Onion extract rich in organosulfur compounds as a clean-label preservative for ready-to-eat hummus

In recent years, consumer demand for ready-to-eat (RTE) foods has significantly increased. Among these, Mediterranean-origin products such as hummus have gained widespread popularity. This study evaluated the antimicrobial effect of a standardized onion (Allium cepa) extract containing 8% organosulfur compounds (mainly thiosulfinates and related derivatives) as a natural preservative for RTE-hummus. Firstly, the in vitro antimicrobial activity was assessed against key food-borne pathogens and spoilage microorganisms, including Escherichia coli, Listeria monocytogenes, yeasts and filamentous fungi. The results demonstrated that the onion extract exhibited significant antimicrobial activity. To validate this antimicrobial potential, the extract was added as an ingredient in hummus, to assess its impact on product shelf-life and quality during storage at 4°C for 28 days. In addition, a challenge test was performed using Zygosaccharomyces bailii, L. monocytogenes and E. coli inoculated at an initial level of 4 log CFU/g. A positive control sample was inoculated with each microorganism without the use of onion extract and a reference sample was treated with a traditional preservative (potassium sorbate). The findings in the food model confirmed the strong in vitro antimicrobial activity, demonstrating that the extracts effectively delayed spoilage, especially yeast proliferation, contributing to shelf-life extension. The extracts significantly reduced Z. bailii populations compared to the inoculated control, outperforming the effect of potassium sorbate. The onion extract was also able to control both L. monocytogenes and E. coli. After 28 days of refrigerated storage, microbial reductions up to 4 log CFU/g compared to the corresponding positive controls were shown. These findings highlight the potential use of onion-derived organosulfur compounds as clean-label preservatives in hummus, with an organoleptic impact fully compatible with the product’s aroma profile. This research was carried out within the framework of the InnoSol4Med project. The InnoSol4Med is part of the PRIMA program supported by the European Union.