general idea on setting premium but not accurate. 1

O caldo de cana adicionado de polpa ou suco de fruta é uma bebida bastante apreciada no Brasil. O presente trabalho consistiu na elaboração, no processamento em escala piloto e no estudo da vida de prateleira de caldo de cana com polpa de maracujá. Processaram-se nove lotes de caldo de cana adicionado de 4% (m/m) de polpa de maracujá, a 85, 90 e 95 °C/30 s, em triplicata. A bebida pasteurizada foi envasada assepticamente em garrafas de polietileno tereftalato (PET) e estocada a 7 °C, na ausência de luz. Testes físico-químicos foram empregados na caracterização da bebida. Procedeu-se à análise do teor de vitamina C no caldo in natura e na bebida processada. Determinaram-se as atividades das enzimas polifenoloxidase (PPO) e peroxidase (POD) antes e após o processamento. A estimativa da vida útil do produto foi fundamentada em testes microbiológicos e sensoriais. A avaliação da estabilidade microbiológica baseou-se na enumeração de bactérias e fungos psicrotróficos. Testes de escala hedônica de sete pontos para avaliação da aparência, aroma, sabor e aceitação global foram empregados na análise da estabilidade sensorial. As médias dos valores de pH, sólidos solúveis e acidez titulável variaram entre 3,9 e 4,0; 17 e 23 °Brix; e 0,15 e 0,19% de ácido cítrico, respectivamente. A polpa de maracujá não incrementou o teor de ácido ascórbico da bebida que ficou entre 2,6 a 2,8 mg/ 100 mL de bebida. A atividade da PPO variou entre 3,1 e 40,3 U/mL para os nove lotes do caldo acidificado, antes da pasteurização. Os três binômios empregados no processamento foram efetivos na inativação da enzima. A atividade da POD oscilou entre 69,8 e 220,4 U/mL; contudo, apenas o processamento a 95 °C atingiu 100% de inativação. As contagens de bactérias e fungos em todos os nove lotes processados foram inferiores a 2 log UFC/mL ao longo de 90 dias de estocagem. A bebida atingiu médias de notas entre 5 e 6 para todos os atributos avaliados após 30 dias de estocagem. As médias dos tempos de vida útil da bebida processada a 85, 90 e 95 °C/30 s atingiram 31, 39 e 52 dias, respectivamente. Concluiu-se que o aumento da temperatura de pasteurização afetou positivamente a estabilidade da bebida. Contudo, o decréscimo da aceitação sensorial limitou a sua vida útil, no qual o sabor foi o principal atributo limitante. / Sugarcane juice, either pure or with fruit pulp addition, is an appreciated beverage in Brazil. The aim of this research was to evaluate the shelf-life of sugarcane juice mixed with passion fruit pulp (4% w/w). Nine batches were processed at 85, 90 and 95 °C/30 s, in three replicates. The pasteurized beverage was aseptically filled into polyethylene terephthalate (PET) bottles and stored at 7 °C without light exposure. pH, soluble solids and titrable acidity were measured during storage. The content of vitamin C was analyzed both in fresh sugar cane juice and pasteurized beverage. Polyphenoloxidase (PPO) and peroxidase (POD) activities were determined both before and after processing. Microbiological stability evaluation was based on psychrotrophic bacteria and fungi counts. Sensory acceptance was estimated by assigning a liking score on a 7-point hedonic scale to the attributes appearance, flavor, taste and overall appreciation. The mean values for pH, soluble solids and titratable acidity ranged from 3.8 to 4.3, 15 to 24 °Brix, and 0.13 to 0.17% of citric acid, respectively, for all processed batches. The passion fruit pulp did not increase the ascorbic acid content in the pasteurized product which ranged from 2.6 to 2.8 mg / 100 mL of beverage. The PPO activity varied from 3.1 to 40.3 U/mL for the nine acidified sugarcane juice batches before pasteurization. The three pasteurization binomials were effective for enzyme inactivation. The POD activity ranged from 69.8 to 220.4 U/mL. However, only processing at 95 °C achieved complete inactivation. The bacteria and fungi counts in all nine pasteurized batches were lower than 2 log CFU/mL up to 90 days of storage. The product achieved scores between 5 and 6 for all sensory attributes evaluated after 30 days of storage. The estimated shelf-life for beverage processed at 85, 90 and 95 °C/30 s was 31, 39 and 52 days, respectively. It was concluded that pasteurization temperature had a positive effect on beverage stability. Nevertheless, the decrease in flavor acceptance was the main limiting factor for the product\'s shelf-life.

