Investigating carotenoid loss after drying and storage of
Investigating carotenoid loss after drying and storage of
Investigating carotenoid loss after drying and storage of
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3.2.10 Statistical analyses<br />
87<br />
3. Preliminary study<br />
Normality <strong>of</strong> distribution <strong>of</strong> sample visible surface area was verified by Kolmogorov-<br />
Smirnov test used for small sample size (n=30). Analysis <strong>of</strong> variance (ANOVA one way<br />
- homogeneity <strong>of</strong> variance test) was carried out to determine whether there were<br />
significant differences between means; a significant difference between means was<br />
determined by a Tukey test. An independent sample T Test was carried out to determine<br />
significant differences between provitamin A compounds before <strong>and</strong> <strong>after</strong> <strong>drying</strong>. All<br />
data were analysed using SPSS 14.00 for Windows (Woking, Surrey, UK).<br />
3.3 RESULTS AND DISCUSSION<br />
3.3.1 Quality <strong>of</strong> flour<br />
Flour from dried sweet potato was evaluated for its moisture content <strong>and</strong> water activity<br />
in order to assess its quality for <strong>storage</strong>. Tray loading <strong>and</strong> <strong>drying</strong> time for each treatment<br />
<strong>and</strong> the moisture contents <strong>and</strong> water activities (aw) <strong>of</strong> flours are shown in Table 3-1. The<br />
tray loading rates for the crimp slices were higher than with the chips in the hot air cross<br />
flow dryer as a result <strong>of</strong> operator error.<br />
Table 3-1: Tray loading, <strong>drying</strong> time, moisture content <strong>and</strong> water activity <strong>of</strong> flours<br />
made from dried chips <strong>and</strong> crimped slices<br />
Dryer<br />
Slice<br />
type<br />
Tray<br />
loading<br />
(kg/m 2 )<br />
Drying<br />
time (h)<br />
Moisture<br />
content<br />
(%)*<br />
Water activity<br />
(aw)**<br />
Hot air cross flow<br />
Chips<br />
Slices<br />
8<br />
15<br />
2.0<br />
7.5<br />
11.0 (0.2) 0.442 (0.001)<br />
9.8 (0.1) 0.378 (0.008)<br />
Solar<br />
Chips<br />
Slices<br />
3.5<br />
3.5<br />
8.5<br />
8.5<br />
10.0 (0.4) 0.413 (0.000)<br />
9.9 (0.3) 0.397 (0.008)<br />
Sun<br />
Chips<br />
Slices<br />
3.5<br />
3.5<br />
8.0<br />
8.0<br />
9.9 (0.3) 0.443 (0.001)<br />
11.2 (0.1) 0.449 (0.001)<br />
*Mean <strong>of</strong> three replicates. **Mean <strong>of</strong> two replicates. Values in brackets refer to the<br />
st<strong>and</strong>ard deviation.<br />
The flour moisture content was between 9.8 <strong>and</strong> 11.2%. Flour water activity that ranged<br />
between 0.38 <strong>and</strong> 0.45 should favour <strong>carotenoid</strong> stability. It was demonstrated on<br />
dehydrated carrots in different conditions that best stability <strong>of</strong> <strong>carotenoid</strong>s was obtained
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