Chapter I. Microbiological Safety of Fresh and Fresh-Cut Produce: Description of the Situation and Economic Impact
September 30, 2001
Analysis and Evaluation of Preventive Control Measures for the Control and Reduction/Elimination of Microbial Hazards on Fresh and Fresh-Cut Produce
Fresh produce has become one of our most desirable foods because today's consumer perceives it as being healthy, tasty, convenient, and fresh. All of these characteristics are strong selling points to a busy and health-conscious consumer. The fruit and vegetable industry has experienced solid growth over the past 10 years as illustrated by increasing consumption and sales data and increasing space devoted to these products in supermarkets and on restaurant menus around the country.
However, with a growing fresh produce market, the industry is facing new challenges that require attention, such as the protection of consumers against microbiological hazards. How do the industry structure and market pressures influence the safety of produce? What are the costs of food safety protection systems and who will be financially able to implement them successfully? These are important questions to address in this overview of the fresh produce industry.
2. Fresh produce market structure
The movement and distribution of fresh produce through the various markets are variable and diverse, as it is depicted in detail in Figure I-1 (Kaufman and others 2000). The diversification of this market may have an impact on food safety of produce because there are many steps in its distribution, thereby increasing the opportunity for potential contamination. In addition, systems to track product through the different distribution channels during food safety investigations or product recalls are variable, which could hinder efforts to identify the source of any microbiological contamination. Today, the fresh produce industry is focusing much of its efforts on training employees about the importance of traceback plans, as well as developing and implementing traceback systems. There are also several guideline documents for reducing hazards in fruit and vegetable production available through the U.S. Food & Drug Administration (FDA) and industry associations such as the International Fresh-cut Produce Association (IAFP). These guidelines are highlighted in more detail later in the chapter.
2.1 Current size of the industry
The total fresh produce market reached $70.8 billion in retail and foodservice sales in 1997, up from $34.6 billion in 1987 (Kaufman and others 2000). Out of that total, the share of produce sales through foodservice outlets has risen 15% over the decade, while retail sales of produce dropped by 16% over the same period (Kaufman and others 2000). This decrease in retail sales is not surprising since consumers are busier, have higher incomes and consequently they are preparing less food at home. There has also been an increase in consumption of fresh produce from 284 pounds per capita in 1987 to 319 pounds per capita in 1997 (Kaufman and others 2000). As indicated previously, these growth trends are spurring the need for improved food safety systems for growing, harvesting, packing, processing and distributing of fresh produce from the field to the consumer at the restaurant and grocery store.
Within the fresh produce market, fresh-cut produce has been defined as "any fresh fruit or vegetable or any combination thereof that has been physically altered from its original form, but remains in a fresh state" by IFPA (2001). Estimated at $11 billion in retail and foodservice sales in 2000 (IFPA 2001), the fresh-cut produce market has grown exponentially since its infancy in the early 1980's. The demand for convenience is driving the growth of value-added produce and the fresh-cut produce market expansion will most likely continue in the near future. As this market continues to grow, the fresh-cut industry is challenged to work with growers, shippers and distributors to obtain high quality, safe produce, as well as continue to process fresh-cut products under safe and sanitary conditions.
U.S. imports of fruits and vegetables have grown from $2.0 billion in sales in 1987 to $4.1 billion in 1997 (Kaufman and others 2000). Today, there is an average of 345 different produce items to choose from in a typical grocery store, up from 173 in 1987 (Litwak 1998). Consumers have become accustomed to having this level of choice on a year-round basis. In order to maintain this current consumer demand for variety, U.S. retailers rely on produce imports when U.S. or locally grown produce is not available. The increase in import volume represents an additional opportunity for exposure to contamination if the product is grown under poor production standards or mishandled during the long distribution cycle.
