Assisted Compatibility, and Balanced Regulation of the Mechanical, Thermal, and Antioxidant Activity of Polyvinyl Alcohol-Chinese Bayberry Tannin Extract Films Using Different Di-Aldehydes as Cross-Linkers

Abstract

Polyvinyl alcohol (PVA)-based films containing Chinese bayberry tannin (BT) were prepared by cross-linking using glyoxal, glutaraldehyde and dialdehyde starch, individually. The presence of cross-linkers was evident to promote the transparency and decrease the moisture content of PVA/BT films, while the water solubility stayed almost unchanged in the cross-linked PVA/BT films. All cross-linkers provided promotion of the water vapor permeability, mechanical property and thermal stability of PVA/BT films. The best water vapor barrier capacity was found in case of glutaraldehyde cross-linked PVA/BT film, while the highest tensile strength was encountered in case of glyoxal cross-linked PVA/BT films, compared with the uncross-linked films. The scavenging action of the films towards DPPH radical activity was influenced by the nature of each cross-linker. Namely, the PVA/AT film cross-linked by glutaraldehyde acquired the lowest radical scavenging activity in a certain time, suggesting that glutaraldehyde decreased the release rate of BT from PVA. Based on the experimental data, glutaraldehyde and dialdehyde starch could be more suitable for PVA/BT film preparation since they can promote the intermolecular interaction of PVA and BT to a reasonable extent.

Facile Fabrication of High-Performance Composite Films Comprising Polyvinyl Alcohol as Matrix and Phenolic Tree Extracts

“…Afterwards, the TLP resin was put into a mold (10 × 10 × 1 cm 3 ), which was left to dry spontaneously over 1 h to obtain TLP film. In addition, PVOH [ 23 ], lignin/PVOH (LP) film and tannin/PVOH (TP) film were prepared under the same conditions for comparison with TLP film. The raw materials and amounts are shown in Table 1 .…”

“…It is expected that adding tannin into PVA system can improve the tensile strength and hardness of the resulting film. However, due to the large steric hindrance, condensed tannins have poor reactivity with PVOH [ 22 ], and due to the large molecular weight of condensed tannins, they undergo agglomeration easily in PVOH, resulting in poor compatibility [ 23 ]. Therefore, in the case of the tannin and PVA system, a matrix with good adhesion properties is needed to uniformly fix the tannin in the PVA system during the mixing process.…”

Natural polyphenol tannin-immobilized composites: rational design and versatile applications

“…Alternatively, the antioxidative and UV-protective properties of the tannin/PVA composite membrane were good, the potential of which is widely used in food packaging. Considering that tannins may be released from PVA, Liao and co-authors 161 prepared a PVA/ tannin (Chinese bayberry tannin (BT)) composite film by crosslinking using three types of aldehydes (glutaraldehyde, glyoxal, and dialdehyde starch) individually. Compared with the uncross-linked films, all the cross-linked PVA/BT displayed improved transparency, thermal stability, mechanical property, and water vapor permeability.…”

Investigation of Potential Use of Soybean Protein Isolate–Chinese Bayberry Tannin Extract Cross-Linked Films in Packaging Applications

“…The radical scavenging assay of DPPH was studied to estimate the antioxidant activity as previously reported in our previous works [ 36 , 37 ]. Initially, 0.1 g of the tested sample was immersed in 30 mL of distilled water while magnetic stirring was applied for 30 min.…”

“…Our previous studies have shown that Chinese bayberry tannin (BT) presented a good antioxidant function of BT incorporated into PVA films [ 36 , 37 ]. However, the imperfect miscibility and weak covalent bonds of two components were generally found, even with the help of aldehydes, due to the large molecular weight of BT, which makes its incorporation into PVA more difficult compared with other polyphenols.…”