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close this bookTraditional Storage of Yams and Cassave and its Improvement (GTZ)
View the document(introduction...)
View the documentPreface
View the document1 Introduction
View the document2 Socio-cultural aspects involved in the production of roots and tubers
View the document3 Basic comments on the storage properties of roots and tubers
close this folder4 Yams
View the document(introduction...)
View the document4.1 The environmental requirements of yams
View the document4.2 The yam tuber
View the document4.3 Farm-economic aspects of yam production
View the document4.4 Yam harvesting
close this folder4.5 Causes of storage losses for yams
View the document(introduction...)
View the document4.5.1 Dormancy
View the document4.5.2 Transpiration
View the document4.5.3 Respiration
View the document4.5.4 Germination
View the document4.5.5 Rot due to mould and bacteriosis
View the document4.5.6 Nematodes
View the document4.5.7 Insects
View the document4.5.8 Mammals
close this folder4.6 Traditional storage systems for fresh yams
View the document(introduction...)
View the document4.6.1 Leaving the yam tubers in the ridges after maturity
View the document4.6.2 Storing the yam tubers in trench silos
View the document4.6.3 Storage of yam tubers in heaps on the ground
View the document4.6.4 Storage of yam tubers in clamp silos
View the document4.6.5 Storage of yam tubers under a conical protective roof made of maize or millet stalks
View the document4.6.6 storage of yam tubers in mud huts
View the document4.6.7 The storage of yam tubers in the yam barn.
close this folder4.7 Measures to improve traditional yam storage
View the document(introduction...)
View the document4.7.1 Care in harvesting transport and storage
View the document4.7.2 Curing
View the document4.7.3 Influencing dormancy
View the document4.7.4 Influencing the storage climate
View the document4.7.5 control of rot
View the document4.7.6 Control of nematodes
View the document4.7.7 Control of insects damaging stored produce
View the document4.7.8 Measures for protection from mammals
View the document4.7.9 The improved traditional yam barn
close this folder5 Cassava
View the document(introduction...)
View the document5.1 The environmental requirements of cassava
View the document5.2 The cassava root
View the document5.3 Economic aspects of cassava production
View the document5.4 Causes of limitations to storage for fresh cassava roots
close this folder5.5 Ways of and limits to. storing fresh cassava roots
View the document(introduction...)
View the document5.5.1 Storing cassava roots in the soil after maturity
View the document5.5.2 Traditional methods of storing fresh cassava roots
View the document5.5.3 Storage of fresh cassava roots in clamp silos
View the document5.5.4 Storing fresh cassava roots in crates
View the document5.5.5 Storing fresh cassava roots in a dip
View the document5.5.6 Storing fresh cassava roots in plastic bags
View the document5.5.7 Use of modern methods to store fresh cassava roots
View the document5.5.8 Measures to prepare fresh cassava roots for storage
View the document5.5.9 Suitability of storage systems for fresh cassava roots on a small farmholder level
close this folder5.6 The processing of cassava roots
View the document5.6.1 The purpose of processing
View the document5.6.2 Hydrogen cyanide and its release
View the document5.6.3 The production of cassava chips
View the document6 Summary
View the document7 Bibliography

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)