SUMMARY AND CONCLUSION

White soft cheese is the most famous cheese in Egypt and Middle East. Most of the consumers preterit be high salt “Domiatti cheese” or low salt “Thalaga cheese”. In 1990, “The Egyptian Organization For Standardization and Quality control” issued the Egyptian Standard number 1867 for the year 1990 which concern the Soft cheese with vegetable fats. On this   standard, types of soft cheese appeared during the past ten years, such as ; “Ghasala” cheese. The “Ghasala” cheese is still existing till today. That is why it is important to study and control it.

This study is divided into two main parts as follows:

I – Survey of “Ghasala” cheese samples produced by small local factories:

Six local factories for making “Ghasala” cheese in Damietta, El-Dakahlia and El-Sharkia governorates were choosen to evaluate their product and also the ingredients used in making this type of cheese. These samples were referred to as A, B, C, D, E and F. Cheese samples were divided into two groups being stored in refrigerator at (5-10ºC) or at room temperature (25-30ºC), respectively. Three replicates, either from the constituents or the final products were examined chemically, microbiologically and the final products were further evaluated organoleptically. Analysis were carried out in the fresh products at 0-time and periodically during period 30 days of storage.

1. The TS% decreased gradually for all samples during storage (30 days in 25-30ºC) also, in cheese samples stored at (5-10ºC) decreased in all cheese samples up to 21 days of storage. The decrease of total solids content with progression of storage period was due to the ability of casein complex to retain some of whey under refrigeration.
2. The pH of the cheese samples, decreased gradually as the storage process advanced at 25-30ºC up to 30 days and at 5-10ºC up to 21 days. Changes in pH values and acidity depend on the changes in lactose, proteins and fats in cheese samples during storage. Mainly the lactose plays an important. The amino acids, peptides, peptones, amines and fatty acids formed during the protein and fat breakdown result in some changes in pH of cheese samples.
3. The  fat content of cheese samples was low in fresh cheese samples and increased after 15 days ; then gradually decreased during the storage period at 30 days in all samples at 25-30ºC, while at 5-10ºC there was decreasing in fat content in all treatments during the storage period compared with the fresh sample. The percentage of fat and fat / dry matter of white cheese samples stored at refrigeration temperature and at room temperature were decreased along the storage periods and this may be due to increase of moisture.
4. The average salt content increased in cheese samples stored at 25-30ºC during the first 15 days then decreased in all samples until the end of storage period (30 days) while, the average salt content in cheese stored at 5-10ºC decreased along the storage period up to 21 days.
5. The TN content increased at the end of storage period in cheese stored at room temperature until 21 days then decreased after the end of storage period (30 days), but increased in samples stored at refrigeration temperature until the end of storage period (21 days). The differences between the samples are due to the differences in moisture and salt contents.
6. The SN values were increased along the storage period in all samples at room temperature and refrigeration temperature, but an increasment in SN at refrigeration temperature was more than at room temperature, this might be due to the increasing of moisture and decrease in acidity. As a result, SN increased and it is leaked out into whey.
7. The NPN values were increased gradually along the storage period in all samples at room temperature and refrigeration temperature, this might be due to phenomenon imbuebation.
8. When cheese stored at 25-30ºC the concentrations of the soluble tyrosin and tryptophan were increased those stored at 5-10ºC.
9. Total bacterial count of cheese stored at room temperature was more those that stored at refrigeration temperature.
10.  All cheese samples tended to reduce the sporeforming bacterial counts by extending the storage period whether under low or high temperature, except after 21days in refrigeration temperature and 30 days at room temperature as the maximum numbers of aerobic spore formers were attained. Meanwhile, the final products aged (21 days at refrigeration temperature and 30 days at room temperature) contained the minimal numbers.
11. The average values of counts of mould and yeasts were in gradually increased along at room and refrigeration temperatures.
12. The Coliforms bacteria were not found in all samples.
13. The Staphylococcus bacteria of cheese stored at room temperature decreased more than that stored at refrigeration temperature, but all positive samples were not coagulum of blood.
14. The psychrophillic bacteria of cheese stored at room temperature was more than that stored at refrigeration temperature and the thermophillic bacteria count of the cheese in all samples decreased as the storaging process advanced.
15. The  percentage  of loss in the weight of “Ghasala” cheese sample after twenty one days at refrigeration temperature were 34.80, 35.90, 32.60, 34.20, 36.10, and 37.40 % for A, B, C, D, E and F, respectively. On the other hand, after 30 days storaging at room temperature. The loss of samples  weights were 50.40, 57.30, 45.20, 43.20, 51.40 and 58.60%, respectively.
16. The results showed that the total score in fresh samples were 78, 81, 85, 80, 73 and 73 for samples A,B,C,D,E and F, respectively. The total score increased in cheese samples stored at refrigeration temperature during first 7 days then decreased in all samples until the end of storage period (21 days). While, the total score in cheese samples stored at room temperature decreased along the storage period (30 days). At the end of 30 days storage at room temperature, the total score were 41, 43, 44, 43, 35 and 32 for samples A,B,C,D,E and F, respectively. At 21 days under refrigeration temperature the total score were 55, 51, 56, 46, 45 and 33 in the same order.       

