Effect of Chemical Preservatives on the Shelf Life of Hummus during Different Storage Temperatures

Different levels of potassium sorbate (PS), sodium benzoate (SB) and sodium metabisulfite (SM) were added individually or in combinations to hummus, which was acidified to pH 4.5, before storage at 5, 10 and 15°C. Addition of 0.05% and 0.1 % PS increased the shelf life of hummus to 35 and 49 days, respectively, while it was 15 days for the control hummus without preservatives. The concentrations 0.1% and 0.15 % of SB were needed to achieve the same shelf life of PS treated hummus. Sodium metabisulfite was the most effective preservative since adding 0.05% and 0.1% was associated with shelf lives of 63 and 77 days, respectively. Combinations of 0.05% of each of SM and PS and of ≥ 0.05% SM and ≥ 0.15% SB extended the shelf life of hummus to 90 days. Keeping hummus at 10 and 15°C reduced the shelf life for all levels and types of preservatives used. Lactic acid bacteria (LAB) formed the predominant microorganisms at the spoilage onset for the control, PS and SB treated hummus; Enterobacteriaceae and both yeasts and molds remained significantly (p ≤ 0.05) at lower counts than LAB. In all SM treatments, LAB, yeasts and molds were predominant while Enterobacteriaceae remained at significantly (p ≤ 0.05) lower counts