United Nations

The Food and Agriculture Organization (FAO) of the United Nations defines food loss and waste as the decrease in quantity or quality of food along the food supply chain. Within this framework, UN Agencies distinguish loss and waste at two different stages in the process:^[16]

• Food loss occurs along the food supply chain from harvest/slaughter/catch up to, but not including, the sales level
• Food waste occurs at the retail and consumption level.

Important components of this definition include:^[12]

• Food redirected to nonfood chains (including animal feed, compost, or recovery to bioenergy) is not counted as food loss or waste. Inedible parts are not considered as food loss or waste (these inedible parts are sometimes referred to as unavoidable food waste)^[12]

Under Sustainable Development Goal 12, the Food and Agriculture Organization is responsible for measuring food loss, while the UN Environmental Program measures food waste.^[17]

European Union

Protest against food waste, Berlin, Germany

In the European Union (EU), food waste is defined by combining the definitions of food and waste, namely: "any substance or product, whether processed, partially processed or unprocessed, intended to be, or reasonably expected to be ingested by humans (...)" (including things such as drinks and chewing gum; excluding things such as feed, medicine, cosmetics, tobacco products, and narcotic or psychotropic substances) "which the holder discards or intends or is required to discard".^{[18]: 2–3}

Previously, food waste was defined by directive 75/442/EEC as "any food substance, raw or cooked, which is discarded, or intended or required to be discarded" in 1975.^[19] In 2006, 75/442/EEC was repealed by 2006/12/EC,^[19] which defined waste as "any substance or object in the categories set out in Annex I which the holder discards or intends or is required to discard".^[20] Meanwhile, Article 2 of Regulation (EC) No 178/2002 (the General Food Law Regulation), as amended on 1 July 2022, defined food as "any substance or product, whether processed, partially processed or unprocessed, intended to be, or reasonably expected to be ingested by humans (...)", including things such as drinks and chewing gum, excluding things such as feed, medicine, cosmetics, tobacco products, and narcotic or psychotropic substances.^[21]

A 2016 European Court of Auditors special report had criticised the lack of a common definition of food waste as hampering progress, and a May 2017 resolution by the European Parliament supported a legally binding definition of food waste.^{[18]: 4, 6} Finally, the 2018/851/EU directive of 30 May 2018 (the revised Waste Framework Directive) combined the two (after waste was redefined in 2008 by Article 3.1 of 2008/98/EC as "any substance or object which the holder discards or intends or is required to discard"^[22]) by defining food waste as "all food as defined in Article 2 of Regulation (EC) No 178/2002 of the European Parliament and of the Council that has become waste."^{[18]: 2–3}

United States

Food waste alternative.

As of 2022, the United States Environmental Protection Agency (EPA) employed three categories:^[23]

• "Excess food refers to food that is recovered and donated to feed people."
• "Food waste refers to food such as plate waste (i.e., food that has been served but not eaten), spoiled food, or peels and rinds considered inedible that is sent to feed animals, to be composted or anaerobically digested, or to be landfilled or combusted with energy recovery."
• "Food loss refers to unused product from the agricultural sector, such as unharvested crops."

In 2006, the EPA defined food waste as "uneaten food and food preparation wastes from residences and commercial establishments such as grocery stores, restaurants, produce stands, institutional cafeterias and kitchens, and industrial sources like employee lunchrooms".^[24]

The states remain free to define food waste differently for their purposes,^[25][26] though as of 2009, many had not done so.^[27]

Other definitions

Bellemare et al. (2017) compared four definitions from:^[13]: 4

1. a Food and Agriculture Organization (FAO) 2016 report: "Food loss is defined as ‘the decrease in quantity or quality of food.’ Food waste is part of food loss and refers to discarding or alternative (nonfood) use of food that is safe and nutritious for human consumption along the entire food supply chain, from primary production to end household consumer level";
2. an Economic Research Service (ERS; a USDA agency) 2014 report: "Food loss represents the amount of food postharvest, that is available for human consumption but is not consumed for any reason. It includes cooking loss and natural shrinkage (for example, moisture loss); loss from mould, pests, or inadequate climate control; and food waste. Food waste is a component of food loss and occurs when an edible item goes unconsumed, as in food discarded by retailers due to color or appearance, and plate waste by consumers";
3. a FUSIONS (an EU project) 2016 report: "Food waste is any food, and inedible parts of food, removed from the food supply chain to be recovered or disposed (including composed [sic], crops ploughed in/not harvested, anaerobic digestion, bioenergy production, co-generation, incineration, disposal to sewer, landfill or discarded to sea)"; and
4. an EPA 2016 report: "The amount of food going to landfills from residences, commercial establishments (e.g., grocery stores and restaurants), institutional sources (e.g., school cafeterias), and industrial sources (e.g., factory lunchrooms). Pre-consumer food generated during the manufacturing and packaging of food products is not included in EPA's food waste estimates."

