الفهرس 
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Abstract
Cheese sauce is a novel cheese product nowadays, not only for being an attractive appetizer but also for being perceived as a first course or a side dish and rather as an ingredient entire, meant to stand by itself. Cheese sauce can be used for wide range of dishes like macaroni and other pasta dishes and can create line – extension opportunities for breaded and battered products, such as chicken breasts, nuggets and fingers, in addition can be added to meat or barbecue dishes. Cheese sauce is not well established in Egyptian market even it can be a very good and cheap appetizer. Most of cited literatures were found in patents and hence, to our knowledge no enough information has been published regarding the manufacture and production of different types of cheese sauce so, this investigation was carried out in four parts and the obtained results can be summarized as follows :
Part I : Cheese sauce in the Egyptian market
Seven cheese sauces samples were collected from the Egyptian local market to investigate their properties and recognize the variations and differences among these sauces. All collected cheese sauces were imported not produced in Egypt, which means that cheese sauces are not produced by Egyptian companies. The surveyed study indicated that, in spite of, there are some brands of cheese sauces sold in the Egyptian market, the rate of the consumption is not like other sauces such as ketchup, tihina or mustard. Collected cheese sauces brands from the Egyptian local market were Kraft, Crystal, Remia, Demy`s, Delicio, Heinz and Lovely garden.
1- For the total solids (TS) content results indicated that Kraft has the highest content and Remia has the lowest among all collected sauces. The average in TS for all collected sauces was 45.69.
2- Fat / Dry matter values of collected cheese sauces samples when compared each other it can be found that, the highest content was for Remia and the lowest was for Kraft. Soy bean oil or palm oil used in different percentages from the brand to another to have the end product.
3- Delicio brand name has the highest total nitrogen content among all collected sauces meanwhile Lovely Garden has the lowest content.
4- Sauce Heinz brand name has the highest salt / moisture content meanwhile, Remia brand name has the lowest content.
5- Ash content of surveyed cheese sauces proved that the maximum level was 4.59 for Lovely Garden and the minimum level among all samples was 2.06 for Heinz.
6- Crystal sauce exhibited the highest value of total volatile fatty acids and Remia exhibited the lowest. The other sauces exhibited values in between and were different when compared.
7- By comparing the pH of all surveyed sauces, it is clear that Delicio had the highest value and Lovely garden had the lowest one.
8- For oil separation index, the data indicated that there were large differences in oil index values among surveyed cheese sauce samples. While, the lowest oil index value was 11.06 for Heinz cheese sauce, it reached the highest for Lovely Garden cheese sauce being 106.89.
9- Among all surveyed sauces samples, Remia brand showed the highest viscosity values at all shear rates while Lovely garden brand showed the lowest values.
10- Kraft brand name was the best one among all collected sauces. Most of these sauces had properties especially in aroma & flavour not appropriate to the Egyptian consumer, so its quality is not favourable as well as the consumer need or used to.
Part II : Investigation of different food stabilizers in cheese sauce manufacture.
Addition of stabilizers or thickening agents such as starches and gums, either individual or in combinations can impart desired properties as well as to added gloss, palatability, and can act as thickener and or binder to improve stability and body & texture. In this part of study different thickening agents has been used to produce cheese sauce with desired and improved quality and to investigate the most suitable addition of type and percentage of thickening agents. Total solid and Fat / DM contents were adjusted in all treatments of cheese sauces to be 25 % and 40 % respectively. Therefore, this part has been done in three different sections as follows :
Section A : Use of different starches in cheese sauce manufacture
Section B : The use of different food stabilizers in cheese sauce manufacture
Section C : Starch and other stabilizers combinations as thickening agents in processed cheese sauce manufacture
Section A : Use of different starches in cheese sauce manufacture
In this section processed cheese sauces has been manufactured by using different starches as thickening agents. Processed cheese sauces blends were formulated of: Ras cheese, butter fat, starch, skim milk powder, emulsifying salt (ES) and nisin as preservative. Therefore, five treatments were formulated, one of them as control with no adding starch as thickening agent and the other four treatments with corn starch, modified corn starch, wheat starch and rice flour. All blends were adjusted to contain 3 % of starch in the finished product of processed cheese sauce.
