P1-124 Extending the Shelf Life and Eliminating Salmonella spp. and Escherichia coli in Tahini-based Dressing

Monday, July 29, 2013
Exhibit Hall (Charlotte Convention Center)
Zeina Kassaify, American University of Beirut, Beirut, Lebanon
Mohamad Abiad, American University of Beirut, Beirut, Lebanon
Introduction: Tahini dressing is a popular Middle Eastern product prepared from sesame-paste (Tahini), water and citric acid. It has a short shelf life of 2 days at room temperature and 5 days when refrigerated, with high risk of Salmonella spp. contamination. Developing effective preservation means with minimal heat treatment is essential due to the high fat and low moisture content of tahini.

Purpose: Investigate a preservation method to extend the shelf-life of tahini dressing stored at 4° and 25°C and eliminate tolerant species of Salmonella and Escherichia coli while maintaining good organoleptic properties.

Methods: Samples were thermally treated at 85°C/15 minutes or 110°C/7 minutes, stored at 4° and 25°C, then analyzed in duplicates at days 0, 7, 14, 28 and 62 for total aerobic counts, E. coli, coliforms, yeasts and molds. Another batch was thermally treated at 85°C/15 min and inoculated with 103 CFU/ml of Salmonella spp. and E. coli strains isolated from tahini. Citrox (2%), sodium benzoate (5 mg/ml) and potassium sorbate (5 mg/ml) were individually added. Samples were stored at 25°C and analyzed for surviving bacteria, peroxidase value, awand pH at days 0, 7, 14, 30, 45, and 60.

Results: The shelf-life of tahini dressing was extended to 2 months with both thermal treatments stored at 4°C and one month with milder treatment stored at 25°C. Higher thermal treatment negatively affected the texture. Sodium benzoate and potassium sorbate completely eliminated Salmonella spp. and E. coli, whereas Citrox was ineffective.  PV, awand pH remained stable with treatments and storage.

Significance: Mild heat treatment combined with lower storage temperature and sodium benzoate and potassium sorbate extended the shelf life of the dressing extensively, inhibited contaminating pathogens while maintaining product quality. This allows better local and international marketability and more confidence in a widely consumed dressing.