## 5 Conclusions  
Okinawan pineapples of different cultivars varied in the color spaces a* (green index) and b* (yellow index), as well as in their total soluble solid and tittatable acidity traits. These cultivars also varied in their content and composition of free volatile compounds, wherein 'Yonekura' contained about 8.07- and 6.77-times higher concentrations than 'N67-10' and 'Yugafu', respectively. They were predominantly comprised of esters (29 compounds), followed by alcohols, terpen, and ketones. The major ester compounds in 'Yonekura' were methyl hexanoate and methyl 3-(methylthio)propionate, respectively. Both esters are known for emitting sweet-pineapple fruits odors that could be strongly related to the overall aroma characteristics of pineapple fruit. Seven alcohols were detected in free form, such as 2-furanmethanol, 2-ethyl-1-hexanol, 1-hexanol, and 1-octanol. Furthermore, glycosylidically bound volatiles were hydrolyzed via enzymatic reactions and eight hydroxyl-group compounds were released, including chavicol, eugenol, geraniol, phenylethyl alcohol, benzyl alcohol, 2-ethyl-1-hexanol, 1-hexanol, and 3-methyl-2-butenol. The amounts of glycosidically bound chavicol, eugenol, and geraniol were greater than 1 ug/100 mL and were significantly higher in 'Yonekura' than in the other cultivars. Moreover, the amounts of released 2-ethyl-1-hexanol and 1-hexanol from the glycoside fractions were approximately a quarter and half those of their free forms, respectively. The sugar moiety of these glycosides was confirmed to be D-glucose. Additionally, the two glycosides were determined to be chavicol-O-\(\beta\)-D-glucopyranoside and eugenol-O-\(\beta\)-D-glucopyranoside in all three cultivars. The aglycones of these glycoside substances should be further carefully utilized as attractive-aroma resources when processing Okinawan pineapple fruits due to their strong medicinal-flaval herb and clove-like scents, respectively. The outcomes of this study, thus, provide important information regarding both free and glycosidically bound volatile compounds in pineapples of Okinawan origin for fresh consumption and processing into various foods and beverages.  
Conceptualization, Y.A., M.T. and K.W.; methodology, Y.A., Y.K., K.T. and K.W; validation, Y.K., K.T. and K.W.; formal analysis, Y.A. and K.S.; investigation, Y.A. and K.T.; resources, M.T. and R.M.; data curation, Y.A. and K.S.; writing--original draft preparation, Y.A. and K.S.; writing--review and editing, Y.A. and K.W.; visualization, Y.A.; supervision, K.W.; project administration, M.T., R.M., and K.W.; funding acquisition, M.T. and K.W. All authors have read and agreed to the published version of the manuscript.  
This research was supported by grants from the research program on the development of innovative technology from the project of the Bio-oriented Technology Research Advancement Institution (BRAIN), grant number JPJ007097.  
Data Availability Statement: Not applicable.  
We thank [PERSON] (University of the Ryukyus) for her technical assistance in the volatile component analysis. The glycoside composition analysis was performed at the Center for Research Advancement and Collaboration, University of the Ryukyus.  
The authors declare no conflict of interest.