Application of oxygen scavengers in gel electromembrane extraction: A green methodology for simultaneous determination of nitrate and nitrite in sausage samples

The generation of oxygen from electrolysis in gel electromembrane extraction (G-EME) causes a negative error when applied to the analysis of easily oxidized species such as nitrite. Nitrite in G-EME is oxidized by oxygen to nitrate, leading to the negative error and the impossibility of simultaneous analysis. In this work, the application of oxygen scavengers to the acceptor phase of the G-EME system was attempted to minimize the oxidation effect. Several oxygen scavengers were selected and examined according to their compatibility with ion chromatography. The mixture of sulfite and bisulfite (14 mg L^-1) showed the highest efficiency in preventing the oxidation of nitrite to nitrate. Under the optimized conditions, a good linear range was obtained (10-200 μg L^-1; R² > 0.998) with a detection limit of 8 µg L^-1 for both nitrite and nitrate. This method was applied to the simultaneous determination of nitrite and nitrate in sausage samples.

Effect of Temperature and Relative Humidity on the Reaction Kinetics of an Oxygen Scavenger Based on Gallic Acid

Gallic acid (GA) is a potential oxygen scavenger for food packaging applications. In this study we investigated the effect of temperature and relative humidity (RH) on the reaction kinetics of an oxygen scavenger consisting of GA and sodium carbonate. The reaction was described by a second-order kinetic law and the reaction rate coefficient k as well as the scavenger capacity n were determined from experimental data using a multiple-run downhill simplex method. Both the rate coefficient and the scavenger capacity increased significantly with higher temperatures. At 21°C it was shown that both the rate coefficient and the scavenger capacity increased significantly with higher RH. However, below 54% RH, there was no detectable reaction. For optimum scavenger performance we therefore recommend GA-based scavengers for packaging of food products with a high water activity stored at room temperature. Prior to application, the packaging materials with GA-based scavengers can be stored at 21°C and 54% RH without losing their scavenger activity. The results of this study provide the basis for the functional design of active packaging systems with GA-based oxygen scavengers.

Active Packaging Applications for Food

The traditional role of food packaging is continuing to evolve in response to changing market needs. Current drivers such as consumer's demand for safer, "healthier," and higher-quality foods, ideally with a long shelf-life; the demand for convenient and transparent packaging, and the preference for more sustainable packaging materials, have led to the development of new packaging technologies, such as active packaging (AP). As defined in the European regulation (EC) No 450/2009, AP systems are designed to "deliberately incorporate components that would release or absorb substances into or from the packaged food or the environment surrounding the food." Active packaging materials are thereby "intended to extend the shelf-life or to maintain or improve the condition of packaged food." Although extensive research on AP technologies is being undertaken, many of these technologies have not yet been implemented successfully in commercial food packaging systems. Broad communication of their benefits in food product applications will facilitate the successful development and market introduction. In this review, an overview of AP technologies, such as antimicrobial, antioxidant or carbon dioxide-releasing systems, and systems absorbing oxygen, moisture or ethylene, is provided, and, in particular, scientific publications illustrating the benefits of such technologies for specific food products are reviewed. Furthermore, the challenges in applying such AP technologies to food systems and the anticipated direction of future developments are discussed. This review will provide food and packaging scientists with a thorough understanding of the benefits of AP technologies when applied to specific foods and hence can assist in accelerating commercial adoption.

Gallic Acid as an Oxygen Scavenger in Bio-Based Multilayer Packaging Films

Oxygen scavengers are used in food packaging to protect oxygen-sensitive food products. A mixture of gallic acid (GA) and sodium carbonate was used as an oxygen scavenger (OSc) in bio-based multilayer packaging films produced in a three-step process: compounding, flat film extrusion, and lamination. We investigated the film surface color as well as oxygen absorption at different relative humidities (RHs) and temperatures, and compared the oxygen absorption of OSc powder, monolayer films, and multilayer films. The films were initially brownish-red in color but changed to greenish-black during oxygen absorption under humid conditions. We observed a maximum absorption capacity of 447 mg O₂/g GA at 21 °C and 100% RH. The incorporation of GA into a polymer matrix reduced the rate of oxygen absorption compared to the GA powder because the polymer acted as a barrier to oxygen and water vapor diffusion. As expected, the temperature had a significant effect on the initial absorption rate of the multilayer films; the corresponding activation energy was 75.4 kJ/mol. Higher RH significantly increased the oxygen absorption rate. These results demonstrate for the first time the production and the properties of a bio-based multilayer packaging film with GA as the oxygen scavenger. Potential applications include the packaging of food products with high water activity (a_w > 0.86).

Modeling of the process of moisture loss during the storage of dried apricots

Moisture content is a reference parameter for dried food because the growth of most microorganisms is inhibited below certain water activity levels. In addition, it has a determining influence on the evolution of important parameters, such as color and flavor, and on other properties and deterioration reactions, such as texture, oxidation processes and nutritional value. During the storage of some dried fruits, moisture is produced due to Maillard reactions and exchanged with the surrounding environment through the packaging. The evolution of dried foods during their shelf life depends on the storage conditions. The aim of this study is to analyze the evolution of the moisture content in dried apricots packaged in different types of containers, namely glass and thermosealed polypropylene trays. The samples were stored at constant temperatures: 5, 15, 25 and 35 °C and were analyzed periodically over a period of 12 months. The sorption isotherms of apricots used in this study were also determined. In order to model how the moisture evolved, an empirical kinetic model was tested. This model considers both water transfer from the fruit and also water production as a result of the Maillard processes. The explained variance was higher than 95% in the samples stored in trays, which were thermosealed with film.