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Previous issue date: 2009-03-27 / CAPES / Brazil is responsible for 25 % of total papaya production in the world, a fruit wich is mainly characterized for its nutritional aspects. The juice and pulp industries have showed an increase in their production in the last years. However, this segment takes only 5% of total papaya produced, while the remaining is consumed as a fresh fruit. This scene is unfavorable, because the high rate of losses during times of big harvests. The processing of papaya can minimize the losses, increasing its shelf life and adding value to this tropical fruit. One of the most used conservation method is HTST pasteurization (high temperature, short time), wich reduces microbial count to safe levels for the consumers and inactivates pectinesterase. This enzyme has an important role during fruit ripening, but it becomes undesirable after process, because acts in pectin and causes undesirable changes in the pulp. The main objective of this study was investigate the effects of temperature and process time on the pectinesterase activity in papaya Formosa pulp. The effects of thermal process on the physical and chemical, nutritional, microbiological and sensorial characteristics were also evaluated. The experiments were carried out following a 22 factorial design with central point. Two independents variables were studied, temperature and time, in the range of 75 to 95?C / 20 to 60 s. The results were submitted to analyses of variance with 95% of confidence interval. In the range of study, factors temperature, process time and interaction did not show significant effects in the characteristics such as pH, titratable acidity, soluble solids contents, vitamin B1, B2 and C contents, antioxidant activity, phenolic compounds, carotenoids contents and colour parameters (L, a, b e ?E). Temperature showed a positive significant (p<0,05) linear effect in the reduction of pectinesterase activity. The best time and temperature ranges for heat processing, which reached more than 95 % of enzyme inactivation were between 20 and 60 seconds at 95?C. The process at 95 ? C/ 60 s promoted a significant decrease in vitamin C content, compared to fresh pulp (Dunnett test at 5% probability level), while the other nutrients did not show significant losses. The presence of coliforms at 45 ?C and Salmonella was not detected. The applied treatments were sufficient to promote a reduction of about 3 logarithmic cycles in the population of molds and yeasts. The Preference Map obtained by the acceptance analyses showed a trend of preference for the pasteurized at 95 ?C / 60 s, 95 ?C / 20 s and fresh samples, while commercial pulps were rejected by consumers. / O Brasil ? respons?vel por 25% do total da produ??o mundial de mam?o, um fruto que se caracteriza principalmente por seus aspectos nutricionais. A ind?stria de sucos e polpas tem apresentado um aumento na sua produ??o nos ?ltimos anos. Entretanto, este segmento aproveita somente 5 % do total de mam?o produzido, sendo o restante consumido in natura. Este quadro ? desfavor?vel tendo em vista os altos ?ndices de perdas nas ?pocas de grandes safras. O processamento em forma de polpa minimiza as perdas, pois aumenta a vida ?til e agrega valor econ?mico ao fruto. Um dos tratamentos mais aplicados para a polpa de mam?o ? a pasteuriza??o do tipo HTST (High Temperature, Short Time), cuja finalidade ? reduzir a carga microbiana a n?veis seguros para os consumidores e inativar a enzima pectinesterase. Esta enzima, que tem um papel fundamental na matura??o do fruto, se torna indesej?vel ap?s o processamento, pois atua sobre a pectina causando altera??es indesej?veis na polpa. Este trabalho teve como principal objetivo avaliar o efeito da temperatura e tempo de processo na atividade da enzima pectinesterase presente na polpa de mam?o Formosa. Tamb?m foram avaliados os efeitos do tratamento t?rmico nas caracter?sticas microbiol?gicas, f?sico-qu?micas, nutricionais e sensoriais da polpa. Os experimentos foram realizados seguindo um planejamento fatorial completo 22 com ponto central, sendo as vari?veis independentes o tempo e a temperatura de processo, em uma faixa de observa??o entre 75 ?C e 90 ?C / 20 s e 60 s. Os dados foram submetidos ? an?lise de vari?ncia com intervalo de confian?a de 95 %. Na faixa observada, tanto os fatores tempo e temperatura como a intera??o entre os fatores n?o apresentaram efeitos significativos nas caracter?sticas como pH, acidez titul?vel, teor de vitamina B1, teor de vitamina B2, teor de vitamina C, teor de caroten?ides, atividade antioxidante, teor de compostos fen?licos e par?metros da cor (L, a, b e ?E). O fator temperatura apresentou um efeito linear significativo (p < 0,05) e positivo para redu??o da atividade da pectinesterase, sendo que os tratamentos a 95 ?C / 20 s e 95 ?C / 60 s foram os que apresentaram maior percentual de redu??o, com aproximadamente 95 %. Em compara??o ? polpa in natura, somente a polpa submetida a 95 ?C / 60 s apresentou um decr?scimo significativo no teor de vitamina C (pelo teste de Dunnett ao n?vel de 5 %), sendo que para os outros nutrientes n?o houve decr?scimo significativo. Nas an?lises microbiol?gicas n?o foi detectada a presen?a de coliformes a 45 ?C e de Salmonella sp. Os tratamentos aplicados promoveram uma redu??o na ordem de 103 na contagem total de fungos e leveduras. Na an?lise sensorial, o Mapa Interno de Prefer?ncia obtido a partir dos dados de aceita??o mostraram uma tend?ncia ? prefer?ncia pelas amostras pasteurizadas a 95 ?C / 60 s, 95 ?C / 20 s e in natura, enquanto que as polpas de marcas comerciais foram rejeitadas.
| Identifer | oai:union.ndltd.org:IBICT/oai:localhost:jspui/2376 |
| Date | 27 March 2009 |
| Creators | RIBEIRO, Monique Lopes |
| Contributors | Furtado, Angela Aparecida Lemos, Furtado, Angela Aparecida Lemos, Cabral, Lurdes Maria Corr?a, Freitas, Suely Pereira, Godoy, Ronoel Luiz de Oliveira, Borguini, Renata Galhardo |
| Publisher | Universidade Federal Rural do Rio de Janeiro, Programa de P?s-Gradua??o em Ci?ncias e Tecnologia de Alimentos, UFRRJ, Brasil, Instituto de Tecnologia |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFRRJ, instname:Universidade Federal Rural do Rio de Janeiro, instacron:UFRRJ |
| Rights | info:eu-repo/semantics/openAccess |
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