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Made available in DSpace on 2015-04-22T22:17:25Z (GMT). No. of bitstreams: 1 SALOMAO ROCHA.pdf: 785933 bytes, checksum: 2a406f595cf4495ac889e48923ddd00c (MD5) Previous issue date: 2012-08-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / During the freezing of fruits pulps, the enzyme activity is not finished completely. Sensory, nutritional and coloring changes may occur on fruits due to the action of oxidative enzymes such as peroxidase and polyphenoloxidase. The frozen cupuaçu pulps, sold in Brazil, have a shelf life of one year and become browned during this period. The aim of this study was to evaluate the effect of frozen storage on the physicochemical characteristics, polyphenoloxidase activity and soluble and ionically bound peroxidases presented in the pulps of four new cupuaçu genotypes over twelve months. The cupuaçu genotypes developed by the West Amazonian Agroforestry Research Center (EMBRAPA) were pulped, frozen and stored at 30 °C. The polyphenoloxidase of the four cupuaçu genotypes showed an increase in activity according to the storage time with peaks in the sixth, ninth and tenth months, but the peroxidases exhibited oscillations in the enzyme activity. The physicochemical properties of the pulps showed variations during the twelve months of storage under freezing. The vitamin C content of D 28-10 and P 3-10 genotypes decreased from the fourth and tenth months, respectively. Moreover P 9-8 e B 28-7 genotypes remained stable. In relation the acidity of citric acid, the B-28-7, D 28-10 and P 9-8 samples were not different, but P 3-10 genotype presented a reduction. The pH and total soluble solids of all genotypes decreased over the study period. There was an increase in sugar concentration of B 28-7, P 3-10 and P 9-8 genotypes, except for D 28-10 sample which remained unchanged. All genotypes were in accordance with physical-chemicals standards required by legislation, except for P 3-10 genotype that showed a lower acidity. In respect of the enzymatic parameters, there were variations in the activity of peroxidase and polyphenoloxidases of all genotypes. / No congelamento de polpas de frutas a atividade enzimática não é completamente cessada. Podem ocorrer mudanças sensoriais, nutricionais e de coloração devido à ação de enzimas oxidativas, como a peroxidase e a polifenoloxidase. Considerando que as polpas de cupuaçu congeladas, comercializadas no Brasil, têm um prazo de validade de um ano e tornam-se escurecidas ao longo deste período, objetivou-se neste estudo avaliar o efeito do tempo de congelamento nas características físico-químicas e nas atividades da polifenoloxidase e peroxidases solúvel e insolúvel presentes nas polpas de quatro novos genótipos de cupuaçu, durante doze meses. Os frutos dos genótipos de cupuaçu, desenvolvidos pela Embrapa Amazônia Ocidental, foram despolpados, congelados e armazenados à temperatura de -30 ºC. A polifenoloxidase das polpas dos quatro genótipos apresentou aumento na sua atividade com picos no sexto, nono e décimo mês e as peroxidases apresentaram oscilações na atividade enzimática. As propriedades físico-químicas das polpas apresentaram variações durante os doze meses de armazenamento sob congelamento. O teor de vitamina C dos genótipos D 28-10 e P 3-10 diminuiu a partir do 4º e 10º mês, respectivamente. Por outro lado os genótipos B 28-7 e P 9-8 permaneceram estáveis. Em relação à acidez em ácido cítrico, as amostras B-28-7, D 28-10 e P 9-8 não diferiram, havendo redução no genótipo P 3-10. O valores de pH e sólidos solúveis totais de todos os genótipos diminuíram ao longo do período avaliado. Houve aumento na concentração de açúcares das polpas dos genótipos B 28-7, P 3-10 e P 9-8, com exceção da amostra D 28-10 que permaneceu inalterada. Todos os genótipos apresentaram-se dentro dos padrões físico-químicos exigidos pela legislação, com exceção do genótipo P 3-10 que apresentou acidez inferior. Em relação aos parâmetros enzimáticos, houve variações na atividade das peroxidases e polifenoloxidases de todos os genótipos avaliados.

