Abstract
There is increasing need for industries to develop innovative technologies that in addition to being low cost, are also fast and provide high yields and efficiency, while at the same time avoiding adverse effects in the environment. One technique that conforms to these requirements is the use of ultrasound, which also offers ease of application and can be used in the extraction of compounds from leaves. The aim of the present work was to evaluate the efficiency of ultrasound in extracting catechins from green tea wastes, employing solvents with different polarities: water, acetone, ethanol, methanol, and isopropanol. The best extraction results were achieved using water as the solvent. Comparison was then made of extractions using water in the presence or absence of ultrasonication. The cavitation in the liquid medium, induced by the sound waves, acted to increase the permeability of the cell walls, leading to increased penetration of the solvent and greater extraction efficiency.
Highlights
O teor de catequina foi obtido utilizando a curva de calibração com solução padrão de catequina (100 mg L-1) e a leitura realizada em espectrofotômetro a 755 nm
Então este ânion reduz o reagente levando à formação dos complexos azul de molibdênio e azul de tungstênio (AZEVEDO, 2014; GONÇALVES, 2008; HUANG et al, 2005)
One technique that conforms to these requirements is the use of ultrasound, which offers ease of application and can be used in the extraction of compounds from leaves
Summary
As folhas secas de chá foram submetidas à extração com diferentes solventes. Os extratos foram preparados com 0,5 g de material seco utilizando 25 ml dos seguintes solventes extratores: água, acetona, etanol, metanol e isopropanol. Os extratos foram levados ao ultrassom por 5 minutos, nas condições de temperatura de 25oC, frequência 42 kHz e potência de 160 W. Após definido o melhor solvente, o mesmo foi utilizado para extrações sem a utilização do ultrassom para efeitos de comparação, sendo retiradas alíquotas nos tempos de 5, 10, 15, 30, 60, 90 e 120 minutos. O teor de catequina foi obtido utilizando a curva de calibração com solução padrão de catequina (100 mg L-1) e a leitura realizada em espectrofotômetro a 755 nm
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