A. Quality Control vs. Quality Assurance
Quality is commonly defined as ''achieving agreed customer expectations or specifications.'' That is, the customers define the quality criteria needed in a product. To meet this standard, the manufacturer puts in a quality control system to ensure that the product meets these criteria on a routine basis. Controlling quality of foods may be achieved by:
Inspection of raw materials to ensure that high-quality ingredients are used
Checking on the process to ensure that the weights of the ingredients and processing conditions, such as temperature and time are correct
Inspecting the final product to ensure that high-quality products are sent to the consumers
The quality-control approach is focused on the process, whereas the problems that customers may face can also occur elsewhere in the production and distribution chain. Quality assurance systems take a much wider view of what is involved in satisfying customers' needs, and focuses on the prevention of problems and not simply on their cure. Curing problems is expensive and quality can't be ''inspected into'' a product (23).
Quality assurance can be defined as a strategic management function that establishes goals and provides confidence that these measures are being effectively applied (24). Quality assurance is the set of systematic and preestablished actions necessary to provide adequate confidence that a product or a service meets the given quality requirement (25). A quality assurance approach includes the whole production and distribution system, from the suppliers of important raw materials, through the internal business management to the customer. Quality assurance systems should be documented in a simple way to show who has responsibility for doing what and when. The focus of quality assurance is prevention, and this should mean that action is taken to meet a specification and prevent failures from occurring a second time. This is done by planning, management action, and agreements with key suppliers and other people in the distribution chain (23).
Quality assurance can only be accomplished when staffs are well trained and motivated. Workers are normally well aware of the causes of most problems, and when quality assurance is used properly they can resolve most quality problems within their control. It is the responsibility of business owners to ensure that the quality assurance system, together with any necessary equipment and information, are available to the workers to allow them to exercise this control. A range of problem-solving techniques can be provided for process workers to use when trouble arises during production. These simple techniques are tried and tested. They involve problem identification, analysis of the cause, suggestions for solutions and implementation, and feedback methods. These techniques allow the operators more control over their work and allow problems to be prevented rather than solved. More advanced statistics-based methods can be used for sampling plans and process optimization, but these are beyond the scope of this book.
Fermented dairy products were originally developed as a means of preserving raw milk in times of excess production and are generally considered to be relatively safe foods. However, several reported outbreaks of foodborne illness have been associated with these products. Organisms such as Listeria monocytogenes, Salmonella, Brucella melitensis, and Escherichia coli O157:H7 have all been involved in cheese-associated outbreaks, causing severe illness and some deaths. Listeria monocytogenes can cause meningitis and blood infections and abortion in pregnant women; some types of Salmonella can cause blood infections and may result in long-term illness such as reactive arthritis; Brucella melitensis causes undulant fever. The disease persists for months if left untreated but is seldom fatal in humans. Toxin-producing types of Escherichia coli (including E. coli O157:H7) may cause hemorrhagic colitis, hemolytic uremic syndrome, and renal failure, which may result in death, particularly in young children. Outbreaks have occurred when milk pasteurization was not carried out properly and when cheese made from pasteurized milk was subsequently contaminated with pathogenic microorganisms. More recently, an outbreak of Staphylococcus aureus enter-otoxin in pasteurized milk resulted in over 14,700 cases in Japan (26).