Made available in DSpace on 2014-06-11T19:23:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-29Bitstream added on 2014-06-13T20:30:22Z : No. of bitstreams: 1 santos_irc_me_arafcf.pdf: 1670522 bytes, checksum: 94cf024bcd75478eee1c840ef55cc77f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A família das anonáceas é composta por muitos gêneros e espécies; dentre essas, a atemóia (Annona cherimola Mill. X Annona squamosa L.), resultante do cruzamento entre a fruta-do-conde (Annona squamosa L.) e a cherimóia (Annona cherimola Mill.). No Brasil, a atemóia vem despertando grande interesse na produção/comercialização dos seus frutos; no entanto um dos obstáculos enfrentados é a facilidade de escurecimento enzimático que a fruta apresenta. Esse tem como responsável a polifenoloxidase (PPO, E.C. 1.14.18.1); que sob diferentes condições de armazenamento e processamento de vegetais na sua fase póscolheita pode atuar sob substratos naturais e resultar na formação de compostos escuros, acarretando diminuição do valor nutricional, modificação das propriedades organolépticas e sensoriais, com consequente rejeição. Os objetivos desse trabalho foram isolar, purificar e caracterizar algumas propriedades da polifenoloxidase de atemóia. Condições de extração para a PPO foram estabelecidas e a enzima foi isolada por precipitação com sulfato de amônio e eluição em Sephadex G-100. Somente um pico de atividade foi eluído no processo de purificação com um fator de purificação de 7,12. O peso molecular determinado foi 82 kDa com valores ótimos de pH 6,0 e 7,0 para 4-metil catecol e catecol, respectivamente; sendo estável por 12 e 24 horas à incubação na faixa de pH 4,0-8,0. A temperatura ótima de atividade foi 35°C e 28°C para 4-metil catecol e catecol, respectivamente. Os valores calculados de energia de ativação (Ea) para esses substratos foram 87,29 cal/mol-1 e 180,97 cal/mol-1. As constantes cinéticas Km e Vmax foram 5,52mmol/L e 1428,57 UA/mL, para 4-metil catecol, e 79,3 mmol/L e 5000 UA/mL, para catecol. A relação Km/Vmax determinou uma maior afinidade da enzima pelo primeiro substrato. A enzima mostrou desprezível atividade... / The family of annonaceae is composed of many genus and species, among these, the atemoya (Annona cherimola Mill. X Annona squamosa L.), resulting from a cross between custard apple (Annona squamosa L.) and cherimoya (Annona cherimola Mill.). In Brazil, the atemoya is attracting great interest in the production / marketing of its fruits, however one of the obstacles faced is the ease of enzymatic browning that gives the fruit. This is as responsible for polyphenoloxidase (PPO, EC 1.14.18.1), which under different conditions of storage and processing plant in its post-harvest can act on natural substrates and result in the formation of dark compounds, causing decrease in nutritional value, modification of the organoleptic and sensory properties, with consequent rejection. The objectives of this study were to isolate, purify and characterize some properties of polyphenoloxidase from atemoya. Conditions for the extraction of PPO were established and the enzyme was isolated by precipitation with ammonium sulfate and elution on Sephadex G-100. Only one peak of activity was eluted in the process of purification with a purification factor of 7.12. The molecular weight of 82 kDa was determined with the optimum values of pH 6.0 and 7.0 for 4-methylcatechol and catechol, respectively. The enzyme was stable for 12 and 24 hours incubation in the pH range 4.0-8.0. The optimum temperatures for activity were 35 °C and 28 °C for 4-methylcatechol and catechol, respectively. The values of activation energy (Ea) for these substrates cal/mol-1 were 87.29 and 180.97 cal/mol-1. The kinetic constants Km and Vmax were 5.52 mmol/L and 1428.57 UA/mL for 4-methylcatechol, and 79.3 mmol/L and 5000 AU / mL for catechol. The Km/Vmax determined a higher affinity of the enzyme by the first substrate. The enzyme showed negligible activity for caffeic acid and chlorogenic as any for L-DOPA, catechin... (Complete abstract click electronic access below)

La conservation des mangues 4ème gamme est limitée par le brunissement enzymatique et la perte de fermeté dus aux différentes opérations de transformation. Cette thèse propose un nouvelle approche pour améliorer la conservation de mangues 4ème gamme : l’application de traitements thermiques par immersion et/ou la conservation sous atmosphère modifiée : passive ou active (5% O2 – 5 % CO2) ou des enrobages (chitosane). Ce travail a permis tout d’abord de déterminer un couple température / temps optimal: 50 °C / 30 min qui permet de maintenir la qualité de plusieurs variétés de mangue (Keitt, Kent, Tommy Atkins). Les effets du traitement thermique sur l’intensité respiratoire, la couleur, la fermeté, les teneurs en antioxydants : vitamine C, caroténoïdes et