Preparation of PVA/PLA-based intelligent packaging to indicate the quality of shiitake mushrooms

Intelligent packaging was prepared and evaluated to determine the quality of shiitake mushrooms using colorimetric sensing. Bromothymol blue/methyl red composite dyes were incorporated into polyvinyl alcohol (PVA) to form a porous indicator via freeze-drying. The PVA indicator was then modified with polylactic acid (PLA). The porous structure of the indicator was investigated using scanning electron microscopy (SEM) imaging, and it was found that the hydrophobicity of the PVA/PLA indicator was significantly improved following modification. A sensitive colorimetric response toward the presence of CO 2 in packaging was achieved using the naked eye. During investigations into the potential application of this system, the ΔE value of the indicator was found to correlate significantly with the quality indices (i.e., the browning index, firmness value, malondialdehyde content, and sensory score) of shiitake mushrooms during storage. Based on these correlations, qualitative identification of the freshness of shiitake mushrooms was studied using principal component analysis, while a prediction model of this freshness was obtained by partial least squares regression. This indicator, therefore, shows potential for application in intelligent packaging for the detection of CO 2 due to the clear visualization of color changes by the naked eye.