الفهرس 
Raw milk qualityOnly 14 pages are availabe for public view
 |  | from | 32 |  |  |
| | | from | 32 | | |
Abstract
IV. SUMMARY AND CONCLUSION
The high acid milk (HAM) is rejected from dairies as it is unfit for pasteurization and distribution in the fluid form. The dairies are, therefore facing a constant problem of disposing off the HAM. Such milk is either rejected or penalties imposed on supplier and producer, which is an impediment in the growth of dairy industry. Thus, proper utilization of such large quantity of HAM is one of the greatest needs of the dairy industry. It is very important, particularly when there is an acute shortage of milk and milk products.
Attempts have been made to the manufacture of some dairy products such as margarine, ice cream, butter and casein acid. But it has not been any systematic attempts to use the high acidity of the milk Mozzarella cheese preparation procedure.
Mozzarella cheese is one of the types of cheese Italian origin which is within the range of the pasta filata, which means in Italian ”cheese with plastic clot” resulting from puddle clot in hot water. The back label this cheese Mozzarella to Italian word called ”Mozza” and dating back to the final form it takes cheese during configuration (Figure pear) has no cheese Mozzarella in the form of different forms, including meningococcal or oval or templates or grated or sliced or braided This is a cheese from half varieties dry, one of more types of cheese production in recent years and the most famous of which is characterized by a set of natural qualities that make uses and wide in the field of pizza or bread, pies and most important of these features, the ability to fusion and configure static layer of rubber with a high degree when placed on the surface of the pie pizza and exposure to high temperature.
In Egypt it increased production of cheese Mozzarella significantly due to increased demand and the spread of fast food outlets such as ready-made pizza shops. Therefore, it increased the amount of production of this product to meet the increasing demand. The advantage of this type of cheese and certain natural properties that must be maintained in the event of any change to the industry
The purpose of this study was to make Mozzarella cheese using high milk acidity of taste acceptable good recipes and to take advantage of the natural acidity of the milk and the resulting lack of efficiency of the cooling loop during transport and high temperatures, especially in the summer and study the effect of the pH values of the milk on some chemical composition, microbiological examination, and physical properties of Mozzarella cheese output during storage period.
Mozzarella cheese is a good source of nutrients namely protein, fat, minerals and vitamins. Investigation was carried out to develop an appropriate technique to utilize high acid cow milk (HAM) for manufacture of Mozzarella cheese. Therefore, this study has three main parts as follows:
Part I: Some physicochemical and bacteriological examination of high acid milk quality was evaluated in order to determined changes occurs in milk. Fresh and high acid milk (has been left at room temperature for 24 hours )were used for this part. Physicochemical and bacterial quality was evaluated.
1- The total bacterial count , coliform count and psychrotrophic bacteria of fresh milk was lower than that of High acid milk.
2- lactose content and pH value were higher in fresh milk than in high acid milk
3- The titratable acidity had a tendency to increase by the time.
Part II: Utilization of high acid milk in manufacture of Mozzarella cheese:
The milk was divided into three parts A,B and C by the manufacturing procedures. First part (A): four types of Mozzarella cheese were manufactured, using only rennet. Second part (B): five types of Mozzarella cheese were manufactured, using a starter culture and rennet, as in conventional manufacture of the control cheese .Third part (C): one type of Mozzarella cheese were manufactured, without using a starter culture or rennet. And this parts of Mozzarella cheese was divided according to the age of the milk at setting(0,4,6,12and 24h). The resultant cheese samples was analyzed for chemical, physical, rheological and microbiological properties.
1- Cheese samples prepared by only use of rennet showed higher L-values than those prepared by use of starter culture and rennet.
2- The yield value for Mozzarella cheese remarkably decrease by increase the age of the milk(pH decreasing ), the yield of cheese samples B (0,4and 6h) were higher than in cheese treatment A .
3- all tested cheese samples showed recoverable elasticity and did not reached the fracture state at the end of the deformation.
4- The total bacterial count , coliform count and psychrotrophic bacteria of High acid cheese was higher than that of fresh cheese.
Part III: Physiochemical and rheological properties of Mozzarella cheese made utilizing high acid milk:
In this part , six types of Mozzarella cheese were selected(6,12and 24h). First part (A) three types of Mozzarella cheese were manufactured, using just rennet. Second part (B) three types of Mozzarella cheese were manufactured, using a starter culture and rennet, as in conventional manufacture of the control cheese .
1- The data indicated that the highest ratio of TS, fat and protein lost in the whey resulted during the manufacture of cheese B24 treatment. Cheese A12 had remarkably the highest level of protein and TS, (30.93 and 53.31, respectively ).
2- The fat content of the B12, A24 cheeses was remarkably higher than that of the B6, B24, A6 and A12 cheeses, which had a similar fat content.
3- Non remarkable difference was found in ash and salt content of all cheeses samples.
4- The results revealed that a gradual increase was observed in acidity value during the storage of all treatments.
5- The data indicated that cheese (A6) treatment had the highest in meltability ,oil separation and free oil values while cheese B24 possessed the lowest value. As the time period of the storage period increased, these values in all the cheeses increased remarkably but the trend of increase remained the same.
6- The stretch length of the tested cheese samples ranged between 58.2 to 280 mm, as seen in the result , the highest value was in cheese A12, followed by A6 and B12(280.8,271.2 and 114 respectively ).
7- The lowest hardness, cohesiveness, springiness values and consequently the chewiness value (mouth work energy) were recorded for the cheese values prepared from milk with start pH of 4.6 .
8- There is a relationship between gumminess and chewiness values. The higher values of the chewiness, are also the higher values of the gumminess of the tested cheese samples.
9- The hardness values in cheese samples were obtained by 60% compression at least double those obtained for 25% compression.
10- On other side, the cohesiveness and springiness values were drastically decreased by 60% compression compared with those obtained by 25% compression in cheese samples.
11- No remarkable differences has been observed in both chewiness and gumminess values between samples of cheese compressed by 60% and those compressed by 25%.
It could be generally concluded from the obtained results that there were a remarkable difference between Mozzarella cheese manufacturing with different rennet and starter culture combined. Evidenced by the obtained results in this study it: -
1. Some of the samples that have been manufactured after 12 hours of age milk were not acceptable in some properties , which was not conform to the specifications and this is due to the high acidity of milk.
2. Deliver the pH values of the thrombus limit to 5.1 during the manufacture can get acceptable of Mozzarella cheese, depending on the acidity degree of milk.
3. Increase in acidity of milk leads to increase the fat and protein lost during manufacturing of Mozzarella cheese.
4. Manufacturing Mozzarella cheese at 6 hours without adding starter culture gave the cheese with a very good rheological properties.
Thus, the results of the study represent a scientific as well as it: - 1. Contributed to the development of the problem of the large quantities of milk, which are often exposed to high acidity solutions as a result of long-distance and after assembly and high temperatures centers and inefficient cooling loop.
2. Possibility for manufacturing Mozzarella cheese based on the natural acidity develop of milk without adding a starter culture and get a cheese taste good and acceptable and affordable properties.
3. This study is the one attempt to utilized the high acidity of cow’s milk in Mozzarella cheese manufacture.
4. Using tensile device as a new technique to measurement the cheese stretchability.