According to Bellemare et al., the inclusion of food that goes to nonfood productive use is flawed for two reasons: "First, if recovered food is used as an input, such as animal feed, fertilizer, or biomass to produce output, then by definition it is not wasted. However, there might be economic losses if the cost of recovered food is higher than the average cost of inputs in the alternative, nonfood use. Second, the definition creates practical problems for measuring food waste because the measurement requires tracking food loss in every stage of the supply chain and its proportion that flows to nonfood uses."^[13]: 4 They argued that only food that ends up in landfills should be counted as food waste, pointing to the 2016 EPA definition as a good example.^[13]: 4 Bellemare et al. also noted that "the FAO and ERS definitions only apply to edible and safe and nutritious food, whereas the definitions of FUSIONS and the EPA apply to both edible and inedible parts of food. Finally, the ERS and EPA definitions of food waste exclude the food that is not harvested at the farm level."^[13]: 4

A 2019 FAO report stated:

'The notion of food being lost or wasted is deceptively simple, but in practice there is no commonly agreed definition of food loss and waste. FAO has worked towards the harmonization of concepts related to food loss and waste, and the definitions adopted in this report are the result of a consensus reached in consultation with experts in this field. This report understands food loss and waste as the decrease in quantity or quality of food along the food supply chain. Empirically it considers food losses as occurring along the food supply chain from harvest/slaughter/catch up to, but not including, the retail level. Food waste, on the other hand, occurs at the retail and consumption level. This definition also aligns with the distinction implicit in SDG Target 12.3. This report also asserts that, although there may be an economic loss, food diverted to other economic uses, such as animal feed, is not considered as quantitative food loss or waste. Similarly, inedible parts are not considered as food loss or waste.'^{[12]: 9–10}

Methodology

The 2019 FAO report stated: "Food loss and waste has typically been measured in physical terms using tonnes as reporting units. This measurement fails to account for the economic value of different commodities and can risk attributing a higher weight to low-value products just because they are heavier. [This] report acknowledges this by adopting a measure that accounts for the economic value of produce."^[12]: 10 Hall et al. (2009) calculated food waste in the United States in terms of energy value "by comparing the US food supply data with the calculated food consumed by the US population." The result was that food waste among American consumers increased from "about 30% of the available food supply in 1974 to almost 40% in recent years" (the early 2000s), or about 900 kcal per person per day (1974) to about 1400 kcal per person per day (2003).^[28] A 2012 Natural Resources Defense Council report interpreted this to mean that Americans threw away up to 40% of food that was safe to eat.^[29] Buzby & Hyman (2012) estimated both the total weight (in kg and lbs) and monetary value (in USD) of food loss in the United States, concluding that "the annual value of food loss is almost 10% of the average amount spent on food per consumer in 2008".^[30]

Production

In the United States, food loss can occur at most stages of the food industry and in significant amounts.^[31] In subsistence agriculture, the amounts of food loss are unknown, but are likely to be insignificant by comparison, due to the limited stages at which loss can occur, and given that food is grown for projected need as opposed to a global marketplace demand.^[32][33] Nevertheless, on-farm losses in storage in developing countries, particularly in African countries, can be high although the exact nature of such losses is much debated.^[34]

In the food industry of the United States, the food supply of which is the most diverse and abundant of any country in the world, loss occurs from the beginning of food production chain.^[31] From planting, crops can be subjected to pest infestations and severe weather,^[35][36] which cause losses before harvest.^[31] Since natural forces (e.g. temperature and precipitation) remain the primary drivers of crop growth, losses from these can be experienced by all forms of outdoor agriculture.^[37] On average, farms in the United States lose up to six billion pounds of crops every year because of these unpredictable conditions.^[38] According to the IPCC sixth assessment report, encouraging the development of technologies that address issues in food harvesting and post-harvesting could have a significant impact on decreasing food waste in the supply chain early-on.^[39]