1- In all treatments total solid contents ( TS ) ranged from 25.91 to 25.10 % while F / DM contents were in range from 40.37 to 40.06 %.
2- Cheese sauce treatments possessed TN values of 1.58, 1.25, 1.24, 1.26 and 1.26 for control and treatments with corn starch, modified corn starch, wheat starch and rice flour respectively. These data indicated that control treatment had higher TN content than that of other treatments.
3- Cheese sauce treatments with corn starch, modified corn starch, wheat starch and rice flour showed ash values of 3.08, 3.12, 2.92 and 2.83 respectively, compared to 3.23 % in control treatment. Ash value was slightly higher in control treatment and lowered by adding starch in the formula being the lowest in treatment with rice flour.
4- These data indicated that control treatment had the highest salt / moisture ratio among all treatments. On the other hand, incorporating food starches in cheese sauce formulas led to lower salt / moisture content in final product.
5- The data revealed that all treatments of processed cheese sauce with different thickening materials had slightly higher pH values than the control. During storage of resultant processed cheese sauces the pH values tended to decrease gradually and the decrease was significant after 3 months of storage at ( 25 ± 2 °C ).
6- Titratable acidity values of cheese sauce samples followed an opposite trend of pH in all treatments. The control treatment has the highest acidity compared to other treatments. Acidity values increased in all treatments including the control with extending the storage period, the increase in acidity values were more pronounced in samples stored at room temperature than those stored in refrigerator.
7- Soluble nitrogen value of control processed cheese sauce was 0.889 % while it was 0.741, 0.799, 0.731 and 0.776 % in treatments with corn starch, modified corn starch, wheat starch and rice flour in order. These data indicated that control treatment had the highest SN content compared to other treatments with different food starch additives.
8- Control cheese sauce had the highest value of TVFA among all treatments meanwhile, Processed cheese sauce with modified corn starch had the highest value compared to other treatments with added starch. Processed cheese sauce with wheat starch showed the lowest value among all treatments including the control. All treatments exhibited higher TVFA values during storage especially after 3 months at room temperature.
9- The results indicated that all treatments with added starch exhibited lower oil separation index (OSI) values compared to control with no added starch. During storage control treatment showed gradual increase in OSI being more pronounced at higher storage temperature meanwhile, the other treatments with added starch exhibited an opposite trend being the lowest at the end of storage period.
10- The treatments showed different flow behaviour with various additions of different thickening agents. The control treatment showed the lowest viscosity values at the different shear rates. Cheese sauce with corn starch had the highest viscosity values, meanwhile sauce with rice flour showed the lowest viscosity compared to other cheese sauce treatments with thickening agents. All sauce samples presented lower viscosity values after storage being lowest at higher storage temperature for wheat starch and rice flour. Control treatment showed the lowest viscosity values among all cheese sauce treatments at the end of the storage period.
11- Results indicated that processed cheese sauce samples with stabilizing agents were significantly high when sensory evaluated being the best in samples with corn starch and modified corn starch. There were a decrease in sensory properties after storage in all sauces. Treatments with corn starch and modified corn starch still showing and scoring the best.
Section B : The use of different food stabilizers in cheese sauce manufacture
In this section different food stabilizers, xanthan, κ–carrageenan, guar gums, pectin and sodium alginate added to the formulations of processed cheese sauces in ratio of 0.5 %.
1- Total solids for all sauces ranged from 25.91 to 25.06 % including the control sauce. Fat / Dry matter content for sauces made with addition of different gums ranged from 40.97 % for sauce with guar gum to 40.19 % for sauce with xanthan gum and for the control sauce it was 40.85 %.
2- The data revealed that processed cheese sauce made with κ–carrageenan had total nitrogen (TN) content 1.56 % being the highest while, sauce with xanthan gum had TN content 1.46 % , being the lowest among all sauces with different stabilizers. The control sauce with no added stabilizers had TN content 1.58 % and was the highest comparing with other sauces made by using different stabilizers.
3- Ash content were 3.23, 3.02, 3.20, 3.20, 3.11 and 3.19 for the control and processed cheese sauces manufactured using xanthan gum, guar gum, pectin, κ–carrageenan gum and sodium alginate respectively.