phénols totaux, et sur l’activité de plusieurs enzymes (pour la fermeté : PME, PG, b-GAL ; et pour la couleur : PPO et PAL) ont été étudiés. Ces travaux ont montré que durant 9 jours à 6 °C, le traitement thermique maintient principalement la couleur par réduction de l’activité de la PPO et réduit la perte en fermeté par réduction de l’activité des enzymes pectolytiques (PME et b-GAL). Par ailleurs, les atmosphères modifiées semblent moins efficaces pour le maintien de la couleur et de la fermeté des mangues 4ème gamme. L’association du traitement 50°C/ 30 min avec une conservation sous atmosphère modifiée apporte peu d’effets additionnels et a même parfois un effet inhibiteur / The storage of fresh-cut mangoes is limited by the enzymatic browning and the loss of firmness due to the various operations of process. This work proposes a new approache to improve the storage of fresh-cut mangoes by: application of heat treatments by dipping with, or not, a storage under modified atmosphere: passive or active (5% O2 - 5% CO2) or using coatings (chitosane). The first step of this work was to determine the traitement 50 °C/30 min as an optimal treatment which maintian the quality of several varieties of mango (Keitt, Kent, Tommy Atkins). Effects of the heat treatment on the respiratory intensity, the color, firmness, the contents antioxydants: vitamin C, carotenoids and phenols total, and on the activity of several enzymes (PME, PG, b-GAL: for firmness; and PPO and PAL for colour changes) were studied. This work showed that during 9 days at 6 °C, the heat treatment maintains mainly the color by reduction of the activity of PPO and reduces the loss in firmness by reduction of the activity of the pectolytic enzymes (PME et b-GAL). In addition, the modified atmospheres seem less effective for the maintenance of the color and the firmness of freshcut mangoes. Combination of heat treatment with a modified atmosphere storage and have less additional effects and has even sometimes an inhibiting effect

Non-enzymatic browning (NEB) due to ascorbic acid degradation is one of the most common reasons the shelf life of many processed foods is reduced. Different methods to minimize or retard the formation of browning pigments have been studied; however, to date, refrigeration is still the most preferable. Unfortunately, the use of low temperatures to preserve food is not always available in many parts of the world. Indeed, an area of concern due to NEB has been identified in meal-ready-to-eat (MRE) individual military rations, specifically diced peaches with syrup. This product was once part of soldiers' menus; however, it was removed due to browning and textural deterioration that occurred when stored under field conditions. We examined two general approaches to reduce NEB: the replacement of ascorbic acid by a more stable form and the use of flavonoids as antibrowning antioxidants in peach systems. These approaches were studied in three objectives. In our first objective, ascorbyl-2-phosphate showed better stability than ascorbic acid at 40°C in peach puree model systems, but not at 50 or 60°C. In the second objective, after the evaluation of the effect of two forms of vitamin C (ascorbic acid and ascorbyl-2-phosphate) and Pycnogenol (0%, 0.01% and 1%) on the quality of diced peaches in retortable pouches, we concluded that neither ascorbyl-2-phosphate nor pycnogenol resulted in improved color or ascorbic acid stability. Finally, in our third objective, after the evaluation of the effect of peach source (fresh, individually quick frozen and canned), addition of calcium chloride, and the addition of a water soluble flavonoid (°-glucosylrutin, °-GR) in diced peaches packaged in retortable pouches stored at 24, 40 and 51°C, there were no significant effects of °-GR on any of the peach sources at 51°C. However, at 40°C, °-GR improved the quality of diced peaches in pouches made of individually quick frozen and canned peaches, but not for fresh peaches. Quality was assessed by color (CIELAB system), which was measured using a handheld colorimeter, and ascorbic acid levels of peaches, which was determined using high performance liquid chromatography. / Master of Science

