Processing Produce: Not Such a Simple Proposition

With the increasing emphasis on incorporating more fresh fruits and vegetables into our diets, there is also an increasing demand for convenience and added value in these categories. At the same time, unfortunately, there seems to be an increase in food safety events associated with fresh produce. How can these conflicting trends be reconciled?

Two experts in the field offer some answers. Jeff Sholl (952-475-9088) is a serial entrepreneur who, after a successful career at Pillsbury, bought the Green Giant brand of fresh produce from that firm and operated it for a number of years.

Sholl became interested in modeling the spread of foodborne illness resulting from accidental or deliberate contamination and turned that interest into a Ph.D. thesis in food science at the University of Minnesota. Sholl worked with the U.S. Food and Drug Administration (FDA), Dept. of Homeland Security (DHS), and the Centers for Disease Control to expand the model, which was then used in the 2008 and 2010 DHS Integrated Risk Assessment. Sholl further developed the model into a commercial venture called BT Safety, which has since been sold. The commercial product, called Shepherd, provides semi-continuous monitoring of all the areas that affect the safety of a fresh food. The fundamental principle is assured ongoing prevention rather than annual or semi-annual third party audits. The inputs for a fresh food are seeds, water, sun, fertilizer, people, and the environment.

The new owners are extending Shepherd to provide traceability of fresh, laser-etched eggs. Currently, if one egg in a carton is damaged, the others cannot be repacked because the date code is only on the carton. If individual eggs are labeled, they can be safely repacked, saving significant costs.

Stephanie Smith (phone 541-571-7954) was chair of the United Fresh Fruit and Vegetable Association, and recently stepped down as CEO of the largest onion grower in the U.S., doing business as Riverpoint Farms. Onions are sold whole peeled, sliced, and diced in packages ranging from retail sizes to 600-pound totes. The process for onions is similar to that used for others: inspecting, washing, drying, peeling, size reduction, and packaging. Washing often includes a sanitizing agent, of which chlorine is most common. Ozone and organic acids are also used on some crops. Drying is continuous and in-line, but may be centrifugal in some cases, as for leafy greens.

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Wastes and By-products
Smith pointed out that produce processing always generates wastes for which uses are sought. The challenge is having sufficient volume to justify collection and further processing. Much produce is seasonal, with harvesting the entire crop taking place in a matter of weeks, so packing sheds and processing plants are overwhelmed and then idle until another crop appears.

The more processed a given item, the more waste is generated. For example, cantaloupes are usually sold whole, usually with just a surface wash. They can also be peeled, seeded, and cut into smaller pieces. The seeds are potentially useful in cosmetics, but collecting, cleaning, and packing them is a challenge. Pet food manufacturers are said to be interested in fruit and vegetable by-products as sources of fiber and other nutrients.

Some crops can be sources of natural colors and flavors, but, again, recovering these in commercial quantities can be difficult.

Fresh-cut Produce
Fruits and vegetables are living organisms, respiring even after harvest. This means that they consume carbon dioxide and oxygen and give off water, ethylene in some cases, and carbon dioxide. So long as the cells are intact, potentially destructive enzymes are inhibited, but once the peel or skin is removed and the interior flesh is disrupted, the fruit or vegetable begins to deteriorate. Refrigeration can slow, but not stop the decline, and preservatives are ineffective.

Ethylene can hasten ripening of some fruits and is employed with bananas, which are harvested green for ease of shipping from their tropical origins. They are ripened by exposure to ethylene at ports and produce markets. In other cases, ethylene must be removed from storage areas to retard senescence (decline in quality due to respiration) of certain crops. For the same reason, refrigerated storage of fresh produce is segregated to isolate ethylene producers from those that are vulnerable.

