الفهرس 
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Abstract
This study provides HACCP system as a structured and systematic approach to identify hazards and assess their occurrence during the preparation of raw milk cheese in Egypt and defines measure for their control. HACCP system has been applied throughout the production lines of raw milk cheese to the implementation of 12 part/7 – principles which is based in a plan to monitor the preparation of the program of measurements and observations that determine the critical control points and through critical limits.
This study aimed to assess the safety of raw milk cheese provided to study, secure health with high efficiency and low cost in addition to documenting the data, control the sources of hazards and supply fall and accurate view of all the manufacturing operation depending upon:
1. Investigation of microbial contamination and CCPs in the preparation and handling of catering foods.
2. The correction of CCPs for each step will be applied and evaluated based on the obtained results.
3. Verification of the whole running system.
The following design was at adopted:
Developing preventive strategy based on HCCP principles
1. Conduct and identify the microbiological and physio-chemical hazard in raw milk cheese in Egypt.
2. Study of control measures to prevent microbiological hazards and their effectiveness.
3. Improve and develop of control measures on microbiological hazards.
4. Establish of hazard analysis and critical control points for some of the studied products, includes hazards analysis, identification of critical control points, setting of satisfactory limits, development of standard monitoring procedures, verification procedures, preservation of documents and records, in dairy plant produce raw milk soft white cheese (Domaiti cheese) in Damietta Governorate in Egypt.
5. Set recommendation for the results of the study, which ensures the safety of products and free of microbiological hazards to ensure food safety.
Results of this study showed the following:
Part 1: Applied study of microbiological hazards in raw milk and pasteurized soft white cheese in Egypt.
1. Assessment of microbiological hazards, physio-chemical compositions and safety for Domaiti raw milk soft white cheese processed by traditional dairy plants in retails market
Raw milk soft white cheese include: Tallaga, Istanbully, Double cream and Baramely cheese.
1.1. Determination of microbiological hazards in raw milk soft white cheese.
Microbiological analysis includes: lactic acid bacteria count, total bacterial count, total coliform, fecal E. coli, Staphylococcus spp, yeast &molds count and detection of pathogens namely E. coli O157:H7, Salmonella spp, Shigella spp, Listeria spp, Bacillus cereus and Campylobacter spp. Results indicated high microbiological hazards. The cheese samples were highly contaminated, having microbial load exceeding the acceptable limits. Total lactic acid bacteria and fecal E. coli were high counts in Double cream raw milk cheese (12.9x 103 and 4.1 x102 cfu/g, respectively). Total bacterial count, Staphylococcus spp and yeast & molds were high counts in Tallaga raw milk cheese (9.2 x105, 13.0 x104 and 9.0x103 cfu/g, respectively). Cheese samples were examined for pathogenic bacteria. Salmonella spp, Shigella spp, Listeria spp, and Campylobacter spp were detected in Tallaga cheese. Double cream cheese was contaminated with E. coli O157:H7, Salmonella spp and Bacillus cereus. Also, found Salmonella spp, Shigella spp. and Listeria spp were detected in Baramely cheese. Istanbully cheese sample were found free of most pathogenic bacteria.
1.2. Physio-chemical quality in raw milk soft white cheese.
Physio-chemical composition were protein %, fat %, total solids %, ash %, NaCl, acidity% and EC (μS). Results indicated that the protein and fat content was high in Double cream cheese (6.80% and 32%, respectively). The pH value was low in Baramely cheese (3.20) and high in acidity (1.30%). Total solid, ash, and EC were high in Istanbully cheese because it is high salt level (13.2%).
2. Assessment of pasteurized soft white cheese processed by modern dairy plants in Egypt
Pasteurized soft white cheeses were Feta, Istanbully, Double cream and Baramely soft white cheese.
2.1. Determination of microbiological hazards in raw milk soft white cheese
Microbiological analysis includes: enumeration of lactic acid bacteria, total bacterial count, total coliform, fecal E. coli, Staphylococcus spp, yeast & molds and detection of pathogens namely E. coli O157:H7, Salmonella spp, Shigella spp Listeria spp, Bacillus cereus and Campylobacter spp.
