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Abstract(s)
O consumo de alguns subprodutos da vinha e do vinho, como sejam as folhas da videira, Ć© conhecido desde longa data na regiĆ£o do MediterrĆ¢neo. As folhas de videira jĆ” estĆ£o presentes na dieta humana e animal em vĆ”rios paĆses do mundo, sendo completamente desvalorizadas como sub-produtos em outras regiƵes. Neste sentido, os principais objetivos deste trabalho foram avaliar entre diversas castas brancas (CĆ“dega do Larinho, FernĆ£o Pires, Gouveio, Malvasia Fina, Rabigato e Viosinho) e tintas (Tinta Amarela, Tinta Roriz, Touriga Franca e Touriga Nacional) do Planalto MirandĆŖs, quais as mais adequadas para processamento alimentar, tendo em vista o seu potencial antioxidante e componentes bioativos. O segundo objetivo principal foi avaliar o comportamento de duas castas selecionadas no potencial antioxidante, composiĆ§Ć£o quĆmica e composiĆ§Ć£o centesimal e valor energĆ©tico em diferentes tratamentos tĆ©rmicos (branqueamento, cozimento durante 60, 75 e 90 minutos em panela de pressĆ£o).
Verificou-se que as castas brancas apresentaram maior atividade antioxidante e compostos bioativos em relaĆ§Ć£o Ć s castas tintas, tendo-se verificado um efeito da casta nos resultados obtidos. A partir destes resultados verificou-se que a casta mais antioxidante foi a Malvasia Fina, e a Touriga Franca a casta com menor potencial antioxidante. Ambas as castas foram selecionadas para serem submetidas aos tratamentos tĆ©rmicos.
O processamento tĆ©rmico causou mudanƧas significativas na cor de ambas as castas, passando de verdes para acastanhadas, muito devido Ć reduĆ§Ć£o do teor em clorofilas e carotenoides presentes em ambas as castas. A atividade antioxidante foi reduzida com o tempo de aquecimento, tendo-se mesmo assim verificado, de uma maneira geral, maior atividade na Malvasia Fina em relaĆ§Ć£o Ć Touriga Franca, tendo-se verificado o mesmo no teor de fenĆ³is totais, flavonĆ³is e derivados do Ć”cido hidroxicinĆ”mico. O valor energĆ©tico das folhas Ć© reduzido durante o aquecimento, muito pela perda de hidratos de carbono para a Ć”gua de cozedura. A gordura das folhas de videira Ć© maioritariamente polinsaturada e rica em Ć”cido linolĆ©nico, verificando um aumento dos Ć”cidos gordos polinsaturados com o aquecimento das folhas e uma diminuiĆ§Ć£o dos Ć”cidos monoinsaturados e saturados. No que respeita ao teor em vitamina E livre, esta aumentou com o aquecimento em ambas as castas, especialmente na Touriga Franca, sendo o Ī±-tocoferol o vitĆ¢mero mais abundante, chegando a ultrapassar os 1000 mg kg-1 com aquecimentos prolongados. A fraĆ§Ć£o volĆ”til das folhas de videira Ć© altamente influenciada pelo tratamento tĆ©rmico em ambas as castas. Com o aquecimento aldeĆdos, Ć”lcoois e Ć©steres responsĆ”veis por aromas verdes e herbĆ”ceos [(Z)-3-hexenal; (Z)-3-hexen-1-ol; e (Z)-3-hexenil acetato)] sĆ£o completamente eliminados, provocando o aparecimento de cetonas caracterĆsticas de processos tĆ©rmicos (6-metil-5-hepten-2-ona) e sesquiterpenos responsĆ”veis por aromas a madeira (cariofileno).
Dos resultados obtidos, verifica-se que a casta Malvasia Fina Ć© a mais adequada para processamento tĆ©rmicos moderados. No entanto para processamentos mais longos as diferenƧas entre as castas desvanece-se, sendo desencorajado processamentos alimentares longos, devido Ć perda de valor nutricional, componentes importantes responsĆ”veis por propriedades funcionais e bioativas, bem como a perda de componentes responsĆ”veis pelo aroma, entre outras caracterĆsticas importantes para o consumidor, como a cor.
