Evaluation of two intelligent packaging prototypes with a pH indicator to determine spoilage of cow milk

Abstract Intelligent packaging utilizes chemical sensors that could identify the quality and help determine the safety of packaged cow milk for consumers. The objective of this study was to evaluate cow milk packaged in two different prototypes of intelligent packaging during the cow milk’s shelf life based on volatile compounds, pH, color change, and sensory attributes. For this evaluation, two intelligent packaging prototypes were filled with cow milk. The prototype bottles were created using High Density Polyethylene (HDPE) with bromothymol blue as a pH indicator (the color of the bottle was designed to change when the pH changes). Treatment 1 changed color from green to yellow when the cow milk changes pH over time. Treatment 2 changed color from blue to green and from green to yellow. Measurements and sensory panels were performed during the shelf life of the cow milk samples, over four separate days. For the cow milk samples, GC–MS 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). Thirtytwo panelists evaluated the samples. There was a correlation of the color parameter chroma and the pH. Sensory panelists could not distinguish the difference of cow milk packaged in the control bottle with the prototypes bottles, HDPE-G and HDPE-B bottles. Our findings suggested HDPE-G and HDPE-B bottles could be used as an intelligent packaging and indicate spoilage of refrigerated cow milk with further studies.