Investigating carotenoid loss after drying and storage of

CHAPTER 9.
GENERAL DISCUSSION AND FUTURE WORK
9.1 OBJECTIVES AND ACHIEVEMENTS
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9. Discussion
The main objectives of the thesis were to measure the level of carotenoid degradation in
orange-fleshed sweet potato (OFSP) after drying and storage. OFSP is currently
promoted for tackling vitamin A deficiency in developing countries, and the potential for
processed products, in particular dried products, needed to be investigated. Earlier
research on food products (such as carrots, cassava, leaves, OFSP) demonstrated that
processing, and in particular, solar and sun drying, which can be affordable techniques
for small-scale farmers in Africa, had a significant impact on carotenoid stability.
However previous research about the losses of carotenoids during solar and sun drying
in OFSP in particular (see Chapter 1) was scarce and showed inconsistent results. There
was therefore a need to evaluate the impact of solar and sun drying, and subsequent
storage on the carotenoid content of OFSP.
• The main achievement of this work has been to quantify carotenoid loss from
orange-fleshed sweet potato (OFSP) following drying and storage. Carotenoid loss
was related to various process variables (such as type of dryer; chip size; variety; and
nature of pre-treatment) both at a pilot scale and field level. Degradation of !-
carotene was limited after drying of orange-fleshed sweet potato (less than 35%) but
was an important issue during the subsequent storage (70-80% loss).
• A secondary achievement has been to gain a better understanding of how carotenoids
degrade during storage of dried OFSP. Some of the observations may be applicable
to dried foods containing carotenoids in general. The impact of enzymatic activity
and the effects of the main factors on carotenoid degradation (water activity,
temperature, oxygen) were measured. Furthermore a quantification of carotenoid
losses along with the compounds produced during degradation was achieved.