Centre for Biotechnology and Fine Chemistry

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Effect of a winter savory leaf extract obtained using high hydrostatic pressure on the quality of carrot juice

Publication . Moreira, Sílvia A.; Pintado, Manuela E.; Saraiva, Jorge A.

BACKGROUND: The consumption of vegetable juices has increased due to their characteristics such as freshness/naturalness, high nutritional value, low in calories, and for being a convenient way of consuming bioactive compounds. High hydrostatic pressure (HPP), which has been mainly used to replace thermal processing, is now also being successfully applied as extraction technology to recover bioactive compounds from herbs. The present work aimed to evaluate the effect of supplementation of carrot juice with winter savory leaf aqueous extract on the final juice characteristics. RESULTS: The extract was added to raw carrot juice (1.0 mg mL–1), which was then submitted to HPP and stored for 15 days under refrigeration. Microbial analyses were performed during storage time, as also were analyzed the physicochemical properties such as pH, colour, bioactive compound concentration and antioxidant activity. Supplemented juices presented lower microbial counts than the non-supplemented ones, and, generally, did not present significant changes (P > 0.05) in pH or colour. Concerning the total phenolics and total flavonoids, as well as antioxidant activity, the values were generally higher (P < 0.05) in supplemented juices, which was proven by the high correlation found between total phenolics and ABTS●+ and FRAP assays. CONCLUSIONS: These data suggest that the addition of winter savory leaf extract in carrot juice treated with HPP can effectively improve microbial safety throughout refrigerated storage as well as antioxidant activity, without risking other characteristics of the juice, such as the colour or the acidity.

2021-01-15Journal article

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Polymeric nanoparticles as oral delivery systems for a grape pomace extract towards the improvement of biological activities

Publication . Costa, Joana R.; Xavier, Miguel; Amado, Isabel R.; Gonçalves, Catarina; Castro, Pedro M.; Tonon, Renata V.; Cabral, Lourdes M.C.; Pastrana, Lorenzo; Pintado, Manuela E.

Grape pomace (GP) is a major by-product from the wine industry, known for its bioactive compounds and their impact upon gastrointestinal (GI) health. However, bioaccessibility is often poor due to their degradation during digestion. This work aimed to encapsulate bioactive GP extract (GPE) into chitosan (CS) and alginate (Alg) nanoparticles (NPs) to mitigate degradation in the GI tract. Alg and CS NPs were optimized using a rotatable central composite design and NPs were characterized for their size, polydispersity, zeta potential and total phenolics (TP) association efficiency. The best formulations showed sizes ranging 523–853 nm, polydispersity indexes of 0.11–0.36, zeta potential of −15.0–14.9 mV and TP association efficiencies of 68 and 65%. FTIR confirmed that there was no formation of new chemical groups after association of the polymers with GPE. Both formulations improved the bioaccessibility of different phenolics following in vitro GI digestion, leading to in-creased antioxidant and antimicrobial activities. Moreover, the permeability of bioactive compounds through a Caco-2/HT29-MTX co-culture was reduced, suggesting a higher residence time in the intestine. Cy5.5 was used for tracking the CS NPs, which did not affect the metabolic activity of Caco-2 and HT29-MTX cells. Confocal microscopy images confirmed the adsorption of NPs to the cellular layer and suggested a reduction of the tight junction protein occludin when cells were incubated with Cy5.5-CS in solution. This study suggests that encapsulation of GPE can offer protection against along the GI tract and improve its biological activity with significant impact for oral delivery applications, including functional foods.

2021Journal article

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Current extraction techniques towards bioactive compounds from brewer’s spent grain - a review

Publication . Bonifácio-Lopes, T.; Teixeira, José A.; Pintado, Manuela

Background: Brewer’s spent grain is one of the most abundant by-products of the brewing industry and is rich in various bioactive compounds (phenolic acids, insoluble dietary fiber and proteins). While at the present brewer’s spent grain is mainly used as animal feed its rich nutritional content makes it an interesting alternative for food applications. Scope and approach: As the range of applications of the bioactive compounds extracted from by-products has been growing in recent years, there is the need to obtain and characterize these bioactive compounds. Extraction methods (supercritical carbon dioxide, autohydrolysis, alkaline hydrolysis, solvent extraction, ultrasound assisted extraction, dilute acid hydrolysis, enzymatic hydrolysis, microwave assisted extraction) have been developed and are always being subjected to new approaches to allow better extraction yields of the bioactive compounds. Key findings and conclusions: This review aims to provide a better understanding of the current advantages and limitations of brewer’s spent grain extraction processes and to provide a background of brewer’s spent grain composition and applications.

