Browsing by Author "Buonocore, G."
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- Monitoring lipid oxidation in a processed meat product packaged with nanocomposite poly(lactic acid) filmPublication . Vilarinho, Fernanda; Andrade, Mariana; Buonocore, G.; Stanzione, M.; Vaz, M.F.; Sanches Silva, A.One of the most detrimental processes in fatty foodstuffs is lipid oxidation, which occurs during production and storage, and influences food composition and safety. Polylactic acid (PLA), a commercially available biopolymer, is biodegradable thermoplastic aliphatic polyester derived from renewable resources. Polymer layered silicate (PLS) nanocomposites have shown potential for enhancing physical, chemical, and mechanical properties of both conventional materials and biopolymers. In the present work nanocomposite films were prepared by incorporating unmodified montmorillonite clay (Cloisite® Na+) in the PLA. Moreover, the lipid oxidation status of a processed meat product packaged with a film incorporating this nanocomposite was evaluated. In line with this, hexanal, Thiobarbituric Acid Reactive Substances (TBARS) and p-anisidine value were monitored after packaging salami during different storage times (15, 30, 60 and 90 days). The results of this study showed that the presence of montmorillonite (MMT) in the polymer film can reduce the lipid oxidation of processed meat products, extending their shelf life and, thus, suggesting that the new film is a potential good alternative to conventional bioplastics.
- Trends in the use of antioxidants in active packagingPublication . Sanches-Silva, A.; Costa, D.; Albuquerque, T.G.; Buonocore, G.; Costa, H.S.Introduction: One of the main roles of food packaging is to retard the natural processes that lead to food deterioration and reduction in quality, safety or both. Food industry has long recognized the importance of using antioxidants (AOs) for this purpose. The use of antioxidants is not restricted to its direct addition to foods, but they can also be added to the food packaging which can act as a reservoir and release them by a controlled mechanism of diffusion. Packaging designed to foster desirable food packaging interactions have been called as active packaging. The active packaging with antioxidant properties either uses AOs in the form of independent sachets or incorporates them in the polymeric matrix of the packaging. Although many of these antioxidants are artificial molecules like butylated hydroxytoluene (BHT) or butylated hydroxyanisole (BHA), nowadays there is a tendency to search for natural molecules with the same properties but which are not related with possible toxicological side effects. The most recent contributions on active packaging with natural antioxidants have been reviewed. Material and Methods: For this study, an extensive bibliographic review on food packaging with incorporated natural antioxidants was carried out. Special attention is given to the antioxidants activity tests carried out in both packaging and packed foods. Results and conclusion: In the last years, different pure standards of natural antioxidants were incorporated in food packaging such as alpha-tocopherol, caffeic acid, catechin, quercetin or carvacrol. On the other hand, sources of natural antioxidants have also been incorporated in packaging for food applications such as cinnamon, oregano, clove, rosemary, ginger, clove and lemongrass essential oils and extracts of barley husks, green tea, mint and pomegranate peel. DPPH (2,2-diphenyl-1-picrylhydrazyl) is the most common test used to evaluate the antioxidant activity (AA) in packaging, while most of the times the determination of the AA of packed foods is carried out with TBARS (thiobarbituric acid reactive substances) assay, although other methods are also used (peroxide value, free fatty acids, conjugated dienes and conjugated triene hydroperoxides, p-anisidine value and hexanal analysis). Generally, because there is no consensus on the best test, most of the studies use more than one test to evaluate the AA. Attention was also devoted to the study of the migration of natural antioxidants into food simulants or foods. Recently, there were great improvements in food packaging materials in order to increase food shelf life and to decrease the impact of packaging in the environment. Therefore, there is a growing interest on the association of active packaging with natural AOs with biodegradable and edible packaging.
- Ultra-high Pressure LC to Determine α-Tocopherol and BHT in Active Plastic Films and to Evaluate their Migration into a Fatty Food SimulantPublication . Sanches-Silva, A.; Costa, H.S.; Albuquerque, T.G.; Buonocore, G.The use of food additives is not restricted to its direct addition to food products and they can also be added to the food packaging which, acting as a reservoir, is able to release it by means of a diffusion mechanism. Low density polyethylene (LDPE) films containing α-tocopherol and BHT, separately or together, with different nominal concentrations have been prepared through a two-step process; first preparation of pellets and then their extrusion. Plastic films were extracted with acetonitrile for 24 h. Extracts were filtered and analyzed by means of an Ultra-High Pressure Liquid Chromatography (Ultra Performance Liquid Chromatography, UPLC) method with diode array detection (DAD). The analytical column (UPLC BEH, 5 x 2.1 mm, 1.7 µm particle size) was used at 30 ºC. A gradient elution method was employed with ultrapure water and acetonitrile. The flow rate was 0.3 ml/min and the injection volume was 10 µl. α-tocopherol was detected at 295 nm and BHT at 277 nm. A calibration curve was obtained in order to quantify the amount of extracted a-tocopherol and BHT. Excellent linearity was obtained for both a-tocopherol and BHT (r2= 0.999) in the range 1-100 µg/ml. Results showed that the film prepared with 1% of α-tocopherol lost a high amount of this antioxidant during processing. On the contrary, films prepared with both α-tocopherol and BHT presented a significantly lower loss. In fact, the residual amount of α-tocopherol after processing was 73% of the initial amount in the case of the plastic film with 0.5% of α-tocopherol and 0.5% of BHT. This means that BHT protects α-tocopherol from degradation, as intended. The migration of the LDPE with 0.25% α-tocopherol and 0.25% BHT into ethanol 95% (v/v), an alternative fatty food simulant, was evaluated at different time contact periods (1, 2, 4, 7, 10, 20 and 30 d), and at different temperatures. The plastic submitted to the migration test was then, extracted in order to evaluate the remaining concentration in the plastic film. The sum of both values is in agreement with the amount found in the initial evaluation of the plastic concentration after processing.