The use of machinery in harvesting can cause loss, as harvesters may be unable to discern between ripe and immature crops, or collect only part of a crop.^[31] Economic factors, such as regulations and standards for quality and appearance,^[40] also cause food waste; farmers often harvest selectively, preferring to leave crops not to standard in the field (where they can be used as fertilizer or animal feed), since they would otherwise be discarded later.^[31] This method of removing undesirable produce from harvest collection, distribution sites and grocery stores is called culling.^[41] However, usually when culling occurs at the production, food processing, retail and consumption stages, it is to remove or dispose of produce with a strange or imperfect appearance rather than produce that is spoiled or unsafe to eat.^[42] In urban areas, fruit and nut trees often go unharvested because people either do not realize that the fruit is edible or they fear that it is contaminated, despite research which shows that urban fruit is safe to consume.^[43]

Food processing

Food loss continues in the post-harvest stage, but the amounts of post-harvest loss involved are relatively unknown and difficult to estimate.^[44]: 1 Regardless, the variety of factors that contribute to food loss, both biological/environmental and socio-economical, would limit the usefulness and reliability of general figures.^{[44]: 1, 7–8} In storage, considerable quantitative losses can be attributed to pests and micro-organisms.^[45][46] This is a particular problem for countries that experience a combination of heat (around 30 °C) and ambient humidity (between 70 and 90 per cent), as such conditions encourage the reproduction of insect pests and micro-organisms.^[47] Losses in the nutritional value, caloric value and edibility of crops, by extremes of temperature, humidity or the action of micro-organisms,^[48] also account for food waste.^[49] Further losses are generated in the handling of food and by shrinkage in weight or volume.^[31]

Some of the food loss produced by processing can be difficult to reduce without affecting the quality of the finished product.^[15]: 3 Food safety regulations are able to claim foods that contradict standards before they reach markets.^[31] Although this can conflict with efforts to reuse food loss (such as in animal feed),^[50] safety regulations are in place to ensure the health of the consumer; they are vitally important, especially in the processing of foodstuffs of animal origin (e.g. meat and dairy products), as contaminated products from these sources can lead to and are associated with microbiological and chemical hazards.^[51][52]

Retail

Discarded bagels

Packaging protects food from damage during its transportation from farms and factories via warehouses to retailing, as well as preserving its freshness upon arrival.^[53] Although it avoids considerable food waste,^[53][54] packaging can compromise efforts to reduce food waste in other ways, such as by contaminating waste that could be used for animal feedstocks with plastics.^[55]

In 2013, the nonprofit Natural Resources Defense Council (NRDC) performed research that suggests that the leading cause of food waste in America is due to uncertainty over food expiration dates, such as confusion in deciphering best-before, sell-by, or use-by dates.^[56] Joined by Harvard's Food Law and Policy Clinic, the NRDC produced a study called The Dating Game: How Confusing Food Date Labels Leads to Food Waste in America.^[57] This United States-based study looked at the intertwining laws which lead labeling to end up unclear and erratic.^[58] This uncertainty leads to consumers to toss food, most often because they think the food may be unsafe or misunderstand the labeling on the food completely. Lack of regulation on labeling can result in large quantities of food being removed from the market overall.^[56]

Retail stores throw away large quantities of food. Usually, this consists of items that have reached either their best-before, sell-by, or use-by dates. Some stores make an effort to markdown these goods with systems like discount stickers, stores have widely varying policies to handle the excess food. Much of the food discarded by stores is still edible. Some stores put effort into preventing access to poor or homeless people, while others work with charitable organization to distribute food. Retailers also contribute to waste as a result of their contractual arrangements with suppliers. Failure to supply agreed quantities renders farmers or processors liable to have their contracts cancelled. As a consequence, they plan to produce more than actually required to meet the contract, to have a margin of error. Surplus production is often simply disposed of.^[59]

