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Abstract(s)
A stevia (Stevia rebaudiana) é uma planta originária da América do Sul que
possui um poder adoçante de cerca de 300 vezes superior ao da sacarose. Atualmente,
os extratos refinados desta planta constituem o adoçante classificado pela European
Food Safety Authority (EFSA) como E960.
De modo a ir de encontro a uma tendência crescente de ingestão de alimentos
com menores teores em açúcares, quer por opção ou por questões relacionadas com a
saúde, neste trabalho procurou-se desenvolver formulações de um produto tradicional
em Trás-os-Montes, o doce de abóbora com amêndoa, com recurso a extratos de S.
rebaudiana, e proceder à sua caracterização físico-química e sensorial.
Neste sentido, numa primeira fase foram desenvolvidas duas formulações: uma
com extrato aquoso de folhas de S. rebaudiana e outra com adoçante em pó. Para cada
fórmula foram confecionados três doces com quantidades diferentes de extrato,
mantendo-se os restantes ingredientes constantes. Para comparação de resultados foi
produzido também um doce com açúcar e foram adquiridos no mercado três doces de
abóbora: o clássico, a versão light e a versão com noz. Posteriormente foram realizados
testes físico-químicos a todos os doces, nomeadamente cor, viscosidade, sólidos
solúveis totais, pH, acidez titulável, humidade, cinzas, proteína, gordura total, fibra
dietética, açúcares redutores, ácido ascórbico e metais (sódio, potássio e cálcio). De
modo a determinar a aceitação dos doces por parte dos consumidores foram realizadas
duas provas sensoriais. Na primeira prova foi analisada a aceitação dos doces
elaborados com os dois tipos de extrato de S. rebaudiana – infusão e pó. Na segunda
prova foi utilizado o doce com a maior quantidade de extrato do tipo preferido na
primeira prova e o doce comercial light.
Relativamente às características físicas, detetaram-se diferenças assinaláveis,
apresentando os doces com açúcar menores valores de luminosidade (L*) e maiores
valores no parâmetro a* o que estará relacionado com reações de escurecimento.
No que se refere às características químicas, os doces com extratos de S.
rebaudiana apresentaram valores de sólidos solúveis totais mais baixos, por possuírem
menor quantidade de açúcares e ácidos adicionados. O pH dos doces variou entre 3,8 e
5,6, tendo o valor mais alto sido obtido para o doce “caseiro” com açúcar. Os doces com
iv
maior teor de humidade foram os produzidos com extratos de S. rebaudiana o que
estará relacionado com o facto de não ter sido adicionado açúcar. O teor em cinzas
variou entre 0,24% e 0,86%, tendo sido superior para os doces “caseiros”.
Relativamente ao teor de proteína, os valores obtidos variaram entre 0,01% e 1,24%,
tendo os valores mais baixos sido obtidos para os doces comerciais clássico e light. A
gordura total variou entre 0,08% e 0,31% de forma semelhante ao teor de proteína. Os
doces comerciais apresentaram percentagens de açúcares redutores muito superiores,
provavelmente devido à utilização de xarope de glucose.
No que diz respeito aos minerais analisados, os maiores teores de sódio e
potássio foram determinados nos doces “caseiros” e para o cálcio os valores mais altos
foram obtidos para a amostra comercial light, devido à adição de cloreto de cálcio como
endurecedor.
Relativamente às provas organoléticas, na primeira prova o doce melhor
classificado em todos os parâmetros analisados foi o preparado com S. rebaudiana em
pó. Na segunda prova, ao testar este tipo de doce com a versão light comercial
verificou-se que os provadores preferiram o doce light comercial, tendo obtido este
pontuações superiores.
