Effect of pH,temperature and time of extraction on the antioxidant properties of Vaccinium meridionale Swartz

Abstract

BACKGROUND:

Vaccinium meridionale is a fruit rich in polyphenols, with coloring and antioxidant properties.

OBJECTIVE:

Decoctions of the fruit were prepared and the effect of temperature, time and pH on oxidative stability and color parameters were evaluated.

METHODS:

To evaluate the oxidative stability the ORAC, FRAP, and DPPH methodologies and the quantification of phenols and anthocyanins by spectrophotometric tests were developed, while colors parameters were determined using a colorimeter and UV- VIS spectrums.

RESULTS:

Rising the temperature from 60 to 100°C increased phenol content, FRAP and ORAC values up to 724.24 mg gallic acid/L, 978.51 mg ascorbic acid/L and 14172μmol Trolox/L, respectively; anthocyanin content decreased above to 80°C. At pH of 3.60 to 7.40 the antioxidant and color properties were not altered, at pH 10 there was a reduction of the antioxidant activity of 48.9%, and loss of the red tones of the decoctions.

CONCLUSION:

The content of phenols increased with temperature, increasing the antioxidant capacity, however the anthocyanins were degraded above 80°C and 20 minutes of processing.