A New Age for Quercus spp. Fruits: Review on Nutritional and Phytochemical Composition and Related Biological Activities of Acorns

The current global food system must adapt to the expected growth of world population (about 9 billion individuals by 2050). This adaptation will probably include an increased consumption of edible wild foods, due to their richness in micronutrients and bioactive compounds, besides providing a cost-effective and sustainable way of improving caloric food security. A striking example of such natural matrices is the Quercus genus, which has the additional advantage of being widespread throughout the Northern Hemisphere. In a traditional sense, Quercus fruits (acorns) were mainly used in animal feeding, despite their potentially important role on the rural economy. But this preconception is changing. In fact, their nutritional value, high contents in phytochemical compounds, biological activity (such as antioxidant, anticarcinogenic, and cardioprotective properties) and use in the treatment of specific diseases (such as atherosclerosis, diabetes, or Alzheimer's disease) have raised the interest in integrating acorns into the human diet. Accordingly, this comprehensive overview was designed to provide an evidence-based review of the literature, with the objective to achieve useful conclusions regarding the nutritional properties, methodologies of extraction, identification, and characterization of a wide variety of bioactive compounds and scientifically validated bioactivities in Quercus species worldwide. The industrial by-products from acorn oil extraction or flour production are also included. Data regarding the analytical techniques, individual compounds, and their bioactivities, are organized in tables. The reported data are discussed and directions for further investigations are suggested, highlighting the use of acorns in food, nutraceutical, and pharmaceutical applications.The authors are grateful for the financial support (UID/QUI/ 50006/2013-POCI/01/0145/FEDER/007265) from FCT/ MEC through national funds and cofinanced by FEDER, under the Partnership Agreement PT2020. J.C.M. Barreira thanks FCT, POPH-QREN, and FSE for his grant (SFRH/BPD/72802/ 2010). The authors thank Telma Oliveira for drawing the acorn sketch depicted in Figure 1.info:eu-repo/semantics/publishedVersio

Baobab: uma fonte natural de vitamina C

Introdução: As vitaminas distinguem-se de outros constituintes dietéticos por, em quantidades mínimas, beneficiarem diversos processos metabólicos. A vitamina C (ácido L-ascórbico), presente em frutas e legumes, é fundamental para a nutrição humana, por ser um antioxidante natural. No entanto, os teores do ácido L-ascórbico, principal forma biologicamente ativa desta vitamina, decrescem significativamente ao longo do amadurecimento dos alimentos. O conhecimento da composição nutricional e fitoquímica de frutos exóticos, caso da múcua (Baobab), pode dar a conhecer novas fontes de bioativos e permitir a sua valorização, contribuindo para a sustentabilidade social e económica da região de origem. Objetivos: Análise quantitativa do teor total de vitamina C da polpa do fruto da Adansonia digitata L., conhecida Baobab, espécie nativa de África. Métodos: O teor de ácido ascórbico foi determinado por HPLC-DAD, segundo um método previamente validado. 2 g de amostra foram adicionados a 12 mL de solução estabilizadora (ácido perclórico 10%, v/v) + ácido metafosfórico 1%, p/v). Para a determinação do teor de vitamina C total, utilizou-se tris(2-carboxietil) fosfina (5 mM). O teor de ácido desidroascórbico (forma biologicamente menos ativa) foi determinado por diferença. Resultados: O teor total de vitamina C foi de 26,1 mg/100 g, sendo 22,8 mg/100 g de ácido L-ascórbico e 3,33 mg/100 g de ácido desidroascórbico. Embora estes valores sejam significativamente inferiores aos descritos na laranja (49,1 mg/100 g) e no kiwi (55,2 mg/100 g), este fruto tem um período de conservação substancialmente maior. Atendendo aos seus teores reduzidos de humidade, o Baobab pode ser uma alternativa natural rica em antioxidantes. Conclusões: Este estudo salienta o potencial efeito antioxidante de uma fruta tropical pouco estudada e apenas consumida pela população local. A estabilidade do teor de ácido L-ascórbico observada no Baobab promove novas perspetivas de exploração e utilização de recursos naturais, no âmbito das ciências da nutrição

