Investigating carotenoid loss after drying and storage of

CHAPTER 5.
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5. Mozambican field study
UNDERSTANDING ON-FARM CAROTENOID LOSSES
AFTER DRYING AND STORAGE OF ORANGE-
FLESHED SWEET POTATO IN MOZAMBIQUE
5.1. INTRODUCTION
Recent studies (Tomlins et al. 2007b) have indicated that experimental results obtained
on a research station do not necessarily transfer to the farm situation because of
variations in farmer knowledge and the situation on-farm. Therefore, it was important to
verify the on-station results obtained in Chapter 4 in a farm situation. In addition, in
order to preserve better provitamin A in sweet potato drying, there was a need to
determine whether some additional product variables (i.e. chip size), which can be
relevant for farmers and chips processors, can also influence carotenoid degradation. In
laboratory trials, chip size has been reported to influence on carotenoid degradation after
sweet potato sun drying in France (Chapter 3) and variety was also reported to influence
carotenoid degradation in the study in Uganda (Chapter 4).
Another query was to determine the rate at which carotenoids are degraded during
storage. Determination of degradation kinetics of carotenoids on dried sweet potato
could help researchers advise farmers about product shelf life with respect to carotenoid
content. At this stage of the research, there also was an additional and more fundamental
research question about how carotenoids are degraded and into which products. The
latter question involved the use of HPLC and GC/MS analysis techniques to identify
carotenoids and their degradation products.
The main aim of the study was to verify results obtained in Chapter 4 (studies at a
research station in Uganda) using simple and low-cost (see Appendix 2b) drying and
storage for orange-fleshed sweet potato in a different setting (on-farm) and a different
country (Mozambique). The effect of sun, shaded and solar (tunnel) dryers was tested.
In order to draw a more complete picture of carotenoid stability during storage,