Background: Dairy products are highly susceptible to microbial spoilage due to their rich nutritional values, leading to reduced shelf life and economic losses. Increasing consumer demand for natural and chemical free preservatives has driven research toward plant-based bio-preservatives with antimicrobial properties.

Objective: The present study aimed to evaluate the efficacy of selected plant extracts as natural bio-preservatives against common dairy spoilage microorganisms.

Method: Plant extracts such as neem (Azadirachta indica), tulsi (Ocimum sanctum), and garlic (Allium sativum) were prepared using both aqueous and ethanolic extraction methods. The antimicrobial activity was assessed against selected dairy spoilage microorganisms, including Escherichia coli, Staphylococcus aureus, and Pseudomonas spp. using agar well diffusion and minimum inhibitory concentration (MIC) methods. The effectiveness of extracts was further evaluated in a model dairy system under refrigerated storage conditions.

Results: All plant extracts exhibited inhibitory effects against the tested microorganisms, with garlic extract showing the highest antimicrobial activity, followed by neem and tulsi. Ethanolic extracts demonstrated significantly higher inhibition zones compared to aqueous extracts (p < 0.05). Application of plant extracts in the dairy model system resulted in a noticeable reduction in microbial load and extended shelf life.