Made available in DSpace on 2015-03-26T13:39:34Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1636884 bytes, checksum: c966934c707a7e6bf40bfe5aee85e5a1 (MD5) Previous issue date: 2009-09-25 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / The objective of this work was to promote the degreening, without losing internal fruit quality, of Poncã tangerine from two regions of Minas Gerais. Two experiments were carried out. In the first, the fruits were harvested from a commercial orchard in the northern region, and the second experiment used fruits from Zona da Mata. Fruits were harvested when showing minimum attributes of 35% juice, 9 ° Brix and soluble solids/tritable acidity ratio of 9.5. Then the fruits were packed in airtight boxes, which were exposed for 24, 48 and 96 h to different concentrations of ethylene gas: 0, 5, 10, 20 and 40 μL.L-1, at 20 + 1 °C and 90 + 5% relative humidity, respectively. Every 24 h, the boxes were opened for renewal of internal atmosphere, by reapplying the gas until treatment end. A post-treatment phase of 96 h duration took place at the end of each exposure time, when the fruits were kept in ethylene-free atmosphere, in cold chamber, at the same temperature and relative humidity used during the exposure to ethylene. During this phase, the fruits were evaluated every 24 h, and the difference in skin color, Hue angle of the peel, total chlorophyll and carotenoid content, soluble solids content, tritable acidity and SS/TA ratio of juice, solute leakage, CO2 production and loss of fruit fresh mass. In the first experiment, the fruits showed stronger degreening with increasing time of exposure to ethylene, most markedly for 96 h. After this exposure time, the Hue angle increased from 96.1o, in the first assessment days, to 82.3o, at the end of 96 h, which was lower than values observed in naturally degreened fruits. Fruits exposed for 24 h showed evolution of the yellow peel color similar to the untreated ones. It was observed that fruits left to ripe on the plant showed non-homogeneous peel degreening. The fruits exposed to ethylene for 96 h showed no visual signs of loss of commercial quality, although there was increased solute leakage from the peel during the treatment. Soluble solids content, tritable acidity and SS/TA ratio remained unchanged throughout the assessment period. The synthesis of total carotenoids in the peel was low, from 6.0 μg/cm2, in control fruits at the end of evaluations, to a maximum of 8.2 μg/cm2, in fruits exposed to ethylene for 96 h. This synthesis was insufficient to reach the orange color, therefore, the degreening of fruit peel was due, almost exclusively, to chlorophyll degradation. In the second experiment, the fruits showed yellowing of the peel stronger than fruits of the first experiment. The exposure time of 96 h proved to be the most efficient in promoting the fruit degreening in comparison with other times. Color evolution was quite similar between the control and fruits treated for 24 and 48 h. Fruits of all treatments had very low synthesis of total carotenoids in the peel, changing from 7.3 μg/cm2 in control fruits to 9.2 μg/cm2, maximum value observed in fruits exposed to ethylene for 96 h. Even in fruits showing the strongest yellowing, there was little participation of new synthesized carotenoids in the composition of the final color. Fruits fully developed in the plant reached the maximum degreening, becoming orange, the typical color of the species. Thus, for fruits produced in the Zona da Mata region, the post-harvest degreening with ethylene is only justified to anticipate the harvest, since the region has favorable climate to natural degreening. However, for fruits produced in northern Minas Gerais, where the high temperatures prevailing