Effect of cold plasma on the physical quality and microbial growth of date fruit during cold storage

The aim of this study was to investigate the effects of atmospheric cold plasma at 40 kV output discharge voltage for 1, 3, and 5 minutes on date fruit kept at 4°C for 5 weeks. Weight, shrinkage, color (lightness (L*), redness-greenness (a*), yellowness and blueness (b*), hue°, chroma, total color difference (TCD), and yellow value (YV)), and water activity are among the quality attributes that are measured. For the indication of microbial availability, the total bacterial count (TBC) and the yeast and mould count (YMC) were also performed. The cold plasma exposure lasting one minute produced the least amount of weight (6.58%). The findings also demonstrated that, over the entire experiment, the dates shrank the least after a 5-minute cold plasma treatment. The length of cold plasma exposure had a significant impact on most color parameters (p<0.05). The TCD values of date fruit were delayed when the duration of cold plasma exposure was increased from one to five minutes. Compared to date fruit that was not treated, fruits treated with cold plasma showed noticeably less color change over the period of storage. The dates' water activity decreased during the second week of storage due to the extended exposure period. A longer plasma exposure period reduced the bacterial load and prevented the growth of mould and yeast, especially during the second, third, and fourth weeks of storage. The correlation analysis showed that the shrinkage of dates resulting from all treatments was strongly correlated with TCD (r=0.793) on treated and non-treated dates during storage. The regression model explains about 77.76%, 84.9%, and 68.9% of the variance in the shrinkage, Hue°, and TCD of dates. Generally, the utilization of cold plasma treatment is promising in storing fruits like dates improving their quality and safety, which provides fresh fruits.