A third niche within the fresh produce category, organic produce has experienced major growth in the past 10 years as well. Estimated at $4 billion in sales in 2000 (PMA 2000), the organic produce industry is projected to have an increase in sales of 7% over the next three years. Clearly, some consumers have found that organic produce meets their desires for "environmentally-friendly" foods. As the demand for these commodities increases, the volume of production goes up and the per unit costs will likely come down, making them even more affordable for the restaurant or grocery store. The recent introduction of national regulations governing the certification of organic produce finally harmonizes many state and local standards (USDA 2000). These standards, however, do not address food safety or nutrition. Therefore, the organic producers, similar to conventional producers, need to utilize Good Agricultural Practices (GAP) and Good Manufacturing Practices (GMP) throughout production.
2.2 Consolidation trends
One major trend affecting the industry is consolidation at the buyer's end of the business. This consolidation is, in turn, driving consolidation at the supplier's end. In 1999, sales at the top eight U.S. retail chains topped out at an estimated $227 billion (FI 2000 Jan 31), which represented a 49% share of the entire food retail business, estimated at $461 billion (FI 2000 Jan 17). Industry estimates project that in several years, or less, there could be five top-selling chains with 50% of the retail business. In foodservice distribution, the trend toward a few companies owning a large proportion of the business is already a reality. According to Refrigerated & Frozen Foods Magazine (Anonymous 2000), the share of the top three foodservice distributors has grown from 32% to 43% of total foodservice sales in 2000. Clearly, the trend toward chain dominance in the food trade is here to stay.
The current tendency to buyer's consolidation has several consequences for the industry: 1) more sophisticated accounting and inventory technologies are needed; 2) new quality and safety standards must be fulfilled; 3) elimination of brokers to control truckloads is inevitable; and 4) products need to be inexpensive and consistent to meet the demands of ever-larger buyers. The increased volumes, new technologies, and loss of experienced brokers or middlemen will have a noticeable impact in the distribution system. For example, large buyers want more direct control of their products for greater accuracy, cost savings, better quality systems, and safety controls. The pressure is on the grower to expand their services to meet these production and food safety demands. The buyers are setting the pace for quality and safety improvements and will continue to influence the growers, packers, processors and distributors to meet their product specifications.
To continue marketing products, growers will need to consolidate, form partnerships or invest resources to expand their services. The current consolidation trend is driving mid-sized and large growers to combine their resources by merging, forming co-ops, acquiring other growers to form larger corporate farms, or creating commodity-based conglomerates capable of meeting the needs of the large corporate buyers of both retail and foodservice chains. Small farming companies, on the other hand, may not be marketing directly to retail or foodservice buyers in this atmosphere of corporate expansion and will be looking for other marketing niches. The success of small farms will depend on supplying specialty produce items to shippers, to state and local farmers' markets, u-pick sites, and larger farm conglomerates. Regardless of size, though, all agricultural operations will benefit if food safety becomes part of their operational plan, and shared through industry groups to effect change.
2.3 Global distribution trends
As mentioned earlier, there is a trend toward greater importation of fresh fruits and vegetables into the United States. Wholesalers are the primary source for imported produce because a retail or foodservice chain does not order enough of any one commodity to assemble a load. When commodities are imported by large wholesale operations and arrive in the United States, their journey has just begun. They may be exposed to many environments because of storage transfers, increased handling because some commodities are repacked to match U.S. requirements, or to longer storage time because some loads must go through quarantine procedures. Global procurement of fruits and vegetables meets the need for year-round access to most commodities but provides ample additional opportunities for possible exposure to contamination.
Several efforts are currently underway to harmonize the food safety standards for global production. The FDA has established minimum guidance recommendations known as Good Agricultural Practices (GAP) for the U.S. industry as well as the international marketplace supplying the United States with fruits and vegetables. These guidelines will be useful in minimizing contamination of fruits and vegetables for both domestic and overseas operations involved in production of produce.
In another global harmonization effort, the Codex Alimentarius Food Hygiene Committee of the Food & Agriculture Organization (FAO) and the World Health Organization (WHO) is developing a standard for the production of fresh produce, fresh-cut produce, and sprouts (CAC 2000). This code is similar to the FDA guidance and has been negotiated through a committee comprised of delegations from more than 50 countries.
