Application of Psidium guajava Leaf Ethanol Extract Coating for Extending the Shelf Life of Indian Prawn (Penaeus indicus) Under Chilled Storage

Abstract

The present study aimed to characterise the Psidium guajava leaf powder and its ethanolic extract and to analyse its preservative effect on Indian prawn (Penaeus indicus) under chilled storage. The dried P. guajava leaf powder contained high levels of fibre, ash, and carbohydrate, as well as high potassium and magnesium content. Antioxidant assays showed 97.40 ± 0.03% (DPPH assay) and 78.20 ± 0.01% (ABTS assay) inhibition with a 20% ethanolic extract, attributable to its total phenolic and flavonoid content. An antimicrobial study revealed that the ethanolic extract at 20% concentration showed strong inhibitory zones against Gram positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) (34.00 ± 0.01 mm), S. aureus (27.00 ± 3.00 mm), and Bacillus cereus (17.00 ± 2.00 mm), but did not exhibit antimicrobial activity against the tested Gram-negative bacteria. During the storage study, biochemical, microbiological, and sensory qualities of P. guajava leaf extract-coated P. indicus were evaluated. In biochemical analysis, TBARS values revealed that the samples treated with 20% and 40% concentration had better shelf life. Similarly, TVB-N and TMA values showed that 20% and 40% treated samples exceeded the acceptable limit on the 18th day of storage, whereas the control sample exceeded the limit on the 12th day. Microbiological analysis demonstrated that 20% and 40% coatings effectively inhibited psychrotrophic and mesophilic bacterial growth and exceeded the acceptable limit on the 18th day of storage, whereas the control sample exceeded the acceptable limit on the 12th day. Overall, P. guajava leaf extract coatings, especially at 20% and 40%, markedly enhanced the shelf life of P. indicus during chilled storage and could be used as a practical natural preservative.