Untitled

Funder

Organizational Unit

Publications

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

Restricted access

Antimicrobial activity of pomegranate peel extracts performed by high pressure and enzymatic assisted extraction

Publication . Alexandre, Elisabete M. C.; Silva, Sara; Santos, Sónia A. O.; Silvestre, Armando J. D.; Duarte, Maria F.; Saraiva, Jorge A.; Pintado, Manuela

This study aimed to assess the effect of high pressure (300 and 600 MPa) and enzymatic extraction (pectinase and cellulase) on the phenolic compounds profile, antioxidant capacity and antimicrobial activity of extracts from pomegranate by-products. Antimicrobial activity against eight different strains of pathogenic and contaminant bacteria and against five beneficial bacteria including Lactobacillus and Bifidobacterium strains were determined. The maximum level of total phenolic content, as well as antioxidant capacity were observed at 300 MPa, however enzymatic extraction did not improve the extraction yields. Punicalagin isomers and bis-hexahydroxydiphenoyl-glucoside isomer were the most abundant phenolic compounds found in the extracts. All pomegranate peel extracts demonstrated selective antimicrobial activity against all pathogenic bacteria without affecting beneficial ones. Pressurized extracts presented lower minimum inhibitory concentration against Bacillus cereus and Pseudomonas aeruginosa and lower minimum bactericidal concentration against B. cereus, while, enzymatic extracts presented lower minimum bactericidal concentration for Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus and Listeria monocytogenes. Principal component analyses reveled that antioxidant activity and phenolic compounds content were strongly related with antimicrobial activity. Pomegranate peels extracts obtained by high pressure extraction could so be used as a source of high added-value bioactive compounds for antioxidant and antimicrobial applications.

2019Journal article

Restricted access

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

Restricted access

High-pressure assisted extraction of bioactive compounds from industrial fermented fig by-product

Publication . Alexandre, Elisabete M. C.; Araújo, Paula; Duarte, Maria F.; Freitas, Victor de; Pintado, Manuela; Saraiva, Jorge A.

High-pressure assisted extraction was employed to obtain fig by-product derived extracts and its impact was evaluated on antioxidant activity and total phenolic, tannin, and flavonoid. A Box-Behnken design was applied to evaluate the effects of pressure, extraction time and ethanol concentration on extractions and optimal conditions were estimated by response surface methodology. The correlation analysis of the mathematical-regression model indicated that a quadratic polynomial model could be employed to optimize the high pressure extraction of compounds. Only the models developed for total antioxidant activity by DPPH · and for total flavonoids presented coefficient determinations lower than 0.95. From response surface plots, pressure, extraction time and ethanol concentration showed independent and interactive effects. The optimal conditions included 600 MPa, an extraction time between 18 and 29 min, depending on the parameter analyzed and a low ethanol concentration (<15%) except for flavonoids (48%). High pressure led to an increase of 8-13% of antioxidant activity and an increase of 8-11% of total phenolics, flavonoids and tannins content when compared to extracts performed at 0.1 MPa. Analysis of variance indicated a high goodness of fit of the models used and the adequacy of response surface methodology for optimizing high pressure extraction.

2017Journal article

Restricted access

Fortification of carrot juice with a high-pressure-obtained pomegranate peel extract: chemical, safety and sensorial aspects

Publication . Trigo, João P.; Alexandre, Elisabete M. C.; Oliveira, Ana; Saraiva, Jorge A.; Pintado, Manuela

High-pressure extraction was used to produce pomegranate peel extract, later incorporated in carrot juice. Chemical, microbiological and sensorial analyses were performed during storage to untreated, high-pressure and thermally processed juices incorporating pomegranate peel extract. Fortified juices showed lower counts for mesophiles and psychrophiles than the nonfortified ones (P < 0.05). Total phenolic and hydrolysable tannin contents, and antioxidant activity had superior values in supplemented juices during storage. The extract did not affect any sensorial parameter. On the 28th day, pressurised juices exhibited lower microbial loads in comparison with heated process, but phenolic compounds, antioxidant activity and several sensorial descriptors were identical between both processing technologies. The beta- and alpha-carotene content decreased after processing, and pressurised juices exhibited higher residual activity for peroxidase (P < 0.05). These data suggest that the application of pomegranate peel extract in treated carrot juices (2.5 mg mL(-1)) improves their microbial safety and antioxidant capacity, without impairing the sensorial aspects.

2020Journal article

Restricted access