Preparation and properties of PVAL/CA/TP films for citrus preservation
Polyvinyl alcohol(PVAL)was used as the film-forming substrate,citric acid(CA)and tea polyphenols(TP)were added in different proportions,and the PVAL/CA/TP composite film was prepared by casting method.The effects of the CA contents on the mechanical properties,barrier properties,water resistance,etc.of the PVAL-based film were studied,and the prepared composite film was used to perform citrus preservation tests.The research results show that as the CA content continues to increase,the tensile strength of the composite film first increases and then decreases.When the CA content(percentage of PVAL mass)is 6%,the tensile strength reaches the maximum value of 17.54 MPa,which is 28.22%higher than that of the film without CA/TP compound.As the CA content increases to 8%,the tensile strength of the film decreases,while the elongation at break continues to rise to a maximum value of 655.27%.When the CA content of the film is 6%,the water vapor permeability coefficient(WVP)value of the film reaches the lowest,which is 0.97(g·mm)/(m2·h·kPa),showing the best gas barrier properties,at the same time,the water absorption also reaches the lowest,which is 10.27%.Therefore,when the CA content is 6%,the overall performanc-es of the film are the best.Finally,films with a CA content of 6%were selected for citrus preservation tests.Compared with unpack-aged citrus and citrus packaged in commercially available PE and PVC films,citrus packaged in PVAL/CA/TP films shows better preservation effects,which has the slowest upward trend for weight loss rate and has not shown any signs of rot after 14 days of storage.The research maintains the commercial value of citrus and provides a certain reference value for the field of food preserva-tion films.
polyvinyl alcoholcitric acidtea polyphenolswater resistancecomposite film
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