Browsing by Issue Date, starting with "2022-10-23"
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- Screening methodologies to extract polyphenols from olive oil pomacePublication . Martins, V.; Ribeiro, T. B.; Pintado, M.; Morais, R.M.C.S.; Morais, A.M.M.B.Olive oil is a product from the fruits of the plant Olea europaea L. About two million ton of olive oil are produced annually, whereas Spain, Italy and Greece are the major producers. Its production worldwide causes 30 million m3 of olive mill waste each year 1, which consist of olive oil pomace and olive wastewater. Following the goals of the ONU agenda for 2030, under the topic of circular economy that includes “zero waste production”, an economy model uses the residues as resources to be valorized 2. The olive oil pomace contains bioactive compounds, such as the hydroxytyrosol, tyrosol, oleuropein 3, which have shown to present antimicrobial and antioxidant proprieties, with applications in the food industry. This works aims to test and optimize different extraction techniques to obtain bioactive compounds from the olive oil pomace byproduct. Techniques such as maceration in water or hydroalcoholic solutions, with or without enzymes, assisted or not by ultra-turrax, ultrasound or microwave. Preliminary results showed that the use of enzymes in extraction allowed a higher yield of extraction. Thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) were used to identify the bioactive compounds present in the extract. Relevant compounds with antimicrobial and antioxidant proprieties will be used in packaging as films or coatings for food applications.
- Antioxidant activity of alginate edible films containing plant extractsPublication . Lopes, Ana Isabel; Silva, Sara; Barros, Lillian; Caleja, Cristina; Pereira, Eliana; Tavaria, Freni; Pintado, ManuelaNowadays, food packaging has been the target of increasing attention. Traditional food packaging is usually made of plastic and accounts for 36.9% of the plastics’ demand, being considered the largest market for plastic industry. Additionally, plastics are mostly produced with polymers from non-renewable sources and so, they contribute to environmental pollution. A way to circumvent this problem is the development of edible films. Edible films can act as complements to traditional plastics because their functional properties are able to extend food’s shelf-life1. Plant extracts are obtained by plants and possess antioxidant activity because of their high concentrations of phenolic compounds. They can be effective at low concentrations, are cost-effective and easy to apply, presenting low toxicity levels and high stability during processing and may not affect the sensory characteristics of food products2. The addition of plant extracts to edible films confers them the ability to act as food preservatives because they present antimicrobial activity against a broad spectrum of food poisoning microorganisms and antioxidant properties that helps to avoid the deterioration of fats and other food constituents 3. So, the main objective of this work was to evaluate the antioxidant activity of alginate edible films containing extracts of licorice (Glycyrrhiza glabra L.), eucalyptus (Eucalyptus globulus Labill.) and sage (Salvia officinalis L.). The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-difenil-1-picrilhidrazil (DPPH) scavenging tests were performed on the films and the results show that the films incorporated with plant extracts present antioxidant activity when compared to the control (alginate film without plant extract). The film incorporated with sage extract was the one that presented the best antioxidant activity by both ABTS (4024,169 Trolox equivalents (M)/mg film) and DPPH (3954,813 Trolox equivalents (M)/mg film), followed by the film with eucalyptus extract (ABTS: 3706,291 Trolox equivalents (M)/mg film; DPPH: 3706,291 Trolox equivalents (M)/mg film). On the other hand, the film incorporated with licorice extract (ABTS: 942,5195 Trolox equivalents (M)/mg film; DPPH: 1040,669 Trolox equivalents (M)/mg film) was the one with least antioxidant activity.