According to the United Nations Environment Program (UNEP), about one third of all food produced worldwide is lost or wasted in how it is created, grown, or consumed. This means that about 25 percent of all calories produced are not able to be consumed, when more than 800 million people around the world struggle with hunger. In the United States alone, wasted food from residences, grocery stores, and food services accounts for nearly 7 percent of the municipal solid waste stream. The per-capita amount of food waste in municipal solid waste has been declining since 1960 due to increased use of garbage disposals and increased consumption of processed foods. Food waste ground in garbage disposals goes into sewer systems and thus ends up in wastewater. Waste generated by the food processing industry is considered to be industrial waste, and is not included in municipal solid waste estimates.
Waste from the food processing industry includes: vegetables and fruits unsuitable for canning or freezing; vegetable, fruit, and meat trimmings; and pomace from juice manufacturing. Vegetable and fruit processing waste is sometimes used as animal feed, and waste from meat and seafood processing can be composted. Liquid waste from juice manufacturing can be applied to cropland as a soil amendment. Much of the waste generated by all types of food processing is wastewater due to such processes as washing, peeling, blanching, and cooling. Some food industries recycle wastewaters back into their processes, but there is potential for more of this wastewater to be reused.
Grocery stores generate food waste in the form of lettuce trimmings, excess foliage, unmarketable produce, and meat trimmings. Waste from grocery stores located in rural areas is often used as hog or cattle feed, whereas grocery waste in urban areas is usually ground in garbage disposals. There is potential for more urban grocery store waste to be either used on farms or composted, but lack of storage space, odor, and pest problems prevent most of this waste from being recycled.
Restaurants and institutional cafeterias are the major sources of food service industry waste. In addition to food preparation wastes, they also generate large amounts of cooking oil and grease waste, post-consumer waste (uneaten food), and surplus waste. In some areas small amounts of surplus waste is utilized by feeding programs, but most waste generated by food services goes to landfills or into garbage disposals.
Most food waste is generated by sources other than households. However, a greater percentage of household food waste is disposed of because there is a higher rate of recycling of industrial and commercial food waste. Only a very small segment of households in the developed world compost or otherwise recycle their food wastes.