2019Journal article

Open access

Optimization of high hydrostatic pressure assisted extraction of stinging nettle leaves using response surface methodology experimental design

Publication . Moreira, Sílvia A.; Pintado, Manuela E.; Saraiva, Jorge A.

High hydrostatic pressure assisted extraction (HPE) is a very promising extraction methodology since it can operate at room temperature and therefore can avoid heat-sensitive compounds changes. Furthermore, it is recognized as a fast technology (only a few minutes) and it is also an already proven environmentally friendly technology. This is the first work to study HPE effect as a new extraction method to obtain improved extracts from stinging nettle, a commonly known weed, traditionally used as folk medicine and with several biological properties proven scientifically. In this work, the HPE process was optimized by an experimental design via response surface methodology using a central composite face-centered design. The effect of pressure level, extraction time, and solvent concentration were evaluated, as also the impact of HPE on total phenolics (TPC), flavonoids, pigments, and antioxidant activity. Results showed that experimental data could be well fitted to second-order polynomial mathematical models, since lack-of-fit values were non-significant and the regression coefficients were above 75%. The optimal conditions for the overall maximization of extraction yield, TPC and antioxidant activity were 200 MPa, 10.2–15.6 min, and 0% ethanol (aqueous extracts), which were tested in a further experiment confirming the predictability of all models (difference by percentage between predicted and experimental optimum were all below 10%. When compared to extraction at atmospheric pressure, HPE allowed increasing the extraction yield about 50.5%; TPC about 84.4%; and antioxidant activity about 77.7%. All the models fitted well the experimental data, being the observed values close to the predicted ones by the model equation.

2020Journal article

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Physicochemical characterisation and release behaviour of curcumin-loaded lactoferrin nanohydrogels into food simulants

Publication . Araújo, João F.; Bourbon, Ana I.; Simões, Livia S.; Vicente, António A.; Coutinho, Paulo J. G.; Ramos, Oscar. L.

Whey protein nanostructures can be used as vehicles for the incorporation of nutraceuticals (e.g., antioxidants or vitamins) aimed at the development of functional foods, because nanostructures provide greater protection, stability and controlled release to such nutraceuticals. Fundamental knowledge is required regarding the behaviour of nanostructures when associated with nutraceuticals and their interactions with real food matrices. In this study, a lactoferrin (LF) nanohydrogel was developed to encapsulate curcumin (nutraceutical model) and its behaviour was evaluated in terms of the LF structure and the interaction with curcumin. The release kinetics of curcumin from LF nanohydrogels was also assessed using food simulants with a hydrophilic nature (10% ethanol) and lipophilic nature (50% ethanol). This system was able to encapsulate curcumin at 80 μg mL−1 with an efficiency of ca. 90% and loading capacity of ca. 3%. Through spectroscopic characterisation, it is suggested that LF and curcumin bind via hydrophobic interactions and the average binding distance between LF and curcumin was found to be 1.91 nm. Under refrigerated conditions (4 °C), this system showed stability for up to 35 days, while at room temperature (25 °C) it was shown to be stable for up to 14 days of storage. The LF nanohydrogel presented higher release rates of curcumin in a lipophilic food simulant (stable after ca. 7 h) as compared to a hydrophilic simulant (stable after ca. 4 h). LF nanohydrogels were successfully incorporated into a gelatine matrix and showed no degradation in this process. The behaviour of this system and the curcumin release kinetics in food stimulants make the LF nanohydrogel an interesting system to associate with lipophilic nutraceuticals and to incorporate in refrigerated food products of a hydrophilic nature.

2020Journal article

Restricted access