throughout the year impair the natural degreening, the postharvest use of ethylene may serve to obtain a more uniform peel color. / The objective of this work was to promote the degreening, without losing internal fruit quality, of Poncã tangerine from two regions of Minas Gerais. Two experiments were carried out. In the first, the fruits were harvested from a commercial orchard in the northern region, and the second experiment used fruits from Zona da Mata. Fruits were harvested when showing minimum attributes of 35% juice, 9° Brix and soluble solids/tritable acidity ratio of 9.5. Then the fruits were packed in airtight boxes, which were exposed for 24, 48 and 96 h to different concentrations of ethylene gas: 0, 5, 10, 20 and 40 μL.L-1, at 20 + 1 °C and 90 + 5% relative humidity, respectively. Every 24 h, the boxes were opened for renewal of internal atmosphere, by reapplying the gas until treatment end. A post-treatment phase of 96 h duration took place at the end of each exposure time, when the fruits were kept in ethylene-free atmosphere, in cold chamber, at the same temperature and relative humidity used during the exposure to ethylene. During this phase, the fruits were evaluated every 24 h, and the difference in skin color, Hue angle of the peel, total chlorophyll and carotenoid content, soluble solids content, tritable acidity and SS/TA ratio of juice, solute leakage, CO2 production and loss of fruit fresh mass. In the first experiment, the fruits showed stronger degreening with increasing time of exposure to ethylene, most markedly for 96 h. After this exposure time, the Hue angle increased from 96.1o, in the first assessment days, to 82.3o, at the end of 96 h, which was lower than values observed in naturally degreened fruits. Fruits exposed for 24 h showed evolution of the yellow peel color similar to the untreated ones. It was observed that fruits left to ripe on the plant showed non-homogeneous peel degreening. The fruits exposed to ethylene for 96 h showed no visual signs of loss of commercial quality, although there was increased solute leakage from the peel during the treatment. Soluble solids content, tritable acidity and SS/TA ratio remained unchanged throughout the assessment period. The synthesis of total carotenoids in the peel was low, from 6.0 μg/cm2, in control fruits at the end of evaluations, to a maximum of 8.2 μg/cm2, in fruits exposed to ethylene for 96 h. This synthesis was insufficient to reach the orange color, therefore, the degreening of fruit peel was due, almost exclusively, to chlorophyll degradation. In the second experiment, the fruits showed yellowing of the peel stronger than fruits of the first experiment. The exposure time of 96 h proved to be the most efficient in promoting the fruit degreening in comparison with other times. Color evolution was quite similar between the control and fruits treated for 24 and 48 h. Fruits of all treatments had very low synthesis of total carotenoids in the peel, changing from 7.3 μg/cm2 in control fruits to 9.2 μg/cm2, maximum value observed in fruits exposed to ethylene for 96 h. Even in fruits showing the strongest yellowing, there was little participation of new synthesized carotenoids in the composition of the final color. Fruits fully developed in the plant reached the maximum degreening, becoming orange, the typical color of the species. Thus, for fruits produced in the Zona da Mata region, the post-harvest degreening with ethylene is only justified to anticipate the harvest, since the region has favorable climate to natural degreening. However, for fruits produced in northern Minas Gerais, where the high temperatures prevailing throughout the year impair the natural degreening, the postharvest use of ethylene may serve to obtain a more uniform peel color.