O presente trabalho consistiu na padronização do ratio, definido como a razão entre o teor de sólidos solúveis (SS) e a acidez titulável (AT), no processamento em escala piloto e no estudo da vida de prateleira (VP) de caldo de cana estocado sob refrigeração. Utilizando-se um delineamento central composto rotacional, com onze formulações de caldo de cana, investigou-se o ratio da formulação que resultou em melhor aceitação sensorial, em uma ampla faixa de SS (13,1 a 25,9 ºBrix) e de AT (0,02 a 0,09 % de ácido cítrico). Determinada a melhor formulação, processaram-se três lotes de caldo de cana padronizado (L1, L2 e L3). A estabilização da bebida foi baseada na seguinte combinação de métodos térmicos e não térmicos: acidificação, pasteurização (95 ºC/ 30 s), envase asséptico em garrafas de polietileno tereftalato (PET) e estocagem refrigerada. Testes físico-químicos, microbiológicos e enzimáticos, incluindo-se a determinação da atividade da peroxidase (POD) e da polifenoloxidase (PPO) foram realizados na bebida in natura e recém-processada (tempo zero da VP). Para o estudo da VP do caldo de cana padronizado pasteurizado, as amostras, em todos os lotes processados, foram fracionadas e estocadas nas temperaturas de 4, 8, 12 e -18 ºC (controle), na ausência de luz. A estimativa de VP do produto foi fundamentada em testes microbiológicos e sensoriais. A avaliação da estabilidade microbiológica baseou-se na enumeração de bactérias e fungos psicrotróficos. Testes de escala hedônica de nove pontos para avaliação da aparência e do sabor foram empregados na análise da estabilidade sensorial. As médias da aceitação sensorial para impressão global das onze formulações não apresentaram diferença estatística (p > 0,05) entre si, nas faixas de SS e AT estudadas. Verificou-se que apenas o efeito da AT foi significativo (p < 0,05) na aceitação da bebida. A formulação escolhida para a padronização do caldo de cana foi aquela com AT equivalente a 0,09 % (pH próximo a 3,9) e 19,5 ºBrix. Para o caldo de cana padronizado pasteurizado recém-processado, os valores de pH foram inferiores a 4,4 em L1, L2 e L3. As contagens de mesófilos não ultrapassaram 50 UFC/ mL, constatando-se a ausência de coliformes termotolerantes e Salmonella em todos os lotes processados. As médias das atividades de POD e PPO foram de 2,11 U/mL e 1,03 U/mL, respectivamente. As contagens de bactérias e fungos psicrotróficos não ultrapassaram 102 UFC/ mL. As médias dos tempos de VP estimadas para as frações dos lotes estocadas a 4, 8 e 12 ºC foram equivalentes a 71, 74 e 23 dias, respectivamente. Concluiu-se que o caldo de cana foi bem aceito pela equipe de provadores, em uma ampla faixa de SS e AT. A combinação dos métodos empregados na estabilização da bebida foi eficiente na redução da atividade enzimática e da contagem microbiana. Além disso, as temperaturas de 4 e 8 ºC mostraram-se efetivas na manutenção da estabilidade da bebida, satisfazendo a uma eventual demanda do mercado consumidor pela bebida processada. / The present study consisted in standardizing the total soluble solids (SS) and titratable acidity (TA) ratio, in small scale processing and in estimating the shelf-life (SL) of sugarcane juice stored under ideal, commercial and abusive temperature conditions. A central composite rotational design with eleven formulations of sugarcane juice was used to investigate the ratio of the formulation that resulted in the best sensory acceptance in a wide range of SS (13,1 a 25,9 ºBrix) and TA (0,02 a 0,09% citric acid). Found the best formulation, three batches of standardized sugarcane juice were processed (L1, L2 and L3). The juice´s stabilization was based on the following combination of thermal and non-thermal methods: acidification, pasteurization (95 °C/30 s), aseptic filling in polyethylene terephthalate (PET) bottles and refrigerated storage. Physico-chemical, microbiological and enzymatic tests, including the determination of the peroxidase (POD) and polyphenol oxidase (PPO) activities, were performed in the fresh and freshly processed (time zero of SL) juice. For the SL study, standardized pasteurized sugarcane juice samples were stored at temperatures of 4, 8, 12 and -18 °C (control), kept in the dark. The estimate of the product´s SL was based on microbiological and sensory tests. The evaluation of the microbiological stability was based on the psychrotrophic bacteria and fungi counts. Nine-point hedonic scale tests for appearance and flavor evaluation were used in order to assess the sensory stability. The mean values of sensory acceptance, for overall impression, of the eleven formulations showed no statistical difference (p > 0.05) among them. It was found that only the effect of TA was significant (p < 0.05). The chosen formulation for sugarcane juice standardization was that one with TA 0.09 % (pH near 3.9) and SS 19.5 ºBrix. For the freshly processed standardized pasteurized juice, the pH was less than 4.4 in L1, L2 and L3. The mesophilic counts did not exceed 50 CFU/mL. The presence of coliforms at 45 ºC and Salmonella was no confirmed. The average POD and PPO activities were 2.11 U/mL and 1.03 U/mL respectively. The psychrotrophic bacteria and fungi counts did not exceed 102 CFU/mL. The juice´s SL stored at 4, 8 and 12 °C were 71, 74 and 21 days, respectively. It was concluded that the juice was well accepted in a wide range of SS and TA, and the combination of methods was effective in reducing the enzyme activity and microbial counts. Moreover, temperatures of 4 and 8 °C were proved to be effective in maintaining the sugarcane juice´s quality for a period of time compatible with the consumer market demand.

