In the beginning… all wild animals and early humans were hunter-gatherers. Hunting-gathering was the only lifestyle available to humans for a very long time. It was successful because it allowed hunter-gatherers to survive and prosper in many different environments while also adjusting to radical climate change. We all marvel at the resourcefulness and ingenuity of our early ancestors. How many modern humans with just a bit of sharpened flint tied to a stick for securing food and a rock shelter to call home could survive a week on the edge of a continental glacier? Given that success, we can only wonder about the invention of agriculture in the rift valley of the Levant approximately 10,000 years ago and independently in at least five other places around the world within the next 4,000 years. What prompted hunter-gathering societies as different and widespread as the arid Middle East, wet south Asia, and the high Andes to suddenly change a lifestyle that had been so successful for so long?

Ten thousand years ago, the world was warming from the end of the latest world-wide glacial event. Studies suggest that as the climate warmed, there was a natural increase in the wild plant and animal resources available to hunter-gatherer societies. This was especially true for certain places where wild plant and animal species that had been useful to humans could thrive and expand their range. With more abundant food resources available, human populations naturally expanded to absorb the surplus. This meant that there were more mouths to feed. In the past, a hunter-gatherer group that was facing food shortages could simply move to a new area. With much larger groups and competition from neighboring groups, however, there was nowhere to go. For the first time in human history, movement was not a viable option to remedy food shortages.

In this environment came the spark that ignited the invention of agriculture. In short, humans needed a reliable food supply when a nomadic lifestyle was no longer able to solve food shortages. Another solution must be found. Agriculture was that solution.

The Beginning of Agriculture

The practice of agriculture is not a natural phenomenon. Agriculture is a very human invention built upon the concept of domestication. Hunter-gatherers had brought home wild plants and animals to be used as food but domestication was different because it involved bringing something home to live and reproduce. Ancient people observed that some wild barley that was brought home fell around the campsite, produced a crop the next year, and then could be saved for seed. Wild animals such as pigs, sheep, and goats that were attracted to the camp by bits of food would eventually become tame, reproduce, and harvested at will. Agriculture then encompasses the deliberate selection of certain living things from wild populations, and their protection and further selection. This is done to increase the food supply and reduce the risk of shortages inherent in the natural ecosystem. Agriculture forever changed the focus of man from being the hunter to being the protector.

The Next Big Step

By their nature, hunting and gathering were essentially opportunistic. Meat is abundant when the hunting is good but scarce when the animals have moved on to another area. Grain and fruit are plentiful during harvest season but rare at other times. The notion of saving a surplus at harvest for use during the season of scarcity must have occurred to early humans from observing animals that practice saving and storing food.

Hunter-gatherer societies were nomadic and did not need permanent villages. Cultivating a certain tract of fertile land forced these groups to settle down. The decision to stay permanently in one location provided greater food security but also made new demands on time and resources. One characteristic of the early farming villages was protection of the harvest. With the increased reliance on agriculture for food security, postharvest handling became a much more important issue.

Granaries were built to protect food from moisture, rodents, and insects. Watchtowers, defensive walls, and armies protected the harvest from hungry neighbors. In a more profound sense, agriculture at this time promoted a heightened sense of property and place. A people who have invested their time and labor to plant, grow, and harvest a crop that they will need for food will work to protect their harvest.

Famine and Plenty

Periods of food scarcity have always existed. After 1900, there was a huge increase in food production as a result of scientific farming and mechanization. In the 1960s, at about the same time that agricultural productivity was leveling off, the research pipeline produced many new technologies that boosted yields to levels that were unthinkable in the past. A good example is India, which was on the verge of mass starvation when the importation of advanced high yielding seed such as the semi-dwarf rice variety named IR8 produced life-saving yields that were 10 times those of traditionally grown rice varieties.

There is no doubt that enhanced technology and research have boosted the production of food. However, critics have also suggested that greater food production has costs in land, labor, fertilizers, pesticides, and dangers to population health. Agriculture aggravates and complicates pest control as more acres of closely spaced crops have become perfect breeding grounds for pests and diseases, and as the potential for environmental harm has gained greater recognition. The development and use of the pesticide DDT is a good example. When first used as a modern synthetic insecticide in the 1940s, DDT was viewed as an inexpensive, effective way to control mosquitoes that carried malaria, typhus, and other agricultural pests. However, by the 1960s, DDT was being blamed for adverse environmental effects on wildlife and serious health problems in humans related to reproductive, immune, and neurological functions. In 1972, the US banned the use of DDT, which was then classified as a probable carcinogen.

