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Category Archives: Cold Plasma
Research – Treatment of Fresh Meat, Fish and Products Thereof with Cold Atmospheric Plasma to Inactivate Microbial Pathogens and Extend Shelf Life
Assuring the safety of muscle foods and seafood is based on prerequisites and specific measures targeted against defined hazards. This concept is augmented by ‘interventions’, which are chemical or physical treatments, not genuinely part of the production process, but rather implemented in the framework of a safety assurance system.
The present paper focuses on ‘Cold Atmospheric pressure Plasma’ (CAP) as an emerging non-thermal intervention for microbial decontamination. Over the past decade, a vast number of studies have explored the antimicrobial potential of different CAP systems against a plethora of different foodborne microorganisms.
This contribution aims at providing a comprehensive reference and appraisal of the latest literature in the area, with a specific focus on the use of CAP for the treatment of fresh meat, fish and associated products to inactivate microbial pathogens and extend shelf life. Aspects such as changes to organoleptic and nutritional value alongside other matrix effects are considered, so as to provide the reader with a clear insight into the advantages and disadvantages of CAP-based decontamination strategies.
Research – Study on the effect of atmospheric and low-pressure plasma and its combination on the microbial reduction and quality of milk
This study is aimed to identify the effects of atmospheric and low-pressure plasma on milk individually and in combination, as the plasma generated and applied at different conditions have variations in the effect on food. Plasma bubbling unit (200 V and 0.24 A) was used for atmospheric plasma and Dielectric Barrier Discharge discharge plasma (70 Pa) with milk passing between the electrodes was used for low-pressure plasma. After treatment, the initial coliform load of 7.62 log CFU/ml was decreased by a maximum of 1.26, 1.58, and 2.2 log reduction, when milk was treated using low-pressure plasma (2 kV and 3 ml/min milk flow rate), plasma bubbling (10 min) and combination of both atmospheric bubbling and low-pressure plasma application (10 min bubbling +2 kV and 3 ml/min milk flow rate) respectively. The conductivity (significantly increased) and pH (slight reduction) of milk supported the presence of reactive species. However, alkaline phosphatase activity was not eliminated in plasma-treated milk; the initial activity in terms of mg phenols/ml of milk was 23.20 which was reduced to 22.57 in low-pressure plasma and 22.35 in plasma bubbling, however, it increased while both the treatments were combined. The sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis uncovered that the plasma processing didn’t have any prominent impact on the protein fractions in milk. Though plasma bubbling was effective compared to low-pressure plasma, the combination was proved to have a synergistic effect on milk. However, the enzyme structure needs to be studied in the future for analyzing the exact change in the activity.
Research – Effects of High-Voltage Atmospheric Cold Plasma Treatment on Microbiological and Quality Characters of Tilapia Fillets
Cold plasma (CP) has become an alternative to conventional thermal processing of food products. In this study, the effect of cold plasma treatment time on the inactivation and quality of tilapia fillets was investigated. The surfaces of tilapia fillets were inoculated with Salmonella enteritis (S. enteritis), Listeria monocytogenes (L. monocytogenes), and a mixture of both before being treated with cold plasma at 70 kV for 0, 60, 120, 180, 240, and 300 s. With the extension of treatment time, the number of colonies on the surface of the fillets decreased gradually; after 300 s of cold plasma treatment, S. enteritis and L. monocytogenes populations were reduced by 2.34 log CFU/g and 1.69 log CFU/g, respectively, and the a* value and immobile water content decreased significantly (p < 0.05), while the free water content increased significantly (p < 0.05). TBARS value increased significantly (p < 0.05) to 1.83 mg MDA/kg for 300 s treatment. The carbonyl value and sulfhydryl value of sarcoplasmic protein significantly (p < 0.05) increased and decreased, respectively, as treatment time extension, while no significant changes were found in myofibrillar protein. No significant differences were observed in pH, b* value, elasticity, chewiness, thiol value, and TVB-N value. The results showed that cold plasma had an inactivation effect on tilapia fillets and could preserve their original safety indicators. It was concluded that CP treatment could be used as an effective non-thermal method to maintain the quality of tilapia fillets and extend their shelf-life. View Full-Text
Research – Nisin-based antimircobial combination with cold plasma treatment inactivate Listeria monocytogenes on Granny Smith apples
A nisin-based antimicrobial and cold plasma combination treatments in reducing Listeria monocytogenes inoculated on apple surfaces purchased from a New Jersey farm and a supermarket in Philadelphia area was investigated. All apples were spot inoculated or by submersion in 107 CFU/ml L. monocytogenes inoculum. Populations of L. monocytogenes recovered on farm and supermarket apples after spot inoculation averaged 5.8 ± 0.24 log CFU/g and 4.6 ± 0.12 log CFU/g, respectively and 4.1 ± 0.22 log CFU/g and 3.6 ± 0.12 log CFU/g, respectively on submerged apples. All apples were treated with antimicrobial solution for 30 s, 40 s, 3 min (180s) and 1 h (3600 s), cold plasma treatments for 30 and 40s, and a combination of antimicrobial and cold plasma treatments and the surface structure of apples were examined using scanning electron microscopy (SEM). Cold plasma treatment at 40s, followed immediately with antimicrobial treatments at 180s and 3600 s led to 2.5 and 4.6 log CFU/g inactivation of L. monocytogenes, respectively. SEM observation showed changes on apple surface structures but not on bacterial cell structure. This result suggests that this combination treatments is effective in killing L. monocytogenes on apple surfaces.