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Master's Dissertation
DOI
https://doi.org/10.11606/D.89.2004.tde-16102006-141648
Document
Author
Full name
Geni Rodrigues Sampaio
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2004
Supervisor
Committee
Torres, Elizabeth Aparecida Ferraz da Silva (President)
Lottenberg, Ana Maria Pita
Tenuta Filho, Alfredo
Title in Portuguese
Ocorrência de óxidos de colesterol e análise do perfil lipídico em camarão salgado-seco
Keywords in Portuguese
Ácidos graxos
Camarão
Camarão salgado-seco
Oxidação lipídica
Óxidos de colesterol
Abstract in Portuguese
Alimentos submetidos a processos tecnológicos que requerem altas temperaturas apresentam um grande potencial para a produção de óxidos de colesterol (OsC). Inúmeras evidências indicaram que os óxidos de colesterol são potencialmente citotóxicos, aterogênicos, mutagênicos e carcinogênicos. Em pescados, a oxidação do colesterol está favorecida pela presença de ácidos graxos poliinsaturados e altos níveis de colesterol. O camarão salgado-seco é particularmente suscetível à formação de óxidos de colesterol devido a sua composição lipídica, ao seu processamento e as condições de estocagem. O objetivo deste trabalho foi determinar a ocorrência de produtos da oxidação do colesterol e analisar o perfil lipídico em camarão salgado-seco. Analisou-se cinqüenta amostras de camarão salgado-seco por cromatografia líquida de alta eficiência (HPLC), através da qual foram determinados os teores de óxidos de colesterol. O colesterol e os óxidos de colesterol (7ß-OH, 7?-OH, 7-Ceto e 25-OH) foram analisados simultaneamente. O perfil de ácidos graxos foi determinado por cromatografia gasosa e para a avaliação da oxidação lipídica foi empregado o teste de TBARS. Os resultados indicaram que as amostras examinadas continham: 7ß-OH (34,63-72,56 µg/g), 7?-OH (5,02-12,12 µg/g), 7-Ceto (7,44-32,68 µg/g) e 25-OH (2,37-22,88 µg/g), sendo o 7ß-OH o óxido predominante. A quantidade de (OsC) nas amostras analisadas variou consideravelmente (4,52 a 77,30 µg/g). Quanto ao teor de colesterol total e a concentração média de TBARS, os resultados variaram de 73,88 a 247,69 mg/100g e 0,023 a 1,30 mgMA/Kg respectivamente. O perfil de ácidos graxos encontrado foi de 27,48 % saturados, 43,90% monoiinsaturados e 28,61% poliinsaturados. Este estudo indicou que as amostras estavam oxidadas, tanto pela presença de produtos da oxidação do colesterol como pelos valores de TBARS. Tal oxidação foi, provavelmente, iniciada no processamento e em condições inadequadas de armazenamento. Os resultados reforçaram a importância da reavaliação dos procedimentos que envolvem o manuseio de pescados, particularmente do camarão salgado-seco, desde a captura até a determinação do tempo de prateleira, no sentido de minimizar as reações oxidativas.
Title in English
Occurrence of cholesterol oxides and lipid profile in salted and dried shrimp
Keywords in English
Cholesterol oxides
Fatty acids
Lipidic oxidation
Salted-dried shrimp
Shrimp
Abstract in English
Foods submitted to technological processes that require high temperature present a great potential for production of cholesterol oxides (COPs). Several evidences have indicated that COPs are potentially cytotoxic, atherogenic, mutagenic, and carcinogenic. In sea food, the cholesterol oxidation is favored by the presence of unsaturated fatty acids and high cholesterol levels. The salted-dried shrimp is particularly susceptible to the formation of COPs due to its lipidic composition, the processing and storage conditions. The objective of this work was to determine the occurrence of cholesterol oxidation products and to analyze the lipidic profile in salted-dried shrimp. Fifty samples of salted-dried shrimp were evaluated, and the cholesterol oxides were quantified by high-performance liquid chromatography (HPLC). Cholesterol and COPs (7ß-hydroxycholesterol, 7?- hydroxycholesterol, 7-Ketocholesterol and 25- hydroxycholesterol) were simultaneously analyzed. The fatty acids profile was determined by gas chromatography, and for the evaluation of lipidic oxidation the TBARS method was used. The results indicated that the samples contained: 7ß-OH (34.63-72,56 µg/g), 7?-OH (5.02-12.12µg/g), 7-Keto (7.44-32.68 µg/g) and 25-OH (2.37-22.88 µg/g). These data indicated that 7?-OH was the predominant product. The amount of COPs in the samples varied considerably, ranging from 4.52 to 77.30 µg/g. Regarding to the total cholesterol content and the average concentration of TBARS, the results varied from 73.88 to 247.69 mg/100g, and 0.023 to 1.30 mgMA/Kg, respectively. The fatty acids profile was: 27.48% saturated, 43.90% monounsaturated and 28.61% polyunsaturated. This study indicated that the samples were oxidized, by the presence of COPs and the values of TBARS as well. Such oxidation was probably initiated under inadequate conditions of processing and storage. These results reinforced the need of revaluation of the fishing handling procedures, particularly the salted-dried shrimp, including all the stages - from the capture to the de shelf-life determination, in order to minimize the oxidative reactions.
 
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Publishing Date
2007-01-04
 
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