A presença de clorofila e/ou seus derivados em óleos provenientes da extração de grãos verdes reduz sua estabilidade oxidativa, confere coloração escura indesejável e diminui a velocidade do processo de hidrogenação, sendo que a sua remoção, eleva o custo da refinação. Da mesma forma, a presença do pigmento reduz o valor comercial dos grãos, levando a prejuízos na comercialização, frente ao enorme volume de exportação brasileira. A retenção da clorofila em sementes oleaginosas, tais como a soja e a canola, pode ocorrer em condições de colheita prematura, que é utilizada para evitar perdas e quebras da safra. A degradação da clorofila é função do estádio de maturação, do teor de umidade e da temperatura de secagem. O pigmento pode ser degradado em condições de secagem lenta à temperatura ambiente, enquanto a utilização de secagem rápida em estufa resulta na retenção da cor verde. Porém, a influência de fatores extemos no mecanismo de degradação da clorofila ainda não está totalmente esclarecida. Não está claro se a via de degradação química ocorre independentemente, ou concomitante à via enzimática e também ainda não estão elucidados quais produtos são formados quando os grãos são submetidos à secagem rápida. Neste trabalho investigou-se a degradação da clorofila e o aparecimento de seus derivados durante a maturação de três cultivares brasileiras de soja, colhidas em seis estádios de maturação e secas em três temperaturas: 25°, 40° e 75°C. Os pigmentos foram extraídos com acetona 80%, identificados por HPLC e confirmados por espectrometria de massa por dessorção de plasma. Tanto na maturação no campo, como na secagem a 25°C, o mecanismo de degradação parece ocorrer por via enzimática, possivelmente mediada por oxigenases, com formação de compostos incolores. A 40°C, houve retenção da cor verde e o mecanismo parece ocorrer por duas vias: enzimática, mediada por clorofilases, evidenciada pelo acúmulo de derivados defitilados e química, evidenciada pelo acúmulo de feofitinas. A 75°C, observou-se também o acúmulo de clorofila e feofitina, provavelmente pela inativação de todas as enzimas e o favorecimento da feofitinização. A degradação completa da clorofila somente pode ser obtida se a soja for colhida a partir do estádio R7. Para evitar a retenção de clorofila e garantir a qualidade dos grãos para a comercialização, sugerimos a colheita em R8, com secagem rápida ou lenta. Se for necessário antecipar a colheita, a secagem deve ser conduzida a temperaturas inferiores a 40°C. / The presence of chlorophyll or their derivatives in edible oils from green seeds decreases its oxidative stability, produces an undesirable color and impairs the hydrogenation process. Besides that, it reduces the commercial value of the crops. The removal of pigments from the crude oils by absorption imposes increasing costs of refining. The maintenance of green color in soybean seeds arises primarily from the common practice of early swathing in order to hasten the harvesting process and to reduce shattering losses. The rate of degreening depends on the stage of maturity, the initial moisture content and the drying temperature. The pigment can be degraded by ambient air drying, whereas fast drying with hot air results in the retention of the green color. Despite this, little is known about the influences of external conditions on the pathways of chlorophyll degradation. It is not c1ear whether the chemical route takes place independently or in addition to an enzymatic pathway, nor is it clear which breakdown products could be accumulated when seeds are submitted to fast drying. Studies on three Brazilian cultivars were performed over the whole maturation period by analyzing chlorophyll and its derivatives produced under three drying conditions: ambient temperature (25°C) and fast drying in oven at 40° and at 75°C with circulating air. Pigments were extracted with 80% acetone and were isolated by HPLC and analyzed by plasma desorption mass spectrometry (PDMS) to confirm their identities. During maturation on the field, as well as drying at 25°C, the degradation route showed to occur mainly enzymatically, probably mediated by oxygenases with formation of colourless compounds, as no further color pigments had been detected. At 40°C, both degradation processes seem to take place: enzymatic, probably mediated by chlorophyllase, with the appearance of small amounts of chlorophyllides and pheophorbides; and chemical, demonstrated by high leveis of pheophytins. At 75°C we observed also high levels of chlorophylls and pheophytins, probably due to inactivation of all enzymes, supporting pheophytinization. In order to avoid retention of chlorophyll and to guarantee marketing quality of seeds, we suggest harvesting at stage R8, followed by fast or slow drying. When it is necessary to hasten swathing, the drying should be performed at temperatures below 40°C, otherwise the seed quality could be compromised.

