## 4 Conclusions  
This manuscript describes for the first time the bioactive potential that apples, one of the largest consumed fruit in the world, can have particularly non-compliant 'Bravo de Esmolfe' variety as a reliable source of polyphenols that could be extracted with sustainable technologies by the opposition to the traditional ones that uses large amounts of toxic solvents. The different extraction techniques (two green extractions (MAE and UAE) and two conventional extractions (CE and UAE)) were applied to compare the different technique to produce a natural antioxidant extract rich in polyphenols using non-compliant BE apples. Data indicate that both MAE and CET are good extraction methodologies for the development of a BE apple antioxidant extract rich in polyphenols comparatively to the other techniques tested. However, MAE is a better method as it is more sustainable than CET. Applying this sustainable extraction technique, it was possible to obtain an antioxidant extract with higher antioxidant activity and polyphenols, including hydroxychinnamic acids (4-caffeoylquinic acid and 5-caffeoylquinic), flavanols ((\((-\))-epicatechin, (\(+\))-catechin, and procyanidins) and chalcone (phoretin and phloridzin). Additionally, this study demonstrated the possibility of using non-compliant BE apple to produce new functional ingredients, such as antioxidant extracts. This might constitute a new and promising way for recovering high value-added compounds from the rejected fruit and which might be of use for human consumption or food industry purposes. Besides this, these circular economy approaches sensitize to the preservation of a traditional PGI variety and minimizing the losses feed, promoting the bioeconomic value of the fruit supply chain, integrating the circular and sustainable principles. To guarantee the food application of these BE apple extracts, future studies about their safeness, toxicity, stability and bioaccessibility will be necessary.  
Conceptualization, A.A.V.-B., A.O. and M.P.; investigation, methodology, validation A.A.V.-B., T.B.R., R.G.-G., C.N. and S.R.; formal analysis, A.A.V.-B. and A.O.; writing--original draft preparation, A.A.V.-B.; writing--review and editing, A.O.; supervision and project administration, M.P. and J.N. All authors have read and agreed to the published version of the manuscript.  
This work was supported by Ministry of Agriculture and Rural Development and co-financed by the European Agricultural Fund for Rural Development (EAFRD), through the partnership agreement Portugal PDR-2020, under the project Nature Bioactive Food: Desenvolvimento de produtos e ingredients alimentares bioativos atraves de recursos agricolas endogenos portuguese para uma alimentacao saudavel (Ref. PDR2020-101-031531) and is a result of the Transfer Empreende project, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF).  
Not applicable.  
The authors would like to thank the Nature Bioactive Food project (PDR2020-101-031531), Transfer Empreende project (Norte-02-0651-FEDER-000081), supported by Norte Portugal Regional Operational Programme (NORTE 2020), and the scientific collaboration of Escola Superior de Biotechnological of Universidade Catolica Portuguesa through CBQF under the FCT project UIDB/50016/2020.  
The authors declare no conflict of interest.