bachelorThesis
Caracterização da bioatividade de folhas de diferentes castas de videira quando sujeitas a processamento alimentar
Fecha
2015-11-27Registro en:
LIMA, Adriano Freitas. Caracterização da bioatividade de folhas de diferentes castas de videira quando sujeitas a processamento alimentar. 2015. Conclusão de Curso (Bacharelado em Engenharia de Alimentos) - Universidade Tecnológica Federal do Paraná, Medianeira, 2015.
Autor
Lima, Adriano Freitas
Resumen
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 (Côdega do Larinho, Fernão Pires, Gouveio, Malvasia Fina, Rabigato e Viosinho) and red varieties (Tinta Amarela, Tinta Roriz, Touriga Franca e Touriga Nacional) from Planalto Mirandês, 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 α-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.