This dissertation consists of three chapters that address two major resource challenges faced by smallholder farmers in Sub-Saharan Africa: (i) weather shocks and (ii) limited land access for agricultural production. The first chapter looks at how weather shocks affect millet production and millet market price seasonality in Niger. In this paper, we use district-level longitudinal production and price data, along with high-resolution rainfall data to investigate the distinct impacts of positive and negative rainfall shocks on millet production and millet price seasonality in Niger. We find that a one standard deviation decrease in seasonal rainfall from historical averages is associated with declines in millet market price initially after harvest, but strong upward pressure on market prices 6 months after harvest. As a result, drought exacerbates existing price seasonality, which in turn can amplify negative impacts on households. Social protection programs need to account for potential increases in seasonal price variability in the design of programs to enhance household resilience to weather shocks. To better understand the household behavior that gives rise to the price responses observed in the first chapter, we explore weather shock impacts on household millet market participation in Niger in the second chapter. We merge a nationally representative household panel data with high-resolution spatially disaggregated rainfall data. We find that households are more likely to participate in the market as net sellers with negative rainfall shocks, but marketed quantity for net sellers decreases with negative rainfall shocks. Diversification into non-agricultural activities can mediate the impacts of negative rainfall shocks on market participation and lead to increases in volume of sales. Policies that support household involvement in the rural nonfarm economy through training and access to credit to help expand businesses may also stimulate millet market participation. In the third chapter, we use a rich dataset of 1,123 households to examine the determinants of individual household member access to groundnut fields, the predominant cash-crop in the Groundnut Basin of Senegal. The analysis also explores the implications of limited land access on groundnut productivity of young adult and female field managers. We find that young adults and females have fewer opportunities to access land compared to older and male household members. Further, we show that higher productivity may not be driving differential access to fields among older adults. Results suggest that with equal access, young adults may be as or more productive groundnut cultivators than older adults. Programs to increase young adult and female economic opportunities should focus on closing gaps in access to resources for production rather than decreasing observed production disparities. / Doctor of Philosophy / This dissertation addresses two major challenges that small farmers face in Sub-Saharan Africa: (i) erratic changes in weather patterns and (ii) land access for agricultural production. We divide the dissertation in three chapters. The first two chapters focus on weather shocks, while the third chapter focuses on land access. In the first chapter, we discuss how low and high rainfall affect the seasonal variation of market prices for the most important staple grain (millet) in Niger (West Africa). We find that lower rainfall than usual makes households sell their millet in the post-harvest period when market prices are generally low, and makes them buy back millet in the lean season when market prices are often high. As a result, policies that aim support household resilience to climate shocks should design programs that account for potential increases in seasonal price variability. In the second chapter, we study how low rainfall levels affect Niger millet farmers' decision to sell or not sell their harvest, as well as the association between low rainfall and the quantity of millet sold and bought. We distinguish three groups of farmers: (i) net buyers who have higher millet purchases than sales, (ii) autarkic who have zero millet purchases and millet sales, and (iii) net sellers who have higher sales than purchases. Our findings show that lower rainfall increases net sellers' probability to sell their millet, whereas it decreases the quantity they sell. Our results also reveal that households who diversify their sources of income into non-agricultural activities increase millet net sales even with low rainfall levels. Policies that support household involvement in these non-agricultural activities may also stimulate millet market participation. In the third chapter, we study the factors that affect household members' access to a groundnut field in Senegal with a particular focus on young adults and females. We show that females and young adults are less likely to access a field compared to older and male household members. Our results also suggest that with equal access, young adults may be as or more productive groundnut cultivators than older adults. Programs to increase young adult and female economic opportunities should focus on closing gaps in access to resources for production.

