The potential of the surface dielectric barrier discharge technique (SDBD) was evaluated to decontaminate the date palm fruit. Preliminary investigations emphasized that Aspergillus niger fungus was predominant in most date samples as a post-harvest infestation. The influence of SDBD techniques on the viability of A. niger isolated from date varieties was investigated and documented. Physical and chemical characterizations of treated Ajwa Dates Price in Pakistan were assessed, and statistical correlation coefficients were calculated and elucidated. A 4 log10 reduction of A. niger radial growth was observed at 3 min exposure/15 days of incubation. Simultaneous reductions in pH, water activity, and moisture content of treated dates were observed when compared to untreated dates. Statistical analysis showed a positive correlation between physical and chemical variables with the viability of A. niger in treated samples. Therefore, we believe that SDBD treatment will be a promising technique for decontaminating date fruits from attacked fungi, which will positively impact sustainable food security and consumer health.

The date palm (Phoenix dactylifera) is one of the most adapted plants in the desert due to its capability to tolerate high temperatures, droughts, and salinity1. Meanwhile, date fruits are distinguished by containing primary essential nutrients and supplements such as proteins, sugars, fatty acids, minerals, and vitamins2. Thus, date fruits represent an essential integrated diet for humans and sometimes animals in the Arabia region1. The Kingdom of Saudi Arabia is the second largest producer of palm dates globally, with an estimated annual production of 1.5 million tons after Egypt, the first producer with an annual production of 1.8 million tons (FAO, 2021). Great efforts were exerted to maintain the date palm quality and safety. Unfortunately, date palm fruit, whether pre-or post-harvest, is attacked by many pests such as fungi, bacteria, and insects, causing an economic loss for this strategic crop yield. Most of the dates offered in the Saudi market are consumed without any kind of treatment to reduce microbial contamination, which could be spread out during transportation, handling, storage, and production lines3.

Furthermore, high levels of converted sugars and moisture content along with the humid weather while harvesting and ripening render date fruit suitable for fungi infections4. Aspergillus flavus, Aspergillus niger, Penicillium chrysogenum, and Rhizopus stolonifer were the most found infectious mycotoxins in marketed dates3. Aflatoxins are specific mycotoxins produced in infected foods by A. flavus and A. parasiticus, which are well known as genotoxic and carcinogenic agents and pose a severe threat to human health5. Furthermore, demand for dates is normally influenced by a lack of product quality and safety, particularly if the dates appear in exotic black due to external or internal fungus growth.

Chemical synthetic fungicides prepeared from organo-thiocarbamates and dithiocarbamates, such as Ziram®, Thiram®, Ferbam®, Maneb®, and Propineb®, were effective against pre- and post-harvest pathogenic fungi. Over the last decade, methyl bromide has been shown to be effective as an ozone-depleting fumigant in controlling post-harvest pests that attack commodities in storage6. The extensive use of methyl bromide resulting in serious impacts on the environment and human health7.

A lot of concerns about the use of methyl bromide in storage or pre-shipment have been raised worldwide, even in developing countries. Therefore, looking for alternative substances or techniques that may be used as decontaminants to protect commodities after harvest has become imperative8. A failure of the temperature-based technique was documented as an alternative disinfectant in combating pathogenic fungi due to its adverse effects on nutritional value as well as agricultural product quality9. Hence, recently, many non-thermal decontamination techniques such as ultraviolet, ultrasound, and non-thermal plasma have been developed to overcome the side effects of traditional thermal decontamination methods10. Recently, the interest in plasma technology has increased due to its special features such as quick treatment, low cost, high impact on microbial inhibition, no use of toxic gas, no harmful by-products, and safety to humans11.

Non-thermal plasma is considered a modern decontamination technique distinguished by the emission of charged reactive particles of oxygen, nitrogen, ozone, and ultraviolet radiation that exhibit effectiveness in microbial inhibition, preserving food commodities and agricultural products12.

Interestingly, the application of non-thermal plasma in agriculture has been increased in treating seeds, water, soil, and food manufacturing as well13,14. Non-thermal plasma stops fungi from growing by breaking conidia and cell membranes, which causes cytoplasm to leak out of fungal cells15.

Non-thermal plasma has more remarkable power to inhibit gram-negative bacteria than gram-positive bacteria due to the different composition of the cell envelope for them16,17. The break of conidiophores and vesicles, the crevasse of cell walls and cell membranes structures, and the cytoplasm leak occur for fungal cells after non-thermal plasma treatment18. Recently, it has been shown that non-thermal plasma has a new effect on how mycotoxins decompose19.

The physicochemical and organoleptic measures, such as color, pH, acidity, and electrical conductivity, of fruit and vegetable juices treated with non- plasma for microbial decontamination did not change20,21,22,23. Also, the non-thermal plasma treatment had no effect on the dry matter or pH of the fresh tomato juice22.

Surface dielectric barrier discharge (SDBD) has recently received broad interest in many applied sectors, especially in the decontamination of products. SDBD is composed of two metal electrodes separated by a dielectric material24,25. Plasma is generated at the electrode-air interface and usually emerges in the form of arrays of many unique sub-millimeter discharges26,27. For food processing, SDBD can be applied to ambient air so that there is no direct contact between the food and the active plasma area. Therefore, only neutral species participate in the decontamination process, and foods are not affected by UV or charged particles, ensuring optimal processing conditions24,25. The concern about the undesirable effects of the generated free radicals in the air using SDBD28 can be overcome by not contacting the products with the active plasma area. Due to its unique design, low operating cost, not using any toxic gas, and uniform distribution of neutral reactive species over the whole sample, SDBD is considered an economical and environmentally friendly alternative to traditional food processing technologies24,25,29.

Generating an optimum and economic ozone dose is the critical outcome of using SDBD in the food processor29. Artificially inoculated cherry fruits revealed that inhibition of fungal spores by the SDBD prolongs their shelf life. The enhancement of the fight against infections can be attributed to the stimulating defense responses in plant tissues that occur during the pretreatment of fruits or vegetables using SDBD30. The inhibition process using dielectric barrier discharge inhibited the growth of bacteria and mold species encountered in spoiled produce (green beans, grape tomatoes, lettuce, and strawberries), resulting in a more significant than 5 log10 decrease of microbial colonies29.

This work aimed to use the surface dielectric barrier discharges (SDBD) system in palm dates decontamination. Investigate the influence of the non-thermal plasma on the vitality of A. niger spores were isolated fr