By-Products and Waste in
Potato Processing
IRWIN B. DOUGLASS, Professor of Chemistry
University of Maine
Orono, Maine
INTRODUCTION
Potato food processing has expanded rapidly since 1946 and is becoming
an element of major importance in the potato industry. In 1956, 16 per cent
of the potato crop was processed into food products; during the present year
well over 20 per cent will be processed and it is estimated that by 1970 that
50 per cent of all the potatoes consumed as food will be in some processed
form.
This increase in processing is only the most recent change which has affected the potato industry. From a high in 1910, when the' annual per capita
consumption of potatoes was 195 lbs, consumption declined steadily until
1952 when it appeared to stabilize at about 100 lbs. Recently economists believe they detect a slight upturn which they attribute to the increase in
processing.
Recurring potato surpluses have greatly affected potato processing, particularly the manufacture of potato starch in the late-producing areas. Over
the years, the declining per capita consumption has been counteracted by an
increasing population, with the result that the total market demand for potatoes has remained nearly constant. This demand is highly inelastic, being
little affected by price, and, when combined with the perishable nature of
potatoes, is responsible for the fact that relatively small surpluses have caused
disastrously low prices. In years of high production, regions of concentrated
potato production where the crop is harvested late in the fall have often found
that food outlets could not absorb a large portion of their crop. These surplus
potatoes, which had to be sold at less than the cost of production, together
with culls, have been the raw material of the potato starch industry.
The effect of surpluses has been aggravated to some extent by the improvements in cultural practices which greatly increased per acre yield. The
full impact of these improvements began in 1946 with the widespread use of
DDT as an insecticide and was a big factor in bringing to an end the government price support program which held over from war-time efforts to increase
production.
In recent years the government attempts to aid the potato growers have
involved efforts to divert surpluses away from the usual food outlets. When
the shippers in a region agreed to market only their better quality potatoes,
in surplus years the government made a supplemental payment for all potatoes
of No. 2 grade or better diverted from the table stock market. Starch manufacture and livestock feeding have been almost the only such diversionary outlets available and as a result in recent years starch factories have been built
in areas where previously there were none. At least one attempt to build a
starch factory in a new area foundered on the problem of waste disposal.
THE ANATOMY AND CHEMICAL COMPOSITION OF THE POTATO
Any consideration of the wastes from potato processing must begin with
the anatomy and composition of the potato itself.   The tuber is essentially a
-  99 -