The application of non-thermal processes pulsed electric fields (PEF) and cross-flow micro-filtration (CFMF) continuous to be studied with the purpose of controlling microorganisms in milk. Trends suggesting increased adoption include the study of Food Safety Objectives as a safety criterion, the promotion of sustainable processing, and the implementation of hurdle strategies. While the advance of gentle processing is counteracted by the risk of enhanced resistance due to microbial stress response, several techniques can be applied to quantitatively assess its impact. The objective of this project was to evaluate the effectiveness of microbial inactivation by PEF and CFMF at various steps of milk processing including shelf-life, its comparison with high temperature short time (HTST) pasteurization, and the quantitative assessment of the cross protection resistance to PEF of Escherichia coli O157:H7. Some differences in mesophilics inactivation were observed in milks (fat contents between 1.1% and 3.1%). Increasing the PEF inlet temperature decreased the treatment time by three or two-fold. The combination of CFMF/PEF yielded similar microbial reductions as CFMF/HTST. Higher inactivation of the coliforms was achieved in homogenized cream (12% fat) compared to non-homogenized. The linear relation between electrical conductivity and nutrient content (fat and solids content) was established. In a parallel study the PEF/CFMF sequence resulted in higher inactivation of mesophilics compared to CFMF/PEF and HTST. The shelf life was acceptable for CFMF/PEF and HTST after 7 days, while enterics and psychrotrophs grew more after PEF/CFMF, thermodurics did after HTST. The growth and stress of Escherichia coli O157:H7 in lactose containing broths was monitored by absorbance and fluorescence expression of stress reporters. Growth was explained using a secondary model, and stress response using mechanistic and probabilistic models. PEF inactivation was evaluated following the Weibull distribution after the cells reached stationary phase or maximum fluorescence expression. Similar resistances were observed within the cells grown in lactose broth at 10, 25 or 40°C, as within stressed cells (starved or cold shocked). Cells grown at 45 °C were more resistant compared to the cells grown in acid, high salt concentration while the ones grown at cold temperatures were the weakest. / Dairy Farmers of Ontario, Natural Sciences and Engineering Research Council.