The consumption of some vine and wine sub-products, such as grape leaves, is known a long time ago in the Mediterranean region. Grape leaves are already present in the animal and human diet in several countries around the world, being completely devalued as sub-products in some other regions. In this sense, the principal objectives of this work were to evaluate among diverse white grape varieties (CĆ“dega do Larinho, FernĆ£o Pires, Gouveio, Malvasia Fina, Rabigato e Viosinho) and red varieties (Tinta Amarela, Tinta Roriz, Touriga Franca e Touriga Nacional) from Planalto MirandĆŖs, the most adequate for food processing , taking in account their bioactive potential and bioactive components. The second main objective was to evaluate the behavior of two selected grape leaves varieties in the antioxidant potential, chemical and centesimal composition, energetic value iat different thermal treatments (bleaching, boiling for 60, 75 and 90 minutes in a pressure pan). It was verified that white grape leaves present higher antioxidant activity and bioactive components in relation to red grape leaves, being verified a varietal effect in the obtained results. From these results it was verified that the most antioxidant variety was Malvasia Fina, and Touriga Franca was the variety with lower antioxidant properties. Both varieties were selected to be submitted to thermal treatments. The thermal processing caused significant changes in the color of both varieties, passing from green to brown coloration, much due to the reduction in chlorophylls and carotenoids present in both varieties. The antioxidant activity was reduced with the heating time, being verified in a general way higher antioxidant activity in Malvasia Fina in relation to Touriga Franca. The same was checked in total phenols content, flavonols, and derivates of hydroxycinammic acid. The energetic value of the leaves was reduced with the thermal process increase, mainly due to the loss of carbohydrates to the boiling water. The fat of grape leaves is mainly polyunsaturated and rich in linolenic acid, being verified an increasein the polyunsaturated fatty acids with the increase of boiling time and a reduction in the monounsaturated and saturated fatty acids. Respecting the vitamin E content, it increased with the boiling time in both varieties, especially in Touriga Fanca, being Ī±-tocopherol the most abundant vitamer, passing the 1000 mg kg-1 with long boiling periods. The volatile fraction of the grape leaves is highly influenced by the thermal treatment in both varieties. With heating aldehydes, alcohols and esters responsible for the green and herbaceous aromas [(Z)-3-hexenal; (Z)-3-hexen-1-ol; e (Z)-3-hexenyl acetate)] are completely eliminated, inducing the appearance of ketones characteristic of thermal processing (6-methyl-5-hepten-2-one) and sesquiterpenes responsible for wood aromas (caryophyllene). From the results obtained, is verified that Malvasia Fina variety is the most adequate fro moderate thermal processes. Meanwhile for longer processing periods the difference between the varieties are reduced, being discouraged the application of longer thermal processes, due to the loss of nutritional value, important compounds responsible for the functional and bioactive properties, as well as the loss of components responsible for the aroma, as well as other important characteristics for the consumer, as the color.
The consumption of some vine and wine sub-products, such as grape leaves, is known a long time ago in the Mediterranean region. Grape leaves are already present in the animal and human diet in several countries around the world, being completely devalued as sub-products in some other regions. In this sense, the principal objectives of this work were to evaluate among diverse white grape varieties (CĆ“dega do Larinho, FernĆ£o Pires, Gouveio, Malvasia Fina, Rabigato e Viosinho) and red varieties (Tinta Amarela, Tinta Roriz, Touriga Franca e Touriga Nacional) from Planalto MirandĆŖs, the most adequate for food processing , taking in account their bioactive potential and bioactive components. The second main objective was to evaluate the behavior of two selected grape leaves varieties in the antioxidant potential, chemical and centesimal composition, energetic value iat different thermal treatments (bleaching, boiling for 60, 75 and 90 minutes in a pressure pan). It was verified that white grape leaves present higher antioxidant activity and bioactive components in relation to red grape leaves, being verified a varietal effect in the obtained results. From these results it was verified that the most antioxidant variety was Malvasia Fina, and Touriga Franca was the variety with lower antioxidant properties. Both varieties were selected to be submitted to thermal treatments. The thermal processing caused significant changes in the color of both varieties, passing from green to brown coloration, much due to the reduction in chlorophylls and carotenoids present in both varieties. The antioxidant activity was reduced with the heating time, being verified in a general way higher antioxidant activity in Malvasia Fina in relation to Touriga Franca. The same was checked in total phenols content, flavonols, and derivates of hydroxycinammic acid. The energetic value of the leaves was reduced with the thermal process increase, mainly due to the loss of carbohydrates to the boiling water. The fat of grape leaves is mainly polyunsaturated and rich in linolenic acid, being verified an increasein the polyunsaturated fatty acids with the increase of boiling time and a reduction in the monounsaturated and saturated fatty acids. Respecting the vitamin E content, it increased with the boiling time in both varieties, especially in Touriga Fanca, being Ī±-tocopherol the most abundant vitamer, passing the 1000 mg kg-1 with long boiling periods. The volatile fraction of the grape leaves is highly influenced by the thermal treatment in both varieties. With heating aldehydes, alcohols and esters responsible for the green and herbaceous aromas [(Z)-3-hexenal; (Z)-3-hexen-1-ol; e (Z)-3-hexenyl acetate)] are completely eliminated, inducing the appearance of ketones characteristic of thermal processing (6-methyl-5-hepten-2-one) and sesquiterpenes responsible for wood aromas (caryophyllene). From the results obtained, is verified that Malvasia Fina variety is the most adequate fro moderate thermal processes. Meanwhile for longer processing periods the difference between the varieties are reduced, being discouraged the application of longer thermal processes, due to the loss of nutritional value, important compounds responsible for the functional and bioactive properties, as well as the loss of components responsible for the aroma, as well as other important characteristics for the consumer, as the color.
Description
Mestrado com dupla diplomaĆ§Ć£o com a Universidade TecnolĆ³gica Federal do ParanĆ”
Keywords
Folhas de videira Subproduto Ingrediente alimentar Processamento alimentar Compostos fenĆ³licos Atividade antioxidante