## 3 Results and Discussion
### Volatile Compound Analysis of Lafun Samples and Raw Cassava Roots  
#### 3.3.1 Gas Chromatography-Mass Spectrometry Analysis  
In this study, SPME-GC-MS was used for the characterisation of key volatile aroma compounds in latfun. The identification and quantitation of 35 volatile organic compounds (VOCs) from latfun samples (\(n=51\)) and raw cassava roots (\(n=3\)) on a dry weight basis was possible using Solid Phase Microextraction (SPME). The VOCs selected for semi-quantitation include a total of 16 aldehydes, 2 carotenoid derivatives, 5 acids, 1 alcohol, 1 furan, 9 ketones, and 2 phenols (only found in the Sango market sample). PCA analysis was performed to determine the impact of the starter cultures and cassava varieties on the identified volatile compounds. PC1 and PC2 accounted for 69.9% of the total variance in the VOCs (Figure 2). The principal components separated samples into three groups: one containing bitter and sweet cassava varieties, the second containing the fortified cassava variety, and the final group containing the market samples at the bottom left side. The variables that determine this separation are aldehydes, ketones, and volatile acids. The latfun samples produced with both bitter and sweet cassava varieties had more abundant lipid degradation compounds (a1-a5; d1-d4 and e1-e7). Those from fortified cassava were richer in carotenoid derivatives (c1 and c2), consistent with their high vitamin A content. The market samples were mainly driven by volatile acids (v2, v3, and v5). The fortified cassava samples had fewer lipid degradation compounds for all cultures, suggesting that it is less prone to the development of rancidity. The PCA score plot of volatile compounds showed that the samples from fortified cassava were considerably different from the others along PC1, explaining 57.3% of the variance (Figure 2). The PCA plot of volatile compounds also showed that 6-methyl-5-hepten-2-one, 6,10-dimethyl-5,9-undecadien-2-one, acetic acid, acetone, and 2-butanone  
Figure 1: Tan \(\delta\) as a function of the frequency of latfun gruel produced using \(L\)_mesenteroides_, typical of fortified (green), bitter (orange), and sweet (blue) cassava varieties (bitter: IBA30527; fortified: IBA011371; and sweet: TMEB117). were closely correlated with lafun from fortified cassava (Figure 3). The correlation of 6-methyl-5-hepten-2-one and 6,10-dimethyl-5,9-undecadien-2-one with the fortified cassava could be as a result of the carotenoids present in this variety. This is reasonable, as these compounds are known to be degradation products or oxidative by-products derived from carotenoids. Carotenoid pigmentation has been reported to affect the volatile composition of some plants [35]. On the other hand, butanoic acid correlated with all market lafun samples, while the majority of identified lipid-degrading compounds were closely correlated to lafun from both sweet and bitter cassava. Organic acids such as heptanoic, hexanoic, and pentanoic acids were related to the negative axis of the PC2 and were correlated to most of the bitter cassava products. Figure 3: Projection of lafun produced with bitter cassava-IBA30527 (red), sweet cassava-TMEB117 (blue), and fortified-cassava IBA011371 (black) with market samples (green) onto the two principal components. B = bitter, S = sweet, F = fortified, L = _L. lactis_, K1 = _W. koreensis_-1, K2 = _W. koreensis_-2, M = _L. mesenteroides_. Figure 2: Principal component plot of volatile compounds (variables: aldehydes, ketones, organic acids,furan), PC1 vs. PC2: red is carotenoid-derived; blue is acid; green is lipid degradation product, and black is ketone. The two components account for 69.9% of the total variance. See Tables 3–5 for volatiles codes. \begin{table}
\begin{tabular}{l l c c c c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{W. _Incornu-1_} & \multicolumn{4}{c}{_L. _Intetis_} & \multicolumn{4}{c}{_W. _Incornu-2_} & \multicolumn{4}{c}{_L.