Orientadores: Marcelo Cristianini, Pilar Rodriguez de Massaguer / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-12T13:04:24Z (GMT). No. of bitstreams: 1 Tribst_AllineArtigianiLima_M.pdf: 3194893 bytes, checksum: 2ef1a8dcf449b5ddd301d699b525063b (MD5) Previous issue date: 2008 / Resumo: O néctar de manga é apreciado por sua cor e aroma. Este produto, pela sua alta acidez, pode ser contaminado por bolores, dentre os quais são de grande relevância aqueles capazes de sobreviver ao processamento térmico. O processamento a alta pressão dinâmica (APD) é um tratamento ¿a frio¿ realizado para inativação de microrganismos visando uma melhor qualidade sensorial e nutricional do produto obtido. Neste estudo, avaliou-se o efeito do processamento a APD isoladamente ou combinado com tratamento térmico (TT) brando na inativação de Aspergillus niger em néctar de manga e, posteriormente, foi realizada a avaliação do efeito dos processos sobre a cor e a concentração de vitamina C do néctar. Paralelamente foi desenvolvida uma metodologia para limpeza e sanificação do equipamento e um processo para a redução de viscosidade do néctar de manga. Foram estudadas pressões entre 100 e 300 MPa para a inativação do Aspergillus niger. A pressão de 300 MPa inativou toda a carga inicial (> 6,24 reduções decimais), 200 MPa provocou uma inativação parcial (aproximadamente 2 ciclos) e, pressões inferiores a 150 MPa não resultaram em inativação significativa do A. niger. Quando o processo de APD foi associado à TT brando (80ºC/15minutos) foi observado um efeito sinérgico entre pré tratamento a APD e posterior TT (aproximadamente 1 ciclo logaritmo); já quando utilizado pré TT seguido de tratamento a APD, foi observado apenas um efeito aditivo. Utilizando-se aplicação de APD seguida de TT, foi realizado um planejamento experimental fixando-se a pressão em 200 MPa e variando-se temperatura e tempo do TT e ratio do néctar de manga (brix/acidez), de forma a obter um modelo que descrevesse o processo. Os resultados indicaram que tempo e temperatura afetaram positivamente a inativação e o ratio do néctar afetou negativamente. A partir do modelo foram estabelecidos que processos a 200 MPa seguido de TT a 73,5ºC/10 minutos ou 61,5ºC/20 minutos eram suficientes para obter 5 reduções decimais do bolor. A avaliação desses processos combinados, do processo térmico tradicional (100ºC/10 minutos) e do processo utilizando apenas pressão (300 MPa) sobre o conteúdo de vitamina C e cor do néctar demonstrou uma inativação de vitamina C muito similar para todos os processos (perdas de aproximadamente 45%) e uma melhor retenção de cor para os produtos processados à APD. O desenho do processo de limpeza e sanificação para o equipamento foi considerado eficaz uma vez que reduziu para < 1 UFC.mL-1 a contaminação de A.niger inicial de aproximadamente 106 UFC.mL-1 na água de enxágüe. Foi utilizada concentração de 0,05% de ácido peracético e 2,5% de detergente comercial cujos princípios ativos eram o toluenosulfonato de sódio e cloreto de didecilmetilamônio. O processo de redução de viscosidade do néctar também foi efetivo através de seu pré tratamento com enzimas pectinolíticas e celulases, que reduziram a viscosidade inicial do néctar em 50%. Pelos resultados obtidos no presente trabalho, observa-se que a APD isoladamente ou aplicada junto com TT brando é uma alternativa viável para a inativação de A. niger termorresistente em néctar de manga. O processo teve efeito negativo sobre a vitamina C do néctar de manga, o que pode ser atribuído tanto à presença de oxigênio na amostra quanto à presença de selos metálicos no equipamento (selos de berílio-cobre) que promovem a passagem de íons metálicos para o suco, os quais atuam como pró-oxidantes de vitamina C, agravando a oxidação da vitamina / Abstract: Mango nectar is appreciated by its color and flavor. Due to its high acidity, this nectar can be contaminated by molds and the most important molds are those able to survive to the heating process. The dynamic high pressure (DHP) is a cold treatment used to inactivate microorganisms with better nutritional and sensory retention in food. In this study, the DHP process isolated or combined with mild thermal treatment (TT) was used to inactivate Aspergillus niger in mango nectar. The effects of these processes were evaluated on color and vitamin C retention. In parallel, a methodology was developed to clean in place (CIP) the DHP equipment. A process to reduce the viscosity of mango nectar was also developed. Pressures between 100 and 300 MPa were studied to Aspergillus niger inactivation. Pressure of 300 MPa completely inactivated the initial load (> 6.24 decimal reduction), 200 MPa caused a partial inactivation (2 log cycles) and pressures up to 150 MPa did not inactivate the mold. A synergistic effect was observed when pre treatment of DHP was associated to mild TT (80ºC/ 15 minutes) with increase of 1 log cycle on mold inactivation. However, only an