Browsing by Author "Cruz, Vasco"
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- Antioxidant and antimicrobial properties of PLA based active packaging with pomegranate peels and extractPublication . Andrade, Mariana; Rodrigues, Pedro; Barros, Carolina; Cruz, Vasco; Machado, Ana; Barbosa, Cássia; Coelho, Anabela; Furtado, Rosália; Correia, Cristina; Saraiva, Margarida; Vilarinho, Fernanda; Ramos, Fernando; Sanches Silva, AnaActive food packaging’ primary goal is to extend foodstuffs’ shelf life, through a dynamic and continuous interaction between the package and the packaged food. In an emission active packaging, the objective is the gradual release of antioxidant and/or antimicrobial compounds into the food surface, to delay the natural foods’ degradation. The active compounds can be extracted from several sources, such as aromatic plants, seaweeds, fruits by-products, among others. Since 50% of pomegranate is composed by peels, and since it is mainly consumed in juice and jam form, pomegranate peels may represent a considerable asset for the extraction of such compounds. The principal objective of this work was to evaluate the antioxidant and antimicrobial properties of polylactic-based active packaging incorporated with 3% (w/w) of pomegranate peels (PLA/3PP) and 3% (w/w) of pomegranate peels extract (PLA/3PPE). For the in vitro antioxidant activity evaluation, 9.08 cm2 of films were immersed in the food simulator, ethanol 95% (v/v), at 40 °C for 10 days. Then, the DPPH radical scavenging assay was performed, as well as the total content of phenolic compounds, total content in flavonoids, content in punicalagin (A+B) and ellagic acid were determined. Also, to fully determine the total content in punicalagin (A+B) and ellagic acid, the films were kept in methanol at 25 and 40 °C for 24 h. The antimicrobial activity of the films was evaluated with Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli, in accordance with ISO 22196:2011. Results showed that PLA/3PPE presented a higher antioxidant potential and higher content in phenolic compounds and flavonoids. Only ellagic acid was detected in the active PLA-based films. Regarding the antimicrobial activity, both films presented antimicrobial activity against S. aureus.
- Effect of pomegranate peels and extract in barrier, optical and mechanical properties of polylactic acid-based active packagingPublication . Andrade, Mariana; Vilarinho, Fernanda; Rodrigues, Pedro; Barros, Carolina; Cruz, Vasco; Machado, Ana Vera; Barbosa, Cássia; Ramos, Fernando; Sanches Silva, AnaBeing more than 50 % of pomegranate (Punica granatum L.) constituted by non-edible parts, namely peels (50%) and seeds (10%), pomegranate is an excellent source of by-products. Its peels and seeds present excellent antioxidant and antimicrobial activities and a high content of phenolic compounds, namely ellagitannins. This work aimed to evaluate the mechanical and optical properties of two polylactic acid (PLA)-based active packaging with 3 wt.% pomegranate peels (3PP) or 3 wt.% pomegranate peel extract (3PPE). All the samples were produced on a laboratory scale with techniques and processing conditions used in industry. The production of packaging with flexible films is mainly carried out by tubular film extrusion. With this processing method it is possible to produce samples with molecular orientation and reduced thickness equal to that of the packages currently on the market. The structural and morphological characterization of the films were evaluated by FTIR and SEM, and the color by UV-vis. Water vapor transmission and mechanical properties were also measured. The color was measured by Shimadzu UV2401PC reflectance spectrophotometer. Water vapor transmission, oxygen permeability and mechanical properties were also measured. The FTIR and SEM results indicate the incorporation of the pomegranate peels and peels extract in the PLA matrix, where PLA/3PPE showed better particle homogenization than the PLA/3PP. Regarding the color variations, the PLA/3PPE presented higher variations in terms of L*, a*, and b*. The incorporation of pomegranate derivates has a negative effect on the tensile strength and Young modulus, but a significant increase of the elongation at break for PLA/3PPE. The PLA film's water vapor barrier properties do not suffer any alteration with the incorporation of pomegranate extract.