Made available in DSpace on 2015-04-17T14:49:20Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1039445 bytes, checksum: c9718b3d3af181ba84c4ac635660ce79 (MD5) Previous issue date: 2009-09-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study aimed to evaluate the use of modified atmosphere (MA) in the conservation of sweet cassava variety 'Pernambuana' minimally processed in plastic containers. In the first stage determined the chemical composition (macro and micronutrients), heavy metals, the cooking time (DTC), quality of cooking and cyanogenic compounds. Minimal processing was the subdivision into two areas, dirty areas: reception of raw materials, selection, classification and pre-wash. In the second step, the clean area: processing (peeling and cutting), rinse, sanitizing, spinning, packing, storage. We analyzed the gas concentration (O2 and CO2) inside the package by 70 pm. The experiment was conducted at temperature 10 °C and stored in polystyrene containers terephthalate (PET) without PVC (CONT), PET with PVC (AMCF), sealed polyethylene bags without vacuum (AMSV) and vacuum (AMCV) at 5 ± 0.2 º C, RH 43% for 20 days. Were performed physical and chemical analysis. The increase in browning (IE), staining of cuttings (L *, C *, H *). and enzyme activity were performed every four days until the 16th day. The microbiological analysis of fecal and total coliforms were performed on the day of processing, with eight and sixteen days. The variety 'Pernambucana‟ has got cooking time of 20 minutes, quality mass formed after cooking and low levels of cyanogenic compounds. It was observed that the pH, ascorbic acid, varied significantly during storage. There were statistical differences (P ≤ 0.05) for the values of reducing sugars, total soluble sugars during periods of storage. Packaging (AMSV and AMCV) had the highest values of L *, the lowest increment of darkening, a smaller reduction of ascorbic acid, however, had the highest pH values. The enzymes showed no statistical differences (P ≤ 0.05) for the activity of peroxidase and polyphenol in storage periods and between treatments. Considering the physico-chemical and microbial life of cassava was 12 days for treatments AMSVand AMCV and eight days for the treatment AMCF. According to the microbiological analysis of cassava breeding minimally processed showed an absence of coliform bacteria at 45 °C, however, treatment with AMCF, and AMSV AMCV showed total coliform counts considered high. / Este trabalho teve como objetivo avaliar o uso de atmosfera modificada (AM) na conservação de mandioca de mesa da variedade Pernambucana‟ minimamente processada em embalagens plásticas. Na primeira etapa determinou-se a composição química, (macro e micronutrientes), metais pesados, o tempo de cocção (DTC), qualidade de massa cozida e compostos cianogênicos. O processamento mínimo consistiu na subdivisão em duas áreas, área suja: recepção da matéria-prima, seleção, classificação e pré-lavagem. Na segunda etapa, na área limpa: processamento (descascamento e corte), enxague, sanificação, centrifugação, embalagem, armazenamento. Analisou-se a concentração gasosa (O2 e CO2) no interior das embalagens, por 70 hs. O experimento foi realizado em câmara fria a 10ºC e armazenados nas embalagens Poliestireno tereftalato (PET) sem PVC (CONT), PET com PVC (AMCF), saco de polietileno selado sem vácuo (AMSV) e com vácuo (AMCV) à temperatura de 5 ± 0,2ºC, UR 43% por 20 dias. Foram realizadas as análises físico-químicas. O incremento de escurecimento (IE), coloração dos toletes (L*, C*, H*). e atividade enzimática foram realizadas a cada quatro dias até o 16º dia. As análises microbiológicas de coliformes totais e termotolerantes foram realizadas no dia do processamento, com oito e dezesseis dias. A variedade Pernambucana apresenta obteve tempo de cozimento de 20 minutos, qualidade massa formada após cozimento e baixo teores de compostos cianogênicos. Observou-se que os valores de pH, ácido ascórbico, variaram significativamente durante o armazenamento. Houve diferenças estatísticas (P≤0,05) para os valores de açúcares redutores, açúcares solúveis totais nos períodos de armazenamento. As embalagens (AMSV e AMCV) obtiveram os maiores valores de L*, os menores valores de incremento de escurecimento, menor redução de ácido ascórbico, no entanto, obteve os maiores valores de pH. As enzimas apresentaram diferenças estatísticas (P≤0,05) para a atividade da polifenol e peroxidase nos períodos de armazenamento e entre os tratamentos. Considerando-se a análise físico-química e microbiológica, a vida útil da mandioca foi de 12 dias para os tratamentos AMSV e AMCV e oito dias para o tratamento AMCF. De acordo com as análises microbiológicas a mandioca de mesa minimamente processada apresentou ausência de coliforme a 45ºC, no entanto, os tratamentos com AMCF, AMSV e AMCV apresentaram contagem de coliformes totais consideradas altas. Palavras-

