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Abstract(s)
Muitas indústrias usam maçãs para a formação de novos produtos para o consumidor final ou essas mesmas maçãs são vendidas na sua forma natural. E nesse fabrico ou venda de maçãs frescas, as empresas necessitam de alguns atributos específicos que devem ser medidos. Um desses atributos é a textura, que é um aspeto da consistência do tecido vegetativo determinado pela maneira como as células são unidas pela lamela média. A sensação sensorial de frescura e suculência é o que o cliente procura, e para a medição destes parâmetros existem vários tipos de instrumentos, dentro dos quais se pode encontrar os instrumentos destrutivos (como penetrómetro ou compressão) e não-destrutivos (como vibração ou medidas acústicas). No entanto, estes instrumentos não são suficientes para avaliar a farinosidade de uma maçã. Nesse contexto, muitos estudos são realizados, para se entender o que se sucede na parede celular de forma metabólica. Em estudos anteriores, já foram encontradas várias enzimas em diferentes níveis durante a maturação da maçã, como é o caso da pectina metilesterase (PME), responsável pela degradação da pectina.
Uma vez que não existe nenhum método específico e barato para a verificação da farinosidade de uma maçã, procurou-se testar vários métodos: medição do brix e da dureza, medição de pH e medição de absorvância. Estes métodos testados foram adaptações feitas, dependendo das nossas necessidades, aos diversos métodos encontrados na literatura.
A medição do brix e dureza, revelaram-se irrelevantes para o estudo, pois quer maçãs de qualidade conforme (suculentas), intermédias e não conformes (farinhentas) apresentavam valores semelhantes, pelo que o brix e dureza não estão diretamente relacionados com a farinosidade da maçã. A medição de pH com fitas de pH também teve pouca utilidade para o estudo, pois todos os grupos de maçã tinham um pH tão próximo que não era detetado pela fita de pH, em comparação com a medição no potenciómetro, em que se denotam diferenças na casa das décimas. O método que se apresentou mais eficaz, e que demonstrava diferenças claramente significativas entre os grupos foi a medição da absorvância do extrato de maçã, nas suas variáveis.
Many industries just sell fresh apples and other industries produce new porducts. To make apple derivatives or to sell fresh apples, the companies need some specific attributes that must be measures first. One of this attributes is the texture, that is na aspect of the consistency of the vegetative tissue determined by the way the cells are joined by the middle lamella. Sensory sensation of crispiness and juiciness is what the costumer wants. The methodology to measure those properties are destructive methods (such as penetrometer or compression) and non-destructive methods (like vibration or accoustic measures) to evaluate the texture of na apple. However, there is not enough methods to compare mealy and non-mealy apple. In this contexto, many studies are made to understand what happens in cell Wall in metabolic ways. Many enzymes were found in diferente levels during the apple maturation, such as pectin methylesterase (PME) tha is responsible for the pectin degradation. Since there is no specific and inexpensive method for checking the mealiness of na apple, several methods have been tested: measurement of brix and hardness, pH measurement and absorbance measurement. The tested methods were adapted from the literature, according with some needs. The measurement of brix and hardness proved to be irrelevante to the study, since both conformal (succulent), intermediate and non-complaint apples (mealy) had similar values, so brix and hardness wre not directly related to the apple. Measurement of pH with pH strip also proved to be useless for the study because all groups had a pH so close that it was not detected by the pH strip compared to the potentiometer measurement, where diferences are noted in house of the tenths. The most effective method, which showed clearly signiicant diferences between the groups, was the measurement of absorbance of the apple extract, in its variables.
Many industries just sell fresh apples and other industries produce new porducts. To make apple derivatives or to sell fresh apples, the companies need some specific attributes that must be measures first. One of this attributes is the texture, that is na aspect of the consistency of the vegetative tissue determined by the way the cells are joined by the middle lamella. Sensory sensation of crispiness and juiciness is what the costumer wants. The methodology to measure those properties are destructive methods (such as penetrometer or compression) and non-destructive methods (like vibration or accoustic measures) to evaluate the texture of na apple. However, there is not enough methods to compare mealy and non-mealy apple. In this contexto, many studies are made to understand what happens in cell Wall in metabolic ways. Many enzymes were found in diferente levels during the apple maturation, such as pectin methylesterase (PME) tha is responsible for the pectin degradation. Since there is no specific and inexpensive method for checking the mealiness of na apple, several methods have been tested: measurement of brix and hardness, pH measurement and absorbance measurement. The tested methods were adapted from the literature, according with some needs. The measurement of brix and hardness proved to be irrelevante to the study, since both conformal (succulent), intermediate and non-complaint apples (mealy) had similar values, so brix and hardness wre not directly related to the apple. Measurement of pH with pH strip also proved to be useless for the study because all groups had a pH so close that it was not detected by the pH strip compared to the potentiometer measurement, where diferences are noted in house of the tenths. The most effective method, which showed clearly signiicant diferences between the groups, was the measurement of absorbance of the apple extract, in its variables.
Description
Keywords
Fruta Qualidade Modificações da parede celular