## 2 Results and Discussion  
### Volatile Composition of Celery Samples  
In total, 100 compounds were identified in the headspace of the six celery samples (Table 1) including 28 monoterenes, 16 sesquiterpenes, 12 alcohols (five of which are classified as monoterool alcohols), nine aldehydes and five phthalides. Quantitative differences were observed between the genotypes used in this study and one-way ANOVA revealed significant differences in the relative abundance of aroma compounds between the genotypes in most compounds. Compounds such as (_E_)-2-penten-1-ol, (_Z_)-3-hexenol, lavandulyl acetate, \(\delta\)-3-carene, \(\beta\)-thujone, \(p\)-1,3,8-menthatriene, fenchol and \(\beta\)-eudesmol expressed no significant difference between genotypes accompanied by several alkanes and unknown compounds. A large proportion of the aroma profile was comprised of monoterenes and sesquiterpenes with limonene, \(\beta\)-pinene, myrcene, \(\gamma\)-terpinene and \(\beta\)-caryophyllene exhibiting the highest relative abundance within their compound groups. These compounds are commonly present in celery and have been reported to contribute to odour notes such as woody, herbal, green, waxy, and earthy [3; 9]. Monoterpenes have been shown to have the highest proportion of the aroma composition in various studies [3; 5; 6]. Genotype 12 exhibited the highest abundance of monoterenes, sesquiterpenes and phthalides, followed by hybrids 22x12 and 12x22, while genotype 25 and hybrid 25x12 had a much lower abundance of these compounds. However, as reported by the authors, these terpenes are not the characteristic compounds in celery [4]. Sesquiterpenes, whilst at a lower relative abundance to monoterpenes are more typical to the mature celery aroma. Previously reported by the authors [9], during maturation, the celery aroma developed significantly, starting as a fresh, citrus, green aroma due to the high proportion of monoterpenes and lack of sesquiterpene and phthalide compounds. As the celery matured, the abundance of sesquiterpenes and phthalides became much more apparent and thus, a change in the perceived aroma was identified [9]. \(\beta\)-Caryophyllene and \(\beta\)-selinene (Table 1) exhibited the highest relative abundance within all genotypes, and this was most obviously observed in genotype 12 and hybrid 22x12. [PERSON] et al. [17] reported \(\beta\)-caryophyllene and \(\beta\)-selinene to be major constituents of Nigerian grown celery and [PERSON], [PERSON], and [PERSON] [18] identified \(\beta\)-selinene to impart a strong celery aroma. Although less abundant in other genotypes, genotype 12 had a high abundance of kessane. Kessane was identified by [PERSON], [PERSON], [PERSON] and [PERSON] [19] in the essential oil of Indian-grown celery seed, comprising between 2.2 and 7.6% of the volatile profile. Phthalides have been shown to contribute to strong celery-like odours in addition to being the most odour-active compounds within celery crop. Upon completing aroma extraction dilution analysis (AEDA), [PERSON] [20] detected phthalide compounds including 3-n-butylphthalide and sedanenolide, also identified within this study, to contribute most to celery odour. This was further confirmed by [PERSON], [PERSON] and [PERSON] [18], whereby sedanenolide, 3-n-butylphthalide and hexahydro-3-n-butylphthalide imparted strong celery odour characteristics. Genotype 12 displayed the highest abundance of phthalide compounds (Table 1) including sedanenolide and 3-n-butylphthalide followed by hybrids 12x22 and 22x12 that also displayed a high abundance of phthalides within their aroma profile. As these compounds consist of strong celery odour notes [8], we can assume these celeries consist of a typical celery flavour. The maternal inheritance of compounds from parent to hybrid was observed most clearly between genotype 25 and hybrid 25x12, whereby similarities between the presence and absence of compounds within the aroma profile as well as the abundance of compounds was apparent (Table 1).