The chances of foodborne pathogens gaining access to dairy products can be reduced by properly controlled pasteurization of milk. The U.S. Public Health Service developed a model regulation known as the Standard Milk Ordinance in 1924 for the important public health considerations related to milk production. During the past decade, problems associated with the sanitary control of milk and milk products have become extremely complex because of new products, new processes, new chemicals, new materials and new marketing patterns, which must be evaluated in terms of their public health significance. In 1978, the United States Department of Health Public Health Service and Food and Drug Administration developed ''The Grade A Pasteurized Milk Ordinance (PMO)'' to translate this new knowledge and technology into effective and practicable public health practices. The PMO was last revised in 1999 (27) and has been used as a guide to allow for uniform regulation of the milk industry. PMO includes information on:
Inspection of dairy farms and milk plants Testing, bacteriological, drug and pesticide residues Construction of facilities Water supply
Toilet and hand-washing facilities
Personnel health and hygiene
Utensils and equipment
Pasteurization equipment and procedures
Cleaning and sanitization
Insect and rodent control
Other prevention and control measures include employing Good Manufacturing Practices (GMPs), Standard Sanitation Operating Procedures (SSOPs), and Hazard Analysis and Critical Control Points (HACCPs). It is well recognized that HACCP can be an effective management tool for reducing the risk of food safety hazards in the food supply. HACCP is a commonsense approach that is based on a preventive rather than a remedial approach to food safety. The FDA has mandated HACCP for high-risk food industries, such as seafood and fruit and vegetable juices, and the USDA requires processors of meat and poultry to develop and implement HACCP programs. Many in the food industry not currently under HACCP regulations realize that a HACCP program makes sense and have voluntarily implemented HACCP programs. Although there are no federal regulations requiring HACCP for manufacturing of dairy products, programs are being initiated in some states, and HACCP appears to be the direction for the future. The International Dairy Foods Association (IDFA) recently published a HACCP plant manual for dairy products (28). The manual provides technical recommendations for development of a comprehensive HACCP food safety system for the entire dairy industry, including specific prerequisite program, preliminary steps, assessment of hazards, hazard analysis guideline, seven HACCP principles, and model HACCP programs covering different dairy products.
C. Good Manufacturing Practices (GMPs)
Good Manufacturing Practices (GMPs) are required by law for all food manufacturing companies. Information on GMPs can be found in the Federal Code of Regulations (CFR) section 21, part 110. GMPs are the foundation and prerequisites for all food safety and food quality programs. GMPs ensure the production of safe and wholesome food of high quality. GMPs are prescribed for four main areas of food processing as outlined in Table 3. The specific operation procedures in dairy plant can be found in the International Dairy Food Association (IDFA) HACCP plant manual for dairy products (28).
D. Sanitation Standard Operating Procedures (SSOPs)
Sanitation Standard Operating Procedures, or SSOPs, are specific step-by-step procedures needed for processes related to sanitation. It is mandatory for all food processing plants as written in the Federal Code of Regulations (CFR) Title 21, part 120.6. SSOPs need to address eight sanitation conditions (29):
1. Safety of water that comes into contact with food or food-contact surface, or is used in the manufacture of ice
2. Condition and cleanliness of food contact surfaces including utensils, gloves, and outer garments
3. Prevention of cross-contamination from insanitary objects to food, food-packaging material, and other food contact surfaces, including utensils, gloves, and outer garments, and from raw product to cooked product
5. Protection of food, food-packaging material, and food-contact surfaces from adulteration with lubricants, fuel, pesticides, cleaning compounds, sanitizing agents, condensate, and other chemical, physical, and biological contaminants
6. Labeling, storage, and use of toxic compounds (cleaning solutions, pesticides, additives)
Table 3 Four Main Areas of GMPs in Food Processing
1. Personnel hygiene Knowing how and when to wash hands
Understanding the importance of clean uniforms
Proper use of hair and beard nets
Policy on jewelry—minimal at best
Policy on chewing tobacco, smoking, and eating
Adequate lighting and ventilation Storage of ingredients (refrigerated and on pallets) Separation of raw ingredients from processed foods Pest management program
3. Equipment and utensils Easily cleaned and sanitized
Easily maintained Meet food grade standards
4. Production and process control Time/temperature control charts
Records on food ingredients Lot identification and coding Product weight controls
7. Control of employee health conditions that could result in the microbiological contamination of food, food-packaging materials, and food-contact surfaces
SSOPs will vary from facility to facility because each facility and process is designed differently. The step-by-step procedure of sanitation operations for dairy plants is described in great detail by Marriott (30) and in the IDFA's HACCP plant manual for dairy products (28). The following tasks were recommended by Marriott as components of a sanitation quality assurance system (30):
