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Ultra-high pressure-assisted extraction of phenolic compounds from watercress: characterization and process optimization

Publication . Pinela, José; Prieto Lage, Miguel A.; Barros, Lillian; Carvalho, Ana Maria; Oliveira, Beatriz; Saraiva, Jorge A.; Ferreira, Isabel C.F.R.

Ultra-high pressure (UHP), usually in the range from 100 to 800 MPa, is a novel technology increasingly used in the food industry as a cold pasteurizing method. UHP has also been reported as a good alternative to the conventional methods of extraction of high added-value compounds from plant materials, as it avoids the degradation of thermosensitive molecules and can improve the process efficiency [1-2]. Therefore, this study was carried out to characterize the phenolic profile of watercress (Nasturtium officinale R. Br., a fast-growing semiaquatic plant with medicinal properties) [3] and optimize the UHP-assisted extraction of these compounds using the response surface methodology. For this, freeze-dried watercress samples were processed according to a five-level full factorial design combining the independent variables: processing time (t, 1.5–33.5 min), pressure (P, 0.1–600 MPa) and solvent (S, 0–100% ethanol, v/v). The individual and grouped phenolic compounds (analysed by HPLC-DAD-ESI/MS) and the extraction yield were used as response variables. The chromatographic analysis revealed that the phenolic profile was constituted mainly by flavonoids, namely quercetin and isorhamnetin glycoside derivatives, whereas phenolic acids were less abundant. In addition, four kaempferol glycoside derivatives were identified for the first time in this species [5]. The developed theoretical models were successfully fitted to the experimental data and used for extraction optimization. The UHP conditions that maximized the extraction yield (crude extract) and the recovery of phenolic compounds were as follows: t= 34 min, P= 531 MPa, S= 26% and t= 3 min, P= 600 MPa, S= 100%, respectively [2]. In conclusion, the developed extraction process promoted the selective extraction of phenolic compounds from watercress using a green solvent and reduced extraction times.

2018Conference object

Open access

Exploring plant tissue culture to improve the production of phenolic compounds: a review

Publication . Dias, Maria Inês; Sousa, Maria João; Alves, Rita C.; Ferreira, Isabel C.F.R.

Plant tissue and organ culture has been extensively used from the beginning of the XX century for the study and comprehension of some primary biological mechanisms such as morphogenesis. However, with the increasing demand of the market for novel products derived from plants, in vitro culture became a reliable technique for the mass production of plant material. Moreover, the potential to use this technique for the production of some bioactive compounds, such as phenolic compounds, is immense since it allows the manipulation of the biosynthetic routes to increase the production and accumulation of specific compounds. This work intends to make a brief historical review of in vitro culture, highlighting its use for the production of bioactive compounds. Also, emphasizes the importance of phenolic compounds for the consumer as well reviews the metabolic pathways involved in its production in plant cells. Furthermore, it was carried out a comprehensive study on the work developed for the production of plant phenolic compounds in in vitro cultures, as well as on the type of elicitors used to increase of the same production; also a brief highlighting of the phenolic compounds which serve as elicitors. There are numerous reports directed to the production of phenolic extracts in in vitro plant cultures, however there is a lack in the production of individual phenolic compounds mainly due to the complexity of the biosynthetic routes and extraction procedures. Elicitation procedures are often used to increase the production of phenolics, archieving in most cases higher yields than in non-elicitated cultures. The increasing production of bioactive phenolic extracts/compounds allows for their further applicability, namely in the industry of functional foods or in pharmaceutical/medical fields.

2016Journal article

Open access

Chromatographic profile of fatty acids and sugars in cupcakes functionalized with an extract rich in rosmarinic acid

Publication . Caleja, Cristina; Barros, Lillian; Barreira, João C.M.; Ćirić, Ana; Soković, Marina; Calhelha, Ricardo C.; Oliveira, Beatriz; Ferreira, Isabel C.F.R.

Currently, the food industry is interested in replacing artificial additives by natural ingredients. Some plant extracts have emerged as possible alternatives to artificial preservatives, namely antioxidants. In fact, dairy, meat and bakery products have been developed, incorporating extracts of aromatic plants, spices or fruits, which have antioxidant properties. In this work, the preserving effectiveness of an extract rich in rosmarinic acid was tested in cupcakes and compared to an artificial additive (potassium sorbate, E202). The extract was obtained from Melissa officinalis L. (lemon balm) by applying an ultrasound technique using a mixture of ethanol/water as the extraction solvent. After confirming its antioxidant properties (free radical scavenging effect EC50 = 79 ± 2 μg/mL; reducing power EC50 = 49 ± 1 μg/mL), antimicrobial (against 8 bacteria and 8 food contaminating fungi), and absence of toxicity (in cell lines), it was incorporated in cupcakes, and analysed immediately after incorporation and after 3 and 5 days of storage at room temperature and protected from light. All samples were analysed chromatographically in terms of fatty acids (GC-FID) and free sugars (HPLC-RI). Regarding fatty acids, a total of 21 molecules were identified, with predominance of saturated fatty acids in all cupcakes samples. Individually, palmitic acid and oleic acid were detected in the highest percentages. Among free sugars, sucrose (the major form) and glucose were identified in all samples. The results demonstrate that the addition of the extract rich in rosmarinic acid caused no changes in fatty acids and sugars’ profiles, having the potential to be used in pastry products, meeting the current consumers demand.

