Evaluation of high-pressure as a novel non-thermal extraction technology to obtain extracts with improved biological activities from medicinal herbs

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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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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.

2019Journal article

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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.

2017Journal article

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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.

2017Journal article

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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.

2018Journal article

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