The production of inexpensive but unhealthy foods has also raised concerns about population health. Farm subsidies that lead to the increased availability of cheaper processed foods and the consumption of high-calorie, sugary beverages have contributed to the growing problem with obesity. In most of the world today, it is obesity and not starvation that is considered the major health issue.

Postharvest Handling

The basic motivation of postharvest handling is the economy and safety in our food supply. Positive postharvest handling provides as much of the crop as possible to the consumer at an acceptable level of quality. The reality is that poor postharvest handling remains the greatest agricultural problem today in terms of lost resources and missed opportunities.

Farming has long been viewed as a way of life. But, farming is also a major economic enterprise that operates by the dictates of the marketplace. Consequentially, farming involves the efficient use of resources, desired profitability for the producer, and the satisfaction of the consumers’ demands for quality at a reasonable price. If you are a farmer who is presently growing 20 acres of a certain crop, the rest of your land may not be suitable for that crop. Some land may be too sandy and drought prone. Other land may be too rocky or on a steep hillside. Some land that is wet or easily flooded may also not be suitable. A prudent farmer will use the 20 acres that are best for the crop in terms of fertility, availability of irrigation, ease of cultivation, and potential yield of the greatest profit.

If the crop you are growing is perishable and has a short shelf life, it is unlikely that you will be able to sell 100% of the crop you have harvested because of postharvest disease, spoilage, weather, or just poor timing. You made the decision to invest in the harvest of the crop (or a portion of the crop) under the rational assumption that it would be marketable at a profit. Yet, for some reason, you were not able to sell it. Keep in mind that the cost of harvest is often a major portion of your total production costs.

The ratio of harvested produce to produce actually sold is known as the “pack out rate.” Pack out rates are a good indicator of the success of postharvest handling at the farm level because the higher the rate, the more you are able to recoup from the cost of production plus a profit. The portion that is harvested and not sold becomes a direct threat to the bottom line because all inputs up to and including harvest are lost if the produce cannot find a market.

A pack out rate of 75% means that only 75% of the produce you pay laborers to harvest has been sold. The other 25% that you paid for seed, fertilizer, machinery, harvest labor, and management time is lost. Twenty-five percent may seem like a lot to lose but for many perishable crops, this is a reality.

The protection and wise use of our food and the resources used to produce it is the underlying foundation of proper postharvest handling. Investing in better postharvest handling has real benefits for farmers. This might involve installing more or improved types of refrigeration, a more gentle packing line, or worker training that can help to increase the pack out rate to 90%. That would mean that you are now able to market 15% more of your crop. You would be marketing 90/75 = 1.2 or 20% more without growing any additional acreage or incurring any additional expenses other than the investment in better postharvest handling. The savings from improvements in postharvest handling go directly to producer’s bottom line.

Along the Food Chain

Few people are aware of the complex processes involved in moving food from the producer to the consumer. This has changed in recent years with the growth of the “field to fork,” “farm to plate,” and “eat local” movements. Most consumers who think about our food chain seem to be more concerned with aspects of food safety than food waste. Food can be wasted at any point from before leaving the farm and all the way until it reaches the consumer.

According to a 2011 study by the Food and Agriculture Organization of the United Nations, on average ⅓ of the harvested food in our country never reaches the consumer. This waste varies by product but generally, the more perishable the produce, the greater the waste.

In developing countries, most food waste occurs between the producer and consumer because of poor or non-existent postharvest handling and transportation facilities. Some of the wealthiest and most productive agricultural areas of the world suffer from food shortages because the food that is grown in the area cannot be transported from where it is grown (rural areas) to where it is consumed (cities) before it spoils. Abundant harvests are often left to rot (see Figure P-1), while cities suffer famine because the storage, handling, packing, and preserving (all the essential functions of postharvest technology), and especially the transportation infrastructure, are underdeveloped.

International aid organizations have been slow to realize that helping farmers improve their growing practices with more fertilizer and better seed may not reduce hunger if the food they grow cannot be distributed efficiently and safely to the areas of need. In well-developed parts of the world, the combination of sophisticated postharvest facilities and efficient transportation facilities limit the amount of the harvested fresh produce that is lost from the grower to the consumer. The goals of proper postharvest handling are simple goals — increasing the efficiency of food production, conserving resources, and providing more high quality food for the consumer.