Retailers usually have strict cosmetic standards for produce, and if fruits or vegetables are misshapen or superficially bruised, they are often not put on the shelf. In the United States, some of the estimated six billion pounds of produce wasted each year are discarded because of appearance.^[60] The USDA publishes guidelines used as a baseline assessment by produce distributors, grocery stores, restaurants and other consumers in order to rate the quality of food.^[61] These guidelines and how they rate are readily available on their website. For example, apples get graded by their size, color, wax residue, firmness, and skin appearance. If apples rank highly in these categories and show close to no superficial defects, they are rated as "U.S. Extra Fancy" or "U.S. Fancy", these are the typical ratings sought out by grocery stores when purchasing their produce.^[62] Any apples with suboptimal levels of appearance are ranked as either "U.S. Number 1" or "Utility" and are not normally purchased for retail, as recommended by produce marketing sources, despite being safe and edible.^[62][63] A number of regional programs and organizations have been established by the EPA and USDA in an attempt to reduce such produce waste.^[64][65] Organizations in other countries, such as Good & Fugly in Australia and No Food Waste in India, are making similar efforts worldwide.^[66][67] The popular trend of selling "imperfect" produce at retail has been criticized for overlooking existing markets for these foods (eg the food processing industry and bargain grocery stores) and downplaying the household-level wasting of food that is statistically a larger part of the overall problem.^[68]

The fishing industry wastes substantial amounts of food: about 40–60% of fish caught in Europe is discarded as the wrong size or wrong species.

This comes to about 2.3 million tonnes per annum in the North Atlantic and the North Sea.^[59]

Food-service industry

Lunch leftovers in a restaurant in Seoul

Addressing food waste requires involving multiple stakeholders throughout the food supply chain, which is a market-driven system. Each stakeholder and their food waste quantification can be dependent on geographical scales.^[69] This geographical scale then results in the production of different definitions of food waste, as mentioned earlier, with respect to the complexities of food supply chains and then create a narrative that further shows the needs for specific research on important stakeholders.^[69] The food service industry suggests to be a key stakeholder to achieve mitigation.^[70] The key players within the food service industry include the manufacturers, producers, farmers, managers, employees, and consumers. The key factors relating to food waste in restaurants include the food menu, the production procedure, the use of pre-prepared versus whole food products, dinnerware size, type of ingredients used, the dishes served, opening hours, and disposal methods.^[71] These factors then can be categorized in the different stages of operations that relate to pre-kitchen, kitchen-based, and post-kitchen processes.^[72]

In restaurants in developing countries, the lack of infrastructure and associated technical and managerial skills in food production have been identified as the key drivers in the creation of food waste currently and in the future.^[69] Comparatively, the majority of food waste in developed countries tends to be produced post-consumer, which is driven by the low prices of food, greater disposable income, consumers' high expectations of food cosmetic standards, and the increasing disconnect between consumers and how food is being produced (Urbanization).^[69] That being said, in United States restaurants alone, an estimated 22 to 33 billion pounds are wasted each year.^[73]

Serving plate size reduction has been identified as an intervention effective at reducing restaurant food waste.^[74] Under such interventions, restaurants decrease the size of plates for meals provided to diners. Similar interventions which have been found to be effective at reducing restaurant food waste include utilizing reusable rather than disposable plates and decreasing serving size.^[74]

Consumption

Consumers are directly and indirectly responsible for wasting a lot of food, which could for a large part be avoided if they were willing to accept suboptimal food (SOF) that deviates in sensory characteristics (odd shapes, discolorations) or has a best-before date that is approaching or has passed, but is still perfectly fine to eat.^[75] In addition to inedible and edible food waste generated by consumers, substantial amounts of food is wasted through food overconsumption, also referred to as metabolic food waste,^{[76][77][78][79]} estimated globally as 10% of foods reaching the consumer.^[80]

By sector

Fruit and vegetables

This section is an excerpt from Post-harvest losses (vegetables).[edit]

Discarded tomatoes on a compost heap at nurseries in the UK

Post-harvest losses of vegetables and fruit occur at all points in the value chain from production in the field to the food being placed on a plate for consumption. Post-harvest activities include harvesting, handling, storage, processing, packaging, transportation and marketing.^[81]

Losses of horticultural produce are a major problem in the post-harvest chain. They can be caused by a wide variety of factors, ranging from growing conditions to handling at retail level. Not only are losses clearly a waste of food, but they also represent a similar waste of human effort, farm inputs, livelihoods, investments, and scarce resources such as water.^[82] Post-harvest losses for horticultural produce are, however, difficult to measure. In some cases everything harvested by a farmer may end up being sold to consumers. In others, losses or waste may be considerable. Occasionally, losses may be 100%, for example when there is a price collapse and it would cost the farmer more to harvest and market the produce than to plough it back into the ground. Use of average loss figures is thus often misleading. There can be losses in quality, as measured both by the price obtained and the nutritional value, as well as in quantity.