Le séchage est un procédé de transformation largement répandu dans le monde qui permet d'augmenter significativement la durée de conservation des denrées alimentaires et d'apporter une valeur ajoutée aux produits. Le traitement thermique appliqué lors de cette opération peut causer des modifications physiques, chimiques et biochimiques aboutissant à des altérations des qualités nutritionnelles et organoleptiques des produits séchés. La couleur est le premier attribut perçu par le consommateur et est généralement corrélé à une représentation de la qualité globale du produit. La maîtrise du brunissement est donc capitale pour préserver le potentiel commercial des produits alimentaires. La filière mangue séchée biologique du Burkina Faso constitue le cadre d'étude de ces travaux de thèse axés sur la compréhension des phénomènes impliqués dans le brunissement des mangues au cours de l'opération de séchage et pendant le stockage. L'objectif principal est d'identifier les paramètres majeurs influant sur le brunissement enzymatique et non-enzymatique afin de proposer des voies d'amélioration de la qualité du produit pertinentes. Une approche expérimentale permettant d'étudier les effets spécifiques de la température et de l'activité de l'eau indépendamment des autres paramètres nous a permis d'identifier les points critiques du procédé induisant des altérations de la couleur. / Drying is a world common transformation process which significantly increase the food shelf-life and the added value of the products. The heat treatment applied during this operation can provoke physical, chemical and biochemical modifications resulting to alterations in nutritional and organoleptic properties of dried products. Color is the first property perceived by the consumer and is generally correlated with a global representation of product quality. Browning knowledge is essential to conserve the commercial potential of food. Dried mango sector in Burkina Faso constitute a part of my course thesis based on the understanding of phenomena involved in the mango browning during drying process and then during the storage. The global objective is to identify the main parameters affecting the enzymatic and non-enzymatic browning in order to propose optimized technological ways improving the final quality of the dried mango products. Experimental approach offering possibility to study temperature and water activity specifics effects independently to other parameters allowed us to identify critical points of the process occurring color variations.

<p><strong>Apstrakt je obrađen tehnologijama za optičko prepoznavanje teksta (OCR).</strong></p><p>Nastajanje i inhibicija stvaranja melanoidina u nečistim rastvorima saharoze je ispitivana na uzorcima neafinisanog i afinisanog C produkta na 80 [&deg;C].</p><p>Utvrdjena je zavisnost obrazovanja bojenih materija tipa melanoidina od vremena reakcije, od sadržaja suve materije, kao i od sadržaja i vrste aminokiselina.<br />Smanjenje obojenosti rastvora zavisi od koncentracije natrikum-sulfita i matematički je definisano Baule-Mitscherlichovim krivama zasićenja. Maksimalni efekat odbojavanja koji se može postići iznosi 30 [%] na 560 [nm], odn. 20 [%] na 420 [nm], ne razlikuje se za rastvore neafinisanog i afinisanog C produkta, a ostaje nepromenjen u vremenu od 1620 [min].</p><p>Povećanje koncentracike vodonik-peroksida je praćeno porastom količine bojenih materija prevedenih u leuko oblike, i produžavanjem vremena oksidacije. U odsustvu slobodnog vodonik-peroksida dolazi do reverzije boje rastvora.<br />Smanjenje obojenosti rastvora neafinisanog i afinisanog C produkta je signifikantno veće pri uzastopnom delovanju oksidacionog i redukcionog sredstva od smanjenja obojenosti postignutog njihovim pojedinačnim delovanjem. Efekti uzajamnog delovanja se ne menjaju u ispitivanom vremenu.</p> / <p><strong>Abstract was processed by technology for Optical character recognition (OCR).</strong></p><p>Reaction and inhibition of melanoidine formation in inpure solutions of sucrose were investigated on affinated and unaffinated C sugar samples carried out on 80 [&deg;C].<br />Melanoidin type colour formation dependending on reaction time, dry matter content and content and variety on amino acids has been studied.<br />Colour decrease in solutions depended on concentration of sodium sulphite and was mathematically defined by Baule-Mitscherlich curve of saturation. Maximum effect of colour decrease wich can be obtained was 30 [%] at 560 [nm], and 20 [%] at 420 [nm] wavelength respectively, and without any difference between affinated and unaffinated C sugar solutions, but it has stayed unchanged during reaction time of 1620 [min]. Hydrogen peroxide concentration rise was followed by increasing amounts of colour compounds transferred in leuco forms and by prolonged oxidation time. Absence of free hydrogen peroxide has induced the reverse formation of colour solutions.</p><p>Colour decrease in unaffinated and affinated C sugar solution was significantly larger, during subsequent treatment of oxidizing and reducing compounds, than during separate reactions. During reaction time the mutual treatment effect was unchangeable.</p>