1. Clear delineation of objectives and policies
2. Establishment of sanitation requirements for processes and products
3. Implementation of an inspection system that includes procedures
4. Development of microbial, physical, and chemical product specifications
5. Establishment of procedures and requirements for microbial, physical, and chemical testing
6. Development of a personnel structure, including an organization chart for a quality assurance program
7. Development, presentation, and approval of a quality assurance budget for required expenditures
8. Development of a job description for all positions
9. Setup of an appropriate salary structure to attract and retain qualified quality assurance personnel
10. Constant supervision of the quality assurance program with written results in the form of periodic reports
Cleaning is the chemical or physical process of removal of visible soil or matter from a surface. Cleaning removes 90-99% of the hazards, but only sanitizing completes the job. Sanitizing is the process that results in reduction/destruction of microbes to a level that is of a safe and healthful nature. Cleaning and sanitizing are part of dairy plant sanitation programs that are included in Good Manufacturing Practices. Cleaned and sanitized equipment and building are essential to the production, processing, and distribution of wholesome dairy products. A good cleaning and sanitizing program can greatly improve the safety and quality of dairy products. Good sanitation programs must be established for:
All equipment used in production
Raw materials handling and storage
Processing hygiene and handling finished goods
Employee hygiene and facilities
Finished product storage
It is important to use appropriate cleaning compounds and equipment so that a sanitation program can be effectively administered in a shorter period of time and with less labor. Table 4 provides a guide to the most appropriate cleaning compound, cleaning procedure, and cleaning equipment for the dairy processing equipment. After cleaning, sani-tizers should be applied to the cleaned surface to help destroy microorganisms. Of the many methods for sanitizing, those most frequently used in dairy plants are steams, hot water, and
Table 4 Optimal Cleaning Guide for Dairy Processing Equipment
Plant floors Most types of self-foaming, or foam boosters added to most moderate to heavy-duty cleaners Plant walls and ceilings Same as above Processing equipment Moderate to heavy-duty and conveyorsa alkalis that may be chlorinated or non alkaline
Low-foam, moderate to heavy-duty chlorinated alkalis with periodic
Foam (high-pressure, low-volume should be sued with heavy fat or protein deposits) Foam
High-pressure, low-volume spray
Portable or centralized foam cleaning equipment with foam guns for air injection into the cleaning solution Same as above Portable or centralized high-pressure, low-volume equipment; sprays should be rotary hydraulic Pumps, fan or ball sprays, and CIP tanks a Packaging equipment can be effectively cleaned with gel cleaning equipment. Source: Ref. 31.
chemical sanitizers. Their applications in dairy processing plants are described in Table 5. In addition, the quality of water is critical because water is the major constituent of almost all cleaners. Because most plant water is not ideal, the cleaning compounds selected should be tailored to the water supply or should be treated to increase the effectiveness of the cleaning compound. It is especially important to reduce suspended matter in water to avoid deposits on clean equipment surfaces. Water hardness complicates the cleaning operation. Suspended matter and soluble manganese and iron can be removed only by treatment, whereas small amounts of water hardness can be counteracted by sequestering agents in the cleaning compounds used in the sanitation operation. If the water is hard or very hard, it is usually more economical to remove or minimize water hardness.
Table 5 Types of Sanitizing Agents and Their Applications in Dairy Plants
Steam Maintain steam in contact with product contact surface for 15 min when condensate leaving the assembled equipment is at 80°C.
Used less in dairy plants because it is difficult to maintain at constant required temperature, energy costs are high, and steam application is more dangerous than other methods.
Hot water Temperature of water has to be maintained at not less than 76.7°C and not more than 90.6°C for a time period of 30 sec.
This technique is expensive because of required energy costs.
Chemicals Chlorine, iodine-containing compounds, and quaternary ammonia are the three most commonly used chemical sanitizers.
For large-volume, mechanized operations, sanitizer can be applied through sanitary pipelines by circulation or pumping sanitizing solution through the system.
For small operations, equipment, utensils, and parts can be sanitized by submission in sanitizer solution.
Closed containers (tanks or vats) can be effectively sanitized by fogging.
Source: Refs. 30 and 32.
The techniques for cleaning dairy plants vary depending on the plant size. The major portion of a large-volume plant is cleaned by the Cleaning-In-Place (CIP) system, which is the recognized standard for cleaning pipelines, milking machines, bulk storage tanks, and most equipment used throughout the processing operation. However, many small parts of equipment and utensils, as well as small containers, can be washed effectively in a recirculating-parts washer, called Cleaning Out of Place (COP) unit. The COP units contain a recirculating pump and distribution headers that agitate the cleaning solution. A COP unit can also serve as the recirculating unit for CIP operation.