2018Conference object

Open access

From the field to the table: ionizing radiation as a feasible postharvest treatment for fresh and dried plant foods

Publication . Pinela, José; Antonio, Amilcar L.; Barros, Lillian; Cabo Verde, Sandra; Carvalho, Ana Maria; Oliveira, Beatriz; Ferreira, Isabel C.F.R.

Food irradiation is a treatment that involves subjecting in-bulk or packaged food to a controlled dose of ionizing radiation, with a clearly defined goal. It has been used for disinfestation and sanitization of food commodities and to retard postharvest ripening and senescence processes, being a sustainable alternative to chemical agents 1 . Doses up to 10 kGy are approved by several international authorities for not offering negative effects to food from a nutrition and toxicology point of view 2 . However, the adoption of this technology for food applications has been a slow process due to some misunderstandings by the consumer who often chooses non-irradiated foods. In this study, the effects of the ionizing radiation treatment on physical, chemical and bioactive properties of dried herbs and its suitability for preserving quality attributes of fresh vegetables during cold storage were evaluated. The studied herbs, perennial spotted rockrose (Tuberaria lignosa (Sweet) Samp.) and common mallow (Malva neglecta Wallr.) were freeze-dried and then irradiated up to 10 kGy in a Cobalt-60 chamber. The selected vegetables, watercress (Nasturtium officinale R. Br.) and buckler sorrel (Rumex induratus Boiss. Reut.) were rinsed in tap water, packaged in polyethylene bags, submitted to irradiation doses up to 6 kGy and then were stored at 4 C for a period of up to 12 days. Physical, chemical and bioactive parameters of irradiated and non-irradiated samples were evaluated using different methodologies the colour was measured with a colorimeter, individual chemical compounds were analyzed by chromatographic techniques, antioxidant properties were evaluated using in vitro assays based on different reaction mechanisms, and other quality analyses were performed following official methods of analysis. The irradiation treatment did not significantly affect the colour of the perennial spotted rockrose samples, or its phenolic composition and antioxidant activity 3 . Medium doses preserved the colour of common mallow and a low dose did not induce any adverse effect in the organic acids profile. The green colour of the irradiated vegetables was maintained during cold storage but the treatment had pros and cons in other quality attributes. The 2 kGy dose preserved free sugars and favoured polyunsaturated fatty acids (PUFA) while the 5 kGy dose favoured tocopherols and preserved the antioxidant properties in watercress samples. The 6 kGy dose was a suitable option for preserving PUFA and the ω-6 ω-3 fatty acids ratio in buckler sorrel samples. This comprehensive experimental work allowed selecting appropriate processing doses for the studied plant foods in order to preserve its quality attributes and edibility.

2016Conference object

Open access

DNA mini-barcodes coupled to high resolution melting (hrm) analysis for the botanical authentication of rosemary honey

Publication . Soares, Sónia; Costa, Joana; Amaral, Joana S.; Oliveira, Beatriz; Mafra, Isabel

Honey is a natural product highly consumed for its taste, nutritional value and health benefits. Monofloral honeys are the most appreciated by consumers and frequently attain high market values, thus being prone to fraudulent practices. Therefore, the development of methodologies to assess and authenticate the botanical origin of honey is of utmost importance. For this purpose, traditional methods based on pollen identification by microscopic analysis are still being used, but they are time‐consuming and greatly dependent on the experience/skill of trained analysts. As an alternative, the use of DNA markers represents promising approach for the identification of botanical species in honey. Currently, DNA barcoding has been regarded with increasing interest for the taxonomic identification of plants, with two plastidial genes (matK and rbcL) being proposed for their differentiation (Bruni et al., 2012). Thus, the objective of this work was to identify the botanical species in rosemary honey using mini‐barcode regions coupled to high resolution melting (HRM) analysis. For this purpose, different plant species (Lavandula spp.) and ten mono‐ and multifloral honeys were used. Three DNA barcoding loci, namely the plastidial coding genes rbcL and matK and the noncoding intergenic trnH‐psbA region, were used to design primers targeting Lavandula spp. (GenBank Z37408.1, KJ196360.1 and HQ902822.1). DNA from plants and honeys was extracted with NucleoSpin Plant II kit (method A), according to Soares et al. (2015). The specificity and sensitivity of the designed primers were assayed by qualitative polymerase chain reaction (PCR) and real‐time PCR. Prior to the specific amplifications, DNA extracts were positively tested targeting a universal eukaryotic sequence (18S rRNA gene). Results from specific PCR assays were further confirmed by real‐time PCR amplification using EvaGreen fluore scence dye. The application of HRM analysis allowed discriminating Lavandula spp. into distinct clusters with high level of confidence. When applying the developed methodology to rosemary honey, samples were classified on the same cluster of Lavandula stoechas (endemic species in Portugal), therefore confirming its botanical origin. To our knowledge, this is the first study using HRM analysis for the rapid discrimination of plant species in honey.

2016Conference object

Open access