Fruits and vegetables, in addition to being low in fat and high in fiber, are also rich in antioxidants, which have been shown
to benefit health. In the past two decades, there has been a greater emphasis by the USDA and public health officials on increasing the consumption of fruits and vegetable for healthy living. With increased consumption of produce in the United States, the outbreaks of human gastroenteritis associated with consumption of fresh produce contaminated with pathogenic bacteria, parasites, and viruses have occurred with increased frequency since early 1990s (NACMCF 1999;
Beuchat 2006). The growth in production, marketing, and trade resulting from increased demand and consumption of fruits and vegetables has also heightened consumers concerns with respect to food-related disease outbreaks (Rangarajan et al. 2000).
Production and marketing of safe food (from chemical, biological, and microbial contamination perspectives) entail a number of inputs and operations in the field or orchard and postharvest value chain (Rangarajan et al. 2000). These researchers asserted that the highly mechanized and diverse agricultural production practices together with increased in- ternational trade have expanded options to consumers.
Sources of potential contaminations can be divided into pre- and postharvest types, as shown in Box 21.1 (Rangarajan et al. 2000).
Food safety is a complex issue that requires a thorough un- derstanding of the mechanisms of food contamination. Fig- ure 21.1 shows the basic food supply chain and possible ways in which produce can be contaminated/cross-contaminated or intentionally contaminated (Beuchat 1996).
Box 21.1 Potential Sources of Contamination
Preharvest:
r Soil
r Irrigation water r Animal manure
r Inadequately composted manure r Wild and domestic animals r Inadequate field worker hygiene r Harvesting equipment
Postharvest:
r Transport containers (field to packing facility) r Wash and rinse water
r Unsanitary handling during sorting and packaging r Equipment used to soak, pack, or cut produce r Ice, for cooling produce
r Cooling units (hydrocoolers) r Transport vehicles
r Improper storage temperature r Improper packaging
r Cross-contamination in storage, display, and prepara- tion
Source: Rangarajan et al. (2000).
Cross/intentional contamination
Animals
Produce (F & V)
Humans
Meat, milk, eggs
Harvesting, handling, and processing
environments
Soil
Feces Insects
Water
Feed
Figure 21.1. Food contamination cycle of produce—fruits and vegetables. (Adapted from Beuchat 1996.)
To minimize food safety and public health problems, it is important to produce fruits not only in a safe man- ner by following GAPs but also to maintain a safe supply chain throughout marketing channels. While it is impossi- ble to completely avoid the risk of microbial contamina- tion, nonetheless, carefully adopted preventative measures can certainly reduce such risks. In 1998, the U.S. Depart- ment of Health and Human Services (HHS), FDA, and Cen- ter for Food Safety and Applied Nutrition (CFSAN) issued
“Guidance for Industry–Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and Vegetables,”which ad- dressed microbial food safety hazards and GAPs and Good Manufacturing Practices (GMPs) (FDA 1998). These guide- lines covered measures common to the growing, harvesting, cleaning/washing, sorting, packing, and transporting of most produce sold to consumers in an unprocessed or minimally processed raw form. Calvin (2003) noted that FDA empha- sizes the fact that GAPs only reduce the risk of microbial contamination and cannot eliminate the risk.
The guidance identifies eight principles of microbial food safety that can be applied to production, harvesting, packing, and transportation of fresh produce; these prin- ciples are based on certain basic principles and practices associated with minimizing microbial food safety hazards from the field through distribution of fresh produce (FDA 1998). These principles emphasize: (1) Prevention of micro- bial contamination of fresh produce over reliance on cor- rective actions once contamination has occurred; (2) Mini- mization of microbial food safety hazards in fresh produce, growers, packers, or shippers should use good agricultural and management practices in those areas over which they have control; (3) That fresh produce can become microbio- logically contaminated at any point along the farm-to-table food chain. The major source of microbial contamination with fresh produce is associated with human or animal feces;
(4) Whenever water comes in contact with the produce, its source and quality dictates the potential for contamination.
Minimize the potential of microbial contamination from wa-
ter used with fresh fruits and vegetables; (5) Practices using animal manure or municipal biosolid wastes should be man- aged closely to minimize the potential for microbial contam- ination of fresh produce; (6) Worker hygiene and sanitation practices during production, harvesting, sorting, packing, and transport play a critical role in minimizing the potential for microbial contamination of fresh produce; (7) Following all applicable local, state, and Federal laws and regulations, or corresponding or similar laws, regulations, or standards for operators outside the United States, for agricultural prac- tices; and (8) Accountability at all levels of the agricultural environment (farm, packing facility, distribution center, and transport operation) is important to a successful food safety program.
Packaging, Transport, and Retailing
Food safety requires that fruits should be handled in safe manner at all steps of food value chain. O’Beirne (2007) suggested the following important considerations at various stages of value chain:
Production and harvesting:(a) producer awareness of role in food safety, (b) training and facilities for workers, (c) avoiding animal manure/sewage/flooded land, (d) irrigating with clean water, (e) cleaning and sanitizing harvesting equip- ment, (f) excluding wild birds and animals from packing- house, (g) minimizing bruising and cutting, and (h) avoiding cross-contamination during delivery to processor.
