INCORPORAÇÃO DE EXTRATO DE INFLORESCÊNCIA DE BANANEIRA EM UM BIOPOLÍMERO COMO INDICADOR DE pH

Abstract

The banana, originating from India and cultivated in tropical countries like Brazil, stands out not only as a popular and nutritious food but also for the potential of its by-product, the banana flower. The banana flower inflorescence, rich in carbohydrates and proteins, is explored as a source of anthocyanins, known for their antioxidant properties and as pH indicators. The study delved into the extraction of anthocyanins from the banana flower bract and their application in a biopolymer. Using the Pareto diagram, the efficiency of anthocyanin extraction was evaluated, considering factors such as time, temperature, and hydrochloric acid concentration. The pKa values were determined, with an approximate pKa of 9.42 at the absorption peak at λ= 420 nm, around 3.12 at the absorption peak at λ = 524 nm, and finally, 10.42 at the absorption peak at λ = 600 nm. The quantification of anthocyanins indicated a concentration of 1.036 ± 0.024 mg C3G/L. The stability of the extract was assessed over time, emphasizing the importance of refrigeration to preserve its indicator properties. The results of the essential metals concentration analysis in the banana bracts and flowers were as follows: Fe (iron): 0.012 ± 0.006 mg/g in the bract and 0.013 ± 0.008 mg/g in the flower; Mg (magnesium): 4.48 ± 0.037 mg/g in the bract and 4.992 ± 0.023 mg/g in the flower; Mn (manganese): 0.038 ± 0.018 mg/g in the bract and 0.062 ± 0.017 mg/g in the flower; Ca (calcium): 2.75 ± 0.032 mg/g in the bract and 3.469 ± 0.036 mg/g in the flower; K potassium): 47.74 ± 0.488 mg/g in the bract and 46.10 ± 0.132 mg/g in the flower; Na (sodium): 0.041 ± 0.02 mg/g in the bract and 0.049 ± 0.018 mg/g in the flower. The analysis of phenolics indicated a higher concentration in the dried samples, with values of 122.64 ± 61.64 for the dry bract and 154.82 ± 23.43 for the dry flower. The incorporation of the extract into the PVA/quitosana biopolymer demonstrated efficacy as a pH indicator, exhibiting visual variations in response to different acidic and alkaline conditions. Measurements of color parameters (L*, a*, b*) varied with the indicator and pH, demonstrating sensitivity to pH changes. In FTIR spectroscopy, subtle differences were observed between biopolymers with and without the indicator. The results of thermogravimetry indicated that both the indicator and non-indicator biopolymers exhibited good thermal resistance, with little difference observed in the TG curve.