4- Salt / moisture content of all sauces made with stabilizers addition were lower than the control sauce which had the highest content of salt / moisture. Among treatments with stabilizers, sauce with xanthan gum had the lowest content in salt / moisture.
5- Sauce made with xanthan gum had the highest pH value meanwhile the control sauce had the lowest comparing with other sauces. After storage for 3 months pH values decreased in all sauces including the control, the decrease were more pronounced in sauces stored at room temperature (25 ± 2 ºC).
6- Among all sauces control sauce with no added stabilizer had the highest soluble nitrogen content while, that with κ–carrageenan had the lowest content. Soluble nitrogen content increased in all treatments especially when stored at room temperature.
7- Processed cheese sauce with xanthan gum had higher volatile fatty acids (TVFA) value than other sauces with added stabilizers meanwhile, volatile fatty acids value of processed cheese sauce with sodium alginate was the lowest among all sauces even the control. On the other hand, a gradual increase in TVFA were noticed during storage in all sauces. The increase were significant in the samples stored at room temperature.
8- Fresh samples of processed cheese sauces made with xanthan gum, guar gum, pectin, κ–carrageenan and sodium alginate exhibited oil separation index values of 22.66, 23.25, 24.12, 24.04 and 21.96 respectively, while the control sauce exhibited 26.15 for oil separation index. During storage oil separation index decreased significantly in all sauces with added stabilizers and increased markedly in the control sauce.
9- Viscosity values showed differences in flow behaviour of sauces with various types of stabilizers. The control treatment had the lowest viscosity values among all treatments. Sodium alginate sauce had very good flow ability and was the best to be a sauce. In addition more decrease in viscosity values were observed in sauces with xanthan and guar gum, its flow ability were good to be a sauces too. After storage for 3 months, viscosity were decreased in processed cheese sauces with xanthan, pectin, κ–carrageenan, sodium alginate and also the control.
10- Addition of stabilizers improved all sensory attributes of the resultant processed cheese sauces. The control treatment exhibited the lowest scores even after storage at the both degrees. On the other hand, processed cheese sauce with guar gum and sodium alginate scored the highest points along the storage period up to the end, either at refrigerator or room temperature.
Section C : Starch and other stabilizers combinations as thickening agents in processed cheese sauce manufacture
In this section corn starch and sodium alginate or guar gum in different combinations has been used in processed cheese sauces manufacture as thickening agents.
1- Among sauce treatments with stabilizers mixtures the total solid contents in the end products ranged from 25.89 % in sauce treatment with corn starch + guar gum 2 : 1 to 24.72 % in sauce treatment with corn starch + sodium alginate 2 : 1. Fat / dry matter content ranged from 41.09 % in sauce treatment with corn starch + guar gum 1: 1 to 40.36 % in sauce treatment of corn starch + sodium alginate 1 : 1.
2- All treatments with added thickening mixtures showed slightly lower values of TN than that of control. The values of TN ranged from 1.55 to 1.47 for all cheese sauce samples with stabilizer mixtures.
3- Ash content has been ranged from 3.03 to 2.91 % in processed cheese sauces with added stabilizers. The control processed cheese sauce had ash content 3.23 % and was the highest among all processed sauces.
4- Salt / moisture ratio of resultant processed cheese sauces ranged from 1.20 to 1.28 in processed cheese sauces with added stabilizers. The control processed cheese sauce had the highest content in salt / moisture compared to the other treatments.
5- The pH values of fresh samples were 5.78, 5.82 , 5.82, 5.83, 5.82, 5.85 and 5.84 for the control, processed cheese sauces with corn starch + sodium alginate 1 : 1, 2 : 1, 1 : 2 and processed cheese sauces with corn starch + guar gum 1 : 1, 2 : 1 and 1 : 2 respectively. During storage of cheese sauce samples up to 3 months the pH values decreased in all treatments including the control. The changes were more pronounced in samples stored at room temperature.
6- Soluble nitrogen content ranged from 0.782 to 0.748 for corn starch + guar gum treated sauces. Meanwhile, soluble nitrogen content was 0.889 % for the control sauce made with no added thickening agents. Extending the storage period for 3 months caused higher degree of hydrolysis directed to higher SN content in all processed cheese sauces.