Many farmers view themselves primarily as producers of food. In the last several hundred years since the beginning of scientific farming, the emphasis in agriculture has been on production. The limiting factor with almost all farming operations has been land. To sustain and grow their farming business, farmers knew they must produce more on the limited acres they own. They do this by using better seed, more fertilizer, efficient irrigation, and improved pest control. As a result, crop yield in almost every category has risen spectacularly in the last hundred years. In general, this strategy has worked for farmers. Farmers would rather be paid at harvest where their responsibilities end and they can do what they do best — farm.

However, today’s farmers now operate in a time when the “consumer is king.” This is especially true for the production of fresh produce. Today’s consumers demand and are willing to pay for produce that is “just picked” quality. To be successful in delivering this level of quality, produce growers must be responsible for delivering that level of quality. This means investing in state-of-the-art postharvest handling facilities and the employees who must be trained to operate them. Proper on-farm postharvest handling is no longer optional — it is essential to producer success.

Figure P-1. Postharvest rots from improper handling can significantly affect the bottom line.

Source: M. Boyette.

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Figure P-1. Postharvest rots from improper handling can significantly affect the bottom line.

Source: M. Boyette.

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Postharvest engineering of fresh fruit and vegetables encompasses a vast and complex body of information. The authors gratefully acknowledge the wisdom and insights of a great many people whose experiences have helped to shape this publication. These include cooperating growers, packers, retailers, and shippers, as well as government and industry personnel and the Extension professionals from land grant universities who are the conduit between university research and its practical application in real-world situations. We also acknowledge the help and insights of the builders, refrigeration contractors, and other industry professionals who have informed and cooperated with us over the years. We are the best-fed people in history.

No single postharvest publication, including this one, can adequately cover all areas or answer all questions that might arise in practice. A bibliography that adequately covers all aspects of postharvest handling of fresh produce would run many pages and be tedious to the reader. Consequently, those seeking a deeper understanding of postharvest engineering subjects are encouraged to consult the many offerings available online.

Adulterated food. A food that contains a poisonous or deleterious substance (natural or added) that can be injurious to health.

Allergen. A type of antigen that produces an abnormally vigorous immune response in some sensitive individuals. The USDA recognizes eight types of food allergens, which include peanuts, tree nuts, soybeans, wheat, milk, eggs, fish, and crustaceans such as shrimp and lobster.

Back haul. The return trip from delivering produce or any item to its destination. For efficiency, truckers try to limit empty back hauls.

Biofilm. A surface-attached community of microbial cells embedded in a self-produced matrix that protects the microorganisms and enhances the likelihood of their survival in adverse environmental conditions.

Biological hazards. Pathogenic microorganisms such as bacteria, viruses, or parasites that attack the host directly or produce toxins that poison the host, weaken the host’s natural defenses, and cause illness.

Brake horsepower (BHP). The measurement of a motor’s maximum sustainable output without consideration of any friction losses from belts or bearings; the real measure of a motor’s highest possible output that will not shorten its service life.

Bulk container. A container that holds a large quantity of produce, which can weigh up to 2,000 lb, and is used with shipping pallets, but are separate from the pallet.

Bulk produce. Produce that is handled in larger lots, and not in small containers such as cartons or bags. Bulk produce is transported in pallet bins, gondolas, dump trucks, or refrigerated vans.

Bushel. A measure of volume commonly used in the US that is equivalent to approximately 1.24 cubic ft.

Carton. A container that is made from either corrugated fiberboard or plastic, which generally contains 50 lb or less of fresh produce.

Chill damage. Chill damage occurs when a plant is exposed to a temperature below its tolerance level.

Cleaning. The physical removal of all non-food matter from a surface. Cleaning is different from sanitizing.

Climacteric. A stage of fruit ripening with increased ethylene production and a rise in cellular respiration. Apples, bananas, melons, apricots, and tomatoes are climacteric fruits, while citrus, grapes, and strawberries are not.

Cold chain. On-farm refrigeration, refrigerated transport, the buyer's refrigerated receiving warehouse, and refrigerated retail displays form the cold chain.

Container. Any type of box, carton, bag, or bin used to contain produce.

