## 3 Results and Discussion
### Volatile Compound Analysis of Lafun Samples and Raw Cassava Roots
#### 3.3.2 Gas Chromatography-Olfactometry Analysis
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & & & & **Variety-Intensity D** \\ \hline
**Odour Description** & **Compound** & **LRI GC-O A** & **LRI GC-MS C** & **ID B** & **M** & **L** \\ \hline green & Hexanal & 800 & 803 & A & 5 & 5 \\ \hline sweet & cis-3-Hexenal & 803 & 804 & A & 5 & 4.5 \\ \hline vegetable & Unknown & 807 & & - & 4 & 3 \\ \hline cheese & Butanoic acid & 810 & & A & 5.5 & ND \\ \hline meat & 2-Methyl-3-furanthiol & 865 & & A & 4 & ND \\ \hline fruity & 2-Heptanone & 898 & 898 & A & 4.5 & ND \\ \hline lamb fat & cis-4-Heptnal & 902 & 902 & A & 5 & 6.5 \\ \hline potato & Methional & 906 & 908 & A & ND & 4 \\ \hline cats pee & 3-Mercapto-3-methylbutanol & 941 & & A & ND & 5 \\ \hline fatty fruity & 2-Heptnal, (E)- & 955 & 959 & A & ND & 5 \\ \hline greenhouse & 2-Methoxy-3-methylpyrazine & 973 & 974 & A & 3 & ND \\ \hline mushroom & 1-Octen-3-one & 979 & 978 & A & 6 & 8 \\ \hline geranium & 1,5-Octadien-3-one, (E)- & 983 & & B & 3.5 & 6 \\ \hline orange & 6-Methyl-5-hepten-2-one & 986 & 987 & A & 5 & 5 \\ \hline orange & Octanal & 1006 & 1007 & A & 6 & 8 \\ \hline fried & 2-4-Heptadienal, (E,E)- & 1011 & 1012 & A & ND & 6 \\ \hline sharp green fuity viney & 2-Hexenyl acetate, (E)- & 1018 & & A & ND & 3.5 \\ \hline fruity ald & phenylacetaldehyde & 1039 & & A & 1.5 & ND \\ \hline greenhouses & 2-Ethyl-3-methoxyyrazine & 1054 & 1055 & A & 4.5 & ND \\ \hline fried & 2-Octenal, (Z)- & 1059 & 1059 & A & 5.5 & 7 \\ \hline fried & 2-Octenal, (E)- & 1064 & 1063 & A & 5 & 6 \\ \hline manure & 4-Methylphenol (p-cresol) & 1077 & 1077 & A & 5 & ND \\ \hline earthy coffee & 2-Ethyl-3,6-dimethylplyrazine & 1081 & 1082 & A & 4 & 4 \\ \hline dry earthy & 2-Ethyl-3,5-dimethylplyrazine & 1087 & 1086 & A & ND & 3 \\ \hline medicinal & Guaiacol & 1091 & 1090 & A & 4 & ND \\ \hline fruity & 3,5-Octadien-2-one, (E,Z)- & 1095 & & B & ND & 5 \\ \hline greenhouses, pea & 2-Isopropyl-3-methoxyyrazine & 1096 & 1096 & A & 4 & ND \\ \hline waxy, fatty & 3-Nonneal, (E)- & 1100 & & B & 2.5 & ND \\ \hline fatty aldehyde & Nonanal & 1106 & 1105 & A & 3.5 & ND \\ \hline fried & 2,4-Octadienal, (E,Z)- & 1112 & & A & ND & 4 \\ \hline coriander & 2-Nonneal, (Z)- & 1148 & & A & 2.5 & 4.5 \\ \hline violets & 2,6-Nonadienal, (E,Z)- & 1155 & 1154 & A & 6 & 5 \\ \hline waxy + medicinal & 2-Nonneal, (E)- & 1160 & 1159 & A & 6 & 6.5 \\ \hline parma violets & 2,6-Nonadienal isomer & 1169 & & B & 6 & ND \\ \hline medicinal & 2,4/5-Dimethylphenol & 1173 & & B & 3 & ND \\ \hline meat & 2-Methyl-3-furyl methyl disulfide & 1174 & 1174 & A & 4.5 & ND \\ \hline greenhouse, bell pepper & 2-Isobutyl-3-methoxyyrazine & 1183 & 1181 & A & 4 & ND \\ \hline fries & 2,4-Nonadienal, (E,Z)- & 1194 & & B & ND & 5 \\ \hline fries & 2,4-Nonadienal, (E,E)- & 1214 & & A & 6 & 6.5 \\ \hline minty & 2-(2-Methylbutyl)-3-methylpyrazine & 1246 & 1246 & A & 5 & 4 \\ \hline dry cardboard, earthy & Unknown pyrazine & 1248 & & & ND & 4 \\ \hline coriander & 2-Decneal, (E) & 1264 & 1265 & A & 4 & 6.5 \\ \hline tea & Unknown & 1273 & & & 4 & 2 \\ \hline dry cardboard, earthy & Unknown pyrazine & 1279 & & & ND & 6 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Odour description and intensity of the volatile compounds detected by GC-O in headspace of lafun. To summarise, aldehydes occurred mostly among the odour-active compounds found in lafun, as mentioned earlier. The shorter-chain aldehydes (<C7) are important contributors to the characteristic 'fresh green' odour of vegetables. They are widely used as food additives because of this fresh green odour [45]. The longer chain and more unsaturated aldehydes are very potent. They are responsible for the rancid notes in many foods and reduce their keeping quality. The results of this study indicate the need for an effective storage method that will lower the rate of oxidation of aldehydes in lafun. The oxidation of aldehydes may lead to the corresponding organic acids [46]. The high concentration of organic acids in the market samples could result from the oxidation of aldehydes.