2.4 Computer technology
Not only has importation influenced food production in the U.S., the technology revolution is also having a major impact on food manufacturing, distribution and purchasing. The world marketplace is being globalized through innovative and rapid technological changes. Perhaps, more important, technology is changing the way companies manufacture and trade their products. With the worldwide spread of computer technology through telecommunication advancements and miniaturization, a company's production of goods and services can still take place locally but are supported by systems that operate globally. For example, a small agricultural farm may produce their commodities on their farm but they are able to sell the products over the Internet and ship the product within days anywhere in the world.
Conversely, large corporations are moving their production operations around the globe looking for the best low-cost location or the expertise that can drive the development of a specific product or service. Consider this story about IBM that appeared in the "Lexus and the Olive Tree" by Thomas Friedman: "A group of computer programmers at Tsinghua University in Beijing is writing software using Java technology. They work for IBM. At the end of each day, they send their work over the Internet to an IBM facility in Seattle. There, programmers build on it and use the Internet to zap it 5,222 miles to the Institute of Computer Science in Belarus and the Software House Group in Latvia. From there, the work is sent east to India's Tata Group, which passes the software back to Tsinghua by morning in Beijing, back to Seattle and so on in a great global relay that never ceases until the project is done" (Friedman 2000). Given these kinds of advancements, it stands to reason that even office work, such as training or payroll, may operate outside the office in centralized low-cost locations by trained experts on the other side of the globe in the near future.
The produce industry has adopted new technology in production and marketing, but has been slow to embrace new sales transaction systems through third party e-Commerce technologies probably because of the prevalence of more personal buying relationships due to the perishability of fruits and vegetables. But because of consolidation and the cost savings gained through greater use of telecommunications and computers, the industry will continue to embrace technology in the future.
Business practices and food safety programs can be improved through computerization. For instance, new systems may include an enhanced traceback system through computerized labeling; better sanitation procedures through automatic chemical feed systems for water disinfection; and direct communications between growers/packers/ processors/distributors to improve handling practices. There is no question, however, that this new level of communication through technology will continue to contribute to the expansion of food distribution from the grower to the consumer.
In addition to improving business practices, communication technologies are impacting the shopping habits of consumers. Today, consumers can order groceries over the Internet and have them delivered to their homes. Popular produce commodities fit into this system, but maintaining food safety standards is imperative in building consumer confidence and repeat orders. In addition, retailers are designing new stores with drive-through windows for customers who have placed their orders over the Internet. The pick-up area has to be convenient and must accommodate three storage areas: dry, refrigerated, and frozen (Anonymous 2001). Therefore, storage and handling will have to take on a new role to preserve consumer confidence in this system.
3. Food safety systems in the produce industry
Fruits and vegetables are unique foods in that they are often consumed raw or with minimal preparation. To date, effective intervention strategies have been developed, but they cannot completely eliminate microbial food safety hazards associated with consumption of uncooked produce. Therefore, preventing contamination of fresh fruits and vegetables with microbial pathogens, dangerous levels of chemical residues, or physical contaminants is the most effective strategy to assure that these foods are wholesome and safe for human consumption.
3.1. Government food safety oversight for produce
Systems that assure the safety and wholesomeness of fruits and vegetables during growing, harvesting, postharvest handling, and fresh-cut processing fall into three prevention program categories:
Good Agricultural Practices (GAPs);
Good Manufacturing Practices (GMPs);
- Hazard Analysis Critical Control Points (HACCP).
For food safety, the FDA has published GAP guidelines to reduce or eliminate pathogen contamination in the field or packinghouse operations. FDA has also promulgated GMP regulations that apply to all food processing facilities, including fresh-cut operations. Currently, the use of HACCP is voluntary, but is widely used in the food processing industry as a successful component of a comprehensive food safety program.
3.1.1. Good Agricultural Practices
The GAP guidelines are generic in nature because of the wide variety of fruit and vegetable commodities, nor do they contain specific testing and monitoring guidelines because very little data are available to use in establishing recommendations for the field. Additional information on how to assess the microbiological hazards would be helpful. For instance, the guidelines recommend that growers confirm they are using microbiologically safe irrigation water, but there are no data available to identify the best procedures to confirm water safety in the field.
The execution of GAP programs falls into three distinct phases. The following is a description of the phases and an estimate of the cost involved. The costs are based on a farm described as a contiguous piece of land with one or more sources of water.