additive effect was observed when pre TT was associated to DHP. An experimental design was carried out using fixed pressure of 200 Mpa followed by mild TT. Temperature and time of thermal treatment and ratio of mango nectar (brix/acidity) was select as experimental design variables. The results indicated that time and temperature affected positively and nectar ratio affected negatively the mold inactivation. By the mathematical model, process of 200 MPa followed by 73.5ºC/10 minutes or by 61.5ºC/20 minutes was able to promote 5 decimal reduction of A. niger. The effect of these processes, the conventional heat and DHP at 300 MPa on vitamin C concentration and nectar color retention was evaluated. The vitamin C losses were around 45% for all processes studied but better color retention was observed on the nectar processed by DHP. The CIP design was considered efficient once it was able to reduce the initial load of A. niger from ~106 CFU.mL-1 to <1 CFU.mL-1. 2.5% of a commercial detergent (active agents: sodium toluenosulfonate and didecylmethilamonium chlorine) and peracetic acid at 0.05% were used in this process. The nectar viscosity reduction was effective by using pectic enzymes and celullase, being able to reduce natural mango nectar viscosity by 50%. The results obtained indicated that DHP isolated or combined with mild thermal treatment are a viable alternative to inactivate A. niger in mango nectar. The process has a negative effect on vitamin C retention. It can be attributed to the oxygen dissolved in mango nectar and also to metals seals of equipment (Be-Cu) which can had promoted an increase in metallic ions concentration in nectar. These ions are pro oxidant of vitamin C, resulting in intense vitamin oxidation / Mestrado / Mestre em Tecnologia de Alimentos

No description available.

La spectroscopie représente un puissant outil en conservation grâce à la possibilité d’effectuer le suivi de la diversité végétale à travers de larges étendues géographiques. La réflectance spectrale montre un potentiel certain pour l’identification des espèces d’arbres et même des taxons inférieurs, mais ceci a rarement été testé sur un grand nombre d’espèces. J’examine la qualité de la classification de 45 espèces d’arbres des forêts tempérées du Québec à partir de plus de 3500 spectres de réflectance foliaires (400-2400 nm). Nous évaluons cette classification sur la base de la variation spectrale des espèces, de même qu’à partir des distances fonctionnelles et phylogénétiques mesurées. Nos résultats indiquent un taux de classification très satisfaisant (κ = 0.736, ±0.005). Nous observons des erreurs de classification plus fréquentes entre les espèces évolutivement proches, alors qu’il semble que la distance fonctionnelle établisse un seuil voulant qu'au-delà d’une certaine distinction fonctionnelle globale, il soit peu probable que deux espèces soient confondues. Ces résultats viennent renforcer le lien entre la diversité spectrale et l’organisation taxonomique des espèces, ajoutant à la valeur de substitution de la première pour la diversité phylogénétique. Cela suggère par contre que de fortes convergences fonctionnelles peuvent faire obstacle à l’identification des espèces à partir de la réflectance spectrale. Cette étude est prometteuse pour la classification de spectres foliaires non préalablement identifiés, et améliore notre compréhension du lien entre les données spectrales et la différenciation des espèces, d’une grande importance pour assurer la validité des estimations de la biodiversité à partir de données de télédétection. / Imaging Spectroscopy is a powerful tool for conservation due to its ability to monitor plant diversity over broad geographic areas. Increasing evidence suggests that spectral reflectance can be used to identify trees at the species level, and even below. However, most studies focus on only a few species. Here, we use foliar reflectance (400-2400 nm) to discriminate among 45 temperate forest tree species from southern Quebec, using over 3500 leaf-level spectra. Furthermore, we connect those classification results to functional and phylogenetic distinctiveness, as well as to intraspecific variation. We find that spectral reflectance shows a very good discriminatory power even with an extensive set of species (κ = 0.736, ±0.005). We find that close phylogenetic species get mistaken for one another more frequently than distantly related species, while functional variation acts as a threshold, beyond which misclassifications are unlikely. These results reinforce the link between spectral diversity and taxonomic organization or phylogenetic diversity, but also reiterate the potential confounding effects of functional convergences on species identification from hyperspectral reflectance. We believe these findings hold promise for the classification of unknown spectra and further improve the link between ground truth and remotely sensed data for biodiversity assessments.