Browsing by Author "Pereira, Celeide"
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- Development of a natural preservative based on catechin and derivatives from plant originPublication . Albuquerque, Bianca R.; Prieto Lage, Miguel A.; Pereira, Celeide; Barros, Lillian; Ferreira, Isabel C.F.R.The controversy and ambiguity related with chemical additives, allied to the sporadic scares, have paved the way for natural additives to gain interest and funding. Today, most consumers prefer foods added with natural additives, which is seen by the food industry as an opportunity to find new and more efficient natural‐based solutions. Polyphenols constitute some of the most interesting groups of natural compounds in the vegetable kingdom and due to their antioxidant capacity, they have been used to develop natural additives in the class of preservatives. They can be added as plant extracts, taking advantage of the synergistic effects between compounds, or as individual molecules. Catechin, a widely known flavon‐3‐ol, is also known for its antioxidant activity. The discovery of new alternative sources of natural additives is also a very important topic, therefore the aim of this study was to obtain an extract enriched in catechins (natural preservative), from fruits of Arbutus unedo L., as an alternative source to the already well studied Camellia sinensis (L.) Kuntze. However, the catechin stability during the extraction and storage processes requires essential conditions that need to be examined cautiously. Therefore, a stability study of the enriched catechin extract powder was performed, evaluating the main affecting conditions involved in the obtaining and storage of the extract and its stability in mimitized food matrices. To determine these effects three main variables (time, temperature and pH) affecting catechin function were considered, being the catechin content monitored by HPLC‐DAD. Mechanistic and phenomenological equations were used to describe the responses and optimal conditions for catechin stability. Overall, with this study the best stability conditions for catechin enriched extracts were established (information protected by a submitted patent) in order to allow its use as a natural preserver by the food industry.
- Production of chitosan-based biodegradable active films using bio-waste enriched with polyphenol propolis extract envisaging food packaging applicationsPublication . Carli, Cristiane de; Aylanc, Volkan; Mouffok, Kheira; Santamaria-Echart, Arantzazu; Barreiro, M.F.; Tomás, Andreia; Pereira, Celeide; Rodrigues, Paula; Vilas-Boas, Miguel; Falcão, SoraiaDeveloping biodegradable active films has been a promising green approach to overcoming global concerns over the environmental pollution and human health caused by plastic utilization. This study aimed to develop active films based on chitosan (CS), produced from waste crayfish (Procambarus clarkii) shells enriched with bioactive extract (5–20%) of propolis (PS) and to characterize its properties, envisaging food packaging applications. The chromatographic profile of PS extract confirmed its richness, with 41 phenolic compounds. With increasing extract addition to the chitosan, the thickness of the films increased from 61.7 to 71.7 μm, causing a reduction in the light transmission rate, along with a greenish colour shift. The interactions between PS extract and CS was confirmed by infrared spectroscopy, at the same time that the microstructural integrity of the films was checked on the scanning electron microscopy micrographs. The findings also showed that addition of PS enhanced the films thermal stability and mechanical properties e.g., tensile modulus, yield strength, and stress at break. Besides, it improved the antioxidant and antimicrobial activities. Overall, CS-based composite films seem a promising green alternative to petroleum-based synthetic plastics allowing to extend the shelf life of food products due to their eco-friendly nature.
- Propolis application in food preservation: development of chitosan-based edible filmsPublication . Carli, Cristiane de; Aylanc, Volkan; Santamaria-Echart, Arantzazu; Pereira, Celeide; Sousa, Miguel; Barreiro, M.F.; Rodrigues, Paula; Vilas-Boas, Miguel; Falcão, SoraiaEdible films derived from chitosan highlight for its potential as coating packages, due to their antimicrobial activity and low oxygen permeability, while propolis has shown effective as a natural additive due to its antimicrobial and antioxidant properties. Thus, its combination to produce edible films, provides a promising approach to enhance the life spam of easily perishable foods. The present study describes the development of edible films based on chitosan produced from chitin extracted crawfish shell, modified with propolis. Chitosan-based films prepared incorporating different concentrations of poplar propolis extracts (0% to 20%), where characterized by FTIR, TGA and SEM. Additionally, mechanical properties, water-solubility, colour and optical transmittance tests were performed to assess the film specificities. The antioxidant and antimicrobial activity of the coating were also studied. The FTIR spectra of the extracted material enable the identification of all major peaks associated to chitosan, corroborating the extraction procedure of chitin/chitosan from crawfish. The addition of propolis to the films decreased the water solubility compared to control. Besides, all films exhibited antioxidant and antimicrobial activity. The output clear indicates that films enriched with propolis may be an alternative candidate for food packing.