Abstract
Background:
Bread spoilage caused by molds, such as Penicillium spp., Aspergillus niger, and Aspergillus ochraceus, shortens shelf life and leads to consumer dissatisfaction, financial losses, and health risks from mycotoxins. Molds can also produce various mycotoxins associated with diseases like cancer and diabetes, as well as damage to internal organs. Recently, there has been increased interest in using natural alternatives to synthetic antifungals to ensure food safety and meet consumer demand for clean-label ingredients.

Aim:
This study aimed to assess the in vitro effect of Libyan raw propolis (LRP) against molds associated with spoiled bread.

Methods:
Aspergillus niger, Penicillium spp., and A. ochraceus were isolated and tested in this study. The effectiveness of LRP was assessed by measuring its inhibitory effects on these molds.

Results:
The frequency of molds indicated that Penicillium spp. was the most prevalent isolate (23.7%), followed by A. niger (20.66%). At a concentration of 68 mg/ml, LRP inhibited A. ochraceus by 88.8% and Penicillium spp. by 33.3%, demonstrating a clear dose-dependent antifungal effect. Aspergillus ochraceus was found to be more susceptible to LRP.

Conclusion:
In this study, raw Libyan propolis showed strong in vitro inhibition of key bread-spoilage molds, suggesting that Libyan propolis could be a promising natural preservative for the baking industry. Given its notable effectiveness against molds such as A. ochraceus and Penicillium spp., future work should focus on optimizing propolis formulation, identifying optimal concentrations for various applications, and evaluating its performance under baking conditions. This knowledge could lead to the development of innovative preservation methods that align with consumer preferences for natural ingredients.

Key words: Libyan raw propolis; Spoiled bread; Anti-mold; Molds