Results showed an absence of lactic acid bacteria (LAB). The absence of LAB indicates it is not using as a starter cultures in this type of cheese. Pasteurized cheeses were free of pathogens. Also, coliforms and fecal E. coli were not detected in cheese samples. The present study showed lower counted of total bacterial count and yeast & molds for pasteurized cheeses comparing with traditional cheeses. The absence of coliform, fecal E. coli and pathogenic bacteria indicate that efficiency of control measures applied in modern plants compared to traditional plants.
2.2. Physio-chemical quality in raw milk soft white cheese
Physio-chemical composition include protein %, fat %, total solids %, ash %, NaCl, acidity% and EC (μS).
Result indicated that the fat content of cheese samples were 25.00, 21.00, 28.00 and 23.00% in Feta, Istanbully and Double cream and Baramely cheese, respectively. These results show that fat contents were high in pasteurized cheeses comparing with traditional soft white cheese.
The Protein content of cheese samples were 4.10, 4.80, 5.30 and 6.80 % in Feta, Istanbully, Double cream and Baramely cheese, respectively. These results blow of stander limit which should be 10% at least. These results are relatively low when compared with protein content in traditional soft white cheese, which ranged from 9 -12%. Total solid, ash, NaCl and EC were low comparing with traditional soft white cheeses, while acidity was high in pasteurized soft white cheese.
3. Detection of preservative agents in pasteurized soft white cheese
Results showed that found preservatives agents in pasteurized soft white cheese produced by modern dairy plants in Egypt. Identification of preservative agents in pasteurized soft white cheese produced by modern dairy plant in Egypt on Listeria spp, Salmonella spp and Staphylococcus spp, indicated inhibition zone with neutralization and catalase test ,while no inhibitory effect was observed for the cell free cheese filtrates when treated with protease enzymes. Results showed some non-traditional dairy sector in Egypt don’t use lactic acids or hydrogen peroxide, but use nisin as a preservative agent during processed pasteurized white soft cheese in Egypt.
PART (2): Assessment of soft white cheese produced by traditional dairy plant and establish HACCP plan
The aim of present study was to assess the microbiological and physio-chemical quality and safety of Egyptian white soft cheese made from raw milk. Investigate possible microbiological contamination sources, microbial loads during production of the raw milk soft white cheese in a small traditional dairy plant at Damietta Governorate. Identifying these points helped us to find several solutions to control the microbial contamination that might occur during cheese production.
1. Microbiological assessment of raw milk soft white cheese produced by a traditional dairy plant in Damietta Governorate.
The chain production line start from receiving area up to final product packaging and storage. The chain production line consists of: receiving area, rennet step, salted heated milk step, milk curd step, fresh cheese step, storage and ripened cheese. Results indicated high contamination in dairy plant and unhygienic condition. There are many microbiological hazards during cheese chain production line, namely:
1.1. Receiving milk step
Raw milk was contaminated with bacteria, coliforms, fecal E.coli, and yeast & molds. Raw milk was contaminated with pathogens such as Staphylococcus spp, Salmonella spp, Shigella spp, Listeria spp and Campylobacter spp. Air in dairy plant was unhygienic, so receiving area was high contaminated with bacteria and yeast & molds (1640 and 42 cfu/30 min, respectively). Receiving milk tank was high contaminated with bacteria and coliform (5.8 x102 and 1490 cfu/15cm, respectively).
1.2. Rennet step
Rennet was contaminated with coliforms, fecal E. coli, and yeast & molds. Rennet was contaminated with pathogens (Staphylococcus spp, Salmonella spp, listeria spp, and Bacillus cereus), renneting vat tank was contaminated with bacteria and coliforms.
1.3. Salted and Heated Milk step
Salted and heated milk contaminated with coliforms, fecal E.coli, and yeast & molds. Salted and heated milk was contaminated with pathogens (Staphylococcus spp and Salmonella spp). Salted and heated milk tank was contaminated with coliform and bacteria.
