Small-Scale Postharvest Handling Practices PDF

CHAPTER 11: FOOD SAFETY PRACTICES Concerns about food safety when handling fresh fruits and vegetables have increased over the past decade. Recent outbreaks of food-bourne disease have been associated with berries, tomatoes, leafy greens and cut fruits. Wholesale buyers and consumers are increasing...

CHAPTER 11: FOOD SAFETY PRACTICES Concerns about food safety when handling fresh fruits and vegetables have increased over the past decade. Recent outbreaks of food-bourne disease have been associated with berries, tomatoes, leafy greens and cut fruits. Wholesale buyers and consumers are increasingly interested in the use of handling practices that will ensure food safety. It is the responsibility of growers and postharvest handlers to document their practices to protect fresh produce from contamination. Retailers such as large supermarket chains are demanding compliance with food safety practices from their suppliers. And soon it may be impossible to export produce to Europe or the U.S. without documenting its safe handling from the farm to the market. Some general food safety practices are being promoted by universities, governmental agencies and private sector organizations around the world. For growers who want to export their produce to the European Community, you should be aware that new standards are being developed by the retail produce industry to guide handling practices for growers and shippers (known as EUREP-GAP). Key concepts are the implementation of GAP (Good Agricultural Practices) on the farm, in the packinghouse and during transport of all fresh produce, and HACCP (Hazard Analysis Critical Control Points) to document the safe handling of farm chemicals, pesticides, packaging materials, etc., especially for processed or fresh-cut produce. There is a EUREP-GAP deadline for food safety looming for fresh products intended for market in Europe. Export growers have until 2003 to meet specifications for hygiene and quality. Most small-scale packinghouses will require new water systems and improved sanitation practices. Current information can be found on the internet (http://www.eurep.org). Guidelines for U.S. growers have been published by various sources. A copy of the publication: “Food safety begins on the farm: A grower’s guide” can be obtained at no cost from Cornell University ’s Good Agricultural Practices Program (e-mail: [email protected] ). The typical causes and sources of food safety problems during production and postharvest handling fall into the following three major categories. Physical Hazards: Examples of physical hazards which may become imbedded in produce during production handling or storage are such things as: fasteners (staples, nails, screws, bolts) pieces of glass wood splinters Chemical Hazards: Examples of chemical hazards which may contaminate produce during production handling or storage are such things as: pesticides, fungicides, herbicides, rodentacides machine lubricants from forklifts or packing line equipment heavy metals (Lead, Mercury, Arsenic) industrial toxins compounds used to clean and sanitize equipment Human Pathogens: There are four main types of human pathogens associated with fresh produce: soil associated pathogenic bacteria (Clostridium botulinum, Listeria monocytogenes) feces associated pathogenic bacteria (Salmonella spp., Shigella spp., E. coli O157:H7 and others) pathogenic parasites (Cryptosporidium, Cyclospora) pathogenic viruses (Hepatitis, Enterovirus). Many of these pathogens are spread via a human (or domestic animal) to food to human transmission route. Handling of fruits and vegetables by infected field-workers or consumers, cross contamination, use of contaminated irrigation water, use of inadequately composted manure or contact with contaminated soil are just a few of the ways that transmission of human pathogens to food can occur. While produce quality can be judged by outward appearance on such criteria as color, turgidity and aroma; food safety can not. Casual inspection of produce cannot determine if it is in fact safe and wholesome to consume. Management of growing and postharvest handling conditions are paramount in preventing the contamination of fresh produce by physical hazards, harmful chemicals and human pathogens. Source: Gorny, J.R. 1999. Chapter 10: Food Safety for fresh horticultural produce. In : Kitinoja, L. and Gorny, J.R. Small-Scale Postharvest Technology: Economic Opportunities, Quality and Food Safety. Postharvest Horticulture Series No.21, Department of Pomology, University of California , Davis. Food Safety on the Farm Practices related to these four simple principles can reduce the risk that produce may become contaminated on the farm. Clean soil Avoid the improper use of manure. Compost manure completely to kill pathogens, and incorporate it into soil at least two weeks prior to planting. Keep domestic and wild animals out of fields to reduce the risk of fecal contamination. Provide portable toilet facilities* near the field. Prevent run-off or drift from animal operations from entering produce fields. Do NOT harvest produce within 120 days of a manure application. Clean water Test surface