Effect of Pomegranate Seed Oil on Certain Food Spoilage Microorganisms and its Role in Shelf Life of Cream.

This study aims to investigate the effect of pomegranate seed oil on the quality of cream during cold storage ( 4ºC). Cream was divided into four equal portions, the first portion with no additives served as a control. For the other three portions, 0.5, 1.0 and 1.5% of pomegranate seed oils were added individually to each portion of cream. The cream was then stored in refrigerator (4ºC) to 45 days. Results showed that the total soluble solids, fat and protein of sour cream increased with the increase of the added pomegranate seed oil, but the carbohydrate content was decreased . The results also reveal that the use of cream containing pomegranate seed oil (PSO) led to increase the peroxide value and refractive index during cold storage. This was more remarkable in cream containing pomegranate seed oil at the higher level of concentration (1.5%). The same data showed that the peroxide values gradually increased, while iodine values showed gradual decrease during cold storage . The main fatty acid of pomegranate seed oil identified by GC was punicic acid (84.59%). The saturated fatty acids, mono-unsaturated acids and polyunsaturated fatty acids were 6.33, 5.8 and 87.87 % respectively.Antimicrobial effect of different concentration of pomegranate seed oil were studied on four bacteria (E. coli , S. aureus , B. cereus and Salmonella typhimurium) and two fungi (Aspergillus niger and Candida albicans) . Results indicated that the higher antimicrobial effect was detected against yeast and mold ( from 20-23 mm). Also , data showed that cream samples fortified with different concentration of pomegranate seed oil were free of libolytic bacteria and yeast mold, compared to control (fresh cream) till one month. Higher scores for organoleptic attributes were achieved for cream containing 0.5% pomegranate seed oil till 30 days . It could be seen that pomegranate seed oil can reduce the oxidative degradation of fatty substances as well as to inhibit the growth of spoilage microorganisms.