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No. of bitstreams: 2 2018-01-07 16h04min-MS-TESE Versão FINAL.pdf: 5381905 bytes, checksum: 7dbc7dc9b2123e87817635d09f0f8f0e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-10-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A maçã, após sofrer dano mecânico, inclusive após o corte no processamento mínimo, sofre rápida degradação das características físico-químicas e sensoriais, podendo tornar-se inapropriada para o consumo. Neste trabalho estudou-se o efeito do tempo de armazenamento refrigerado de maçã in natura; combinado com o efeito de aplicação de antioxidante e de coberturas comestíveis, imediatamente após o corte para obtenção de fatias em forma de gomo, com epiderme. Maçã cv. ‘Gala’, proveniente de Vacaria, RS, colhida no ano de 2015, selecionada, higienizada, sanitizada, tratada com 1-MCP, e refrigerada (1 °C ± 1 °C e 90 % ± 5 % de UR), conforme procedimento padrão da Empresa RASIP, foi transportada até o laboratório de Fisiologia Pós-colheita da Embrapa Clima Temperado, em Pelotas, RS, e armazenadas in natura, sob refrigeração, por 60 d, 120 d e 180 d. Ao final do armazenamento a maçã foi novamente sanitizada, cortada longitudinalmente em oito fatias, imersa por 1 min em solução de cloreto de cálcio (1,0 % m/v), com ou sem o antioxidante eritorbato de sódio (5,0 % m/v), drenada, e imediatamente imersa por 1 min em solução de fécula de mandioca (3,0 %, m/v), alginato de sódio (2,0 %, m/v) ou quitosana (1,5 %, m/v), para formação da cobertura comestível, e finalmente secagem com ar forçado (4,3 m/s, a 16 °C ± 1 °C e 65 % ± 5 %, por 20 min). A unidade experimental consistiu em oito fatias de maçã colocadas em uma bandeja de polietileno, seladas com camada única de filme de PVC, com espessura de 9 μm, e armazenadas por 0 d, 3 d, 6 d e 9 d, a 4 °C ± 1 °C e 90 % ± 5 % de UR. Após cada período de armazenamento foram avaliadas variáveis físico-químicas e sensoriais, e também atividade enzimática. Empregou-se o teste F (p ≤ 0,05) na análise de variância, o teste DMS (Diferença Mínima Significativa) (p ≤ 0,05) na comparação de médias de tratamento e análise fatorial de correlação entre variáveis. Na fruta in natura observou-se aumento na variável ratio (sólidos solúveis totais / acidez total titulável) ao longo do armazenamento. O efeito do tempo de armazenamento da maçã in natura foi significativo em algumas variáveis físico-químicas, mas sem repercussão na análise sensorial. A aplicação de eritorbato de sódio, combinada com aplicação de 8 fécula de mandioca, proporcionou os melhores resultados, tanto na avaliação sensorial quanto nas características físico-químicas, inclusive no retardamento de escurecimento de polpa. / The apple, following mechanical damage, such as cutting for the production of the minimally processed fruit, undergoes rapid degradation of the physicochemical and sensorial characteristics, and may become inappropriate for consumption. In this work, the effect of refrigerated storage time of fresh apple; combined with the effect of applying antioxidant and edible toppings, immediately after cutting the fruit into eight slices with wedge shape, was studied. Apple cv. 'Gala', from Vacaria, RS, harvested in the year of 2015, selected, sanitized, treated with MCP, and refrigerated (temperature of 1 °C ± 1 °C and relative humidity of 90 % ± 5 %), according to standard procedures used by RASIP Company, was transported to the Postharvest Physiology Laboratory of Embrapa Clima Temperado, in Pelotas, RS, and stored in natura, under refrigeration, for 60 d, 120 d and 180 d. At the end of each period of storage, the apple was re-sanitized, cut longitudinally into eight slices of same size and with wedge shape, immersed for 1 min in calcium chloride solution (1.0% w/v), with or without the antioxidant sodium erythorbate (5.0% w/v), drained, and immediately immersed for 1 min in cassava starch solution (3.0%, w/v), sodium alginate (2.0%, w/v) or chitosan (1.5% w/v), to form the edible cover, and finally dried with forced air (4.3 m / s at 16 ° C ± 1 ° C and 65% ± 5% RH, for 20 min). The experimental unit consisted of eight slices of apple placed in a polyethylene tray, sealed with a single layer of PVC film, 9 μm thick, and stored for 0 d, 3 d, 6 d at 4 °C ± 1 C and 90% ± 5% RH. After each storage period, physicochemical and sensory variables were evaluated, as well as enzymatic activity. The F test (p ≤ 0.05) was used in the analysis of variance, the DMS test (p ≤ 0.05) in the comparison of means of treatment and factorial correlation analysis between variables. In the in natura fruit it was observed an increase in the variable ratio (soluble solids / acidity) throughout the storage. The effect of the storage time of the apple in natura was significant in some physical-chemical variables, but without repercussion in the sensorial analysis. The application of sodium erythorbate, combined with the application of cassava topping, provided the best results, both in 10 the sensorial evaluation and in the physicochemical characteristics, including the delay of darkening of pulp.

