Preservation of Pacific white shrimp (Penaeus vannamei) by pullulan and melleolide composite preservatives

The qualities of Penaeus vannamei that are prone to spoilage have a significant impact on its economic profitability. To extend the shelf life of shrimp, this study formulated a novel composite preservative with pullulan and protoilludane sesquiterpene aryl esters (melleolides). Two melleolide compounds, namely armillarin and armillaripin, were identified using high-performance liquid chromatography-triple quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF-MS/MS) analysis of the ethyl acetate extract of Floccularia luteovirens. The antibacterial activity of melleolides was investigated through the disc diffusion method, and it exhibited the most potent effect against methicillin-resistant Staphylococcus aureus (MRSA) among the tested bacteria, producing an inhibition zone diameter of 15.6 mm. The composite preservative displayed competitive inhibition of polyphenol oxidase, with an IC50 value achieved at a melleolides content of 6.27%. Furthermore, the effects of the composite preservatives on shrimp quality were evaluated through sensory, colour, pH, TVB-N, APC, and TBARS assessments. The results indicated that S-PM8 treatment group inhibited the growth of the APC in shrimp from 8.98 log CFU/g (S-C) to 7.48 log CFU/g. The TVB-N content was maintained within 28.7 mg/100 g throughout the storage period. The content of TBARS was 0.97 mg MDA/kg at Day 12, which was significantly lower than that of the control group. Additionally, the composite preservatives substantially improved sensory scores and colour retention during storage. These findings demonstrate the potential of pullulan-melleolides composite preservative to extend the shelf life of P. vannamei.