- Extending beef meat shelf life: an approach using active food packaging with pomegranate extract and peelsPublication . Andrade, Mariana; Rodrigues, Pedro; Barros, Carolina; Cruz, Vasco; Machado, Ana; Barbosa, Cássia; Coelho, Anabela; Furtado, Rosália; Correia, Cristina; Saraiva, Margarida; Vilarinho, Fernanda; Ramos, Fernando; Sanches Silva, AnaMore than 50% of the pomegranate fruit (Punica granatum L.) is not considered edible, being composed by peels (50%) and seeds (10%). Pomegranate peels represent an excellent source of bioactive compounds with excellent antioxidant and antimicrobial activities due to the peels’ high content in phenolic compounds, specially punicalagin (A+B) and ellagic acid. The aim of the present study was to evaluate the potential effects of a polylactic acid (PLA) based active packaging incorporated with pomegranate peels and an ethanolic extract from pomegranate peels in the shelf-life extension of fresh meat. Two PLA-based active packaging incorporating 3% (w/w) of pomegranate peels (PLA/3PP) and 3% (w/w) of pomegranate peels extract (PLA/3PPE) were used to pack beef meat. The samples were stored at 4 °C, for a maximum of 11 days. The meats’ lipid oxidation and microbial contamination was evaluated at the end of 1, 4, 6, 8 and 11 storage days. Lipid oxidation was measured by the Thiobarbituric Acid Reactive Substances assay (TBARS)[1]. Meat’s total microorganisms count at 30 °C was performed using the automated method TEMPO® Aerobic Count- AFNOR BIO 12/35–05/13. Both PLA active packaging significantly delayed meat’s lipid oxidation and microbial growth. The meat with PLA/3PP and PLA/3PPE presented a difference up to 3 log CFU/g on the 11th storage day. Even though both active packaging were able to inhibit meat’s lipid oxidation, these results showed that PLA/3PP was more efficient, providing insights for the use of this bio-waste towards environmental sustainability.
- Extending High Fatty Foods Shelf-Life Protecting from Lipid Oxidation and Microbiological Contamination: An Approach Using Active Packaging with Pomegranate ExtractPublication . Andrade, Mariana A.; Rodrigues, Pedro V.; Barros, Carolina; Cruz, Vasco; Machado, Ana Vera; Barbosa, Cássia H.; Coelho, Anabela; Furtado, Rosália; Correia, Cristina Belo; Saraiva, Margarida; Vilarinho, Fernanda; Ramos, Fernando; Silva, Ana SanchesThe search for new forms to extend foodstuffs’ shelf-life through the use of natural compounds and extracts continues to grow among researchers and the industry. In this line of thought, the main objective of this work was to develop, characterize and evaluate the effectiveness of an active food packaging based on polylactic acid (PLA) and incorporated with natural extracts obtained from grape and/or pomegranate by-products. In vitro, antioxidant methods were applied to evaluate the antioxidant capacity of three extracts: wort extract, freeze-dried pomegranate peels extract (PPE-FD), and natural pomegranate peels (PPE-N). Punicalagin (A + B) and ellagic acid were determined in PPE-FD, PPE-N, and active films by UHPLC-DAD. New PLA-based active packaging with PPE-FD (PLA/3PPE) and pomegranate peels (PLA/3PP) were developed, and their chemical, mechanical, and barrier properties were evaluated. Moreover, the effectiveness of the new film was carried out through the study of lipid oxidation state and microbial contamination of two high-fat content foodstuffs, almonds and beef meat. PPE-FD presented high antioxidant capacity and high content in total phenolics and flavonoid compounds. The PLA/3PPE and PLA/3PP prevented the lipid oxidation of meat and presented antimicrobial activity against Staphylococcus aureus. The addition of the PPE-FD and the pomegranate peels to the PLA did not affect the morphology of the polymer. Although both PPE-FD and pomegranate peels presented punicalagin (A + B) and ellagic acid, only ellagic acid was identified and quantified in the active PLA. Active PLA films were not effective in delaying the lipid oxidation of almonds, but they showed to be significantly effective in delaying the lipid oxidation of beef meat and reducing the microbial growth in this food matrix over time.