Repository logo
 

Search Results

Now showing 1 - 10 of 10
  • 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.
  • Comparison of emerging technologies to extract high-added value compounds from fruit residues: pressure- and electro-based technologies
    Publication . Alexandre, Elisabete M. C.; Castro, Luís M. G.; Moreira, Sílvia A.; Pintado, Manuela; Saraiva, Jorge A.
    Fruit consumption has significantly increased due to their attractive sensory properties and the growing recognition of its nutritional and therapeutic values. Nevertheless, several tons of fruits are processed by the food industry for the production of different products such as juices and jams, leading to the production of a great amount of fruit waste. Until a few decades ago, fruit residues were not considered a cost neither a benefit but resulted in a significant negative impact on the environment, ending up being used as animal feed, brought to landfills or sent to composting sites. The extraction of high-added value compounds from fruit residues is usually done through conventional methods, such as Soxhlet, hydrodistillation, maceration, and enzyme-assisted extraction. Although these methods are easy to perform and cheap to operate, they present several concerns mainly due to thermo-sensible compound degradation and environment pollution. Recently, new extraction technologies have been in development to improve extraction of high-value compounds, such as high pressure, pressurized liquid extraction, instantly controlled pressure drop, pulse electric fields, and high-voltage electrical discharges, as well its combinations between each other’s. These technologies are considered environmentally friendly, allow the use of lower amounts of organic solvents and the reduction in extraction time and energetic consumption, conducting to higher yields and high-quality final extracts.
  • Effect of emergent non-thermal extraction technologies on bioactive individual compounds profile from different plant materials
    Publication . Moreira, Sílvia A.; Alexandre, Elisabete M. C.; Pintado, Manuela; Saraiva, Jorge A.
    Extraction is the first step for isolation and purification of interesting bioactive compounds, by mixing of the plant material with an adequate solvent. Those bioactive compounds are, usually, secondary metabolites, such as phenolic acids and flavonoids which are present in closed insoluble structures, making its extraction a challenge. There are many different traditional extraction methods, such as Soxhlet, heat reflux, and maceration. Nevertheless, due to several disadvantages, they are being replaced by new methods, using emergent technologies, such as high hydrostatic pressure, ultrasounds, pulsed electric fields, and supercritical fluids. The use of novel technologies allows enhancing mass transfer rates, increasing cell permeability as well as increasing secondary metabolite diffusion, leading to higher extraction yields, fewer impurities on the final extract, extractions at room temperature with thermo-sensitive structures preservation, use of different non-organic solvents, low energy consumption, short operation time, and have no significant or lower effect on the structure of bioactive compounds. This paper aims to review the effect of the main emergent extraction technologies (high hydrostatic pressure, pulsed electric fields, ultrasounds, and supercritical fluid assisted) on the individual profile of bioactive compounds from plant material.
  • 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.
  • Emerging technologies to extract high added value compounds from fruit residues: sub/supercritical, ultrasound-, and enzyme-assisted extractions
    Publication . Alexandre, Elisabete M. C.; Moreira, Sílvia A.; Castro, Luís M. G.; Pintado, Maria Manuela; Saraiva, Jorge A.
    Food waste is a growing problem for the food industry, leading to an increase of pollution and economic problems. Fruits and vegetables are very rich in bioactive compounds having many benefits for humans. These biocompounds can be found not only in the fruit/vegetable itself but also in its wastes, after processing. Nonetheless, the conventional extraction methods are highly problematic, due to solvent consumption, long extraction time, and low extraction yields, making it necessary to develop new extraction techniques. In this review, we aim to review the most recent literature on the extraction of bioactive compounds from fruit peels and seeds, using sub/supercritical fluids, ultrasound, and enzymes.
  • Optimization of antioxidant activity and bioactive compounds extraction of winter savory leaves by high hydrostatic pressure
    Publication . Moreira, Sílvia A.; Pintado, Manuela E.; Saraiva, Jorge A.
    Winter savory is often used in traditional medicine, having several recognized biological properties. This study aimed to evaluate the effect of high pressure-assisted extraction (HPE) and its optimization by response surface methodology to obtain winter savory extracts with a high content of bioactive compounds and high antioxidant activity (the effect of extraction pressure, extraction time, and ethanol concentration were investigated). Results showed that data could be well fitted to second-order polynomial mathematical models for total phenolics, total flavonoids, chlorophylls, carotenoids, and extraction yield, as well as for antioxidant activity. The models predicted optimal conditions ranging 200–500 MPa, extraction time 1–20 min, and ethanol concentration 0–70% (v,v). In comparison with extraction at atmospheric pressure, HPE showed to be more efficient, allowing obtaining an increase of about 40% for all compounds, and an increase of 29, 48, and 70% for antioxidant activity by FRAP, DPPH and ABTS assays, respectively.
  • Effect of a HPP pretreatment on thermal inactivation kinetics of polyphenoloxidase obtained from three apple cultivars
    Publication . Machado, Maria F.; Sousa, Alexandra; Castro, Sónia M.; Moreira, Sílvia A.; Saraiva, Jorge A.