The effectiveness of the CIP approach depends on the process variables, time, temperature, concentration, and force. Cleaning and sanitizing agents should be used exactly following the product directions. Rinse and washing time should be minimized to conserve water and cleaning compounds but should be long enough to remove soil and to clean effectively and efficiently. Temperature of cleaning solution should be as low as possible and still permit effective cleaning with minimal use of the cleaning compound. CIP operations in dairy plants are usually divided into two major categories: spray cleaning and line cleaning. The detailed description can be found in Marriott (30). A current trend has been toward modification of CIP system to permit final rinses to be utilized as makeup water for the cleaning solution of the following cleaning cycle and to segregate and recover initial product-water rinses to minimize waste discharges.
When COP equipment is used in dairy plants, the following steps are recommended
1. A prerinse with tempered water at 37° to 38 °C to remove gross oil
2. A wash phase through circulation of a chlorinated alkali cleaning solution for approximately 10 to 12 min at 30° to 65°C for loosening and eradicating soil not removed during the prerinse phase
3. A postrinse with water tempered to 37° to 38°C to remove any residual soil or cleaning compound
In ''Item 9p—Milk Plant Cleanliness'' of PMO, it is clearly stated that'' All rooms in which milk and milk products are handled, processed or store, and/or in which containers, utensils or equipment are washed or stored, shall be kept clean, neat and free of evidence of insects and rodents''. In Item 10p—Sanitary Piping, it states that''All sanitary piping, fittings and connections which are exposed to milk or milk products, or from which liquids may drip, drain or be drawn into milk or milk products, shall consist of smooth impervious, corrosion-resistant, nontoxic, easily cleanable material which is approved for food contact surfaces. All piping shall be in good repair. Pasteurized milk and milk products shall be conducted from one piece of equipment to another only through sanitary piping.''
Eight cleaning steps in dairy operations are recommended. Their specific applications are described in Table 6.
E. Hazard Analysis and Critical Control Points (HACCPs)
One of the main building blocks used for developing a quality assurance system is the Hazard Analysis Critical Control Point (HACCP) system. HACCP is a management system in which food safety is addressed through the analysis and control of biological, chemical,
Table 6 Recommended Eight Cleaning Steps in Dairy Operations
Cover electrical equipment Remove large debris
Disassemble equipment as required Prerinse
Apply cleaning compound
Covering materials should be polyethylene or equivalent.
This task should be accomplished during the production shift and/or prior to prerinsing.
Prerinsing can remove up to 90% of the soluble materials and also loosens tightly bound soils and facilitates penetration of the cleaning compound in the next cleaning step. This step can be simplified through proper selection and use of processing and clean equipment, proper location of equipment, and reduction of soil accumulation. Further reduction of soil buildup is possible through use of the minimum required temperature for heating products a minimum amount of time; cooling product heating surfaces, when practical, before and after emptying of processing vats; and keeping soil films moist by immediately rinsing foam and other products with 40° to 45°C water and leaving it in the processing vats until cleaning. This step solubilizes and carries away soil. Rinsing also removes residual soil and cleaning compounds and prevents redeposition of the soil on the cleaned surface. Inspection is essential to verify that area and equipment are clean and to correct any deficiencies A sanitizer is added to destroy any residual microorganisms. By destruction of microorganisms, the area and equipment contribute to less contamination of the processed products.
and physical hazards from raw material production, receiving and handling, to manufacturing, distribution, and consumption of the finished product. HACCP helps food processors compete more effectively in the world market, where HACCP is becoming the standard food safety assurance program. HACCP places responsibility for ensuring food safety appropriately on the food manufacturer or distributor. The features of HACCP include:
Focusing on identifying and preventing food safety hazards
Being proactive—preventive strategies are considered early in the process
Sound science basis
Forcing manufacturers to monitor their process continuously
Permitting more efficient and effective government oversight
Seven principles are included in developing a HACCP program. They are listed and briefly described in Table 7 (33).