System Evaluation and Needs Assessment - A needs assessment comprises: 1) an assessment of the systems currently in place; 2) an initial needs assessment or audit to determine what actions need to be taken to prevent chemical, physical and microbiological contamination; and 3) determination of what documentation is needed to assure continuous compliance and traceability of specific product lots.
Costs: Needs Assessment = $300 - $500 per audit per farm
Implementation - Once the initial evaluation has been performed, the grower must take steps to implement new practices to reduce the risks identified. Although it is not possible to estimate all costs because of the variability of operational changes over time, the following steps are typical examples of what an average size farm may encounter. Training and documentation costs may be minimized if generic packages could be developed for use across the country.
- Employee training and monitoring (pruning, irrigation, harvest, packing crews)
- Testing and/or monitoring of soil amendments, water and finished products (microbes & pesticides) may include:
- Multi-residue pesticide screen in the field
- E. coli water test in the field or packinghouse
- Environmental Listeria swabs in the packinghouse
- Development of documentation
- Maintenance of documentation
- Labor cost
- Cleaning and sanitation
- Food safety program administration
- Record keeping
- Capital Expenditures
- Water treatment
- Cleaning and sanitation equipment
- Employee equipment (gloves, boots, hairnets, smocks)
- Cleaning and sanitation chemicals
- Fencing to exclude animals
- Changes due to manure management, such as composting, and so on
- Field latrines
- Record keeping systems (computers, manual)
Food Safety Program Verification - Once the program is implemented, independent third party audits for verification are valuable on a random basis. Procedures are based on visual observation, documentation review, employee interviews, and finished product testing.
Costs: $300-500 per audit per farm
3.1.2. GAP cost variables
The costs associated with implementing a GAP food safety program vary considerably based on a number of factors. Large grower/shippers may have in-house technical expertise to evaluate risks and design programs to reduce food safety risks. Smaller growers may not have in-house expertise and must outsource technical expertise to do risk assessments and design food safety programs. The cost of designing and implementing an on-farm food safety program will vary depending upon:
- Number and size of ranches (contiguous piece of growing ground) involved,
- Number of water sources used for irrigation, spray applications and so on,
- Ability of growers to develop food safety program documentation themselves,
- Increased labor costs associated with administering steps such as record keeping,
- Cost of chemical (pesticide, heavy metals, organics and so on) and microbiological tests needed to assure prevention of point contamination sources,
- Employee and/or harvest crew training session costs (direct labor, administration costs),
- Capital equipment costs to assure that people, water, and soil amendments do not contaminate produce.
Independent Third Party auditors (ITP) are playing a major role at the behest of food retailers and foodservice buyers in monitoring produce suppliers for compliance to GAPs as well as helping growers develop food safety programs. Direct costs of ITP audits and food safety design and implementation are largely being borne exclusively by grower/shippers because there is no evidence that farm-gate prices are rising beyond historical market prices. Even though there are many factors that work to keep the farm-gate price low, there is some evidence that buyers are beginning to partner with the grower to share in responsibility for the development of food safety programs. Unless there is a contract price established for the commodity, or the grower can reduce production costs in another category, there is no mechanism for additional food safety costs to normally be passed on to the buyer on the open market.
Currently, compliance with the FDA's GAPs is not mandatory because they are guidelines. This may give growers who are not implementing GAPs or food safety programs competitive advantage in the marketplace, since they do not incur the costs of developing or sustaining a food safety program. However, with the growing food safety awareness, these farms may eventually have difficulties continuing in the marketplace because many customers from the foodservice and retail markets are demanding evidence of these programs from their suppliers.
Horticultural crops have drastically different farm gate values often due to the direct costs associated with production, supply and demand forces, and location of the grower. The cost of implementing a food safety or GAP program for any given commodity will vary significantly depending upon what cultural practices are involved in production. Thus, GAP implementation costs will be a higher percentage of farm gate prices for lower priced commodities.
