Previous - Next
3 Basic comments on the storage properties of roots and tubers
In contrast to cereals which have good natural properties making them suitable for storage, tropical roots and tubers are, without exception, perishable crops The factors determining the difference between these two product groups and their storage properties can be seen in Table 5.
From the varying determinants affecting the storage behaviour of these two groups of products it is evident that storage methods which have proven suitable for durable food crops cannot simply be applied to perishable crops. In addition, the roots and tubers are not a homogenous group where their storage properties are concerned but show varying differences specific to each product. It therefore becomes necessary to develop specific storage methods for each root and tuber, which is illustrated by the great variety of traditional storage systems.
It is for this reason that this investigation will proceed to treat both crops, yams and cassava, in separate sections.
Table 5: Comparison of cereal storage properties with those of roots and tubers
| Durable food crops | Perishable food crops |
| pronounced seasonal harvest, long-term storage necessary | continual or semi-continual harvesting possible. Long-term storage this often avoidable |
| processing (apart from threshing) to prepare the produce rarely necessary | processing to dried products often an alternative to storing fresh produce |
| low moisture content of crops, mostly between 10 - 15% or less | high moisture content of crops, mostly between 50 - 80% |
| small units mostly weighing less than 1 gramme | large units, mostly weighing between 5 g and 5 kg or more |
| slow respiratory activity of stored crops and thus low development of heat | high to very high respiratory activity of stored crops, consequently great degree of heat development particularly under tropical conditions |
| hard condition of tissue, good protection from injury | soft condition of tissue, easily injured |
| stable, good natural preservation, storage possible over several years | perishable, natural preservation of up to several months (great variations in species and varieties) |
| storage losses mostly exogenous (mould, insects, rodents) | losses partially endogenous (respiration, transpiration, germination), partially exogenous (rot, insects) |
Source: FAO, 1984 (modified)