Effects of clove (Syzygium aromaticum) extract on antibacterial activity, phytochemical properties, and storage quality of flavored milk beverages.

Abstract

The antibacterial efficacy of clove extracts (Syzygium aromaticum) prepared using 80% ethanol and water against pathogenic bacteria was evaluated, along with the development of a novel antimicrobial milk beverage incorporating these extracts. Seven flavored milk beverage (FMB) treatments were prepared: a control and 6 with clove extracts at 0.5%, 0.7%, and 1% for each solvent. The effects on physicochemical, phytochemical, antioxidant, microbiological, color, and sensory properties were assessed over 15 d of storage at 4 ± 1°C. The ethanolic clove extract exhibited significantly higher antimicrobial activity against Staphylococcus aureus, Listeria monocytogenes, E. coli O157, Salmonella typhi, and Klebsiella pneumoniae, with inhibition zone diameters of 20 mm, 21 mm, 20 mm, 19 mm, and 20 mm, respectively, compared with the aqueous extract. On d 0, the sample of 1% ethanolic clove extract (FMB3) showed the highest proximate analysis values, including TS (22.41%), protein (4.61%), fat (4.58%), ash (0.97%), and gross energy (108.65 Kcal). It also showed the highest pH (6.7), flavor score (19.20), texture score (9), and overall acceptability score (39.50) and the lowest carbohydrate content (12.27%), lightness value (69.60), and yellowness value (97.47). Over the 15-d storage period, the total phenolic content (TPC), total flavonoid content (TFC), and total antioxidant capacity (TAC) increased, with the FMB3 sample exhibiting the highest TPC (58.70 mg/100 g), TFC (46.15 mg/100 g), and TAC (487.10 mg/100 g). All beverages remained free from yeasts and molds, and FMB3 exhibited the lowest bacterial count (5.13 log cfu/mL). The results indicate that ethanolic clove extract effectively inhibits spoilage and pathogenic organisms and enhances the sensory and functional properties of FMB. This finding offers a promising approach for improving the quality and safety of dairy products.