A presença de clorofila e/ou seus derivados em óleos provenientes da extração de grãos verdes reduz sua estabilidade oxidativa, confere coloração escura indesejável e diminui a velocidade do processo de hidrogenação, sendo que a sua remoção, eleva o custo da refinação. Da mesma forma, a presença do pigmento reduz o valor comercial dos grãos, levando a prejuízos na comercialização, frente ao enorme volume de exportação brasileira. A retenção da clorofila em sementes oleaginosas, tais como a soja e a canola, pode ocorrer em condições de colheita prematura, que é utilizada para evitar perdas e quebras da safra. A degradação da clorofila é função do estádio de maturação, do teor de umidade e da temperatura de secagem. O pigmento pode ser degradado em condições de secagem lenta à temperatura ambiente, enquanto a utilização de secagem rápida em estufa resulta na retenção da cor verde. Porém, a influência de fatores extemos no mecanismo de degradação da clorofila ainda não está totalmente esclarecida. Não está claro se a via de degradação química ocorre independentemente, ou concomitante à via enzimática e também ainda não estão elucidados quais produtos são formados quando os grãos são submetidos à secagem rápida. Neste trabalho investigou-se a degradação da clorofila e o aparecimento de seus derivados durante a maturação de três cultivares brasileiras de soja, colhidas em seis estádios de maturação e secas em três temperaturas: 25°, 40° e 75°C. Os pigmentos foram extraídos com acetona 80%, identificados por HPLC e confirmados por espectrometria de massa por dessorção de plasma. Tanto na maturação no campo, como na secagem a 25°C, o mecanismo de degradação parece ocorrer por via enzimática, possivelmente mediada por oxigenases, com formação de compostos incolores. A 40°C, houve retenção da cor verde e o mecanismo parece ocorrer por duas vias: enzimática, mediada por clorofilases, evidenciada pelo acúmulo de derivados defitilados e química, evidenciada pelo acúmulo de feofitinas. A 75°C, observou-se também o acúmulo de clorofila e feofitina, provavelmente pela inativação de todas as enzimas e o favorecimento da feofitinização. A degradação completa da clorofila somente pode ser obtida se a soja for colhida a partir do estádio R7. Para evitar a retenção de clorofila e garantir a qualidade dos grãos para a comercialização, sugerimos a colheita em R8, com secagem rápida ou lenta. Se for necessário antecipar a colheita, a secagem deve ser conduzida a temperaturas inferiores a 40°C. / The presence of chlorophyll or their derivatives in edible oils from green seeds decreases its oxidative stability, produces an undesirable color and impairs the hydrogenation process. Besides that, it reduces the commercial value of the crops. The removal of pigments from the crude oils by absorption imposes increasing costs of refining. The maintenance of green color in soybean seeds arises primarily from the common practice of early swathing in order to hasten the harvesting process and to reduce shattering losses. The rate of degreening depends on the stage of maturity, the initial moisture content and the drying temperature. The pigment can be degraded by ambient air drying, whereas fast drying with hot air results in the retention of the green color. Despite this, little is known about the influences of external conditions on the pathways of chlorophyll degradation. It is not c1ear whether the chemical route takes place independently or in addition to an enzymatic pathway, nor is it clear which breakdown products could be accumulated when seeds are submitted to fast drying. Studies on three Brazilian cultivars were performed over the whole maturation period by analyzing chlorophyll and its derivatives produced under three drying conditions: ambient temperature (25°C) and fast drying in oven at 40° and at 75°C with circulating air. Pigments were extracted with 80% acetone and were isolated by HPLC and analyzed by plasma desorption mass spectrometry (PDMS) to confirm their identities. During maturation on the field, as well as drying at 25°C, the degradation route showed to occur mainly enzymatically, probably mediated by oxygenases with formation of colourless compounds, as no further color pigments had been detected. At 40°C, both degradation processes seem to take place: enzymatic, probably mediated by chlorophyllase, with the appearance of small amounts of chlorophyllides and pheophorbides; and chemical, demonstrated by high leveis of pheophytins. At 75°C we observed also high levels of chlorophylls and pheophytins, probably due to inactivation of all enzymes, supporting pheophytinization. In order to avoid retention of chlorophyll and to guarantee marketing quality of seeds, we suggest harvesting at stage R8, followed by fast or slow drying. When it is necessary to hasten swathing, the drying should be performed at temperatures below 40°C, otherwise the seed quality could be compromised.