GMPs and SSOPs are the prerequisite programs of HACCP and help to create an operating environment that allows the production of safe, wholesome food. All prerequisite programs should be documented and regularly audited along with the HACCP plan. In addition, product and process information, including product description, ingredient list, and process flow chart are the foundation for developing a HACCP plan. The IDFA's
Table 7 Seven HACCP Steps and Their Brief Description
Step 1. Conduct a Biological, chemical, and physical hazards are conditions that may pose hazard analysis an unacceptable health risk to the consumer. During the hazard analysis, all food safety hazards associated with each specific step of the manufacturing process are listed and those that are significant are identified.
Step 2. Identify critical Critical Control Points (CCPs) are steps at which control can be applied control points so that a food safety hazard can be prevented, eliminated, or reduced to acceptable levels. Examples of controls include pasteurization, cooking, curing, acidification, or drying steps in a food process.
Step 3. Establish critical All CCPs must have preventive measures that are measurable. Critical limits limits are the operational boundaries of the CCPs that control the food safety hazard(s). They might include pasteurization time/ temperature limits, end cooking temperature, or product pH. Critical limits are set according to regulations in place (pasteurization of milk or cold holding temperatures at retail), experience with a product, research data, or in consultation with food safety authorities familiar with your product process. If critical limits are not met, the process is ''out of control,'' and it is possible that food safety hazard(s) are not being prevented, eliminated, or reduced to acceptable levels.
Step 4. Monitor CCPs Monitoring is a planned sequence of measurements or observations to ensure the product or process is in control (critical limits are being met). It allows processors to assess trends before a loss of control occurs. Adjustments can be made while continuing the process. The monitoring interval must be adequate to ensure reliable control of the process. Monitoring could include checking temperatures of a cooler twice per day, the use of a continuous temperature monitoring device on a pasteurizer, or a pH test.
Step 5. Establish corrective HACCP is intended to prevent product or process deviations. However, actions should loss of control occur, there must be definite steps in place for handling the product in question and for correction of the process. Corrective action plans must be thought out and written as part of the HACCP plan, not determined at the time of the deviation. If, for instance, a cooking step must result in a product center temperature between 165°F and 175°F, and the temperature is 163°F, the corrective action could require a second pass through the cooking step with an increase in the temperature of the cooker.
Step 6. Record-keeping The HACCP system requires the preparation and maintenance of a written HACCP plan together with other documentation. This must include all records generated during the monitoring of each CCP and notations of corrective actions taken. Usually, the simple record-keeping system possible to ensure effectiveness is the most desirable.
Step 7. Verification Verification has several steps. The scientific or technical validity of the hazard analysis and the adequacy of the CCPs should be documented. Verification of the effectiveness of the HACCP plan is also necessary. The system should be subject to periodic revalidation using independent audits or other verification procedures.
HACCP Plant Manual (28) describes specific guidelines for developing and implementing even steps of HACCP in dairy plants. Model HACCP programs for milk and milk products, frozen desserts including ice creams and yogurts, cheeses, and butter are provided.
Here are the practice guidelines for designing and implementing HACCP in dairy operations.
Set up a record-keeping system that is easy to use and easily accessed. Product records need to be reviewed before shipping.
Keep for your records minutes of discussions related to hazard evaluation, selection of critical control points, critical limits, potential monitoring activities, corrective actions, and so forth.
Begin the HACCP process early. Involve and use the experience and knowledge of people involved in each step, process or department.
Train employees so that they know what they are supposed to do and when they are supposed to do it.
Take a look at problems you have had in the past. Address those problems in your HACCP plan.
Activities covered by your SSOPs or GMPs probably do not need to be included in your HACCP plan.
Once you have developed your flow diagram on paper, go out into the plant and verify the flow diagram. Check product flow and employ related activities.
Once you have a HACCP plan draft, test it out in small segments.
Reassess your plan often in the beginning. Later you may need to reassess only 1-2 times per year.
Once your HACCP plan is in action and reassessment is made, document when and what changes are made to the plan. When changes are made, it is important that the plan and employee-related duties changes are made at the same time.
Establish a plantwide feedback system for continuous improvement.
Document in your plan where records are stored. Store HACCP records that need to be accessed separate from other company records.
Say WHAT will be done, HOW it will be done, and WHO will do it—then, DO WHAT YOU SAY.
