Abstract

GARCIA-ELIZALDE, Argelia  and  GARCIA-ELIZALDE, Grecia. Hydroalcoholic extract of turmeric (Curcuma longa L.) as an indicator in acid-base titration of foods. Acta univ [online]. 2021, vol.31, e3188.  Epub June 20, 2022. ISSN 2007-9621.  https://doi.org/10.15174/au.2021.3188.

Curcumin is a bright yellow pigment present in turmeric rhizomes. This pigment is a Brönsted-Lowry weak acid that changes from yellow to red when changing the pH from acidic to basic. A turmeric hydroalcoholic extract (EHC) was elaborated and evaluated as an acid-base titration indicator against phenolphthalein. Turmeric was disinfected, dehydrated, and macerated in an ethanol-water solution. Aliquots of natural yogurt, lemonade-flavored soft drink, and fresh pineapple juice were titrated. Employing EHC as an indicator, the acidity estimations exhibited repeatability. Elevated standard deviation existed in the acid yogurt estimations when using EHC. Fisher’s exact probability test (assuming a p = 0.05) showed that the acidity medians were statistically equal between EHC and phenolphthalein for lemonade soda and pineapple juice, but not for yogurt. Consequently, EHC provides accurate and similar estimates of acidity compared to those obtained with phenolphthalein for lemonade-flavored soft drinks and fresh pineapple juice.

Keywords : Acidity; food; turmeric; extract; indicator.