## 5 Conclusions  
HS-SPME/GC-MS combined with chemometric tools was successfully applied to explore the similarities and differences among apple fruits, juices, and ciders from different apple varieties (Festa, Branco, Domingos). A total of 142 VOCs belonging to different chemical families were identified, namely, 58 esters, 34 alcohols, 19 aldehydes, 10 ketones, 8 terpenoids, 7 acids, 3 sulphur compounds, 1 dioxolane, 1 lactone, and 1 aromatic hydrocarbon. From these, only 9 VOCs were detected in all analysed matrices (fruit, juice, and cider) and in all apple-tested varieties (Festa, Branco, and Domingos). Moreover, remarkable difference in terms of the qualitative and semiquantitative profiles was observed, which indicated that apple variety has a significant effect on the volatile profile. Esters and alcohols were the dominant chemical families, contributing 48.81%, 56.75%, and 94.04% on average for the total volatile profile of apple fruits, juices, and ciders, respectively. In qualitative terms, butyl butanoate (42), 1-octen-3-one (55), hexyl propanoate (66), butyl hexanoate (75), \(\alpha\)-farnesene (122) and 2-hydroxy-\(\gamma\)-butyrolactone (141) were only detected in apple fruits, whereas butanal (4), 2,4,5-trimethyl-1,3-dioxolane, (7) 1-penten-3-ol (28), 2-penten-1-ol (58), and 2-butoxyethanol (70) were found in juices. On the other hand, methyl octanoate (38), styrene (47), 3-methyl-1-pentanol (62), ethyl 9-decenoate (119), and octanoic acid (139) were detected in all ciders. Moreover, there were VOCs that were of unique variety, such as benzyl alcohol (130) for the Festa, linalool (95) and estragole (113) for the Branco, and decanal (89) and benzothiazole (134) for the Domingos apple varieties. Accordingly, VOCs could be used as authenticity indicators to classify fruits, juices, and ciders according to apple variety, providing local producers with multiple benefits and legal protection against the misuse of the products. The following are available online at [[http://www.mdpi.com/2304-8158/9/12/1830/s1](http://www.mdpi.com/2304-8158/9/12/1830/s1)]([http://www.mdpi.com/2304-8158/9/12/1830/s1](http://www.mdpi.com/2304-8158/9/12/1830/s1)). Figure S1. Total ion chromatograms obtained by HS-SPME/GC-qMS analysis of apple fruits, juices, and ciders of the different varieties (Festa, Branco, Domingos). Conceptualization, S.M., R.P. ([PERSON]), and J.S.C. ; methodology, S.M. and R.P. ([PERSON]); software, S.M. and R.P. ([PERSON]); validation, S.M. and R.P. ([PERSON]); formal analysis, S.M. ; investigation, S.M. and J.S.C. ; resources, R.P. ([PERSON]) ([PERSON]) and J.S.C. ; data curation, S.M. and R.P. ([PERSON]); writing--original-draft preparation, S.M. ; writing--review and editing, R.P. ([PERSON]) and J.S.C. ; visualization, R.P. ([PERSON]) and R.P. ([PERSON]) ([PERSON]); supervision, S.M. and J.S.C. ; project administration, J.S.C. ; funding acquisition, R.P. ([PERSON]) ([PERSON]) and J.S.C. All authors have read and agreed to the published version of the manuscript. **Funding:** This work was supported by FCT-Fundacao para a Ciencia e a Tecnologia (project PEst-OE/QUI/UI0674/2019, CQM, Portuguese government funds), through the Madeira 14-20 Program, project PROEQUIPRAM Reforco do Investimento em Equipamentos e Infraestruturas Cientificas na RAM(M1420-01-0145-FEDER-000008) by ARDITI-Agencia Regional para o Desenvolvimento da Investigacao Tecnologia e Inovacao, through project M1420-01-0145-FEDER-000005--Centro de Quimica da Madeira CQM + (Madeira 14-20). SM was supported by the postdoctoral fellowship granted by ARDITI CQM + project (ARDITI-CQM/2017/008-PDG). RP was supported by an FCT postdoctoral grant (SFRH/BPD/97387/2013). **Acknowledgments:** The authors thank the Direcao Regional de Agricultura (Regiao Autonoma da Madeira, Portugal) for the supply of apple fruits and ciders. **Conflicts of Interest:** The authors declare no conflict of interest.