Controlled atmosphere. A facility or package in which the mix of gasses around the produce is controlled and optimized to ensure the longest possible shelf life.

Corrugated fiberboard. Common packaging material made from a layer of corrugated fiberboard sandwiched between two additional layers of fiberboard. Sometimes mistakenly called pasteboard or cardboard. Printing can be either before lamination (pre-printed) or after (post-printed).

Count packing. A packing method in which a certain specified number of sized and graded items are placed in the carton.

Culls. The portion of harvested produce discarded at the packing facility because of poor quality.

Desiccant. Substances such as silica gel, bauxite, calcium sulfate, and montmorillonite clay that pull moisture away from hydrophilic food items such as crackers or dry cereal to keep them fresh and crispy.

Dump tank. A water-filled tank used at the beginning of a packing line where bins of produce are dumped to begin the postharvest cleaning process. The water helps cushion the impact and remove heavy soil. A conveyor constantly removes the produce from the bin in a steady stream.

Duty cycle. A cycle of a machine or operation that is intermittent and not continuous.

Edge crush strength. The heaviest load or pressure that can be applied to the edge of a corrugated box before it is crushed.

Eliminator. A specialized piece of packing line equipment which either automatically or manually removes produce that is not suitable for commerce.

Engineered package. A package where the interaction between the produce and the packing material actively regulates a beneficial mix of environmental gases. (See modified atmosphere package.)

Enteric pathogens. Pathogens caused by fecal contamination that attack the gastrointestinal tract and cause nausea, vomiting, and diarrhea.

Equilibrium moisture content. In a stable ambient environment of temperature and humidity, a sample will eventually reach an equilibrium moisture content.

Ethylene. A plant hormone used to accelerate the ripening of certain climacteric fruits such as tomatoes, bananas, pears, and apples.

Face packing. A packing method in which most of the container is loose or filled by volume except for top layer, which is arranged in an orderly pattern for an improved appearance.

Facultative pathogen. An organism that may engage in parasitic activity, but does not always rely on any specific host for completion of its life cycle.

Fan curve. A graph that shows the pressure/volume relationship for an individual fan that is useful for selecting fans for different applications.

Fiberboard. A paper material, usually made by converting wood to wood pulp, with a thickness greater than .008 in.; may contain additional materials that add strength and resistance to water.

Field packing. Packing method in which all harvesting, grading, and packing functions are performed at the same time in the field or orchard.

Food chain. The complex infrastructure through which food moves from growers’ fields to consumers by production, processing, distribution, retailing, and consumption.

Food contact surface. Any surface that may have direct contact with food or any surface from which drainage onto the produce or onto surfaces that contact the produce may occur during the normal course of operations; includes harvest/storage wagons and bins, workers’ hands, conveyors, belts, brushes, rollers, sorting tables, racks, and utensils; does not include tractors, forklifts, hand trucks, and pallets that are used for handling or storing large quantities of contained or packed fresh produce and that do not come into actual contact with the food.

Food facility. Any building and other physical structure (usually on a farm) used for the harvesting, washing, sorting, storage, packaging, labeling, holding, or transport of fresh produce. (See packing house.)

Food hazard. A biological, chemical, or physical agent with the potential to cause illness or injury to consumers.

Foodborne pathogen. An organism (viruses, bacteria, and parasites) that produces illnesses that result from pathogens, either by an infection that multiplies inside the gastrointestinal tract or a toxico-infection where the pathogen is consumed, multiplies, and produces toxins that cause illness.

Food Safety Modernization Act (FSMA). The FSMA specifies actions for reducing contamination at each point in the global supply chain. These include controls for human and animal food, identification of hazards and appropriate preventive controls, produce safety, foreign supplier verification, third party certification, food defense against intentional adulteration, and sanitary transportation.

Food service. An enterprise that supplies food items, including fresh produce, to institutions, restaurants, and increasingly, to grocery outlets.

Forced-air cooling. A common cooling method that utilizes specially constructed portable fans or rooms that draw chilled air horizontally through pallets or stacks of packaged produce. A properly designed forced-air cooling system is fast, energy efficient, and relatively inexpensive, and can be used with most types of produce.

Fresh-cut. A value-added process, also called pre-cut or ready-cut, through which fresh produce is shredded, trimmed, sliced, and prepared for consumer use. Fresh-cut produce, which is generally prepared by a processor or retailer, requires increased attention to sanitation, packaging, handling, storage, and labeling.