    Enzymatic browning due to the action of polyphenoloxidase (PPO) is highly undesirable and efficient methodologies to avoid/reduce it are of great interest for food industry. The effect of a pressure pretreatment (100 MPa, 15 min, room temperature) on the activity of PPO extracts obtained from three apple cultivars (Bravo de Esmolfe [BE], Reineta [RN], and Golden delicious [GD]), and subsequent thermal inactivation kinetics was evaluated, as a way to more efficiently achieve thermal inactivation of PPO. The effect of pH on PPO activity was also assessed to define the value at which carry out the thermal inactivation of PPO. The enzymatic activity decreased in the order BE, RN, and GD. Two log-linear ranges ([62.5-72.5]degrees C and [72.5-80.0]degrees C) of D-value with temperature were found. The pressure pretreatment caused enhanced stability within the range of 62.5-67.5 degrees C, caused no changes at 70.0-72.5 degrees C, and decreased the stability at 75.0-80.0 degrees C (e.g., at 75 degrees C the D-values for BE, GD, and RN ranged, respectively, from 25.6/27.3, 14.5/18.6, and 8.8/10.4, after/before the pressure pretreatment) and increased thermal sensitivity (decreased the z-value), particularly in the lower temperature range studied (up to 72.5 degrees C). Practical applicationsKnowledge of PPO activity level and its thermal resistance for different cultivars is of interest to develop efficient and optimized enzymatic browning control by thermal treatments. Sequential combination of low intensity pressure treatments followed by thermal treatments can be an interesting approach to enhance enzyme inactivation. In this work was found that after a low intensity pressure pretreatment (100 MPa, 15 min), apple PPO temperature stability could be reduced, since a lower stability (lower D-values) and increased sensitivity toward temperature (lower z-value) was systematically found for PPO thermally inactivated at T>72.5 degrees C. These findings are of interest for a more efficient PPO inactivation for enhanced browning control.
  • Effect of high hydrostatic pressure extraction on biological activities and phenolics composition of winter savory leaf extracts
    Publication . Moreira, Sílvia A.; Silva, Sara; Costa, Eduardo; Pinto, Soraia; Sarmento, Bruno; Saraiva, Jorge A.; Pintado, Manuela
    Satureja montana L. has several biological properties related to its diverse composition of secondary metabolites. Nevertheless, it has been mainly studied for its essential oil, with only a few studies on the profile and bioactivities of the bioactive compounds from its leaf extracts being reported. This work aimed to study the antioxidant activity (by oxygen radical absorbance capacity (ORAC) assay), antimicrobial minimum inhibitory and bactericidal concentrations (MIC and MBC) determination, antibiofilm (by colorimetry), impact upon DNA (anti- and pro-oxidant assay), and cytotoxicity (by cell metabolism viability assays) of S. montana extracts obtained by high-pressure-assisted extraction (HPE). The extract obtained at 348 MPa, 35% (v/v) ethanol presented the highest concentration of individual phenolic compounds, and a minimum bactericidal concentration of 20 mg/mL against Listeria monocytogenes. HPE extracts showed antioxidant activity not only in ORAC but they were also able to prevent/attenuate peroxide-induced damage upon DNA. Moreover, on its own, HPE extract induced less oxidative damage than the control extract. Concerning the cytotoxicity, HPE extracts (at 0.5 and 1.0 mg/mL) were not harmful to HT29 cell lines, while control extracts (obtained at atmospheric pressure) at higher concentrations (>1.0 mg/mL) slightly reduced the metabolism of the cells. Finally, all extracts showed inhibition of the viability of 3 cancerous cell lines (>2.0 mg/mL for Caco-2, HeLa, and TR146) to below 15%.
  • Effect of high hydrostatic pressure extraction on biological activities of stinging nettle extracts
    Publication . Moreira, Sílvia A.; Silva, Sara; Costa, Eduardo M.; Saraiva, Jorge A.; Pintado, Manuela
    Stinging nettle is traditionally used as a therapeutic herb. In the present work, the biological properties and toxicity of novel nettle leaf extracts obtained by high pressure assisted extraction (HPE) were studied and compared with similar extracts obtained with the same solvent under atmospheric pressure conditions. The studied extracts were obtained at pressure levels of 200 and 500 MPa, ≈10 min, 0 to 70% ethanol : water (v/v). Each extract was characterized for its individual compound profile and different biological properties, such as antioxidant activity, pro-oxidant activity (DNA degradation capacity) and antihypertensive activity, as well as cytotoxicity against Caco-2 and HaCat cell cultures. The main results indicate that in addition to the antioxidant and antihypertensive activities observed for the control extracts, a clear improvement of all the biological activities of the extracts obtained by HPE was observed. The extracts obtained at 200 MPa, 10 min, 35 and 70% ethanol were the ones presenting higher concentrations of phenolic acids and flavonoids, such as chlorogenic acid, isoferulic acid, and rutin; besides, they showed better results concerning all the studied biological activities. Those extracts also showed potential for DNA protection, since they were able not only to cause less damage in the DNA molecule than the controls, but also showed no pro-oxidant activity. Concerning cytotoxicity, it was observed that HPE extracts, at a concentration up to 1.0 mg mL−1, presented a metabolism inhibition below 10 and 15% for Caco-2 and HaCat cell lines, respectively.