الفهرس 
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Abstract
SUMMARY AND CONCLUSION
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.
Hassan H. Mohamed, M.Sc., 2015
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SUMMARY AND CONCLUSION
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 that of triangle or cup form samples.
Hassan H. Mohamed, M.Sc., 2015
PART ІІ: Manufacture and properties of processed cheese spread cooked at different procedures
This part of study has been conducted to investigate the properties of processed cheese spread produced at different cooking process. Processed cheese spread was produced by using traditional process (95 ̊C/2min), or UHT process (140 ̊C /20sec.). The produced spreads were evaluated for chemical, physical and sensory properties when fresh and after 1 monthly up to 6 months of storage. The results obtained can be summarized as follows:
1. The moisture contents were reduced in all treatments whether stored at 5ºC or 25ºC. The decrease in moisture contents was more pronounced in processed cheese samples cooked at 95ºC and stored at 25ºC up to 6 months.
2. Fat/DM percentage in processed cheese products showed similar trend as moisture content.
3. Total nitrogen (TN) percent was increased in the samples during storage but this effect was more noticeable in traditional treatment than UHT treatment.
4. Soluble nitrogen (SN) contents in processed cheese spreads were affected by cooking temperature. UHT processed cheese showed slightly lower (SN) contents than that of traditional product cooked at 95ºC.
5. Salt percent increased with prolonging the storage period up to six months. The salt percent was higher in the samples of traditional processed cheese (95ºC) especially when stored at 25 ºC than that of UHT treatment.
6. The cooking method of processed cheese has no effected on lactose content. Storage of cheese samples significantly affected the lactose content was not affected by the cooking method of the processed cheese. Storage of the cheese samples significantly affected the lactose content as it decreased with increasing the storage temperature and period.
Hassan H. Mohamed, M.Sc., 2015
7. Processing cheese at different cooking methods has no effect on pH values. The pH values were decreased being more noticeable in the sample stored at 25 ̊C±2. Acidity was content also increased at the level of all the samples stored at room temperature
8. Processed cheese meltability was affected by heat treatments and storage periods.
9. The oil separation index of processed cheese was highly significant in traditional processed cheese samples than UHT samples.
10. Protease activity increased during storage in all treatments being higher in samples stored at 25ºC±2.
11. Lipase activity was increased in all treatments during storage being pronounced in traditional processed cheese samples stored at 25 ̊C±2 compared with UHT processed cheese samples stored at the same temperature.
12. Total aerobic viable bacterial counts increased in all treatments during storage. The increase was more pronounced when the processed cheese was stored at 25 ̊C±2.
13. Anaerobic viable count was decreased during storage in all processed treatments being more pronounced in UHT cheese.
14. Hardness, chewiness, gumminess springiness cohesiveness were increased in all samples, during storage periods.
15. UHT processed cheese showed much better quality attributes than traditional processed cheese samples. UHT processed samples were shinier, and had well body & texture with clean and pleasant flavor. The sensory scores gradually decreased in both cheese types along the storage period showing the lowest scores at the end of storage period, either at 5ºC or 25ºC.