Stevia (Stevia rebaudiana) is a plant native from South America that possesses 300 times the sweetness of sucrose. Currently, refined extracts of this plant represents a sweetener classified by European Food Safety Authority (EFSA) as E960. In order to respond to the growing interest of the population for low sugar products, either by choice or by health reasons, in this work several recipes of a traditional product of Trás-os-Montes have been developed: pumpkin jams with almond, sweetened with S. rebaudiana extracts. Moreover, the physicochemical and sensory characterization of these jams has also been done. In this sense, initially two recipes were developed, one with S. rebaudiana aqueous extracts, and other with powdered sweetener. For each recipe, three jams with different amounts of extract were prepared, keeping the remaining ingredients constant. For results comparison a jam with sugar was also produced and three pumpkin jams of the same trade mark were bought on the market, namely, the classic, light and with walnut jams. Subsequently, physicochemical analyses were done to all of jams, in particular color, viscosity, total soluble solids, pH, titratable acidity, moisture, ash, protein, total fat, dietetic fiber, reducing sugars, ascorbic acid and metals (sodium, potassium and calcium). In order to determine the jams’ acceptance of consumers, two sensory analyses were made. In the first assay it was evaluated the acceptance of both jams prepared with the two types of stevia extracts – infusion and powder. In the second assay, the most accepted jam prepared with Stevia extract determined in the first assay and the light commercial jam were analyzed. Relatively to physic characteristics, marked differences were detected, having the lowest L* values (lightness) and the highest a* values been obtained with the sugar jams, due to browning reactions. In relation to chemical characteristics, jams with S. rebaudiana extracts showed the lowest values of total soluble solids because sugar and acids were present in less quantity. The pH values ranged between 3,8 and 5,6, being the highest value obtained on sugar jam. The highest values of moisture were obtained on jams made with S. rebaudiana extracts because sugar wasn’t added to those jams. The ash values ranged between 0,24% and 0,86%, being the highest values obtained on the jams prepared in vi the present work. Concerning protein, the obtained values ranged between 0,01% and 1,24%, being the lowest values obtained on the classic and light commercial jams. Total fat ranged between 0,08% and 0,31%, similarly to the protein variation. Commercial jams showed the highest reducing sugars percentages, probably due to the addition of glucose syrup. Concerning metals, the highest values of sodium and potassium were determined on the prepared jams while the highest values on calcium were obtained on the light commercial jam because calcium chloride was added as hardener. In relation to the sensory analyses, in the first assay the jam with the highest score in all of analyzed parameters was the jam made with the S. rebaudiana powdered sweetener. In the second assay, testing this jam with the light commercial jam, the consumers gave the highest scores to the light commercial jam.
Stevia (Stevia rebaudiana) is a plant native from South America that possesses 300 times the sweetness of sucrose. Currently, refined extracts of this plant represents a sweetener classified by European Food Safety Authority (EFSA) as E960. In order to respond to the growing interest of the population for low sugar products, either by choice or by health reasons, in this work several recipes of a traditional product of Trás-os-Montes have been developed: pumpkin jams with almond, sweetened with S. rebaudiana extracts. Moreover, the physicochemical and sensory characterization of these jams has also been done. In this sense, initially two recipes were developed, one with S. rebaudiana aqueous extracts, and other with powdered sweetener. For each recipe, three jams with different amounts of extract were prepared, keeping the remaining ingredients constant. For results comparison a jam with sugar was also produced and three pumpkin jams of the same trade mark were bought on the market, namely, the classic, light and with walnut jams. Subsequently, physicochemical analyses were done to all of jams, in particular color, viscosity, total soluble solids, pH, titratable acidity, moisture, ash, protein, total fat, dietetic fiber, reducing sugars, ascorbic acid and metals (sodium, potassium and calcium). In order to determine the jams’ acceptance of consumers, two sensory analyses were made. In the first assay it was evaluated the acceptance of both jams prepared with the two types of stevia extracts – infusion and powder. In the second assay, the most accepted jam prepared with Stevia extract determined in the first assay and the light commercial jam were analyzed. Relatively to physic characteristics, marked differences were detected, having the lowest L* values (lightness) and the highest a* values been obtained with the sugar jams, due to browning reactions. In relation to chemical characteristics, jams with S. rebaudiana extracts showed the lowest values of total soluble solids because sugar and acids were present in less quantity. The pH values ranged between 3,8 and 5,6, being the highest value obtained on sugar jam. The highest values of moisture were obtained on jams made with S. rebaudiana extracts because sugar wasn’t added to those jams. The ash values ranged between 0,24% and 0,86%, being the highest values obtained on the jams prepared in vi the present work. Concerning protein, the obtained values ranged between 0,01% and 1,24%, being the lowest values obtained on the classic and light commercial jams. Total fat ranged between 0,08% and 0,31%, similarly to the protein variation. Commercial jams showed the highest reducing sugars percentages, probably due to the addition of glucose syrup. Concerning metals, the highest values of sodium and potassium were determined on the prepared jams while the highest values on calcium were obtained on the light commercial jam because calcium chloride was added as hardener. In relation to the sensory analyses, in the first assay the jam with the highest score in all of analyzed parameters was the jam made with the S. rebaudiana powdered sweetener. In the second assay, testing this jam with the light commercial jam, the consumers gave the highest scores to the light commercial jam.
Description
Keywords
Extratos de S. rebaudiana Doces de abóbora com amêndoa Análises físico-químicas Análises sensoriais