Grains

This section is an excerpt from Post-harvest losses (grains).[edit]

Grain silos in Australia

Grains may be lost in the pre-harvest, harvest, and post-harvest stages. Pre-harvest losses occur before the process of harvesting begins, and may be due to insects, weeds, and rusts. Harvest losses occur between the beginning and completion of harvesting, and are primarily caused by losses due to shattering. Post-harvest losses occur between harvest and the moment of human consumption. They include on-farm losses, such as when grain is threshed, winnowed, and dried. Other on-farm losses include inadequate harvesting time, climatic conditions, practices applied at harvest and handling, and challenges in marketing produce. Significant losses are caused by inadequate storage conditions as well as decisions made at earlier stages of the supply chain, including transportation, storage, and processing, which predispose products to a shorter shelf life.^[83]

Important in many developing countries, particularly in Africa, are on-farm losses during storage, when the grain is being stored for auto-consumption or while the farmer awaits a selling opportunity or a rise in prices.

Global extent

Efforts are underway by the Food and Agriculture Organization (FAO) and the United Nations Environment Programme (UNEP) to measure progress towards SDG Target 12.3 through two separate indices: the Food Loss Index (FLI) and the Food Waste Index (FWI).^[84]

According to FAO's The State of Food and Agriculture 2019, globally, in 2016, around 14 percent of the world's food is lost from production before reaching the retail level. Generally, levels of loss are higher for fruits and vegetables than for cereals and pulses. However, even for the latter, significant levels are found in sub-Saharan Africa and Eastern and South-Eastern Asia, while they are limited in Central and Southern Asia.^[12]

Estimates from UN Environment's Food Waste Index suggest that about 931 million tonnes of food, or 17 percent of total food available to consumers in 2019, went into the waste bins of households, retailers, restaurants and other food services.^[4]

According to a report from Feedback EU, the EU wastes 153 million tonnes of food each year, around double previous estimates.^[85]

Individual countries

France

Food waste

In France, approximately 1.3–1.9 million tonnes of food waste is produced every year, or between 20 and 30 kilograms per person per year.^[102] Out of the 10 million tonnes of food that is either lost or wasted in the country, 7.1 million tonnes of food wasted in the country, only 11% comes from supermarkets.^[103] Not only does this cost the French €16 billion per year, but also the negative impact on the environment is also shocking. In France, food waste emits 15.3 million tonnes of CO₂, which represents 3% of the country's total CO₂ emission.^[104] In response to this issue, in 2016, France became the first country in the world to pass a unanimous legislation that bans supermarkets from throwing away or destroying unsold food. Instead, supermarkets are expected to donate such food to charities and food banks.^[105] In addition to donating food, many businesses claim to prevent food waste by selling soon-to-be wasted products at discounted prices. The National Pact Against Food Waste in France has outlined eleven measures to achieve a food waste reduction by half by 2025.^[106]

United Kingdom

This section is an excerpt from Food waste in the United Kingdom.[edit]

Food waste in the United Kingdom is a subject of environmental, and socioeconomic concern that has received widespread media coverage and been met with varying responses from government. Since 1915, food waste has been identified as a considerable problem and has been the subject of ongoing media attention, intensifying with the launch of the "Love Food, Hate Waste" campaign in 2007. Food waste has been discussed in newspaper articles, news reports and television programmes, which have increased awareness of it as a public issue. To tackle waste issues, encompassing food waste, the government-funded "Waste & Resources Action Programme" (WRAP) was created in 2000.

A significant proportion of food waste is produced by the domestic household, which, in 2007, created 6,700,000 tonnes of food waste. Potatoes, bread slices and apples are respectively the most wasted foods by quantity, while salads are thrown away in the greatest proportion. A majority of wasted food is avoidable,^[d] with the rest being divided almost equally by foods which are unavoidable (e.g. tea bags) and unavoidable due to preference (e.g. bread crusts) or cooking type (e.g. potato skins).