1.4. Milk curd step
Milk curd was contaminated with coliforms, fecal E. coli, and yeast & molds. Milk curd was contaminated with pathogens (Staphylococcus spp, E. coli O157:H7 and Salmonella spp). Milk curd tank was contaminated with bacteria and coliforms.
1.5. Fresh cheese
Fresh cheese was contaminated with coliforms, fecal E.coli, and yeast & molds. Fresh cheese was contaminated with some pathogens include Staphylococcus spp, E. coli O157:H7, Salmonella spp, Listeria spp and Bacillus cereus. Cheesecloth, cheese cutting tool, cheese plastic bag and cheese tin were contaminated with bacteria and coliform packaging area was contaminated with coliforms and yeast & molds.
1.6. Ripened cheese (storage for cheese)
Microbial counts of coliforms, fecal E. coli, and yeast & molds were decreased in ripenied cheese, while lactic acid bacteria was increased durning ripening up to (21.6 x102 cfu/g). Ripened cheese was free of all pathogens. Results indicated that the contaminated air in the chain production line. The air is identified as a source of contamination with air borne microorganisms including total mesophilic bacteria and yeast & molds.
2. Physio-chemical composition of raw soft white cheese produced by a traditional dairy plant at Damietta Governorate
The physiochemical characteristics of raw materials, in process, final cheese and whey. In the present study the observed difference of reported composition, may be attributed to use mixed cow and buffalo’s milk in making cheese. Total solid was (12.40 %) for raw milk. These results are in agreement with Egyptian standards. Total solid was increased during cheese process up to a maximum in ripened cheese (42.60 %), which fulfill the cheese standard requirement. pH value in raw milk was (6.0), then decrease in fresh and ripened cheese (4.10 and 3.91, respectively). Ash content in milk sample was 0.69%. The salt content (12.74%) is typical for this type of cheese. Acidity increased in ripened cheese (0.98%) while pH decrease as a result of the microbial activity during the ripening process.
PART 3: Validation of HACCP plan for production of Tallaga raw milk soft white cheese in model experiment
The objective of this study was to validate of HACCP plan for production of Tallaga cheese to improve the microbiological hazards quality physiochemical and safety of Tallaga soft white cheese. The established HACCP plan is implemented to validate and control Staphylococcus spp, Salmonella spp and Listeria spp in raw soft white cheese. Tallaga cheese was manufactured with different salt levels (ranged from 6 to 10 % salt), mesophilic and thermophilic lactic acid bacteria cultures (LABC) and ripening for 90 days in refrigerator at 5°C. The cheese was sampled for physiochemical and microbiological analysis at 1, 30, 60 and 90 days. Production of Tallaga raw milk soft white cheese was carried out by using different cultures and salt combinations.
During the storage time (ripening period), results indicated that an increase in thermophilic and mesophilic lactic acid bacteria counts. The counts were at maximum by the end of ripening period (90 days) in different salt levels. Results indicated that both counts of Staphylococcus spp, coliform bacteria and yeast and molds were decreased in the cheese made with 8% and 10 % salt compared to 6 % salt. Also, similar reduction trends were observed as the ripening period increased up to 90 days. The highest counts were observed in 6 % salt cheese without culturing. The similar trends were observed for yeast and molds, but with relatively lower counts. The fully reduction of Listeria spp and Salmonella spp in Tallaga cheese manufactured with salt levels (8%, 10% salt), mesophilic and thermophilic LAB after repining period 90 days at 5°C comparing with control treatment.
Physio-chemical composition of Tallaga cheese made with different salt levels and lactic acid bacteria cultures, inoculated with pathogen isolates and ripened for 1, 30, 60 and 90 days at 5° C were different during storage. Results indicated that during the storage (ripening) the pH decreased both developed acidity and total solids increased in cheese with lactic acid bacteria cultures, especially thermophilic culture. Also, the same parameters reached the maximum by the end of the ripening period (90 days). The HACCP plan design shown in the results which include control measure for microbiological and physiochemical composition hazards for Tallaga soft white cheese.