Effect of seasonal variation and storage period on the insect infestation of Ras cheese

Twenty samples of green Ras cheese were collected at random from different local supermarkets at Giza City each season through one year. Cheese samples were stored for ripening at 15C +/- 2C till 6 months, and examined months for infestation with insects, also analyzed for moisture, titratable acidity%, salt%, fat% and total protein content through the period of storage. Obtained data were analyzed statistically. The obtained results recorded that main insects of cheese samples are Lasioderma serricorne, Dermestes maculatus and Tribolium confusum during the storage period. The infestation percentage of samples with insects was gradually increased with progression of storage period in all seasons with different values; however, the highest percentage of infestation was recorded in summer cheese samples [68.3%] at the end of storage; while the lowest percentage [15.0%] was noticed in winter cheese samples. No correlation between the chemical composition of cheeses and percent of insects infestation was recorded

Influence of salt concentration on survival of listeria monocytogenes during Domiati cheese ripening

Domiati cheese was made from a pasturized mixture of cowbuffalo milk [1:1], which was inoculated with Listeria monocytogenes and with different ratio of sodium chloride 6 and 9 and 12%. Aportion of the cheese was held in a refrigerator [5-7°] while another portion was held at room temperature [20-22°]. Pickled cheese was analysed microbiologically [aerobic bacterial count, lactic acid bacteria count and numbers of L. monocytogenes], as well as chemically for moisture, total acidity, sald content, soluble nitrogen/total nitrogen and formol ripening index] were done every 15 days for a period of 3 months. Results obtained showed that numbers of total bacteria, lactic acid bacteria, and L. monocytogenes increased in pickled cheese stored at room temperature to a greater extent than in cheese held at 5?7° for all different levels of salt concentration. During holding of cheese, the numbers of L. monocytogenes decreased gradually throughout the entire period of storage. A decrease in the population of L. monocytogenes was correlated with an increased in titratable acidity and also with an increase in salt concentration in cheese milk