The

sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledonous plant that belongs to the Convolvulus, bindweed or morning glory family (biology), family, Convolvulaceae. Its large, starchy, sweet-tasting tuberous roots are used as a r ...

(''Ipomoea batatas'') is a very important crop for

subsistence farm Subsistence agriculture occurs when farmers grow food crops to meet the needs of themselves and their families on smallholdings. Subsistence agriculturalists target farm output for survival and for mostly local requirements, with little or no su ...

ers in

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

and

developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...

in other regions. Its relatively short growing period, tolerance to drought and high yield from poor soils lead to its use as a famine reserve for many of these households. However, it is a highly

perishable Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...

food source that is susceptible to destruction by

microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

s, metabolic spoilage, physical destruction and pests. Therefore, it is not generally stored for long after harvest. This is a major barrier for the optimal use of the crop and causes much waste. Most subsistence farmers who eat sweet potato do not use a storage technique of any kind, instead using a method of continuous cultivation and leaving the

tuber Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...

s in the ground until they are ready to be used. While less common, simple methods of storage do exist. The common ones include pit, clamp, and indoor storage and all extend the storage time of sweet potatoes by some degree. Maintaining proper storage temperature is probably the most significant barrier to good storage for subsistence farmers. Pretreatment of sweet potato can help to minimize risk of losses. Curing can toughen the skin and heal minor physical damage, while

drying Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be considered ...

can reduce spoilage and inactivate metabolic degradation. Optimum storage of sweet potatoes occurs at and 85–90%

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depe ...

(RH) and requires proper ventilation to remove excess

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

() and bring in

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

() for

respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellula ...

. At these conditions sweet potatoes have been shown to last 5 months to a maximum of a year compared to 2–3 months normally.

Susceptibility to spoilage

Sweet potatoes are a highly perishable crop and difficult to store for extended periods of time. This is mainly due to their high moisture content, metabolic activity following harvesting and thin, permeable skin. Following harvest, sweet potatoes are susceptible to spoilage by physical, physiological,

pathological Pathology is the study of the causal, causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when us ...

and environmental means, including by pests.

Physical

Physical losses occur when sweet potatoes are damaged by mechanical force during harvest, handling, and transportation of the tubers, including injury by cutting, bruising, and skinning. Delicate skin and poor harvesting and handling techniques are the main cause of these problems. Damage to tubers by physical means can be minimized by handling the tubers carefully and storing them in rigid boxes or cartons rather than cloth sacks.

Physiological

Physiological processes within the plant can contribute highly to spoilage. Natural

transpiration Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth a ...

causes water loss and results in an unappealing

pithy {{Short pages monitor is to wrap the tubers in black

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging ( plastic bags, plastic films, geomembranes and containers including bo ...

sheets and leave them in the sun for five days. The black plastic sheets hold moisture in and collect heat to produce the necessary conditions for curing. Immediately after curing, the temperature of the tubers must be lowered quickly to prevent them from sprouting.

References

{{Sweet potatoes Sweet potatoes Food storage