Investigating carotenoid loss after drying and storage of

Norisoprenoids peak area (units)
Trans-B-carotene content (!g/g)
5.0E+08
4.5E+08
4.0E+08
3.5E+08
3.0E+08
2.5E+08
2.0E+08
1.5E+08
1.0E+08
5.0E+07
0.0E+00
500
450
400
350
300
250
200
150
100
50
0
unstored MGCL01 4mth stored MGCL01
unstored MGCL01 4mth stored MGCL01
134
5.0E+08
4.5E+08
4.0E+08
3.5E+08
3.0E+08
2.5E+08
2.0E+08
1.5E+08
1.0E+08
5.0E+07
0.0E+00
500
450
400
350
300
250
200
150
100
50
0
5. Mozambican field study
unstored Resisto 4mth stored Resisto
unstored Resisto 4mth stored Resisto
Figure 5-7: Comparison between the norisoprenoid formation and carotenoid
degradation in dried traditional slices of Resisto and MGCL01 before storage and
after 4 month (120 days) storage. Error bars refer to standard deviation of triplicate
determinations.
In this present study, the highest quantities of volatiles (!-ionone; 5,6 epoxy-!-ionone
and DHA) were found in 4 month-stored samples of dried slices of Resisto and
MGCL01 (peak areas were 3.9.10 8 and 2.4.10 8 units respectively respectively) that had
the lowest !-carotene content (54.4; 13.7 "g.g -1 respectively).
The presence of norisoprenoids in unstored sweet potatoes could be attributed to a
degradation of carotenoids either during storage of the flour or could be the result of
naturally present norisoprenoids in fresh sweet potato. These could be formed by the
plant metabolic system during the ripening process (Lewinsohn et al. 2005). In the
biosynthesis pathway of carotenoid formation (see Chapter 1; Figure 1-12), carotenoid
cleavage enzymes that are responsible for the degradation of neoxanthin to abscisic acid
can be also responsible for formation of norisoprenoids (Balderman et al. 2005).
The lowest quantities of volatiles were found in unstored dried slices of Resisto and
MGCL01 (peak areas were 1.4.10 8 and 1.0.10 8 units respectively) that had the highest !-