## 4 Discussion  
The three major cultivars of Okinawan pineapple--viz., 'N67-10', 'Yugafu', and 'Yonekura'--differed in their green-yellowish color attributes, whilst their fruit size and flesh brightness indexes were comparable (Table 1). 'Yonekura' could be distinguished by its presentation of a significantly higher color space \(\mathrm{b}^{\star}\) than the others, in which this yellow color index could be considered one of important physical traits that strongly influence the sensory attributes and acceptance of pineapple [8]. This distinct color quality is derived from phytopigments such as carotenoids, including violaxanthin, lutein, zeaxanthin, \(\beta\)-cryptoxanthin, \(\alpha\)-carotene, and \(\beta\)-carotene [5; 18]. Furthermore, variations in the total soluble solid and titratable acidity, as well as the ratio of total soluble solid to titratable acidity, could reveal distinctive balances of soluble solids and acidity in the edible pineapple flesh of different cultivars. These traits might also influence the development of perceived aroma, and thus, increase the overall sensorial quality of pineapple [8; 19]. Altogether, fruit weight, CIE L*a*b* color spaces, total soluble solid, and titratable acidity descriptions are basic physicochemical information that can be used for databases in future research. 'Yonekura' contained about 8.07- and 6.77-times more free volatile components than 'N67-10' and 'Yugafu', respectively (Figure 1A), indicating its potent superior aroma strength, and thus, greater scent character. The proportions of volatile compounds in Okinawan pineapple (Figure 1B) are comparable with pineapple cultivars from other countries such as China, Cuba, and Costa Rica, in which the major components in those pineapple were also esters [2; 3; 19]. Methyl hexanoate and methyl 3-(methylthio)propanoate, which were predominant esters in 'N67-10' and 'Yonekura', could provide sweet-pineapple odors to both cultivars (Table 2) [2; 20]. On the other hand, in addition to comprising methyl hexanoate, which might be responsible for emitting the distinct sweet-pineapple fruity odor, 'Yugafu' might be enriched with additional fruity odors from ethyl acetate, ethyl 2-methylbutanoate, ethyl hexanoate, and ethyl 3-(methylthio)propanoate, with distinct augmented scents [7; 20]. For instance, ethyl acetate might emit solvent-like notes, whilst ethyl hexanoate could also produce a wine-like scent. In general, short-chain esters are derived from fatty acids, and the biosynthesis of these compounds is catalyzed by the alcohol acyltransferase reaction in acyl-CoA and alcohol precursors [21; 22]. For instance, methyl hexanoate might be derived from methanol and hexanoyl-CoA substrates. On the other hand, thioether esters such as methyl 3-(methylthio)propanoate and ethyl 3-(methylthio)propanoate might be synthesized from L-methionine through methionine aminotransferase catalyzation [23]. Figure 3: Glycosidically bound volatile compounds of Okinawan pineapple (\(\mathrm{\SIUnitSymbolMicro mol}\)/100 mL). Each value is expressed as the mean \(\pm\) standard deviation of three replicates. Means in the same group followed by the same letter are not significantly different at \(p<0.05\). In the alcohol group, 2-furanmethanol could further supplement pineapple's fruity odor with caramel-like and cooked-nutty scents [24; 25]. Additionally, 1-hexanol and 2-ethyl-1-hexanol might provide floral-oily-green and rose-green aromas, respectively [26; 27; 28]. Furthermore, terpen could enhance distinct herbaceous scents in pineapple flavor, including sweet and minty (eucalypt), spicy and woody (\(\alpha\)-copaene), grassy and woody (\(\beta\)-elemene), green and waxy (terpinen-4-ol), sweet and herbal [(E)-\(\beta\)-ocimene], and herbal (\(\delta\)-cadinene) scents [26; 29; 30; 31] Moreover, it is noteworthy that Okinawan pineapple, particularly \"Yonekura', also possessed furanones and lactones. These ketone components could also greatly contribute to the overall aroma characteristics of pineapple fruit [2; 7; 20].