CHANGES THAT OCCUR DURING STORAGE OF PROCESSED CHEESE AND THEIR EFFECTS ON PRODUCT QUALITY

Abstract

Processed cheese is one of the most popular types of cheese consumption in the world. Processed cheese consumption increased in Egypt in recent years, because it has a high nutritional value, ability to save for long periods at room temperature, great diversity of images and shapes, can consume in different forms (cheese blocks, strips, triangles etc.), cooked from various dairy products, in addition to its high economic revenue. Storage of processed cheese for long periods in the harsh conditions may cause regardless incomprehensible changes in spite of the thermally treatment during the manufacturing process. These changes may result spoke to cut the cheese quality output, leading to considerable material losses. For that, this study was conducted to find out the main reasons for the negative changes that occur in processed cheese during storage and thus attempt to reduce them to improve the quality of an important product and thus improve the economic returns and increasing the number of consumers. The study was conducted in two parts:

PART І: Survey of processed cheese in the Egyptian market: Twenty six processed cheese samples were collected randomly from different retails outlet in Egypt. The samples were classified depending on the fat source into two groups (milk fat, vegetable fat) and shape into three groups (triangles, cups, and blocks). All processed cheese samples were stored at 5ºC until required for analysis. The results obtained can be summarized as follows: Processed cheese samples contain milk fat: 1. Moisture content was higher in the formula of cup forms than that of triangle shapes 2. Processed cheese showed higher Fat/Dry Matter (F/DM) contents in cup samples than that of triangles samples except the Domty brand in cup form which had the lowest. Total nitrogen (TN) content of triangles forms was higher than that of cup forms. 3. The average of soluble nitrogen (SN) values in samples of cup forms was lower than that of triangle forms. 4. Values of salt/moisture in triangles were higher than that of cups. 5. The average values of the ash triangles sample was 4.56%, while the average of the cup samples 3.4%. 6. The average values of pH and acidity were 1.64 and 5.71% respectively in triangles samples while it was 1.85, and 5.72, respectively in cup form samples containing milk fat. 7. Meltability values were higher in cup form than triangles samples while the average value of oil index in triangle was higher than that of cup forms. Processed cheese samples contain vegetable fat: 1. Moisture contents of collected processed cheese with vegetable fats indicated that the samples in cup forms contained the highest and block form showed the lowest. 2. F/DM was highest in samples of cup forms and lowest in samples of block forms. 3. Total nitrogen values were higher in triangle samples, while a cup sample has the lowest. The highest soluble nitrogen content was showed in samples of cup forms, while block samples has the lowest. 4. The highest average ratio of salt/moisture was shown with surveyed samples in block form, while cup form showed the lowest. 5. Ash values were in the same line with salt / moisture. 6. Block processed samples showed lowest pH values with highest acidity content. 7. Some brands of block forms (Farag Allah, Teama, and Halayb) were not meltable and others showed very low meltability. The oil separation index of block form samples was lower than th