3.1.3. GMPs and HACCP
GMPs are FDA regulations directed at food processors and are located in the U.S. Code of Federal Regulations 21(CFR) Part 110.1 -- 110.99. GMPs cover all aspects of a processing environment from the design of a sanitary facility to rules forbidding jewelry on workers. Unlike GAPs, GMPs are rules that are clearly defined and easy to apply because a processing environment has easily defined boundaries and the processing activities can be contained and controlled.
Even though HACCP is not mandatory, it has been embraced by the fresh-cut processing industry as a useful tool for implementing food safety practices in the production environment. HACCP is well suited to identify hazards, monitor production for adherence to operational standards, and develop an effective record keeping system in a fresh-cut produce facility. With close attention to prerequisite programs, a processor can implement HACCP to round out their food safety program.
The terms HACCP and food safety are used interchangeably in the food industry, implying that HACCP may be the only approach to food safety. But HACCP is merely a component or tool in an overall food safety program and cannot be implemented without prerequisite programs such as GAPs, GMPs, and a Sanitation Plan firmly in place. This "cafeteria" style approach to food safety has served the fruit and vegetable industry well because the variety matches the multiple needs of the various produce business models from the fields to the fresh-cut processing facilities.
Estimates of the cost of HACCP and GMP implementation require a thorough analysis by expert economists. As an example, Table I-1 indicates the average costs of HACCP and GMP implementation in a typical medium sized fresh-cut processing facility as compared to recent fresh juice figures generated by the FDA in the final rule for fresh juice regulations (FDA 2001). The fresh-cut facility costs were derived from a medium-sized operation located in the middle of the United States and based on real costs averaged over the last 2 years. Costs were estimated based on the current practices in that facility.
Even though these operations use similar raw products, and have similar production activities, juice plant costs differed from the fresh-cut operation costs in several areas. One example is in the line item for pathogen controls. The cost differential occurs because pathogens must be controlled in the juice throughout the production process whereas pathogen control is only applicable in the wash water step for a fresh-cut processor. Also, the start-up costs for installation of a pasteurization system will be much higher than the cost of a chlorination system, but the recurring annual costs are similar. Another area of difference occurs in item 3, Monitoring the Standard Operating Procedures (SOP). The fresh-cut processor's food safety program relies almost exclusively on the prerequisite programs such as sanitation and GMPs to prevent contamination whereas the juice processors rely on pathogen controls such as pasteurization as illustrated in item 6 in Table I-1. In item 9 in Table I-1, outside testing costs are different because the fresh-cut processor has elected not to have an in-house laboratory; therefore, they send all the microbiological tests to an outside lab. Other differences are generally due to different philosophies of management.
|Recurring Annual Cost
|Recurring Annual Cost
|2||Prerequisite program SOPs||$575.00||$500||$0.00||$0.00|
|7||Natural toxin controls||$173.33||$0||$173.33||$0.00|
|10||Corrective action plan||$130.00||$80||$0.00||$0.00|
|15||HACCP monitoring/ recordkeeping||$2,888.33||$3,500||$2,888.33||$3,500.00|
4. Economics of intervention strategies to reduce or eliminate pathogens
4.1 In the field
Currently, the depth of implementation of intervention strategies to reduce pathogens in the produce industry depends on safety awareness and resource capability. Very often the larger grower/shippers with large economies of scale are the companies that can meet stricter requirements imposed by some customers because they have the most resources to invest in the needed equipment, training and monitoring procedures. For growers, in general, additional resources are needed in field operations for food safety programs including more employee training, a focus on sanitary facilities for the workers and an awareness of the sources of pathogenic bacteria. The testing of various matrices in the field for hazard potential has not been required by GAPs, but testing can determine the risks associated with various steps in produce operations. Additional research is also needed before adequate recommendations can be made to growers about preventive measures and effective treatments to remedy hazards in the field.
4.2 In the packinghouses
Packinghouses act as a central location for large volumes of fruits and vegetables to be combined before being redistributed to the marketplace. They play a very important role in cooling, washing, trimming, and packing the product for shipment. These operations may be owned by individual grower/shippers, or co-ops owned by many small farmers. Good sanitation procedures are essential for these operations as pathogens, if present, could spread through pooling of product.
