Shelf Life Extension of Metapenaeus ensis by Chitosan-litchi Wood Essential Oil Edible Films
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Abstract:
To evaluate the preservation performance of chitosan-litchi wood essential-oil edible films for Metapenaeus ensis, shrimp were first subjected to dip coating to apply chitosan films with 8% litchi wood essential oil (V/V, based on the volume of chitosan solution) and then stored at 4 ℃ for six days. Variations in the sensory and quality indices, including pH, total volatile base-nitrogen (TVB-N), texture, color difference, and the total number of bacterial colonies during storage, were determined. The results show that chitosan-litchi wood essential oil edible films can significantly prolong the shelf life of Metapenaeus ensis by doubling it from three days to six days. Meanwhile, the quality deterioration is slowed down considerably. The TVB-N content of shrimp in ordinary preservative films is 31.58 mg/100 g at day 4, indicating that the shrimp have no edible value. In contrast, the TVB-N content of shrimps in composite films is still lower than 30 mg/100 g at day 6. Furthermore, the pH of shrimps in ordinary preservative films exceeds 7.6 at day 4, while the shrimps in composite films have no edible value at day 6. The total number of bacterial colonies in shrimps in ordinary films equals 6.89 lg (CFU/g) at day 3, suggesting that decomposition reaches its end, while shrimps in composite films are still first-grade fresh in terms of the total bacterial colony number. In summary, chitosan-litchi wood essential oil edible films can preserve Metapenaeus ensis reasonably well and double its shelf life. This study provides a reference for the use of chitosan-essential oil composite films to preserve aquatic products.