water that is used for irrigation for fecal pathogens on a regular basis, especially if water passes close to a sewage treatment or livestock area. Keep livestock away from the active recharge area for well-water that will be used for irrigation. Keep chemicals away from the active recharge area for well-water that will be used for irrigation. Filter or use settling ponds to improve water quality. Where feasible, use drip irrigation to reduce crop wetting and minimize risk. Use potable water for making up chemical pest management sprays. Clean surfaces Tools and field containers must be kept clean. Wash and sanitize these items before each use. Clean hands Workers who harvest produce must wash their hands after using the toilet. Provide soap, clean water and single-use towels in the field and insist that all workers wash their hands before handling produce. * (For information on obtaining portable toilet facilities, contact the Portable Sanitation Association International at (800) 822-3020.) Source: Cornell University GAPs Program. 2000. Reduce Microbial contamination with Good Agricultural Practices. Proper hand-washing is an effective strategy for reducing risk of contamination, but food safety experts have observed that few people wash their hands properly. Cornell's Good Agricultural Practices Program provides the following steps: Wet hands with clean, warm water, apply soap and work up a lather. Rub hands together for 20 seconds. Clean under the nails and between the fingers. Rub the fingertips of each hand against the palm of the opposite hand.  Rinse under clean, running water. Dry hands with a single use towel. Source: Cornell University GAPs Program. 2000. Reduce Microbial contamination with Good Agricultural Practices. Minimizing pathogen contamination during harvest During harvesting operations field personnel may contaminate fresh fruits and vegetables by simply touching them with an unclean hand or knife blade. Portable field latrines as well as hand wash stations must be available and used by all harvest crew members. Monitoring and enforcement of field worker personnel hygiene practices such as washing hands after using the latrine are a must, to reduce the risk of human pathogen contamination. Workers who are ill with hepatitis A or who have symptoms of nausea, vomiting or diarrhea should not be assigned to harvest fresh produce. Produce once harvested should not be placed upon bare soils before being placed in clean and sanitary field containers. Field harvesting tools and gloves should be clean, sanitary and not be placed directly in contact with soil. Field containers should be cleaned and sanitized on a regular basis as well as being free of contaminants such as mud, industrial lubricants, metal fasteners or splinters. Do not allow workers to stand in field bins during harvest to reduce pathogen spread by shoes. Plastic field bins and totes are preferred to wooden containers since plastic surfaces are easier to clean and sanitize, which should be done after every use. If containers are not cleaned and sanitized after every use, they may become contaminated and then contaminate the next products which are placed in the container. Wooden containers or field totes are almost impossible to sanitize since they have a porous surface and wooden or metals fasteners such as nails from wooden containers may accidentally be introduced into produce. Cardboard field bins if reused should be visually inspected for cleanliness and lined with a polymeric plastic bag before reuse to prevent the risk of cross contamination. Depending upon the commodity, produce may be field packaged in containers that will go all the way to the destination market or be temporarily placed in bulk bins, baskets or bags which will be transported to a packing shed. Employees, equipment, cold storage facilities, packaging materials and any water which will be contacting the harvested produce must be kept clean and sanitary to prevent contamination. Source: Gorny, J.R. 1999. Chapter 10: Food Safety for fresh horticultural produce. In : Kitinoja, L. and Gorny, J.R. Small-Scale Postharvest Technology: Economic Opportunities, Quality and Food Safety. Postharvest Horticulture Series No.21, Department of Pomology, University of California , Davis. Minimizing pathogen contamination during postharvest handling Employee Hygiene Gloves, hairnets and clean smocks are commonly worn by packinghouse employees in export oriented packing sheds. The cleanliness and personnel hygiene of employees handling produce at all stages of production and handling must be managed to minimize the risk of contamination. Adequate bathroom facilities and handwash stations must be provided and used properly to prevent contamination of produce by packinghouse employees. Shoe or boot cleaning stations may also be in place to reduce the amount of field dirt and contamination which enters the packing shed from field operations. Employee training regarding sanitary food handling practices should be done when an employee is hired and reviewed before they begin work each season. Equipment Food contact surfaces on conveyor belts, dump tanks etc. should be cleaned and sanitized on a regular scheduled