Abstract:

To develop a new packaging material for fresh-keeping of salted egg products, polyvinyl alcohol (PVA) was chemically cross-linked with stearic acid. Effects of major cross-linking reaction conditions on film-forming properties of the resulting coating material were examined. Results showed that the film formed from the PVA/stearic acid compound coating material obtained using glutaraldehyde added at 0.4% level (calculated on the basis of the volume of water used to dissolve PVA) as cross-linking agent exhibited a water vapor transmission rate (WVTR) of 22.3 g/(m2·24 h), with an approximate 2.5-fold enhancement of water barrier performance when compared with the film formed without the addition of glutaraldehyde. Longer cross-linking time and lower film-forming temperature resulted in significantly higher water barrier and water resistance performance (P＜0.05). There was a significant increase in antibacterial effect of the film formed from the PVA/stearic acid compound coating material obtained using a higher concentration of glutaraldehyde (P＜0.05). The optimal formula of crosslinking system consisting of a mixture of 5% aqueous PVA solution and 5% ethanol solution of stearic acid (10:4, V/V) was first left to react at pH 6.2 for 45 min under the catalysis of glutaraldehyde added at 0.4% level and subsequently dried at 55 ℃ for 6 h, and a PVA/stearic acid compound film with an optimal compromise among high water resistance performance, excellent antimicrobial effect and low WVTR was obtained.

Key words: coating material, polyvinyl alcohol, stearic acid, cross-linking reaction, water vapour transmission rate, antibacterial effect