Avaliação de práticas de manipulação de hortaliças visando a preservação de vitamina C e carotenóides

• Autor(a) principal: Campos, Flavia Milagres
• Data de Publicação: 2006
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2744
• topic: Vitamina C; Carotenóides; Hortaliças; Armazenamento; Preparo; Distribuição; Vitamin C; Carotenoid; Vegetables; Storage; Manipulation; Distribution; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS::VALOR NUTRITIVO DE ALIMENTOS

Vitamin C and carotenoids are important compounds for human health. However, vitamin C is very unstable in the presence of heat, oxygen and metals and carotenoids are unstable in the presence of light and oxigen. Vegetables are one of the main sources of vitamin C and carotenoids in the diet. However, the processes they are submitted from harvest to consumption can reduce its content. It is believed that the adoption of good handling practices could minimize vitamin C and carotenoids losses in vegetables during preparation. The objectives of this study were to optimize a methodology for vitamin C (ascorbic acid and dehydroascorbic acid) analysis; to determine ascorbic acid, dehydroascorbic acid, lycopene and β-carotene content in tomato and collard green; and, to select handling practices for vitamin C, β-carotene and lycopene loss control in those vegetables during storage and preparation. The analysis method was high pressure liquid chromatography. Chromatographic conditions were based on isocratic elution, reversed fase columm separation and UV-visible detection. For vitamin C analysis, different extration solutions and chromatographic conditions were tested. Studies carried out until this moment did not consider dehydroascorbic acid (DHA), although it also present vitamin C activity. DHA quantification was done indirectily by its reduction with dithiothreitol (DTT). The optimized methodology may also be used for vitamin C analysis in oil added vegetables. Some conditions were tested for the selection of handling practices for vitamin C and carotenoids loss prevention: storage at 10 ºC and 23 or 24 ºC (during 24 e 72 hours), sanitization time (15, 45 and 75 minutes), slicing method (slices and cubes for tomato; hand torn and strips for collard green) and time before consumption (0, 30 and 60 minutes). The retentions of β-carotene in collard green and ascorbic acid (AA) in tomatos, after 24 hours of storage, were greater at refrigerated temperature than at room temperature. On the other hand, the retentions of DHA and lycopene in tomatoes were greater at room temperature. The sanitization for more than 15 minutes negatively influenced the AA retention in collard green samples storaged under refrigeration (about 12% less after 75 minutes of sanitization). There were no differences between slicing methods and the times between preparation and consumption used for tomatoes in relation to retention of any compounds under study. The time between cooking and consumption of stir-fried collard green negatively influenced AA retention for both striped and teared collard green. Refrigerated storage, control of sanitization time and control of the time between preparation and consumption are recommended to minimize vitamin C and carotenoids losses in collard green and tomato.