basis with food contact surface approved cleaning compounds. A 200 parts per million sodium hypochlorite (bleach) solution is an excellent example of a food contact surface sanitizer. Sanitizers should be used only after thorough cleaning with abrasion to remove organic materials such as dirt or plant materials. Use of steam to clean equipment should be avoided since steam may actually cake organic materials and form a biofilm, which renders equipment almost impossible to sanitize. Steam may also aerosolize bacteria into the air and actually spread contamination throughout the packing house facility. Packaging materials All packaging materials should be made of food contact grade materials to assure that toxic compounds in the packaging materials do not leach out of the package and into the produce. Toxic chemical residues may be present in some packaging materials due to use of recycled base materials. Empty packages such as boxes and plastic bags should be stored in an enclosed storage area to protect them from insects, rodents, dust, dirt and other potential sources of contamination. These actions protect not only against the potential loss of valuable materials but protects the integrity and safety of these materials. Wash and Hydrocooling Water All water which comes in contact with produce for washing or hydrocooling must be safe to drink. Water should contain between 100 and 150 parts per million total chlorine and have a pH of between 6 and 7.5. Chlorine use prevents the potential for cross contamination of all produce in the washing or hydrocooling system, it will not sterilize the produce. Change the water in dump tanks and hydro-coolers regularly. For more information about water disinfection, see publications by Trevor Suslow under the "Publications Organized by Topic" section of the "http://postharvest.ucdavis.edu"; Internet site. Ice for cooling Use ice made from only potable water sources. Refrigerated Transport Produce is best shipped in temperature controlled refrigerated trucks. Pre-cool the vehicles prior to loading. Maintaining perishables below 5ºC (41º F) even while being transported to destination markets will extend shelf-life and significantly reduce the growth rate of microbes including human pathogens. Temperatures used for tranporting chilling sensitive produce will not protect against the growth of most pathogens. Trucks used during transportation should be cleaned and sanitized on a regular basis. Trucks which have been used to transport live animals, animal products or toxic materials should never be used to transport produce. Sources: Gorny, J.R. 1999. Chapter 10: Food Safety for fresh horticultural produce. In : Kitinoja, L. and Gorny, J.R. Small-Scale Postharvest Technology: Economic Opportunities, Quality and Food Safety. Postharvest Horticulture Series No.21, Department of Pomology, University of California , Davis. Cornell University GAPs Program. 2000. Reduce Microbial contamination with Good Agricultural Practices. Harris, L.J., D. Zagory, and J. R. Gorny. 2002. Safety factors. p. 301-314, in: A.A. Kader (ed). Postharvest Technology of Horticultural Crops, third edition. University of California , ANR Publ. No. 3311. Sanitizing field containers, tools and packhouse surfaces High pressure wash, rinse and sanitize all crop containers, tools and packhouse surfaces prior to each day’s harvest. Sanitizers should be used only after thorough cleaning with abrasion to remove organic materials such as dirt or plant materials. Most commercial sanitizers contain chlorine or quaternary ammonium compounds (QUATS, QAC, benalkonium chloride, N-alkyl dimethybenzyl ammonium chloride). Chlorine solutions prepared from chlorine gas, hypochlorites and cloramines are not compatible with quaternary ammonium compound sanitizers. Selection of the sanitizer to use depends upon the surface to be cleaned, hardness of the water, application equipment available, effectiveness under ambient conditions and cost. All require extreme care when handled as either compressed gas, powders or concentrated liquids. Use the following table to assist in the selection of appropriate sanitizers for your operation. Hypochlorites Chloramines Quaternary ammonium Chlorine gas (Na, K or Ca (di- or tri-chloro- compounds hypochlorite) isocyanuarate) Non-food contact, All food contact All food contact Used for: All food contact suffaces porous materials, suffaces suffaces drains, walls. Sanitizer properties Concentration 25 to 200 ppm 25 to 200 ppm 25 to 200 ppm 200 ppm Germicidal activity High High High Varies Specificity General General General Good against molds Speed Fastest Fastest Fast Moderate  Powder better than Form Compressed gas Powder Concentrated solution liquid Stability Good Good Good Excellent Toxicity Low Low Low None Effective over broad pH range Best at 6-7.5 Best at 6-7.5 Best at 6-7.5 range Temperature Maximum 115°F Maximum 115°F Maximum 115°F Maximum 120°F Activity decreases in Activity decreases in Effectiveness in Activity decreases in very Inactivated in hard very hard water very hard water hard water hard water (>500ppm) water (>500ppm) (>500ppm) Slight to moderate Slight to moderate Low Corrosion None Very corrosive at pH