Chemical profiling, antioxidant, and antimicrobial activity of spent coffee grounds aqueous extract and its use to enhance antioxidant, microbiological, and sensorial properties of shrimp under storage.

This study investigates the potential of spent coffee grounds aqueous extract (SCGAE) as a natural preservative for deep-water pink shrimp (DWPS). The SCGAE was initially assessed for chemical profiling, antioxidant, and antimicrobial activity. DWPS samples were treated with SCGAE (0.5, 0.75, and 1%) against salt 0.1% (positive control) and stored under vacuum and air at frozen conditions. Total phenolic content TPC (as mg gallic acid equivalent, GAE), antioxidant activity (as mg ascorbic acid equivalent, AAE), total viable counts (TVCs), coliform bacteria (CB), and lactic acid bacteria (LAB) were measured. Chlorogenic acids and derivatives (over 65%) were the main SCGAE compounds contributing to significant antioxidant (EC50DPPH = 1.04 mg/mL) and antimicrobial activity against Gram-positive bacterium (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli, Salmonella enterica, Klebsiella pneumoniae, Vibrio anguillarum, and Vibrio parahaemolyticus), and a yeast (Candida albicans) with a minimal inhibitory concentration of 0.06-0.13 mg/mL. Incorporating SCGAE at 0.5, 0.75, and 1% enriched DWPS meat with phenolics (TPC was between 92.38-116.65 mg GAE/100 g) and antioxidants (7.65-19.86 mg AAE/100 g) in a dose-dependent manner while increasing pigments level. Samples stored under vacuum exhibited higher antioxidant levels than positive and negative controls. SCGAE 1% reduced the microbial load (TVC, CB, and LAB) significantly up to 90% under different storage conditions. Scanning electronic microscopy showed a dense and uniform coating of SCGAE, improving DWPS antioxidant and antimicrobial properties, flavor, and acceptability. To conclude, SCGAE is a promising natural alternative to synthetic food preservatives, improving phenolic content, antioxidant activity, and microbiological quality of preserved shrimp.