Packinghouses need to put resources into the development of sanitation programs for equipment and buildings, employee training, and preservation of water quality. The GAP document outlines employee hygiene and sanitation processes that are important for packinghouse operations.
4.3 In the fresh-cut produce plant
In contrast to the farm, food safety guidelines have been well documented for the fresh-cut produce processors by the industry. GMPs are part of the FDA's regulations for all food processors and apply to fresh-cut produce as well. The industry has published its own "Food Safety Guidelines for the Fresh-cut Produce Industry" through IFPA (Gorny 2001). The IFPA guidelines incorporate GMPs as well as other food safety standards such as a model HACCP plan, sanitary facility design, and proper use of antimicrobials.
Chapter V on intervention strategies to reduce or eliminate pathogen contamination covers, in detail, the approved antimicrobials for processors to use in the production of safe fresh-cut products as well as the advantages and the disadvantages as of this writing. These antimicrobials are used primarily to keep the processing water free from pathogens and are not intended for sanitizing the surface of fruits and vegetables. Table I-2 details costs associated with most antimicrobials in wash water for small to mid-sized fresh-cut operations. These wash water disinfection processes are essentially equivalent to each other with regard to efficacy.
Active Ingredient Additives
|Operating Costs Per Year||Labor Costs Per Year||Total Cost per Annum
|Chlorine - Gas||$1,500||$43||$0||$100||$12,480||$14,023|
|Chlorine - NaOCl||$2,500||$172||$1000||$100||$12, 480||$16,252|
|Chlorine - Ca(OCl)2||$2,500||$150||$1000||$100||$12, 480||$16,230|
|Chlorine Dioxide||$2,500||$2,600||$80||$100||$12, 480||$17,760|
|Peroxyacetic Acid||$2,500||$41,429||0||$100||$12, 480||$56,509|
Table I-2 is a cost matrix of the capital and operating costs for the most commonly used wash water disinfection systems used in produce operations such as hydro-cooling and washing. The cost martrix was developed to allow comparison of the costs associated with various wash water disinfection systems and it should be noted that there are many confounding cost variables. Therefore, this data should be looked at as a starting point for cost comparison. The data presented in Table I-2 are valid only in relation to the following assumptions and changing these assumptions will directly affect the costs associated with any given operation.
Assumptions. To reduce the confounding affects and dynamic system specific variables such as the organic load, water quality, and so on, it was assumed that:
- The water used in this example is not re-circulated.
- There is no organic demand in the water such as produce, mud or dirt.
- The disinfectant levels stated are at levels of disinfectant necessary to assure that the water will not support the survival of vegetative cells of human pathogens such as Escherichia coli O157:H7 or Salmonella spp.
In this cost matrix a volume of 20,000 per day was chosen to simulate what a small or medium sized fresh-cut or whole produce operation may use in a day. It was also assumed that operations would be carried out 6 days per week 52 weeks per year for a total of 312 operating d /y. This means that approximately 6,000,000 gallons of water/y would be utilized by such an operation. This cost matrix is constructed in such a way as to compare the cost of treating 6,000,000 gallons of water to the following disinfectant levels:
- 2 ppm Free Chlorine
- 1 ppm Chlorine Dioxide
- 1 ppm Ozone
- 50 ppm Peroxyacetic Acid
Cost factors such as reduced sewage user fees, water use fees and other local considerations have not been factored into this cost matrix due to the wide variance in these fees on a per operation basis.
Assumptions. The following assumptions were made: 6 d/wk operations;312 operating d per y (6 d/wk X 52 wk/y), 20,000 gallons of fresh water used per d (6,000,000 gallons per y); operational labor costs = $40/h x 6 h/wk x 52 wk/ y.
Conversion Factors. The conversion factors used were: 8.3 lbs equals one gallon of water; and 2.2 lbs equals 1 Kg.