7- Fresh processed cheese sauce with corn starch + sodium alginate 1 : 2 was the lowest in total volatile fatty acids value meanwhile, the processed cheese sauces with corn starch + guar gum 1 : 1 was the highest, comparing with the other sauces with thickening agents. By increasing the storage period from 1 month to 3 months the total volatile fatty acids values increased in all stored samples.
8- Oil separation index values were 26.15, 22.08, 19.24, 23.38 , 20.00 , 22.58 and 19.20 for the resultant control processed cheese sauce, processed cheese sauces of corn starch + sodium alginate 1 : 1, 2 : 1, 1 : 2 and processed cheese sauces of corn starch + guar gum 1 : 1, 2 : 1 and 1 : 2 respectively. When the storage period increased oil separation index increased in the control sauce meanwhile, it decreased in the other sauces made using sodium alginate or guar gum when added to corn starch in the base blends.
9- The data showed that all treatments of sodium alginate had higher viscosity values than that of guar gum. Viscosity values for the control treatment was the lowest at the all. After storage for 3 months the behaviour of the treatments were different, each group also had a different trend. In spite of treatments of sodium alginate showed a decrease in viscosity values, the trend was in opposite for the treatments of guar gum and exhibited an increase in viscosity values.
11- For sensory evaluation processed cheese sauces scored 84.5, 92.5, 93.5, 92.5 , 94.0 , 96.5 and 93.5 points for the control sauce, sauces of corn starch + sodium alginate 1 : 1, 2 : 1, 1 : 2 and sauces of corn starch + guar gum 1 : 1, 2 : 1 and 1 : 2 respectively. The control sauce had the lowest total score because the score for body & texture were lower than any other sauce. During storage the scores of the treatments with added guar gum & corn starch in the different ratios had higher scores than that of sodium alginate & corn starch. At the end of storage period sauce of corn starch + guar gum 2 : 1 had the highest score even when stored at (25 ± 2 ºC).
Part III : Impact of different food protein sources in processed cheese sauce manufacture
Milk protein concentrate, total milk proteinate, UF- retentate curd, skim milk powder and soy protein concentrate were used as partial Ras cheese base replacement in processed cheese sauces. It gives smooth texture and flavour functionality as real cream cheese sauce without the higher costs. The ingredients incorporated to form the blends were: Ras cheese, protein source, butter fat, corn starch & guar gum 2 : 1, skim milk powder, emulsifying salt and nisin as preservative. All blends were adjusted to contain 25 % TS, 40 % F/ DM, in the processed cheese sauce as a finished product. The process is successfully achieved to produce cheese sauce not only using new ingredients but also with full flavour and acceptable moisture / texture profile, shelf stable and high quality.
1- The determined total solids in treatments ranged from 25.96 % in processed cheese sauce with milk protein concentrate to 25.23 % in processed cheese sauce with total milk proteinate. Fat / Dry matter also showed a range from 40.86 % in control processed cheese sauce to 40.0 % in processed cheese sauce with milk protein concentrate.
2- Total nitrogen values of processed cheese sauces were 1.43 , 1.55 , 1.45 , 1.24 , 0.94 and 1.11 for the control processed cheese sauce and cheese sauces with milk protein concentrate, total milk proteinate, UF-retentate curd, skim milk powder and soy protein concentrate respectively.
3- The results indicated that processed cheese sauce with milk protein concentrate had ash content being the highest, while processed cheese sauce with total milk proteinate had ash content being the lowest among all treatments.
4- Salt / moisture ratio was 1.27 in the control processed cheese sauce while it was 1.09, 1.06, 1.07, 1.08 and 1.05 in processed cheese sauces with milk protein concentrate, total milk proteinate, UF-retentate curd, skim milk powder and soy protein concentrate respectively.
5- The pH values ranged from 5.85 in cheese sauce with UF- retentate curd to 5.78 in cheese sauce with soy protein concentrate. Control cheese sauce possessed a slightly lower pH value 5.75 comparing with other sauces. During storage pH values of all treatments decreased by extending the storage period up to 3 months. The decrease in the treatments stored at the room temperature (25 ± 2 ºC) were higher than that stored in the refrigerator ( 5 ± 2 ºC).