Le bruissement enzymatiques, appelé mélanose post mortem chez les crustacés est un phénomène enzymatique catalysé par des protéines à activités phénoloxydases (tyronase, catécholase, laccase et hémocyanine). L'utilisation de conservateurs de type sulfites (E220 à E228 et E539) reste à l'heure actuelle la solution la plus répandue pour éviter le développement de cette coloration peu attrayante pour le consommateur. Mais une partie de la population développe des réactions d'hypersensibilité en consommant des aliments sulfités. Dans l'onbjectif de rechercher une alternative à ces conservateurs, deux axes de recherche ont été développés durant ces travaux de thèse : la caractérisation biochimique des protéines responsables de la mélanose post mortem chez la crevette P. monodon, puis la recherche de molécules inhibitrices. Un fractionnement sur résine Phenyl Sepahrose™ CL-4B (HIC) suivie d'une séparation par électrophorèse SDS-PAGE ont montré la présence de trois protéines de 46, 82 et 89 kDa à activité principalement laccase. Une identification par RP-HPLC-Q/TOF a mis en évidence la présence d'hémocyanine uniquement. Un pH de 7,0 et une température comprise entre 37 et 50 °C ont mis en évidence les activités les plus importantes, en utilisant le dosage enzymatique dit "test au MBTH". Par ailleurs, un criblage à haut débit de 45 molécules potentiellement inhibitrices a été réalisé dans des conditions d'analyses standardisées grâce à l'outil de robotique de la plateforme Realcat. Une inhibition a été mise en évidence pour 23 composés, certains étant suffisamment efficaces pour être utilisés seuls. D'autres pourraient être introduits dans un cocktail de molécules inhibitrices aux fonctionnalités complémentaires. Les résultats des tests de trempage réalisés sur des crevettes entières ont montré qu'il était indispensable de compléter les études in vitro avec des essais à l'échelle de la matrice alimentaire dans son intégralité. / Enzymatic browning, called post mortem melanosis in crustaceans, is an enzymatic phenomenon catalyzed by proteins with phenoloxidase activities (tyronase, catecholase, laccase and hemocyanin). The use of sulfite preservatives (E220 to E228 and E539) remains at present the most widespread solution to avoid the development of this unattractive color towards consumers. But, a part of the population develops hypersensitivity reactions by consuming sulfited foods. With the objective to find an alternative to these conversators, two research axes have been planned : the biochemical characterization of the proteins responsible for post mortem melanosis in the P. monodon shrimp, then the search for inhibitory molecules. Fractionation on Phenyl Sepahrose™ CL-4B resin (HIC) followed by SDS-PAGE electrophoresis separation showed the presence of three proteins of 46, 82 and 89 kDa with mainly laccase activity. Identification by RP-HPLC-Q / TOF revealed the presence of hemocyanin only. A pH of 7.0 and a temperature between 37 and 50 °C showed the most important activities, using the enzymatic assay called "MBTH test". On the other hand, a high throughput screening of 45 potentially inhibitory molecules could be performed under standardized analysis conditions thanks to the robotic tools of the Realcat platform