Reducing the amount of food waste has been deemed critical if the UK is to meet international targets on climate change, limiting greenhouse gas emissions, and meet obligations under the European Landfill Directive to reduce biodegradable waste going to landfill. Equally great emphasis has been placed on the reduction of food waste, across all developed countries, as a means of ending the global food crisis that leaves millions worldwide starving and impoverished. In the context of the 2007–2008 world food price crisis, food waste was discussed at the 34th G8 summit in Hokkaidō, Japan. Then-UK Prime Minister Gordon Brown said of the issue "We must do more to deal with unnecessary demand, such as by all of us doing more to cut our food waste".^[120]

In June 2009, then-Environment Secretary Hilary Benn announced the Government's "War on waste", a programme aimed at reducing Britain's food waste. The proposed plans under the scheme included: scrapping best before and limiting sell by labels on food, creating new food packaging sizes, constructing more "on-the-go" recycling points and unveiling five flagship anaerobic digestion plants. Two years after its launch, the "Love Food, Hate Waste" campaign was claiming it had already prevented 137,000 tonnes of waste and, through the help it had given to over 2,000,000 households, had made savings of £300,000,000.

In the UK, 6,700,000 tonnes (6,590,000 long tons; 7,390,000 short tons) per year of wasted food (purchased and edible food which is discarded) amounts to a cost of £10.2 billion each year. This represents costs of £250 to £400 a year per household.^[121]

Food rescue

There are multiple initiatives that rescue food that would otherwise not be consumed by humans anymore. The food can come from supermarkets, restaurants or private households for example. Such initiatives are:

• food banks,
• online platforms like Too Good To Go and Olio,
• public foodsharing shelves like those from foodsharing.de and
• dumpster diving.

Consumer marketing

One way of dealing with food waste is to reduce its creation. Consumers can reduce spoilage by planning their food shopping, avoiding potentially wasteful spontaneous purchases, and storing foods properly (and also preventing a too large buildup of perishable stock).^[130] Widespread educational campaigns have been shown to be an effective way to reduce food waste.^[138]

A British campaign called "Love Food, Hate Waste" has raised awareness about preventative measures to address food waste for consumers. Through advertisements, information on food storage and preparation and in-store education, the UK observed a 21% decrease in avoidable household food waste over the course of 5 years.^[139]

Another potential solution is for "smart packaging" which would indicate when food is spoiled more precisely than expiration dates currently do, for example with temperature-sensitive ink,^[140] plastic that changes color when exposed to oxygen,^[141] or gels that change color with time.^[142]

An initiative in Curitiba, Brazil, called Cambio Verde allows farmers to provide surplus produce (produce they would otherwise discard due to too low prices) to people that bring glass and metal to recycling facilities (to encourage further waste reduction).^[143] In Europe, the Food Surplus Entrepreneurs Network (FSE Network), coordinates a network of social businesses and nonprofit initiatives with the goal to spread best practices to increase the use of surplus food and reduction of food waste.^[144]

An overarching consensus exists on the substantial environmental benefits of food waste reduction.^[145] However, rebound effects may cause substitutive consumption as a result of economic savings made from food waste prevention, potentially offsetting more than half of the avoided emissions (depending on the type of food and price elasticities involved).^[146][147]

Landfills and greenhouse gases

Dumping food waste in a landfill causes odour as it decomposes, attracts flies and vermin, and has the potential to add biological oxygen demand (BOD) to the leachate. The European Union Landfill Directive and Waste Regulations, like regulations in other countries, enjoin diverting organic wastes away from landfill disposal for these reasons. Starting in 2015, organic waste from New York City restaurants will be banned from landfills.^[149]

In countries such as the United States and the United Kingdom, food scraps constitute around 19% of the waste buried in landfills, where it biodegrades very easily and produces methane, a powerful greenhouse gas.^[150]

Methane, or CH₄, is the second most prevalent greenhouse gas that is released into the air, also produced by landfills in the U.S. Although methane spends less time in the atmosphere (12 years) than CO₂, it is more efficient at trapping radiation. It is 25 times greater to impact climate change than CO₂ in a 100-year period. Humans accounts over 60% of methane emissions globally.^[151]

Fodder and insect feed

Large quantities of fish, meat, dairy and grain are discarded at a global scale annually, when they can be used for things other than human consumption. The feeding of food scraps or slop to domesticated animals such as pigs or chickens is, historically, the most common way of dealing with household food waste. The animals turn roughly two thirds of their ingested food into gas or fecal waste, while the last third is digested and repurposed as meat or dairy products. There are also different ways of growing produce and feeding livestock that could ultimately reduce waste.