GAP (Good Agricultural Practices). Voluntary audits that verify that fruits and vegetables are produced, packed, handled, and stored in ways that minimize risks of microbial food safety hazards.

Global GAP. A certification program that originated in Europe and covers food safety, traceability, biodiversity, workers’ and animal welfare, integrated crop and pest management, quality system and hazard analysis, and critical control points (HACCP).

GMPs (Good Manufacturing Practices). Requirements for methods, equipment, facilities, and production and process controls that ensure food safety. Food that is not produced in environments that comply with GMPs may be considered adulterated.

Hazard. A biological, chemical, physical, or allergenic agent that is reasonably likely to cause illness or injury in the absence of its control.

HACCP (Hazard Analysis and Critical Control Points). A system that identifies, evaluates, and controls hazards that affect food safety.

Hundredweight. A unit of one hundred pounds; abbreviated as CWT.

Hurdle technology. Use of several different technologies simultaneously to increase the shelf life and safety of processed foods; may include drying, low pH, low temperature, salting, and sugaring; refers to the hurdles that must be overcome to prevent spoilage.

Hydrocooling. Cooling freshly harvested produce by flooding, immersing, or spraying with large quantities of cold water; the method is fast, generally thorough, and limited to produce items that can tolerate water.

Icing. Cooling fresh produce with crushed ice or a slurry of crushed ice and water over the top of a load or individual packages; limited to produce items that are not harmed by contact with ice.

Invasive Infection: Foodborne illness in which pathogens infect and multiply in a body (such as Salmonella and Listeria).

Kill-step. A point or process where potentially dangerous pathogens in a food are eliminated; can occur at the food processing facility or, in the case of raw agricultural commodities, by the application of heat in cooking.

Layer packing. A packing method in which the entire package of produce is packed in orderly layers.

Liquid icing. A method of adding water and crushed ice to packages of fresh produce; the cold water quickly cools the produce and drains out, which leaves the crushed ice for residual cooling.

Locavore. A person whose diet includes only locally grown food for the personal benefits and the benefits for the local community.

Lug. A sturdy container, usually plastic, that has high stacking strength; often used for soft fruit such as grapes, berries, or tomatoes that are easily damaged by crushing.

Maillard reaction. A form of non-enzymatic browning or toasting which typically proceeds rapidly from 280°F to 330°F; the chemical reaction between amino acids and reduced sugars gives browned foods, such as breads and toasted marshmallows, their distinctive flavor.

Master (flat). A type of carton with smaller units of produce; the 8 quarts, or 12 pints or half pints are commonly used with strawberries and other small fruit.

Mixed load. A single truckload of fresh produce with two or more products; reduces transportation costs but requires care to prevent ethylene or odor contamination.

Modified atmosphere packaging. A method of packaging in which the produce is packed in a sealed container into which a specific mix of gases are introduced; the container prevents the gases from escaping and does not regulate the mix.

Mule train. A slang term for a specialized mobile harvesting machine that allows workers to harvest, trim, package, and palletize produce in the field as the unit moves down rows; normally used in situations where the produce is very uniform in size and quality.

Norovirus. Known as the “cruise ship sickness”; responsible for over one-half of all foodborne illnesses, most of which occur in long-term care or assisted-living facilities; leafy greens are the single largest source of Norovirus outbreaks.

Obligate pathogen. An organism that cannot survive for extended periods or complete its life cycle without its host; all viruses are obligate.

Outbreak. A sudden rise in the usual number of cases of a disease along with laboratory identification of a causative agent; can be caused by contaminated food or water, or animal contact.

Package. Any type of box, carton, bag, or bin. (See container.)

Packinghouse or packing shed. A facility where raw agricultural commodities are washed, trimmed, sorted and packed in commercial containers such as cartons or totes.

Packing house. A food facility designed for washing, grading, sorting, or trimming harvested produce and packaging the produce for sale.

Pack out rate. The ratio of harvested produce to the portion, often expressed as a percentage, of harvested produce that is actually packed for shipment.

Pallet. A low platform made of wood or plastic that is used to stack cartons of produce or other items for transport by a forklift; available in multiple sizes with the standard domestic “grocery” pallet 40 in. by 48 in. (1.0 by 1.2 meters).

Pallet bin. A bulk bin built of wood or plastic into a pallet for the transport of bulk produce between the field/orchard and packing house.