Disinfection equivalents were 2 ppm Free Chlorine = 1ppm Chlorine Dioxide = 1ppm Ozone = 50 ppm Peroxyacetic Acid based on oxidation reduction potential (ORP). Lethality Equivalents are more like 3.5 ppm HOCl = 1ppm ClO2 = 0.05 ppm O3 = 2 ppm Peroxyacetic Acid
On the basis of these assumptions, the cost calculations are as follows:
Cost of Chlorine Reagent
Available Chlorine Per Pound
Chlorine is commercially available in a number of different forms. Chlorine gas is commercially available as a compressed gas in 150 lb. compressed or larger gas cylinders. Sodium hypochlorite is typically commercially available as a bulk liquid solution that is 10-15% NaOCl. Calcium hypochlorite is typically commercially available in a powder or pellet form which is 65-70% Ca(OCl)2
|Chlorine Gas (100% Cl2)
Sodium Hypochlorite (10% NaOCl)
Calcium Hypochlorite (65-70% Ca(OCl)2)
|Therefore: 1.2 lbs. NaOCl = 1.0 lbs. Cl2 gas
Therefore: 1.5 lbs. Ca(OCL)2 = 1.0 lbs. Cl2 gas
Cost of Available Chlorine Per Pound
|Cl2||$ 0.27 - 0.41 per Lb.|
|NaOCl||$1.64 per Lb. = $1.20 per gallon X 1.2 Equivalent Concentration Factor|
|Ca(OCl)2||$1.44 per Lb. = $1.09 per Lb. X 1.5 Equivalent Concentration Factor|
Chlorine Demand Per D (Residual of 2ppm)
14 Gallons Per Minute (GPM) = 840 gallons per hour ~ 20,000 gallons per day ~ 6,000,000 gallons per annum
0.336 lbs./day = 0.012 X 14 (GPM) X 2 ppm
(0.012 is a dimensional conversion factor to attain the final units of lbs/day)
|Cl2||$0.41 per Lb. X 0.336 lbs./day X 312 days per year =||$ 43.00/Year|
|NaOCl||$1.64 per Lb. X 0.336 lbs./day X 312 days per year =||$172.00/Year|
|Ca(OCl)2||$1.44 per Lb. X 0.336 lbs./day X 312 days per year =||$151.00/Year|
Cost of Citric or Phosphoric Acid
Food grade acids are routinely used to buffer the pH of hydro-cooling and wash water because addition of NaOCl to water will increase its pH. Wash water systems are routinely buffered to a pH of 6.5 - 7.5 to keep chlorine in it most active bactericidal form of hypochlorous acid (HOCl).
Citric Acid = $4-5 per gallon
Phosphoric Acid = $1.50 per gallon
- Buffering Acids are used at about a quarter of the rate of NaOCl
- Citric Acid most commonly used due to its food grade status and its low cost
Assume about 1 gallon per day used = 312 gallons per year
|312 X $5.00 per gallon Citric Acid =||$1,560.00/year|
|312 X $1.50 per gallon of Phosphoric Acid =||$468.00/year|
The cost of an actuated pump is $2,500 for a basic unit for NaOCl and Citric Acid and $500 for alarm systems (low pressure, no water, no chemical etc).
Cost of Ozone
|Capacity:||15 GPM to deliver 1.5ppm O3|
|Electrical Usage:||3.6 kW|
|15 GPM = 900 GPH =||6666.66 operating hours to treat 6,000,000 gallons|
|6666.66 hours X 3.6 KW =||24,000 Kw hours|
|24,000 kW hr X $0.10 per kW hr =||$2,400 (where the cost of kW hr is averaged from different states)|
Cost of Peroxyacetic Acid
40-60 ppm used (80 ppm Max by Law)
|Wholesale Price:||$17 per gallon|
|Bulk Price:||$12 per gallon|
|Average Price:||$14.50 per gallon|
1 fluid ounce Peroxyacetic Acid (PA) per 16.4 gallons
1 gallon PA per 2,100 gallons
2,857 gallons of PA per 6,000,000 gallons
$41,429 to treat 6,000,000 gallons
Commercial wash water disinfection systems are targeted for minimum oxidation reduction potential (ORP) of 650 mV to assure almost instantaneous destruction of most vegetative pathogen cells. However, peroxyacetic acid wash water disinfection systems normally have a lower minimum ORP set point of 400-450 mV because peroxyacetic acetic acid's bactericidal mode of action is both by oxidation reduction potential and as metabolic poison. Peroxyacetic acid wash water systems also may utilize both ORP and time actuated control dose concentration because it has been observed that use of ORP alone may be insufficient to control peroxyacetic acid concentrations in produce wash water systems.
