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- Evaluation of the antioxidant activity of extracts obtained form cherry seeds.Publication . Dulyanska, Y.; Cruz-Lopes, Luísa; Esteves, Bruno; Ferreira, José; Domingos, Idalina; Lima, M. J. Reis; Correia, Paula; Ferreira, Manuela; Fragata, Anabela; Barroca, Maria João; Silva, A. M.; Guiné, Raquel P. F.Annual cherry production in Portugal is around 19,000 tonnes, in an area of about 6,450 ha and covering about 11,100 farms, concentrated in some northern and central interior territories. It is also in these regions that in recent decades there has been a significant increase in farms specialized in the production of cherry, using new cultivars and new technologies in a business production model. Apart from being consumed in fresh form, cherries are used for many food preparations, like sweets, jellies or confectionary. In the plants that transform cherries, a significant amount of cherry seeds (also called cherry pits) is generated as residue or waste. The possible usage of these residues as raw material for extraction of compounds with antioxidant properties is beneficial in term of economic value as well as environmental impact. Hence, the objective of this work was to obtain extract rich in compounds with antioxidant activity from cherry seeds. The cherry seeds were obtained from a local waste management company, Nutrofertil, located in Tondela, in the district of Viseu (Portugal). They were grinded and then submitted to extraction procedures testing different operating conditions: magnetic stirrer versus ultrasound, different solvents (methanol, ethanol, water) and temperatures (from 35 ºC to 80 ºC). For the obtained extracts antioxidant activity was evaluated through spectrophotometric methods, using the DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-di-(3-ethylbenzthiazoline sulfonic acid)) radicals, and also the Ferric Reducing Antioxidant Power Assay (FRAP). All measurements were replicated at least trice, and were expressed as mg Trolox equivalents per gram (mg TE/g). The results obtained for the different experimental conditions indicated that least efficient extractions at ambient temperature were obtained with methanol using magnetic stirrer and with water using ultrasounds, for which the antioxidant activities measured by the DPPH method were 0.26 and 0.33 mg TE/g and by the ABTS method were 0.82 and 0.86 mg TE/g, respectively. Most efficient methods were water:ethanol (at 50% concentration) and water (100%), using magnetic stirrer in both cases. Highest antioxidant activity was obtained for water:ethanol by the DPPH method (0.72 mg TE/g) and for water (100%) by the ABTS method (1.25 mg TE/g). Tests with different concentrations for the aqueous solutions of ethanol and at different temperatures revealed that with increasing concentration of water the antioxidant diminished, from 0.62 to 0.27 mg TE/g at 35 ºC using the DPPH method. Additionally, the variation in temperature allowed reaching a maximum extraction of compounds with antioxidant activity at 70 ºC and decreasing thereafter. The maximum values obtained were registered at 70 ºC for all cases and were 0.74 mg TE/g for the water:ethanol 50:50 (v/v) by the DPPH method, 2.16 mg TE/g for the water:ethanol 60:40 (v/v) by the ABTS method and 3.43 mg TE/g for the water:ethanol 60:40 (v/v) by the FRAP method. The results obtained by the different methods were concordant in terms of the observed trends but giving different values of the measured antioxidant activity, which is a common characteristic observed in these types of evaluation techniques. This research allowed establishing some operational conditions that should be selected in order to maximize the extraction of compounds with antioxidant activity from cherry seeds. The use of ultrasounds was not found beneficial and the magnetic stirrer technique revealed to be more useful. Also the use of methanol was not found suitable, which is a good point given that this solvent is more pollutant and has more problems of toxicity. With respect to temperature, it was found that temperatures higher than 70 ºC are not beneficial because they induce the degradation of some bioactive compounds thus reducing the antioxidant activity of thee extracts.
- Extração de compostos fenólicos de caroço de cerejaPublication . Dulyanska, Yuliya; Guiné, Raquel P. F.; valente, Luisa; Esteves, Bruno; Ferreira, José; Domingos, Idalina; Correia, Paula; Ferreira, Manuela; Fragata, Anabela; Cardoso, Ana Paula; Barroca, Maria João; Silva, Aida Moreira; Lima, M. J.Os resíduos agroalimentares provaram ser um biorecurso que pode ser usado para obter uma variedade de materiais, ingredientes e produtos químicos valiosos. Neste trabalho foram testadas as condições ótimas para extração de compostos bioativos dos caroços de cereja com diferentes solventes e temperaturas. Os critérios escolhidos basearam-se na capacidade de extração mais eficiente, buscando técnicas mais limpas e com menor impacto no meio ambiente. Alguns solventes de extração foram testados em diferentes combinações e temperaturas. Os extratos obtidos foram avaliados utilizando métodos espectrofotométricos quanto a compostos fenólicos totais, bem como algumas famílias de compostos fenólicos. Os resultados obtidos mostraram que a maior extração de compostos fenólicos totais foi a 70°C com razão água:etanol de 60:40 (% v/v) (2,65 mg GAE/g), enquanto os máximos resultados para flavonoides foram obtidos a 80°C e solução aquosa etanólica 50% (7,26 mg QE/g). O maior valor para orto-difenóis foi de 21,47 mg GAE/g para 50°C e solução água:etanol 50:50. As maiores quantidades de proantocianidinas e flavonóis foram obtidas para solução 50:50 a 70 °C (6,43 mg CE/g e 3,88 mg QE/g, respetivamente), enquanto a mesma solução a 80 °C permitiu obter o máximo de ácidos fenólicos (1,68 mg CAE/ g). A extração de antocianinas varia significativamente com a concentração e temperatura, sendo mais alta na faixa de 35-40 °C, quando se utiliza uma solução de água:etanol 80:20. Em conclusão, verificou-se que os extratos de caroços de cereja obtidos possuem compostos bioativos relevantes com aplicações nas indústrias alimentícia, farmacêutica ou cosmética.