6- Soluble nitrogen content of processed cheese sauces made using Ras cheese, milk protein concentrate, total milk proteinate, UF- retentate curd, skim milk powder and soy protein concentrate were 0.890, 0.609 , 0.687 , 0.769 , 0.542 and 0.221 in order. By increasing the storage period and the storage temperature soluble nitrogen content increased in all treatments even the control.
7- The data revealed that among cheese sauces with protein sources, cheese sauce with UF- retentate curd showed the highest total volatile fatty acids value meanwhile that with milk protein concentrate had the lowest. Total volatile fatty acids values changed during storage period and increased in all cheese sauces including the control.
8- Values of oil separation index of processed cheese sauces with different sources of protein when compared showed that processed cheese sauce with skim milk powder had the highest oil separation index value while that with soy protein concentrate had the lowest. Oil separation index values of sauces with added protein sources decreased where it increased in that with soy protein concentrate by increasing the storage period especially at the room temperature.
9- The use of different protein sources in formulating processed cheese sauces blends has affected the viscosity of the resultant sauces. Viscosity values of fresh sauce samples cleared that cheese sauce treatment with soy protein concentrate had the highest viscosity comparing with all other treatments while, treatment with milk protein concentrate had the highest viscosity comparing with treatments with added milk protein sources even the control. After storage for 3 months viscosity for control processed cheese sauce sample and that with total milk proteinate and soy protein concentrate increased to higher values at the refrigerator temperature and being more higher at the room temperature. Meanwhile, in processed cheese sauce with UF-retentate curd and that with skim milk powder viscosity changed to decrease and being lower at the room temperature.
10- The total scores of sensory quality attributes for cheese sauces with different protein sources were 92.0 points for control sample compared to 94.5, 96.0, 96.5, 93.0 and 89.0 points for treatments with milk protein concentrate, total milk proteinate, UF-retentate curd, skim milk powder, soy protein concentrate respectively. These scores indicated that all cheese sauces were acceptable but cheese sauce with UF-RC showed significantly highest acceptability. Sensory quality attributes of cheese sauces with different protein sources were affected by storage period and temperature. Processed cheese sauce with UF- retentate curd was the most acceptable sauce with no undesirable flavour in opposite to the control cheese sauce which had more mature undesirable flavour or that with soy protein concentrate which had a more oily stored beany flavour.
Part IV : Shelf stable processed cheese sauces with different preservatives.
Preservatives could be anti-microbial or antifungal, which inhibit the growth of bacteria and fungi, or antioxidants such as oxygen absorbers, which inhibit the oxidation of food constituents. The ingredients used and incorporated to produce sauces with shelf life stability and to formulate the blends were: Ras cheese, UF- retentate curd, butter fat, corn starch & guar gum 2 : 1, skim milk powder, emulsifying salt, nisin and natamycin or potassium sorbate as preservatives. All blends were adjusted to contain 25 % TS, 40 % F/ DM, in the processed cheese sauces as a finished product.
1- The data cleared that there were very slight and non significant differences in total solid contents and F / DM ratio of all treatments. The average of total solids was 25.36 while the average of F / DM ratio was 40.32.
2- Total nitrogen (TN) contents exhibited values of 1.27 , 1.25 , 1.26 , 1.24 and 1.24 meanwhile, ash content exhibited values of 2.92, 2.86, 2.89, 2.84 and 2.82 for control cheese sauce with no added preservatives and cheese sauces with nisin, nisin + natamycin, nisin + potassium sorbate and nisin + natamycin + potassium sorbate consecutively.
3- Salt / moisture content of processed cheese sauces varied from 1.17 to 1.13 for all treatments including the control with no added preservatives.
4- Control cheese sauce with no added preservatives expressed pH value 5.82. The results indicated that all treatments with added preservative systems had pH values in narrow range and were slightly higher than the control. pH values changed to decrease gradually in all samples till the end of storage period. The decrease were more pronounced in the control treatment with no added preservatives.
5- Differences in soluble nitrogen content among all treatments were slightly and not significant. During storage soluble nitrogen content increased in different rates. Control processed cheese sauce had the highest content and that with added nisin + natamycin + potassium sorbate had the lowest comparing with the other treatments.
6- Fresh samples of processed cheese sauces with preservatives exhibited total volatile fatty acids values of 11.0811.39, 10.89 and 10.47 for processed cheese sauces with nisin, nisin + natamycin, nisin + potassium sorbate and nisin + natamycin + potassium sorbate respectively. Control processed cheese sauce exhibited value of 11.58 for total volatile fatty acids. An increase in total volatile fatty acids of control sauce and sauces with different preservatives were monthly observed up to 3 months of storage. These observed increase were directed as values being the highest in control processed cheese sauce and being the lowest in processed cheese sauce with added nisin + natamycin + potassium sorbate.
7- The control processed cheese sauce had the highest value of oil separation index and processed cheese sauce with added nisin + natamycin + potassium sorbate had the lowest. When the samples stored for 3 months a gradual decrease in oil separation index values were noticed in all treatments. At the end of storage period the control sauce had the highest value while that with added nisin + natamycin + potassium sorbate had the lowest comparing with the other treatments.
8- Viscosity values of processed cheese sauces samples when compared showed that, control cheese sauce with no added preservatives had higher viscosity values than other treatments. Nevertheless, processed cheese sauce with added nisin exhibited the lowest viscosity values. After 3 months of storage at room temperature viscosity values were decreased in different rates in all stored processed cheese sauces. The decrease was so clear and obvious in control processed cheese sauce with no added preservatives.
9- Detected viable total bacterial count as log cfu / ml in fresh samples were 2.47, 2.40, 2.30, 2.30, 2.20 for control processed cheese sauce with no added preservatives and processed cheese sauces with added nisin, nisin + natamycin, nisin + potassium sorbate and nisin + natamycin + potassium sorbate respectively. Among treatments with added preservatives, it is clear that processed cheese sauce with added nisin had higher viable total bacterial count than that with added mixtures of preservatives meanwhile, processed cheese sauce with added nisin + natamycin, nisin + potassium sorbate had the lowest. By extending the storage period a gradual increase in total bacterial count were detected. Control processed cheese sauce had the highest detected number especially at the end of the storage period comparing with the other treatments. The lowest number were detected in processed cheese sauce with added mixture of nisin + natamycin and mixture of nisin + potassium sorbate.
10- The results revealed that the control processed cheese sauce, processed cheese sauce with added nisin and that with added nisin + natamycin had the same and highest spore forming bacterial count nevertheless, processed cheese sauce with added nisin + potassium sorbate and that with added nisin + natamycin + potassium sorbate had lower count than the other treatments. During storage the number of the aerobic spore forming bacteria decreased gradually in all treatments including the control in spite of, the control treatment had the highest count at the end of the storage period. Processed cheese sauces with added mixtures of preservatives had the same count and were lower than that with added nisin.
11- The obtained data indicated that there were no detected anaerobic spore forming bacteria in fresh samples of processed cheese sauces with added preservatives including the control. During storage the count of anaerobic spore forming bacteria slightly increased in all treatments especially at the end of the storage period. Control processed cheese sauce had the highest detected number meanwhile, processed cheese sauce with added nisin + natamycin + potassium sorbate had the lowest.
12- All fresh processed cheese sauces manufactured with added preservatives and the control with no added preservatives were free from yeast and mould. Furthermore, yeast and mould could not be detected in all treatments along the storage period up to the end.
13- Fresh samples of all processed cheese sauces including the control scored the same points and had the same properties for the outer appearance and inner appearance “ body & texture “. All samples had white and shiny outer appearance and smooth flow ability inner appearance. Addition of preservatives in different ratios caused a slight variation among resultant sauces for aroma & flavour properties. processed cheese sauces with added nisin or nisin + potassium sorbate were more favourable than that with added natamycin. When the storage period increased for 3 months it can be seen that, sensory properties of all sauces were influenced in different degrees. The deterioration were more higher in control cheese sauce as a result of the increase in bacterial count. Processed cheese sauce with added nisin + potassium sorbate still the best and the more favourable sauce that when compared with the other sauces containing natamycin.