The Effect of Non-Thermal Plasma on Physical-Chemical and Microbial Properties of Cinnamon and Cumin

Introduction: In recent years, cold plasma has gained increasing attention for its potential use in food preservation. Cold plasma as an emergent technology can be an effective approach for inactivating pathogenic and spoilage microorganisms without significantly impacting food quality. The antimicrobial efficacy of cold plasma processing can be enhanced when combined with a sanitizer In the area of food processing, plasma is currently tested to change the functionality of food ingredients; cold plasma is also under research to remove pesticides from crops or to remove allergens from specific foods, to mention few of them.Spices are one of the flavors of natural origin that are most frequently used in food preparation and formulation. The majority of spices are made using traditional techniques. Spices produced in unhygienic conditions often have high amounts of pathogenic bacteria, molds, and yeasts. Some bacteria are known as human pathogens and thus require disinfection processes that reduce the potential harm they might do to the active components of spices. The use of contaminated spices in food can significantly reduce the shelf life of food items and may pose health hazards to consumers. To increase the nutritional and sensory quality of food while simultaneously ensuring the products' microbiological safety, one of the key targets is to find alternatives to current food processing and preservation technologies. Emerging innovations in the field of food science and food engineering have developed consistently and quickly over the past 20 years. The innovative food processing method called "cold plasma" uses energetic reactive gases to inactivate contaminating bacteria in spices. Cold plasma decontamination techniques are significantly safer and more efficient than previous ones. Furthermore, the impacts of cold plasma on bioactive components are negligible, and the almost final quality of the products after operations is consistent. In this study, cinnamon and cumin spices were exposed to cold plasma processing with argon gas in order to examine their microbiological, chemical, physical, and organoleptic qualities.

Material and methods:
In order to perform cold plasma treatment, cinnamon and cumin spice samples were first weighed in a sterile Petri dish. Then, the plate containing the sample was placed in the location of sample, plasma treatment was performed with the DBD system for three minutes. Cold plasma was produced at atmospheric pressure by argon gas. An AC source with a maximum voltage of 10 kV, a frequency of 1 to 16 kHz and a power of 100 W was used. In order to carry out the tests, plasma delivery was done with the DBD system for three minutes. In order to evaluate the microbial load of the samples, total count, total coliform, mold and yeast count were done. In order to check the chemical parameters moisture, aqueous extract of cinnamon and cumin, Total amount of phenolic compounds and antioxidant activity to DPPH radical reduction method and total ash amount were measured. In order to physically evaluate the samples, morphology was evaluated with scanning electron microscopy (SEM), and solubility in water, color, and sensory evaluation was also done. In order to show the proficiency of plasma influence, the prepared samples were compared to the controlled sample(non-plasma).
Results and discussion: In this study the results of plasma application had a significant effect (p<0.05) on the microbial contamination of cinnamon and cumin. The coliform reduction rate was 92% in cinnamon and 91% in cumin. Regarding the reduction of mold, we saw the same reduction (22%). The total count reduction was 7.69% in cinnamon and 9.08% in cumin. In the investigation of chemical characteristics, the moisture content of cinnamon decreased by 46.87%, but no change was observed in the moisture content of cumin. The results of plasma application had a significant effect (p<0.05) on the microbial contamination of cinnamon and cumin. The coliform reduction rate was 92% in cinnamon and 91% in cumin. Regarding the reduction of mold, we saw the same reduction (22%). The total count reduction was 7.69% in cinnamon and 9.08% in cumin. In the investigation of chemical characteristics, the moisture content of cinnamon decreased by 46.87%, but no change was observed in the moisture content of cumin.
Conclusion:
Cold plasma is used as an innovative solution in production and distribution of healthy and high-quality foods.The reduction of bacterial populations in food could be accomplished by using the cold plasma treatment .Since heat treatments may lead to the loss of beneficial vitamins and even the molecular taste and profile of food, using new non-thermal methods, such as cold atmospheric plasma, could result in the production of foods with minimal pathogens, which could even have health benefits. Some of these benefits include the significant reduction of waste and environmental pollution, lower energy consumption compared to thermal methods, and the reduction of the microbial load in heat resistant agents. It is hoped that by using non-thermal pasteurization methods such as cold atmospheric plasma, a new step would be taken toward the improvement of the food industry. Further studies with plasma technology are necessary to produce natural products free of chemical additives.