In general, fermented dairy products are considered to have a low risk of causing food poisoning because they contain natural acids that prevent the growth of foodborne bacteria. Processing, such as fermentation (lowering pH) and heating (pasteurization), also reduces the risk of contaminating bacteria. However, the products can be infected with pathogens during processing or after. Processors should start with good-quality raw materials and have strict controls over hygiene and handling. The generalized process flow chart for fresh cheeses is shown in Figure 3 and a summary of the main quality assurance procedures for fresh cheese processing is shown in Table 8. The quality assurance procedures in the table are discussed in more detail in the following sections.
1. Raw Materials Handling, Storage, and Inspection
The basic ingredient of fermented dairy products is milk, hence ensuring high quality of incoming milk is essential to achieve high quality and safe products. Basic tests on the standard plate counts, coliforms, drug resdues, and phosphatase of milk are required for
determining milk quality. The PMO standards on grade A pasteurized milk are illustrated in Table 9. Other raw materials used in the production of fermented dairy products, including starter cultures, rennet, and packaging materials, have to be subject to examination, too. The standard methods for the examination of milk and milk products can be found in Marshall (34) and Fox et al. (35).
Milk pasteurization is a critical control point in a dairy processing HACCP program. An appropriate heating temperature and time is essential to destroy or prevent the growth of undesirabl microorganisms. Table 10 lists PMO recommended minimum pasteurization temperature and time combinations for milk and milk products. The basic pasteurization principle is that ''every particle of milk or milk product be heated to at least a minimum temperature and held at the temperature for at least the specified time in properly designed and operated equipment.'' In addition to the basic operation procedures for high-temperature short-time (HTST) milk pasteurization suggested by PMO, other requirements are:
Calibrate thermometers in the pasteurizing unit to ensure the correct temperature readings.
Reject milk not heated to the required temperature for the required time, and redirect it through the pasteurizer again.
Check at startup that the flow diversion valve on continuous flow pasteurizing units are operating correctly.
Table 8 Quality Assurance Procedures for Fresh Cheese Processing
Raw material handling and storage
Raw material inspection
batch preparation Processing control
Storage and distribution
Receive milk from farms, and purchase starter cultures and rennet supplies.
Record amount and quality of milk and other raw materials.
Weigh and mix ingredients
Pasteurize milk, adding start culture, rennet, curd setting; cut, drain, and wash curd to make required products.
Fill product into packages, seal and label. Pack into distribution boxes.
Store finished product. Dispatch products in required amounts to retailers or customers.
Arrival temperature of milk should be <10°C, and storage at <6°C. Starter cultures and rennet should be stored at cold and dry places. Specification of milk quality based on the total colony counts, inhibiting substance, composition, etc., microbiological examination, activity tests, and absence of contamination on starter cultures. Training in accurate weighing and keeping records of ingredients used. Preparation of processing schedule and training of operators to ensure: control of temperature and time of heating correct amount of starter culture and rennet added at the correct time in the processing Establish standards for operator hygiene and schedule for cleaning of equipment and processing room Establish specifications for package quality, labels, and fill weight. Implement inspection, check-weighing, and recording procedures. Control store room temperature and implement cleaning schedule and stock rotation procedures. Ensure records are kept. Establish inspection and recording procedures to ensure that customers receive the correct product in the amount specified.
Regularly monitor the results of phosphatase testing of pasteurized milk to ensure that the heating plates of the HTST pasteurizer do not leak. Maintain, correctly calibrate, and service equipment regularly.
3. Packaging, Storage, and Distribution
Packaging, storage, and distribution should be performed in such a way that product is protected against contamination through the following measures.
Packaging of milk and milk products shall be done at the place of pasteurization in a sanitary manner by approved mechanical equipment.
Cottage cheese, dry-curd cottage cheese, and reduced-fat or low-fat cottage cheese may be transported in sealed containers in a protected, sanitary manner from one plant to another for creaming and/or packaging.
Seals on lids should have close and continuous contact with the container rim. Plastic and glass seals should not be contaminated with product or else the seal will leak.
Grade A raw milk and milk
Cooled to 7°C (45°F) or less within
products for pasteurization,
Was this article helpful?