Work

Microwave-assisted extraction of annatto: Effects of pH and time on antibacterial activity

Year: 2026

Type: article

Abstract: Annatto seeds possess antimicrobial properties, but extraction methods may degrade bioactive compounds. This study investigated the impact of pH-adjusted microwave-assisted extraction using distilled water on antibacterial activity to obtain safe food-grade extracts. Extractions were performed at pH values of 4, 7, and 9 for extraction times of2, 4, and 6min, using a microwave power setting of 100W. The antimicrobial activity of the extracts was assessed against Escherichia coli and Staphylococcus aureus through inhibition zone analysis and viable bacterial cell count reduction. In parallel, the total phenolic content of each extract was quantified to examine the correlations between phenolic concentration and antibacterial activity. The findings revealed that extraction at pH 4 for 2min yielded the most pronounced antibacterial activity with a minimum inhibitory concentration (MIC) of 5%. The application of a 20% annatto extract resulted in the lowest viable cell counts of both E.coli and S.aureus. Variations in pH and extraction time did not result in significant differences in total phenolic content, suggesting that antimicrobial efficacy may be influenced not only by phenolic concentration but also by the specific profile of active compounds.

Source: Czech Journal of Food Sciences

DOI: 10.17221/129/2025-cjfs

Authors: Isti Handayani, Aisyah Tri Septiana, Budi Sustriawan, Karseno Karseno

Institution: Jenderal Soedirman University

Language: English

Topic: Essential Oils and Antimicrobial Activity

Subfield: Food Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $609