Fabrication of freshness indicators based on methylcellulose-containing color indicator solutions for monitoring the quality of coconut water

Abstract

This is the first study to apply intelligent packaging to coconut water. The purpose of this study was to determine the best color indicator solution for making freshness indicator labels based on methylcellulose along with the color change profile of coconut water during storage at room temperature. Three color indicator solutions were used, namely phenol red, bromothymol blue, and methyl red, which were then continued with the fabrication of freshness indicator labels based on methylcellulose from each of these color indicator solutions and applied to coconut water at 25 °C room temperature storage for 24 h with observations every 4 h in the form of pH, total dissolved solids, total acid, turbidity, total microbes, CO2 gas, O2 gas, and freshness indicator label color changes. The values of pH, total soluble solids, and O2 gas decreased with storage time, whereas the values of total acid, turbidity, total microbes, and CO2 gas continued to increase. The methylcellulose-based phenol red freshness indicator label provides the best color change profile that matches the freshness condition of coconut water, namely purplish red (fresh), orange (immediately consumed), and yellow (damaged) so that it can be used as intelligent packaging to monitor the quality of coconut water.