Clemson University, Clemson, USA
Intelligent packaging are being developed to ensure the quality and safety of packaged food and provide clarity for consumers regarding shelf life. The purpose of this study was to evaluate color changing pH sensitive bottles to contain cow milk packaged in two different prototypes during refrigerated storage.
Two intelligent packaging prototype bottles composed of high-density polyethylene with two different color indicators (green and blue) based on the pH were filled with cow milk. Sensory panels were performed during the shelf life of the cow milk samples, over four separate days. Thirty-two panelists from Clemson University evaluated sensory attributes of samples. Gas chromatography-mass spectrometry was used to identify and quantify the volatile compounds (n=48) and the pH was determined by a pH meter (n=48). The color change of the bottle was measured using the Minolta L*a*b* colorimeter (n=48). The color change of the two intelligent bottles changed as expected upon change in pH level. The pH of the milk in only one of the two intelligent packaging (green) changed significantly different due to the buffer characteristics of milk. Regarding the volatile compounds, hexanal could be a potential biomarker for milk oxidative stress and spoilage. The participants of the sensory panel were rejecting the milk when the intelligent packaging changed colors.