Agriculture Reference
In-Depth Information
Chapter 19
Postharvest Factors Affecting Potato
Quality and Storability
Sastry S. Jayanty
19.1 Introduction
Potato (
Solanum tuberosum
L.) is an important crop grown in the temperate, tropical, and
subtropical regions of the world as a staple food because of its high nutritional value.
It ranks fourth in annual production behind the cereal species rice (
Oryza sativa
), wheat
(
Triticum aestivum
), and barley (
Hordeum vulgare
) and is one of the major vegetables
consumed (Ross, 1986). Potato is the highest-yielding crop per hectare of arable ground.
In North America and Europe, potatoes are consumed primarily in the form of processed
food, where as in Southeast Asia and Latin America, it is mostly consumed fresh (FAO-
STAT, 2005). The fall season production accounts for 70% of the total potato crop in the
United States. The majority of the crop is stored for long term to meet the demands of
the fresh market and processing industries. A proper postharvest storage situation is essen-
tial for a yearlong supply of potatoes to the consumer. Postharvest losses are mainly due
to poor handling and improper storage. They typically account for 8-30% of the overall
loss in the potato industry, and sometimes even greater losses are reported. Disease and
sprouting are the main postharvest issues facing the potato storage industry to ensure year-
long supply of quality potatoes to the consumer. Minimizing these losses greatly improves
profitability.
The potato tuber is a modified underground stem. Tubers are formed below the soil at
the tips of lateral shoots called stolons. The terminal bud of the stolon undergoes dormancy
and initiates tuberization through both cell division and cell elongation. During tuberization,
starch and other nutrients are translocated to the tuber. A tuber may have up to 20 eyes/bud
that are arranged spirally. The buds on the tuber, after a period of dormancy, can give rise
to sprouts if conditions are favorable to allow propagation by vegetative amplification. The
tuber is an important human food source and also represents seed stocks to produce a crop.
Seed potatoes form an essential element in the total production cost of potatoes. This crop
is more vulnerable to diseases and pests in storage because many of these are transmitted
with seed tubers. Certified seed potatoes form an essential element in the potato production
areas to minimize losses due to disease and pests.
Potatoes are rich in carbohydrates and are also a good source of minerals and vitamins.
Recent low-carbohydrate diets and misconceptions of potato painted a bad picture about
nutritional value of the potato. An average (5.3-6.0 oz) potato with the skin contains 18% of
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