Development and evaluation of an HPLC/DAD method for the analysis of phenolic compounds from olive fruits

A new HPLC/DAD methodology for separating nine phenolic compounds is described. This methodology is applied to the definition of qualitative and quantitative profiles of three Portuguese olive fruit cultivars (Cobrançosa, Madural and Verdeal). Two different extraction methods were needed for the complete definition of their profiles, one of them including a Sep-pack C18 cleaning step. The chromatographic separation was achieved using a Spherisorb ODS2 (25.0 × 0.46 cm; 5 μm, particle size) column. The solvent system used was a gradient of water-formic acid (19:1) and methanol, with a flow rate of 0.9 mL/min. The detection limit values for phenolic compounds were between 0.04 and 4.32 μg/mL and the method was precise. As a general rule, the recovery values were high. This technique can also be useful in the discrimination of Portuguese olive fruit cultivar

Improving bioactive compounds extractability of Amorphophallus paeoniifolius (Dennst.) Nicolson

Elephant foot yam (Amorphophallus paeoniifolius (Dennst.) Nicolson) is an underground, unbranched deciduous plant that produces a large tubercle (rhizome) with recognized health effects. In this study, the influence of solvent nature (water, water/etanol (1:1) and absolute ethanol) and processing type (fresh, lyophilized and boiled) on the antioxidant activity and bioactive compounds extractability of elephant foot yam was evaluated. Extracts were compared for their contents in total phenolics, flavonoids and tannins. Moreover, their antioxidant capacity was assessed by the ferric reducing antioxidant power (FRAP) and the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH▪) scavenging capacity assays. Phenolics (154 mg GAE/L) and tannins (109 mg GAE/L) were maximized in lyophilized samples extracted with the hydroalcoholic solvent, which attained also the highest FRAP value (711 mg FSE/L). In turn, flavonoids reached the highest yields in lyophilized samples (95 mg ECE/L) extracted with pure ethanol, as well as the highest DPPH▪ scavenging activity. These findings might have practical applications to define the best processing methodology regarding the enhancement of elephant foot yam, either for prompt consumption, as well as to develop food supplements or pharmaceutical related products.J.C.M. Barreira and R.C. Alves thank to FCT, POPH-QREN and FSE for their grants (SFRH/BD/76019/2011 and SFRH/BPD/68883/2010, respectively). This work received financial support from the European Union (FEDER funds through COMPETE) and National Funds (FCT) through project LAQV UID/QUI/50006/2013. This work also received financial support from the European Union (FEDER funds) under the framework of QREN through Project NORTE-07-0124-FEDER-000069

Chemical and antioxidant profiles of acorn tissues from Quercus spp.: Potential as new industrial raw materials

The bioactivity of different organs and tissues of Quercus spp. (Fagaceae), an important group of evergreen or deciduous trees from temperate and tropical climatic areas, represents a good starting point for possible industrial applications. Nevertheless, Quercus fruits, generally known as acorns, are currently undervalued and underexploited. Accordingly, the proximate composition, fatty acids and tocopherols profiles, chlorophyll, lycopene and ß-carotene contents, as well as the antioxidant activity, were studied in different Quercus species to boost new applications in food, cosmetic and pharmaceutical industries. In general, significant differences were found among the nutritional parameters, fatty acids and tocopherols contents and bioactivity indicators, either considering phenotypic (studied species) or botanical (acorn tissues) factors. The acorn tissues and the Quercus species that optimize the production of each nutrient and bioactive compound, as well as that allowing the highest antioxidant activity were thoroughly identified. The obtained information provides an increased knowledge to define potential industrial applications for acorn tissues, potentially offering economic advantages to this underutilized natural resource.The authors are grateful for the financial support to REQUIMTE/LAQV (UID/QUI/50006/2013 – POCI/01/0145/FEDER/007265) and CIMO (UID/AGR/00690/2013) from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020. J.C.M. Barreira thanks FCT, POPH-QREN and FSE for his grant (SFRH/BPD/72802/2010).info:eu-repo/semantics/publishedVersio