ORP of 400-450 for PA (650 for NaOCl based system)
May require ORP + time actuated control due to over shooting by ORP measurement. Therefore, not good for multiple application lines.
Significant cost savings in sewer use fees if water can be discharged.
Cost of Ultra-Violet Light (UV)
|Electrical Usage:||0.5 kW|
|15GPM = 900 GPH =||6,666.66 operating hours to treat 6,000,000 gallons|
|6,666.66 hours X 0.5 KW =||3,333.33 Kw hours|
3,333.33 KW/hr X $0.10 per kW hr = $333.33 (where the cost of kW hr is averaged from several states)
UV light wash water disinfection systems may also require an additional capital cost of a filtration system to remove particulate matter from the wash water stream if water is re-circulated. However, filtration systems commonly used to protect re-circulation pump integrity are often sufficient to remove large particulate matter that may interfere with the efficacy of UV wash water disinfection units.
Cost of Chlorine Dioxide
There are currently four types of common commercially available chlorine dioxide wash water sanitation systems.
||Cl2 gas, and NaClO2|
Chlorine dioxide generators are generally leased and not sold. The stabilized form was recommended for our application.
- 1 gallon per day of 2% NaOCl2 would be needed per day
- $8.34 per gallon or $1 per pound for the 2% NaOCl2 Solution
- 312 days X $8.34 per Gallon = $2,600 per year for 2% NaOCl2
- Need approximately 1/4 volume of acid per volume of 2% NaOCl2 used, therefore 0.25 gallons per day
- 312 d X 0.25 gallons of Phosphoric Acid per day = $80
A complicating factor in determining the economics of produce food safety systems is the diversity in business models currently used. Large produce companies may be completely vertically integrated enterprises to include growers (farmland owners or lessors) / shippers / processors completely in control of all aspects of production, marketing and distribution. Other companies may simply grow specific crops and sell them to a marketer or distributor who in turn sells to foodservice or retail accounts. Or a marketer/distributor may not grow any of the crops that they market and distribute, but may own the label or brand and the packinghouse in which the products are packed in.
Like produce farms, packinghouse operations are not always controlled by large corporations that may have the resources to apply effective safety procedures. Co-ops or commodity groups representing a group of small farmers may not have the same level of resources as a corporation, yet they operate packing systems for many commodities. Packinghouse operations are designed to preserve and package produce commodities and are currently included under the GAP guidelines and exempted from the GMP regulations. Irrespective of the size of operation, food safety programs must be implemented at all packinghouses.
In an attempt to reduce liability, some buyers are promoting strict safety expectations through purchasing specifications and third party audit requirements for their suppliers before any standards have been identified and tested for effectiveness. These requirements continue to drive the supply side of the produce industry to seek proper safety programs but the industry needs more scientific answers to reduce risk. Effective steps for reducing contamination can be implemented throughout the distribution system through cooperation between each segment of the supply chain.
In the next decade, mid-sized and large companies in the produce industry may experience unprecedented growth through consolidation by merging in an attempt to reduce costs and increase production. On the other hand, small companies may flourish because of the demand for more unique and readily available choices for niche markets. Diversity in marketing through increased imports, the use of biotechnology for development of new varieties, continued demand for convenience foods and the quest for longer shelf life all affect the food safety aspects of fruit and vegetable production. Intervention strategies developed to reduce and eliminate contamination must be flexible to serve small and large farming and processing operations while assuring that they are affordable, effective and efficient controls. Otherwise, food safety will continue to be a confusing mix of old wives tales, scientific jargon and sales pitches for the produce industry.
6. Research needs
Evaluate the cost of measures to ensure fresh produce safety and to minimize public health hazards. The evaluation should take into consideration the size of the industry, and how company size may play a role in the extent of the impact of strict implementation of these measures.
- Research and develop feasible pathogen prevention and control strategies, especially in the case of small size companies with limited financial resources.
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