II- An Attempt to improve the “”Ghasala” cheese-making methods:

1. 1.     Effect  of  Homogenization  (150 bar)

During the course of this part, the same ingredients (C) (in part I ) were used to make soft cheese by using the homogenizer (150 bar) to blend the constituents instead of washing machine. The cheese made in this treatment was referred to as G. Comparison of the chemical and microbiological as well as organoleptic evaluation of the resultant cheese were carried out by cheese made with the previously described method “Ghasala” cheese, which was referred to as C. Analysis were also periodically carried out at refrigeration and at room temperature. 

1. After 30 days storage at room temperature, the TS % decreased to 39.40 and 38.20 % for “C” and “G”, respectively. On the other hand, the TS% content in cheese samples stored at refrigerator decreased to 35.60, and 35.00 % after the end period of storage (21 days) in the same order. Total solids content in cheese samples stored at (5-10ºC) decreased in all cheese samples in 21 days after storage.
2. The pH of the cheese samples, decreased gradually as the storage process advanced.
3. The percentage of fat and fat / dry matter of white cheese samples stored at refrigeration temperature and room temperature were decreased along the storage periods.
4. The average salt content increased in cheese samples stored at room temperature during the first 15 days then decreased in all samples until the end of storage period (30 days) while, the average salt content in cheese stored at refrigeration temperature decreased along the storage period (21 days).
5. The TN content increased at the end of storage period in cheese stored at room temperature until 21 days then decreased after the end of storage period (30 days), but increased in samples stored at refrigeration temperature until the end of storage period (21 days).
6. The SN values were increased along the storage period in all samples at room temperature and refrigeration temperature, but increasing SN at refrigeration temperature was more than at room temperature.
7. The averages percent of NPN values were increased gradually along the storage period in all samples at room temperature and refrigeration temperature.
8. It was also noticed that when cheese stored at 25-30ºC the concentrations of soluble tyrosin and tryptophan were increased those when stored at 5-10ºC.
9. Total bacterial count of cheese stored at room temperature was more than those stored at refrigeration temperature.
10. The Staphylococcus bacteria of cheese stored at room temperature decreased more than those stored at refrigeration temperature. But, all positive samples were not coagulum of blood.
11. All cheese samples tended to reduce the sporeforming bacterial counts by extending the storage period whether under low or high temperature, except after 21 days at refrigeration temperature and 30 days at room temperature as the maximum numbers of aerobic sporeformers were attained. Meanwhile, the final products aged (21 days at refrigeration temperature and 30 days at room temperature) contained the minimal numbers.
12. The average values of counts of mould and yeasts were in gradual increase along at room and refrigeration temperature.
13. The coliforms bacteria not found in all samples.
14. The psychrophillic bacteria of cheese stored at room temperature decreased more than that stored at refrigeration temperature. But, the thermophillic bacteria count of the cheese in all samples decreased as the storaging process advanced.
15. The total score of organoleptic properties increased in cheese samples stored at refrigeration temperature during the first 7 days then decreased in all samples until the end of storage period (21 days). While, the total score in cheese samples stored at room temperature decreased along the storage period (30 days). At the end of 30 days storage at room temperature, the total score were 44 and 46 for samples control without homogenization “C” and in cheese made with homogenization 150 bar “G” respectively. At 21 days under refrigeration temperature, the total score were 56 and 50 in the same order.

1. 2.     Effect of Heating Constituents To 85ºC. For 18 sec. 

Two treatments were carried out in this part. Treatment (H) in which the constituents were subjected to heating at 85C for 18 sec. followed by cooling to 45C and cheese was made by the previously mentioned method. Control cheese (C) was made by the method described for making “Ghasala” cheese. 

