Microbiological Evaluation of Raw Camel Milk and Improvement of its Keeping Quality

摘要

Forty samples of raw camel?ˉs milk were collected from different zones of Al-Ahsa area and analyzed to evaluate their microbiological quality and to identify predominating lactic acid bacteria (LAB) and the data were confirmed by the PCR based methods. Furthermore, the pathogens such as Staphylococcus aureus, Salmonella, Bacillus cereus, E. coli 0157:H7 and Listeria monocytogenus were detected. The following mean average of LAB and total viable counts (TC) were 4.9 and 1.3?á107 cfu/ml, respectively. While yeasts and moulds count were relatively lower (4.5 x103 cfu/ml). Coliform numbers were 7 ?á102 cfu/ml. Staphylococcus aureus was found in 30 % of samples while 0.4% of samples were Salmonella positive. Bacillus cereus, was located in 20% of the samples and the mean average count was 3.4 log cfu/ml. All samples tested were negative for E.coli 0157:H7 and Listeria monocytogenus. Results indicate the potential health risk of consuming raw camel milk under the present production conditions. Twenty-two LAB strains were isolated and identified as Lactobacillus plantarum, Streptococcus thermophilus, Lactobacillus rhamnosus, Lactococcus lactis and Enterococcus faecium. Lactoperoxidase enzymes system (LPS) and essential oils (EOs) were used for improving the keeping quality of camel milk. The result revealed a highly significant effect of lactoperoxidase (LPS) as milk preservative. Use of (LPS) at final concentration 15ppm extend the shelf life of camel milk up to 15 days in compared to the control samples and the effect was increased when the samples were stored at low temperature (4??C). Total viable count was significantly decreased by activation of the (LPS) in raw camel milk. Cold treated camel milk samples at (4??C) with (LPS) were found to show an increase in the shelf life of 15 to 21, compared to 3 to 7 days for control samples. Data showed that 0.2ppm of Marjoram or Sage as (EOs) could be recommended for increasing the shelf life of camel milk up to 21days, but with lesser extent than the use of (LPS). Sage oil was more acceptable and has stronger feect than Marjoram oil which was nearly similar to the control. The influence of oils as preservative was increased with use of cooling. However, it could be recommend that by using natural plant oils as a way to save the food especially with availability of plants in the areas of milk production as well as improving their healthy value. It could be concluded that the LPS and EOs have a positive effect on the keeping quality of camel milk by expanding its shelf life.