Most fruits and vegetables cannot retain their fresh character after heat treatment. Thus, value-added preparation for improved convenience in the home or foodservice relies on precise logistics to deliver products that are safe and of good quality. Cutting fruits and vegetables releases nutrients on which pathogens and spoilage microbes can live. Surface washing may help somewhat, and the use of sanitizers is common, but some leave a residue that may affect flavor. Rigid sanitation of the environment is the best precaution so some packing areas almost resemble clean rooms, with HEPA filters on air supply, garbing of workers, and positive pressure maintained.

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Organic Produce
Goodness Greeness is a family-owned, Chicago-based distributor of organic produce. Bob Scaman (phone 773-224-4411), company President, described his business as using semi-trailers as shopping carts, going from farm to farm in California and the Midwest, collecting what was available from certified organic growers. Originally, the trucks delivered to a central distribution center in which loads were broken down and redistributed to customers. Now that the business has grown, more customers take drop shipments from the supply trucks, requiring less handling in the distribution center and extending shelf life somewhat. Goodness Greeness repacks some products from cases to retail packages, but does little other processing. Certification as an organic grower is complex, requiring several years of chemical-free cultivation before a certified organic crop is produced.

Blueberries
A real estate developer in China was required by the government to invest in agricultural land in return for permission to build a golf resort. He chose blueberries as the preferred crop and planned to build a cold storage facility. Blueberries produce several crops in a given season, with the first having the largest and most valuable berries and subsequent pickings usually done manually, declining in quality. The best berries are sold fresh but have limited shelf life. Other grades are used as ingredients in baking and ice cream, and the lowest grade is used for juice.

Blueberries can be stored refrigerated for weeks and frozen for months. The original plot plans for the cold storage building in China had insufficient space around it for truck traffic, and it fell to me to break that news to the developer.

Sprouts
Sholl said that Smith and he are now marketing what many claim is the most dangerous fresh produce product—sprouts from seeds. Sprouts are grown by moistening seeds in a warm environment, which is a perfect condition for pathogens to grow on the surface of the seeds. Many producers are not very sophisticated processors, and there have been repeated outbreaks traced to sprouts.

The FDA has published good practices for growing sprouts, which include using 13,000 ppm of chlorine to wash the seeds and monitoring the growth water carefully. Their company, California Sprouts, has instituted a number of operating procedures including environmental and final product pathogen testing with no sprouts shipped prior to a negative hold-and-release result. Sholl stated that employee training and engagement in the manufacturing process is crucial to producing safe and wholesome sprouts. Sprouts are grown from seeds of alfalfa, clover, broccoli, and mung beans.

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The Food Safety Modernization Act poses new challenges for the fresh produce industry. Testing alone is not adequate to ensure safety. As Sholl has learned, prevention is essential. All food manufacturers must have a food safety plan that is essentially a hazard analysis critical control point (HACCP) plan. This requires identifying the potential hazards, which, as mentioned, increase as more is done to fresh fruits and vegetables. Some of the traditional tools of food preservation, such as thermal treatment, are not available for this industry.

HACCP is inherently preventive in that it anticipates potential hazards and identifies critical control points. HACCP plans also have prerequisite programs, including good manufacturing practices (GMP), standard operating procedures (SOP), and sanitation standard operating procedures (SSOP). Much of what Sholl advocates are included in these programs, including sanitary facility design, good agricultural practices (GAP) ensuring quality raw materials, and maintaining a sanitary environment to prevent contamination.

Smith met with Michelle Obama as a representative of the fresh produce industry to discuss the First Lady’s campaign to reduce obesity by improving the American diet. With such prominent endorsement, the demand for fresh and safe produce can only increase. It will fall to food scientists and food engineers to design, build, and operate the facilities in which these foods are packed, prepared, and distributed. Without the traditional tools of food preservation, we need to rely on sanitary design, worker understanding and cooperation, perhaps new technologies such as irradiation and high pressure, and a farm to fork perspective. Finally, as fresh produce is further processed, there will be increasing quantities of potentially valuable by-products that must be captured, converted, and marketed. This is a great opportunity for creative research and innovation.

J. Peter Clark,
Contributing Editor,
Consultant to the Process Industries,
Oak Park, Ill.
[email protected]