Investigating carotenoid loss after drying and storage of

74
2. Assessment of Methods
Doering et al. (1995) reported that isomerisation preferentially occur at temperatures
higher than 35ºC. Therefore there is little susceptibility for carotenoids to isomer when
stored at lower temperatures than 35ºC. It should be noted that the ambient temperature
in Uganda and Mozambique rarely reach the threshold temperature of 35ºC.
2.7 PREPARATION FOR FIELD WORK
2.7.1 Influence of choice of roots or fresh chips as initial point to determine
carotenoid losses
Sweet potato roots and freshly chipped sweet potatoes were compared in 11 samples for
their total carotenoid levels (extraction in triplicate): 7 varieties from the harvesting lot
1; 2 varieties from lot 2 and 2 varieties from the lot 3. (Figure 2-7).
Total carotenoid content ("g/g)
400
350
300
250
200
150
100
50
0
SPK004/1 lot1
roots
chips
SPK004/1/1 lot1
SPK004/6 lot1
SPK4/6/6 lot1
Ejumula lot1
Kakamega lot1
Naspot lot1
Ejumula lot2
Kakamega lot2
Ejumula lot3
Kakamega lot3
Figure 2-7: Total carotenoid content (!g.g -1 ) on a dry weight basis in roots and
fresh chips from various samples. Variety and date of drying date are for information
only. Mean total carotenoid value (standard deviation): roots: 142.4(106.0) "g.g -1 ;
chips: 135.6(96.4) "g.g -1 . T-test for equality of means. Sig. (2-tailed) Significant at
p