Abstract—The strawberry tree (Arbutus unedo L.) is a small tree or shrub from botanical Ericaceae family that grows spontaneously nearby the Mediterranean basin and produce edible red fruits. A traditional processed fruit application, in Mediterranean countries, is the production of a spirit (known as aguardente de medronho, in Portugal) obtained from the fermented fruit. The main objective of our study was to contribute to the knowledge about the influence of the degree of maturation of fruits in the volatile composition and quality of arbutus spirit. The major volatiles in the three distillates fractions (head, heart and tail) obtained from fermentation of two different fruit maturation levels were quantified by GC-FID analysis and ANOVA one-way was performed. Additionally, the total antioxidant capacity and total phenolic compounds of both arbutus fruit spirits were determined, by ABTS and Folin-Ciocalteau method, respectively. The methanol concentration is higher (1022.39 g/hL a.a.) in the spirit made from fruits with highest total soluble solids, which is a value above the legal limit (1000 g/hL a.a.). Overall, our study emphasizes, for the first time, the influence of maturation degree of arbutus fruits in the spirit volatile composition and quality. Keywords—Arbutus fruit, maturation, quality, spirit. I. INTRODUCTION HE strawberry tree (Arbutus unedo L.) is a forest specie present in the most of Portuguese continental territory, known for its great rusticity, resiliency, annual production and fast entry in production, that is to say, it is one of the Portuguese forest species with the biggest potential for progression. The arbutus fruit is seldom consumed fresh and is mainly processed to give various products, including jam, jelly, vinegar, liquor and spirit [1]-[8]. The main application of arbutus has been in production for a known spirit in Portugal as aguardente de medronho [2], [9], in Spain as aguardiente de madroño [10], in Greece as koumaro [1] and in Italy as Financial support: Fundação para a Ciência e a Tecnologia (FCT), project - PTDC/AGR-FOR/3746/2012 and PRODER program, Project nº 43748, 4.1, Cooperation for Innovation. PEst-OE/AGR/UI0681/2014 for CERNAS, PEst- OE/AGR/UI4033/2014 for CITAB and PEst-OE/AGR/UI0115/2014 for ICAAM being the three I&D Units co-funded by FEDER/Compete and National Budget. Goreti Botelho is with CERNAS Research Unit and Coimbra College of Agriculture, Polytechnic Institute of Coimbra (IPC), 3045-601 Coimbra, Portugal (corresponding author to provide phone: +351239802940; fax: +351239802979 e-mail: goreti@esac.pt). Filomena Gomes is with CERNAS Research Unit and Coimbra College of Agriculture, IPC, 3045-601 Coimbra, Portugal (e-mail: fgomes@esac.pt). Fernanda M. Ferreira is with CITAB Research Unit, UTAD and Coimbra College of Agriculture, IPC, 3045-601 Coimbra, Portugal (e-mail: fferreira@esac.pt). Ilda Caldeira is with ICAAM Research Unit, University of Évora and National Institute of Agricultural and Veterinary Research – INIAV, 2565-191 Dois Portos, Portugal (e-mail: ilda.caldeira@iniav.pt). corbezzolo [11]. This alcoholic drink is a traditional product produced in family size units or small industrial units which makes the strawberry tree a shrub with a socio-economic relevance [1]-[3]. As far as we know from the scientific literature, there is still a lack of knowledge in the arbutus fruit spirit production process optimization in order to improve the sensory quality of the final product. Hence, the major goal of this research was to study the effect of initial ripening level of arbutus fruit on the obtained spirit volatile composition (and on the fractions head and tail), and, at last, quantify the total antioxidant capacity and total phenolic compounds from that same spirits. II. MATERIALS AND METHODS A. Samples and Experimental Design Mature fresh arbutus fruits were used for the experiment in this study. All fruits were collected in a 16 ha instalation located in the center of Portugal, at high about 680 m from sea level. Two distinct sets of fruits were collected in October 2013: A – arbutus fruits collected directly from protections covering the floor under the plants after their natural fall; B – arbutus fruits collected directly from the plant. All the fruits A and B, were carefully examined to avoid the presence of dust, dirt, immature and damaged fruits and rapidly transported to a laboratory for alcoholic fermentation process. The experimental design involved two sets of four fermentation containers in equal controlled experimental conditions: A1 and A2 containers with 4 kg of fruits from set A in spontaneous fermentation each; B1 and B2 containers with 4 kg of fruits from set B. After the end of the alcoholic fermentations, all the fermented fruits were distilled in a small size copper alembic (16 dm 3 ). The alcoholic fermentation of arbutus fruits was monitored throughout the time all the way through physical and chemical parameters analysis, pH, total soluble solids (TSS, ºBrix) and its temperature. After the end of fermentation, distillation took place, and three fractions were obtained out of it: head, heart and tail. The quantification of volatile compounds was performed towards the three fractions, using the gas chromatography technique and the obtained analytical data was compared to the legal limits established in the Decree-Law n.º 238/2000 [12]. The first part with approximately 5 % (above 70 % vol., with a strong, pungent and unpleasant flavour) of the distillates was collected as head fraction. The heart fractions obtained by single distillation, were collected when the ethanol concentration varied from 70 to 35 % v/v; finally, the tail fractions were obtained when the alcoholic content decreased below 35 % v/v. The ethanol content of distillates Influence of Maturation Degree of Arbutus (Arbutus unedo L.) Fruits in Spirit Composition and Quality Goreti Botelho, Filomena Gomes, Fernanda M. Ferreira, Ilda Caldeira T World Academy of Science, Engineering and Technology International Journal of Agricultural and Biosystems Engineering Vol:9, No:6, 2015 615 International Scholarly and Scientific Research & Innovation 9(6) 2015 ISNI:0000000091950263 Open Science Index, Agricultural and Biosystems Engineering Vol:9, No:6, 2015 publications.waset.org/10001403/pdf