Bread and other cereal products discarded from the human food chain could be used to feed chickens. Chickens have traditionally been given mixtures of waste grains and milling by-products in a mixture called chicken scratch. As well, giving table scraps to backyard chickens is a large part of that movement's claim to sustainability, though not all backyard chicken growers recommend it.^[152] Ruminants and pigs have also been fed bakery waste for a long time.^[153]

Certain food waste (such as flesh) can also be used as feed in maggot farming.^[154] The maggots can then be fed to other animals. In China, some food waste is being processed by feeding it to cockroaches.^[155]

Composting

Inevitable waste: peels of potato, onion, lemon, tangerine, banana, kiwi, egg shell

Food waste can be biodegraded by composting, and reused to fertilize soil. Composting is the aerobic process completed by microorganisms in which the bacteria break down the food waste into simpler organic materials that can then be used in soil.^[156] By redistributing nutrients and high microbial populations, compost reduces water runoff and soil erosion by enhancing rainfall penetration, which has been shown to reduce the loss of sediment, nutrients, and pesticide losses to streams by 75–95%.^[157]

Composting food waste leads to a decrease in the quantity of greenhouse gases released into the atmosphere. In landfills, organic food waste decomposes anaerobically, producing methane gas that is emitted into the atmosphere. When this biodegradable waste is composted, it decomposes aerobically and does not produce methane, but instead produces organic compost that can then be utilized in agriculture.^[158] Recently, the city of New York has begun to require that restaurants and food-producing companies begin to compost their leftover food.^[159] Another instance of composting progress is a Wisconsin-based company called WasteCap, who is dedicated towards aiding local communities create composting plans.^[160]

Municipal Food Waste (MFW) can be composted to create this product of organic fertilizer, and many municipalities choose to do this citing environmental protection and economic efficiency as reasoning. Transporting and dumping waste in landfills requires both money and room in the landfills that have very limited available space.^[161] One municipality who chose to regulate MFW is San Francisco, who requires citizens to separate compost from trash on their own, instituting fines for non-compliance at $100 for individual homes and $500 for businesses. The city's economic reasoning for this controversial mandate is supported by their estimate that one business can save up to $30,000 annually on garbage disposal costs with the implementation of the required composting.^[158]

Anaerobic digestion

Anaerobic digestion produces both useful gaseous products and a solid fibrous "compostable" material. Anaerobic digestion plants can provide energy from waste by burning the methane created from food and other organic wastes to generate electricity, defraying the plants' costs and reducing greenhouse gas emissions. The United States Environmental Protection Agency states that the use of anaerobic composting allows for large amounts of food waste to avoid the landfills. Instead of producing these greenhouse gasses into the environment from being in a landfill, the gasses can alternatively be harnessed in these facilities for reuse.^[162]

Since this process of composting produces high volumes of biogas, there are potential safety issues such as explosion and poisoning.^[163] These interactions require proper maintenance and personal protective equipment is utilized.^[164] Certain U.S. states, such as Oregon, have implemented the requirement for permits on such facilities, based on the potential danger to the population and surrounding environment.^[165]

Food waste coming through the sanitary sewers from garbage disposal units is treated along with other sewage and contributes to sludge.

Commercial liquid food waste

Commercially, food waste in the form of wastewater coming from commercial kitchens' sinks, dishwashers and floor drains is collected in holding tanks called grease interceptors to minimize flow to the sewer system. This often foul-smelling waste contains both organic and inorganic waste (chemical cleaners, etc.) and may also contain hazardous hydrogen sulfide gases. It is referred to as fats, oils, and grease (FOG) waste or more commonly "brown grease" (versus "yellow grease", which is fryer oil that is easily collected and processed into biodiesel) and is an overwhelming problem, especially in the US, for the aging sewer systems. Per the US EPA, sanitary sewer overflows also occur due to the improper discharge of FOGs to the collection system.^[166] Overflows discharge 3–10 billion U.S. gallons (11–38 million cubic meters) of untreated wastewater annually into local waterways, and up to 3,700 illnesses annually are due to exposure to contamination from sanitary sewer overflows into recreational waters.^[167]