Fresh-cut processing:(a) program for sanitizing surfaces and machines, (b) good preliminary decontamination and in- spection, (c) avoiding severe peeling/cutting techniques that result in higher tissue injury, (d) eliminating/minimizing hu- man contact with processed product, (e) deploying effective washing/antimicrobial dipping, and (f) avoiding postdipping contamination.
Packaging/Distribution/Retail: (a) careful selection of packaging material, (b) monitoring microbial quality of pack- aged product, (c) ensuring a temperature of⬍4◦C, (d) process
Table 21.2. Maintaining the Cold Chain for Perishables Value-Chain
Stage Suggested Actions
Harvest r Protect the product from the sun r Transport quickly to the packinghouse Cooling r Minimize delays before cooling
r Cool the product thoroughly as soon as possible
Temporary storage
r Store the product at its optimum tempera- r turePractice “first-in-first-out” rotation r Ship to market as soon as possible Transport to
market
r Use refrigerated loading area r Cool truck before loading
r Load pellets toward the center of the truck r Put insulating plastic strips inside door of
reefer if truck makes multiple stops r Avoid delays during transport
r Monitor product temperature during trans- port
Handling at destination
r Use a refrigerated unloading area r Measure product temperature
r Move product quickly to the proper stor- age area
r Transport to retail markets or foodservice operations in refrigerated trucks
r Display at proper temperature range Handling at
foodservice outlet or home
r Monitor product temperature during trans- r portStore product at proper temperature r Use the product as soon as possible Source: Adapted from Kader (2003).
at low temperature, (e) suitably designed vehicles, (f) proper vehicle loading practices, including chill cabinet loading, (g) modest shelf life labeling, and (h) education of retailer and consumer.
Maintaining a desired cold chain throughout marketing channels not only extends the shelf life of perishable com- modities, including fresh fruits, but it also minimizes risks of microbial growth due to temperature abuse. Kader (2003) suggested a number of actions needed to maintain the cold chain throughout the postharvest handling system for per- ishable horticultural crops; these actions are summarized in Table 21.2.
Quality and Shelf Life
For quality and shelf life of intact and fresh-cut fruits, selec- tion of best quality fruits, temperature, and relative humidity (RH) control are important factors (Gross et al. 2002; Kader 2002). Kader (2003) reported that there is a continuing trend toward increased precision in temperature and RH manage-
ment to provide the optimum environment for fresh produce during cooling, storage, and transport; precision temperature control and management tools, including time–temperature monitors, are becoming more common in cooling/storage fa- cilities and during transportation and shipping (Figure 21.2).
In addition, edible coatings, waxing, sanitizers, innovative packaging, etc., can further enhance the postharvest safety and shelf life of fruits.
Kader (2003) noted that the emphasis of continuing re- search on produce safety is on developing reliable and quick detection methods for human pathogens, improving efficacy of water disinfection techniques, and developing methods for reducing microbial load on intact and fresh-cut fruit. Other as- pects of produce safety included ensuring that the pesticides residues are within the legal limits and avoiding handling conditions that lead to contamination with mycotoxins.
Critical Food Safety Violations
As compared with vegetables, the critical food safety vio- lations reported for fresh fruits are relatively few. The low pH or high acidity of fruits plays an important role in the overall safety of fresh fruits. Food safety violations/recalls are reported comprehensively by FoodHACCP.com (Anon 2011), which also publishes monthly “Food Safety” maga- zine, and USDA’s Food Safety and Inspection Service (FSIS 2011). The violations/recall reported at both of these sites cover food-borne illnesses.
Other types of violations, such as related to pesticide appli- cation/residue, are spelled out in state food and agricultural codes. California Food and Agricultural Code (CFAC 2011), section 12671–12674, lists regulations related to such vio- lations. For example, section 12671 says “It is unlawful for any person to pack, ship, or sell any produce that carries pes- ticide residue in excess of the permissible tolerance which is established by the director.”
Organic Fruits
The general GAPs guidelines for produce safety can be used for the production of organic fruits. However, it must be noted that there are specific regulations with respect to or- ganic foods production, handling, and marketing (USDA- AMS 2011).
According to USDA-AMS (2011), “organic production is a system that is managed in accordance with the Organic Foods Production Act (OFPA) of 1990 and regulations in Ti- tle 7, Part 205 of the Code of Federal Regulations to respond to site-specific conditions by integrating cultural, biological, and mechanical practices that foster cycling of resources, promote ecological balance, and conserve biodiversity. The National Organic Program (NOP) develops, implements, and administers national production, handling, and labeling stan- dards.” Title 7, Section 205 regulations are available online
0 20 40 60 80 100 120 140 Temp. and RH outside the optimum range (1)
(1) + supplement treatments Optimum temp. and RH ranges (2) (2) + supplement treatments
Relative shelf life Figure 21.2. Relative postharvest shelf life of perishable commodities. (Adapted from Kader 2003.)
(e-CFR 2011). Readers are also referred to NOP Web site for detailed information on many aspects of organic food production (USDA-AMS 2011).