Pathogen. A biological microorganism such as bacteria and viruses that can cause disease or illness.

Physiology. The branch of biology that focuses on the normal functions and activities of living organisms, animal or plant, and their parts.

Phytosanitation. The process of controlling pests and plant diseases in agricultural crops.

Plant disease. Infection of plant tissues by a pathogen that interferes with the plant’s normal structure or function.

Postharvest handling. Any operation that is performed after harvest; includes washing, grading, packing, storing, cooling, transporting, and marketing.

Precooling. The practice of cooling bulk produce before grading, packaging, and transport.

Psychrotrophs. Pathogens that can function at refrigeration temperatures (32°F to 50°F) and can lead to food spoilage; example — Listeria monocytogenes.

Raw agricultural commodity (RAC). Any food in its raw or natural state, including all fruits and vegetables that are washed, colored, or otherwise treated in the unpeeled natural form before marketing.

Ready-to-Eat (RTE) food. Foods that need no further preparation (washing, cutting, or reheating) before eating.

Recall. An action taken by a food producer, the Food and Drug Administration, or the US Department of Agriculture to remove a product from the market based on the potential danger to the public.

Room cooling. The practice of storing bulk or packaged produce in a refrigerated room for an indefinite period; heat is gradually removed from the produce by conduction and convection.

Sanitizing. The treatment of a previously cleaned surface to reduce or eliminate microorganisms.

Senescence. The changes that take place during the aging and degradation of plants and vegetables such as loss of flavor and texture.

Shelf-life. The length of time a food may be stored under normal conditions before the quality becomes unacceptable.

Shipper. An individual or company that transports produce from the grower to the buyer; growers, packers, or buyers often assume their own shipping functions.

Sizer. A specialized piece of packing line equipment that separates produce items according to size, weight, color, or shape; can be simple conveyors with belts with different size openings or sophisticated computer controlled devices that can discriminate with computer vision.

Sign. The physical evidence of pathogens, pests, spores, fruiting bodies, or bacterial ooze.

Slip sheet. A sheet of material, roughly the size of a pallet, of corrugated fiberboard, plastic, or a combination that serves as a replacement for a shipping pallet.

Spore. A reproductive body of some microorganisms capable of independently developing into a new individual; resistant to wet and dry heat, chemicals, enzymes, and radiation.

Stacking strength. The maximum amount of weight a container can resist before it is crushed.

Symptom. The visible response of an organism to living and non-living factors in the environment that cause a change or abnormality in the organism.

Throughput. The amount of produce that is expected to be cooled and/or stored over a specific period of time.

Ton. A unit of refrigeration capacity equivalent to the cooling possible by melting one ton of ice in 24 hours for a total of 288,000 Btu or 12000 Btu/hr.

Toxico-infection. Foodborne illness in which viable pathogens multiply and produce toxins in the body (such as Clostridium).

Traceability. The process that makes it possible to track a product from its point of origin to a retail location where it is purchased by consumers; provides information on the source, location, movement, and storage conditions of produce, and allows growers, packers, processors, and distributors to identify factors that affect quality and delivery; also aids regulators and processors during a recall to identify and recall affected products, and address supply chain issues that can prevent future recalls.

Undeclared allergen. One not shown on an ingredient label; even trace amounts can be dangerous to those susceptible.

Vacuum cooling. Quick, efficient process that uses a partial vacuum to remove water and cool packaged produce; generally more effective on items with a large surface area- to-weight ratio such as lettuce and greens.

Vibration fill packing. Packing method designed to reduce bruising and scratching of produce; after filling, the package is vibrated gently to increase product density and stability.

Volume fill packing. Packing method in which a specified volume of produce is packed in a container; the number of individual produce items and the weight may vary in volume fill packing.

Water activity. The property of food that describes the amount of free water in food; expressed as the ratio of the vapor pressure in the food to the vapor pressure of pure water with a range from 0.0 for a bone dry food to 1.0 for pure water; useful for predicting if the water available in the food product will affect spoilage and shelf-life.

Weight packing. Packing method in which a specified minimum weight, and not the number of produce items, are packed in a container.

Zoonotic pathogens. Those bacterial, viral, or parasitic pathogens capable of spreading between animals and humans through any human contact with domestic, agricultural, or wild animals; severe example is rabies, which can be life-threatening.