1)      The control sample was dissolved under this storage condition after 21 days at refrigeration temperature and after 30 days at room temperature, but the sample made with heat treatment 85ºC/18 sec - 45ºC dissolved under this storage condition after 45 days at refrigeration temperature and after 60 days in room temperature. TS% in cheese samples stored at 5-10ºC, decreased in cheese sample “C” in 21 days andsample “H” in 45 days after storage.

2)      The pH of the cheese samples, decreased gradually as the storage process advanced.

3)      The percentage of fat / dry matter of white cheese samples stored at refrigeration temperature and room temperature were decreased along the storage periods.

4)      The average salt content decreased in all samples until the end of storage period (30 days in sample “C” and 60 days in sample “H”) while, the average salt content in cheese stored at 5-10ºC decreased along the storage period (21 days in sample “C” and 45 days in sample “H”).

5)      The TN, SN, NPN, the soluble tyrosin and tryptophan contents were increased gradually after the end of storage period (30 days in sample “C” and 60 days in sample “H”) at room temperature and (21 days in sample “C” and 45 days in sample “H”) at low temperature.

6)      Total bacterial count of cheese stored at room temperature was more than those stored at refrigeration temperature.

7)      The Staphylococcus bacteria was found in this type of cheese in sample “C”, but not found in sample “H”. Generally speaking, all positive samples were not coagulum of blood.

8)      All cheese samples tended to reduce the sporeforming bacterial counts by extending the storage period whether under low or high temperature, except after (21 days in sample “C” and 45 days in sample “H”) in refrigeration temperature and (30 days in sample “C” and 60 days in sample “H”) at room temperature as the maximum numbers of aerobic sporeformers were attained. Meanwhile, the final products aged (21, 45 days in refrigeration temperature and 30, 60 days at room temperature) contained the minimal numbers.

9)      The presence of mould and yeasts in the experimental cheese gradually increase up to the end period.

10) The Coliforms bacteria were not found in all samples.

11) The results showed that the total score in fresh samples were 85 and 88 for “C” and “H” respectively. The total score increased in cheese samples stored at (5-10ºC) during first 7 days then decreased in all samples until the of end storage period (21 days and 45 days). While, the total score in cheese samples stored at (25-30°C) decreased along the storage period (30 days and 60 days). At the end of 30 days storage at (25-30°C), the total score were 44 and 70 for “C” and “H”, respectively, and after 60 days were 62 in sample “H”. At 21 days under refrigeration temperature the total score were 56 and 84 in the same order, and after 45 days were 55 in sample “H”.

1. 3.     Effect homogenization (150 bar) and heat treatments at 85ºC.for 18 sec.

Three treatment were carried out in this section. Treatment “G” in which using the homogenizer (150 bar), treatment “H” in which the constituents were subjected to homogenization (150 bar) at 60ºC and heating at 85ºC for 18 sec., followed by cooling to 45ºC and cheese was made by the previously mentioned method. Control “C” was made by the method described for making “Ghasala” cheese.

1)      The control sample “C” and sample “G” was dissolved under this storage condition after 21 days at refrigeration temperature and after 30 days at room temperature, but the other sample “H” (made with heat treatment 85ºC/18 sec - 45ºC) dissolved under this storage condition after 45 days at refrigeration temperature and after 60 days at room temperature.

2)      Generally TS%, pH values, fat, fat / dry matter and salt content of the cheese samples decreased gradually as the storage process advanced.

3)      The TN%, SN%, NPN%, the soluble tyrosine and tryptophan content increased gradually at different temperature examined for storage.

4)      Total bacterial count of cheese stored at room temperature was more than those stored at refrigeration temperature.

5)      The Staphylococcus bacteria were present in samples “C” and “G”. All positive samples were not coagulum of blood. On the other hand, the staphylococcus bacteria were not found in sample “H”.

6)      Cheese samples tended to reduce the sporeforming bacterial counts by extending the storage period whether under low or high temperature, except after (21 days in sample “C”, “G” and 45 days in sample “H”) at refrigeration temperature and (30 days in sample “C”, ”G” and 60 days in sample “H”) at room temperature as the maximum numbers of aerobic sporeformers were attained. Meanwhile, the final products aged (21, 45 days in refrigeration temperature and 30, 60 days at room temperature) contained the minimal numbers.

7)      Mould and yeasts in the experimented cheese increased gradually at different temperature examined for storage.

8)      The Coliforms bacteria were not found in all samples.

