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Authors
Abstract(s)
A secagem das uvas é um excelente método de conservação que origina produtos com elevado valor nutritivo. As passas são um produto alimentar consumido mundialmente e com grande popularidade no que respeita aos seus benefícios para a saúde. Este trabalho teve como objetivos secar uvas de variedade Crimson e posteriormente fazer uma avaliação física, química e sensorial das uvas passas. As uvas da variedade Crimson foram secadas por diferentes processos: por exposição direta ao sol, numa estufa solar na Escola Superior Agrária de Viseu; e em estufas ventiladas com caudal de ar constante programadas à temperatura de 50ºC e 60ºC. As uvas passas são naturalmente ricas em compostos fenólicos. Por esse motivo, inicialmente procedeu-se à extração destes compostos para posteriormente quantificar os fenóis totais, as antocianinas totais e os taninos totais. Entre outras propriedades químicas quantificou-se também os açúcares totais e a acidez. A avaliação das propriedades reológicas e a cor são aspetos fundamentais para uma boa aceitação dos produtos secados por parte do consumidor. Por fim, foi ainda efetuada a análise sensorial dos produtos secados para avaliar a sua aceitabilidade por parte dos consumidores. As uvas passas produzidas pelos diferentes métodos e temperaturas não apresentaram diferenças significativas a níveis químicos e físicos. No entanto, com o método de secagem em estufa ventilada obteve-se produtos com menor humidade em menos tempo, 14,59% de humidade com uma duração de 47 horas à temperatura de 60ºC, enquanto em estufa solar se obteve uma humidade de 19,43% durante 721 horas de secagem. A nível sensorial os provadores consideraram que as amostras de uvas secadas apresentavam semelhanças com algumas uvas passas existentes no mercado.
ABSTRACT: Grape drying is a great preservation method that originates products with high nutritive value. Raisins are a food product consumed worlwide and have a big popularity that concerns the health benefits. These work's objectives are dry table grapes seedless from Crimson variety and after do a physical, chemical and sensory evaluation of raisins. The Crimson grapes were drying by different ways: sun direct exposition, in a solar stove in Escola Superior Agrária de Viseu; and ventilated stoves with constant air flow at 50ºC and 60ºC temperatures programmed. Raisins are naturally rich in phenolics compounds. For this reason, at beginning did the compounds extraction and after were quantified total phenol, total anthocyanins and total tannins. Also, it were quantified the total sugars and acidity. The evaluation rheological properties and the color are fundamental aspects for a dried products good acceptation by the consumers. Lastly, was made yet a sensorial analyze of dried products to evaluate its acceptability by consumers. The raisins produced by the different methods and temperature didn't show chemical and physical significant differences. However, with ventilated stoves drying method were obtained products with less humidity in less time, 14,59% at humidity with 47 hours of duration at 60ºC temperature, while in solar stove was obtained 19,43% of humidity during 721 hours of drying. The sensory level, the tasters considers that dried grapes samples showed similar with some commercially raisins.
ABSTRACT: Grape drying is a great preservation method that originates products with high nutritive value. Raisins are a food product consumed worlwide and have a big popularity that concerns the health benefits. These work's objectives are dry table grapes seedless from Crimson variety and after do a physical, chemical and sensory evaluation of raisins. The Crimson grapes were drying by different ways: sun direct exposition, in a solar stove in Escola Superior Agrária de Viseu; and ventilated stoves with constant air flow at 50ºC and 60ºC temperatures programmed. Raisins are naturally rich in phenolics compounds. For this reason, at beginning did the compounds extraction and after were quantified total phenol, total anthocyanins and total tannins. Also, it were quantified the total sugars and acidity. The evaluation rheological properties and the color are fundamental aspects for a dried products good acceptation by the consumers. Lastly, was made yet a sensorial analyze of dried products to evaluate its acceptability by consumers. The raisins produced by the different methods and temperature didn't show chemical and physical significant differences. However, with ventilated stoves drying method were obtained products with less humidity in less time, 14,59% at humidity with 47 hours of duration at 60ºC temperature, while in solar stove was obtained 19,43% of humidity during 721 hours of drying. The sensory level, the tasters considers that dried grapes samples showed similar with some commercially raisins.
Description
Dissertação de Mestrado em Qualidade e Tecnologia Alimentar
Keywords
Uva de mesa Passa de uva Secagem natural Estufa solar Composto fenólico Propriedade físico-química Textura Análise organoléptica Drying Grapes Raisins Phenolic compounds Texture Color