Development of the tape pH indicator acid-basic from açai pulp extract

Abstract

Euterpe oleracea Mart. known as acai, it is a palm of bacaceous fruit, distributed throughout Brazil in states such as Amazonas, Pará, Maranhão, Rondônia and Tocantins. The objective of this work was to produce an acid-base indicator strip from the hydroalcoholic extract of the pulp of Euterpe oleracea Mart. to determine acidity by colorimetric method, also seeking to develop in a simple, fast and low cost, being an alternative way to be used in teaching Chemistry in experimental practical classes with the subject covered in Inorganic Functions in Teaching: Elementary, Middle and Higher. The methodology used was carried out in stages: (i) obtaining the acai pulp from the fruits of the açaizeiro, (ii) obtaining the extract from the pulp of Euterpe oleracea Mart., (iii) building a pH scale (0- 14), (iv) obtaining a pH paper from the hydroalcoholic extract, (v) identification of acidic and basic substances in everyday use with both the extract and the pH indicator paper, (vi) determining the acetic acid content in commercial vinegars, and (vii) a comparison of the results obtained from% acetic acid, both with the synthetic indicator (phenolphthalein) and with the natural indicator. Through the tests with the tape and with the pulp extract of Euterpe oleracea Mart. satisfactory results were obtained. Thus, the pH tape and the Euterpe oleracea Mart. pulp extract identified the acidic, basic and neutral substances of everyday life, showing an alternative for teaching with practical experimental chemistry classes, being financially viable, and exploring an application of Euterpe oleracea Mart. pulp. as forest treasure for future industrial applications, such as the production of a pH indicator strip.

Extrato hidroalcóolico da espécie Iroxa chinensi como indicador ácido-base

“…A sequência da metodologia foi descrita nos itens 2.1 ao 2 foi baseada nos autores Correia et al (2020) e Nunes et al (2021).…”

“…Alguns vegetais podem ser utilizados como indicadores ácido-base devido a presença de pigmentos conhecidos como antocianinas, as quais conferem a variedade de cores como o azul, vermelho e roxo que aparecem em flores, frutos e folhas. Os grupos das antocianinas pertencem a classe dos flavonoides que são espécies glicosídicas, em meio aquoso são derivadas da estrutura básica do cátion flavilium e possuem uma estrutura policíclica de 15 carbonos (Santos, 2017;Silva et al, 2018, Correia et al, 2020. As antocianinas têm um elevado potencial como corante natural, pois apresentam diversas cores de acordo com condições como o pH e temperatura do meio (Silva et al, 2018).…”