9)      The Organoleptic properties of white cheese samples were evaluated during the storaging period. The results showed that the total score in fresh samples were 85, 81 and 88 for control sample “C”, “G” and “H”, respectively. The total score increased in cheese samples stored at refrigeration temperature during first 7 days then decreased in all samples until the end of storage period (21 days and 45 days). While, the total score in cheese samples stored at room temperature decreased along the storage period (30 days and 60 days). At the end of 30 days storage at room temperature (25-30°C), the total score were 44, 46 and 70 in the same order, and after 60 days were 62 in sample “H”. At 21 days under refrigeration temperature the total score were 56, 50 and 84 in the same order, and after 45 days were 55 in sample “H”.

1. 4.     Effect of Some Stabilizers.

Three treatments were carried out in this section. The ingredients used in making this type of cheese by using different stabilizers. Control samples “I” without any stabilizers and each of them was used at the rate “0.33%” on “Yone cream 300” in sample “J” and “moon song 2111” in sample “H”.

1)      TS%, pH values, fat, fat / dry matter and salt content of the cheese samples were decreased gradually as the storage process advanced.

2)      The TN%, SN%, NPN%, the soluble tyrosin and tryptophan content were also increased gradually at different temperature examined for storage.

3)      Total bacterial count of cheese stored at room temperature was more than those stored at refrigeration temperature.

4)      The average values of counts of mould and yeasts were in gradual increase along at room and refrigeration temperatures.

5)      The Coliforms bacteria  and The Staphylococcus bacteria were not found in all samples.

6)      The Organoleptic properties were evaluated of white cheese samples during the storaging period. The results showed that the total score in fresh samples were 87, 88 and 87 for control samples “I” and in cheese variants “J” and “H”,respectively. The total score increased in cheese samples stored at refrigeration temperature during first 7 days then decreased in all samples until the end of storage period (45 days). While, the total score in cheese samples stored at room temperature decreased along the storage period (60 days). At the end of 60 days storage at room temperature, the total score were 57, 62 and 57 for control samples “I” and in cheese variants “J” and “H”,respectively. At 45 days under refrigeration temperature, the total score were 49, 55 and 50 in the same order.

5.     Effect of substituting Vegetable oils with natural fats from buffalo’s milk

Two batches of white cheese samples were made by using the same blend with the exception of substituting varied amounts of the vegetable oils in the control “H” with the same weight of natural fat obtained from the buffalo’s milk in the experimental variants. For making the two experimental variants, the same above mentioned blend was prepared with the exception of substituting 10 and 20% vegetable oils in the control “H” with the same weights of natural fats from buffalo’s milk. The same ingredients “H” were used to make white cheese by using the substituting 10, 20 % vegetable oils “tekerlen” with natural fats from buffalo’s milk, the cheese made in this treatments were referred to as “K” and “L”, respectively.

1)     TS%, pH values, fat, fat / dry matter and salt content of the cheese samples were decreased gradually as the storage process advanced.

2)     TN%, SN%, NPN%, soluble tyrosin and tryptophan content were increased gradually at different temperature examined for storage.

3)     Total volatile fatty acids TVFA were estimated in white cheese samples stored at room temperature as well as at refrigerator. Gradually increased during storaging of all samples.

4)     Total bacterial count of cheese stored at room temperature was more than those stored at refrigeration temperature.

5)     The average values of counts of mould and yeasts were in gradual increase along at room and refrigeration temperatures.

6)     The Coliforms bacteria and The Staphylococcus bacteria were not found in all samples.

7)     The Organoleptic properties were evaluated of white cheese samples during the storaging period. The results showed that the total score in fresh samples were 87, 91 and 93 for control sample “H”, and in cheese variants “K” and “L”,respectively. The total score were increased in cheese samples stored at refrigeration temperature during first 7 days then decreased in all samples until the end of storage period (45 days). While, the total score in cheese samples stored at room temperature decreased along the storage period (60 days). At the end of 60 days storage at room temperature, the total score were 57, 61 and 62 for control sample “H”, and in cheese variants “K” and “L”,respectively. At 45 days under refrigeration temperature the total score were 49, 60 and 61 in the same order.

Recommendations:

ü Using Homogenization (150 bar) in this type of cheese.

ü Using heat treatment (85ºC 18 sec. – 45ºC).

ü Addition of  the stabilizer used in sample “H”.

ü Substituting 20 % vegetable oils with natural fats from buffalo’s milk.

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