Characterization of polylactic acids-polyhydroxybutyrate based packaging film with fennel oil, and its application on oysters

With the addition of fennel (FEN) oil, a biodegradable film based on polylactic acids (PLA) and polyhydroxybutyrate (PHB) was developed to possess antimicrobial ability. Barrier property and mechanical property tests were performed on three films, including PLA-PHB film, PLA-PHB film integrated with FEN oil (PLA-PHB-FEN) and ethanol vinyl alcohol (EVOH) film, whereby oxygen transmission rate (OTR), water vapor permeation (WVP), tensile strength and elongation at break were gathered. In addition, active properties including releasing, antibacterial and antioxidant abilities were measured. The profile showed that the mechanical properties of PLA-PHB film were comparable to those of EVOH film, except for the oxygen barrier ability. The FEN oil released from PLA-PHB-FEN film significantly inhibited the growth of E.coli and Staphylococcus by 1.2 and 1.3 Log CFU/g, respectively. PLA-PHB-FEN film showed the potential to be compatible with oily food as the maximum release (38.82 mu g/mL) of FEN oil took place in fat simulants (65% ethanol). Afterward, the three films were used on the preservation of oysters for empirical tests. The results showed that the abundance of both aerobic and anaerobic bacteria were reduced by 1 Log CFU/g in the packaging of PLA-PHB-FEN film, which was supported by pH value and TVB-N level of oysters. Texture profile analysis and free amino acids quantification were also conducted. The data suggested that the PLA-PHB-FEN film could prolong the shelf-life on oysters for 2-3 days while maintaining their quality compared to EVOH film. This study provides insight into biodegradable packaging by which synthetic packaging could be substituted.