Abstract
By 2050, the population on Earth is estimated to reach 10 billion. Fresh and minimally processed plant products are important sources of nutrients and health-promoting compounds in the human diet; however, incidences of foodborne outbreaks are often associated with their consumption. Hence, the need for agri-food industries to develop innovative and sustainable processes to ensure their safety, quality, and nutritional properties. Plasma activated water (PAW), among cold plasma technologies, has shown promising results in terms of microorganisms, mycotoxins, and pesticide degradation thanks to the synergistic effect given by low pH, high concentration of reactive oxygen and nitrogen species(RONS), and high oxidative-reduction potential. However, the effects of PAW on plant food endogenous enzymes, on sensory and functional properties, and on the production of harmful chemical compounds still need clarification. Moreover, common PAW experimental setups have limitations of in-batch processes and do not enable in-situ and on-demand dispensing of RONS. The PAA-FOOD project aims to overcome the PAW related-drawbacks by designing, developing, and testing “plasma-activated aerosol” (PAA) systems for the surface decontamination and preservation of fresh produce (FP) and minimally processed plant foods (MPFV). The project activities are organized in 8 Work Packages (WPs), each having a specific goal. Two different prototypes will be developed for PAA generation, i.e., a system producing plasma-activated water (PAW) coupled with an aerosolization device (PAWA), and a system allowing for the in-situ generation of Plasma-Aerosol (PAS) (WP1). Both systems will be characterized for the energy consumption, aerosol characteristics, concentrations of reactive species in aerosol droplets, plasma behavior, and chemical composition of gas-phase (WP2); additionally, the PA system will be tested on selected FP (strawberries, tomato cherries) and MPFV (lettuce, apples)products. After a preliminary optimization of the process conditions (WP3), both PAA treatments will be applied on FP and MPFV to evaluate their effects on products' sensory, quality, and biochemical properties during storage (WP4), microbiological and chemical hazards (WP5), and nutritional and functional properties (WP6). Project data will be modeled (WP7) to describe the effects of PAA treatments on the different considered parameters. WPs will be developed through the collaboration of two Research Units (RUs) involved in different activities according to their expertise. All RUs will contribute to the dissemination of project results (WP8). The project aims to provide a wide overview of the PAA-induced changes in FP and MPFV. Moreover, the project, through the identification of transient and long-lasting radical species, will provide information on safety aspects that so far are unknown and could contribute to the approval of this novel technology by governments' regulatory agencies. RESULTS ACHIEVED The PAA-FOOD project (“Plasma Activated Aerosol for the Preservation and Decontamination of Fresh and Minimally Processed Plant Foods”) explored the use of plasma-based technologies to enhance the safety, quality, and shelf life of fresh plant foods, focusing on the development and evaluation of plasma-activated aerosol systems (PAA), including (i) plasma-activated water aerosol (PAWA), obtained by aerosolisation of plasma-activated water, and (ii) in situ plasma-activated aerosol (PAS), generated directly in the aerosol phase. The project led to the design and construction of two prototype systems (PAWA and PAS), which were subsequently subjected to electrical, physical, and chemical characterization, with particular focus on aerosol properties, reactive species generation, and plasma behavior. These activities highlighted clear differences between the two configurations, showing the limitations of PAWA in preserving reactive species and the higher potential of PAS systems for the in-situ generation and delivery of reactive species. The work was carried out within a multidisciplinary framework combining plasma engineering, food technology, food chemistry and microbiology, as defined in the original proposal. During the project, the research activities focused on selected fresh products (strawberries, cherry tomatoes and raspberries) and on model systems, with particular attention to physicochemical, enzymatic, microbiological, toxicological and nutritional parameters. This enabled a comprehensive evaluation of the effects of PAWA and PAA treatments on overall quality, enzymatic activity, and microbiological aspects of plant matrices, as well as on selected contaminants, including pesticide residues (e.g. boscalid, spinosad) and mycotoxins such as patulin and ochratoxin A. In parallel, preliminary investigations on the persistence of radical species in treated matrices were carried out by electron paramagnetic resonance (EPR) spectroscopy, providing qualitative information on the presence and evolution of radical signals in selected plant matrices (tomato and strawberry) and supporting a first assessment of the stability of reactive species and their interaction with the food matrix. Although minimally processed plant foods were initially included among the target matrices, the experimental results showed limited or inconsistent effects on some of the investigated parameters, particularly on enzymatic activity. For this reason, part of the work was redirected towards model systems, in order to better understand whether the reduced efficacy was mainly due to the complexity of the food matrices which may quench reactive species, or to intrinsic limitations of the technology itself. In this context, comparative tests were also carried out by applying plasmaactivated water both by spraying/aerosolization and by direct immersion. Experiments on cherry tomatoes showed that both approaches have slight effects, with some differences in immediate antimicrobial effects and in their persistence during storage. This comparison helped to clarify the role of the application mode and to distinguish it from matrix-related effects. Overall, the project contributed to advancing knowledge on plasma-based non-thermal technologies for food decontamination and preservation. In addition to the applicative aspects, the work also provided useful insights into the factors that influence treatment efficacy, helping to better define the actual potential and current limits of these systems and to guide future optimisation and scale-up.
Dettagli del progetto
Responsabile scientifico: Romolo Laurita
Strutture Unibo coinvolte:
Dipartimento di Ingegneria Industriale
Coordinatore:
Università degli Studi di TERAMO(Italy)
Contributo totale Unibo: Euro (EUR) 88.407,00
Durata del progetto in mesi: 24
Data di inizio
12/10/2023
Data di fine:
28/02/2026
