Abstract:

The moisture absorption and antioxidant activity of poly-(vinyl alcohol) (PVA)-based active packaging
film containing tea polyphenols (TP) with different concentrations (0%, 0.5%, 1%, 1.5%, and 2% of dry PVA weight)
were investigated. Its moisture absorption characteristics were studied through moisture absorption experiment and the
experimental data were fitted based on the frequently used moisture absorption isotherm model. The antioxidant activity
was determined through DPPH radical scavenging array. The results showed that all PVA films had water absorbability and
were generally similar with respect to their moisture absorption isotherms, which belonged to type II moisture absorption
isotherm. The equilibrium moisture content of all PVA films increased significantly with increasing water activity (P < 0.01),
especially when the water activity exceeded 0.6. The hydrophobicity of PVA films was enhanced by TP modification. So
the moisture absorption capacity reduced as the quantity of tea polyphenols in the PVA film increased under the same water
activity condition, but there was no significant difference among five PVA films (P > 0.05). The experimental data were
best fitted with the GAB moisture absorption isotherm mode (R2 ≥ 0.996). The DPPH radical scavenging experiment showed
the inhibitory rate of PVA films higher in TP was higher than that lower in TP (P < 0.01). It was shown that the antioxidant
activity of the PVA films was enhanced with increasing quantity of TP in films, suggesting that there will be a good prospect
of this active packaging film served as inner layer or intermediate layer in the packaging system to improve the storage
quality of moisture-sensitive and lipid-containing foods.

Key words: poly-(vinyl alcohol), tea polyphenols, active packaging film, moisture absorption, antioxidant activity