Investigating carotenoid loss after drying and storage of

69
2. Assessment of Methods
Significant correlations were found between total carotenoids measured on
spectrophotometer and trans-"-carotene measured on HPLC: R=0.725 for a range
between 177.3 and 300.8"g.g -1 db (Figure 2-4); and R=0.973 for a range between 11.7
and 427.1"g.g -1 db (Figure 2-5). Chavez et al. (2004) also found a very good correlation
(R=0.957) between total carotenoids in spectrophotometer and total carotene in HPLC
on yellow-fleshed cassava on 24 samples; measured in four replications on a range of
10-100"g.g -1 db. A wide range of carotenoid levels may increase the strength of the
correlation as observed in the two Pearson coefficients; correlation on five varieties from
two locations was stronger than on one variety.
Other factors can explain these differences such as inter and intra laboratory and method
variation. Equations from both figures presented similar coefficients respectively 0.7719
and 0.8127 which suggested that a common trend may exist between spectrophotometer
and HPLC measurements in OFSP.
Total carotenoid content by spectrophotometric reading gives a close estimation of the
total carotenoid content of a sample determined by HPLC (Table 2-5; Figures 2-4; 2-5):
HPLC and spectrophotometer instruments also gave the similar levels of total
carotenoids (Independent T-test; p