The simultaneous influence of ultraviolet rays and cold plasma on the physicochemical attributes and shelf life of dried pistachios during the storage period

Abstract

This investigation aimed to assess the simultaneous impact of ultraviolet (UV) and cold plasma (CP) on the quality and microbial attributes of dried pistachios during the storage period. Currently, novel nonthermal technologies exhibit high potential as a low‐cost, efficient, additive‐free, and nonpolluting strategies for fungi deactivation and mycotoxins degradation in foods. Over recent years, the combination of CP with other procedures, such as ultraviolet (UV) irradiation, ultrasound, ozone, and so forth, has been proposed and attracted lots of attention. For this purpose, in this study, the simultaneous effects of ultraviolet rays and cold plasma on dried pistachios artificially contaminated with aflatoxigenic fungi were assessed. The physicochemical attributes and surface morphology of pistachios were evaluated as well. The concentration of aflatoxin produced was investigated via high‐performance liquid chromatography. Artificially contaminated pistachios were treated with cold plasma at 80 W constant power level at both 10 and 15 min. Following the plasma treatment, pistachio samples were treated by ultraviolet rays at 354 nm wavelength and current intensity in 0.25 A at the same time. The results of this study revealed the fungal deactivation rate achieved by UV‐CP treatment was greater than the sum of the deactivation rates of distinct UV and CP treatments, as maximum reduction of Aspergillus oryzae count (3.7 CFU/g) observed after simultaneous UV‐CP treatment for 15 min (p < 0.05). Moreover, no substantial modifications were detected in the investigation of pH and DPPH radical scavenging activity of samples treated with UV‐CP (p > 0.05). The results of this study confirm the effectiveness of the simultaneous application of UV rays and CP in nuts to maintain quality and increase useful life, along with an alternative method for thermal treatments.Practical applicationsUsually, nonthermal procedures lead to their destruction by changing the chemical structure of mycotoxins. Ultraviolet (UV) radiation being a nonthermal technology, the benefits of its usage are various: the least loss of nutrients and sensorial quality of foods, no toxic residues, and low energy consumption compared with other thermal treatments normally applied for food decontamination. The latter is the main purpose of this technique due to its effectiveness in the inactivation of pathogenic microorganisms and spoilage. Besides this, Cold plasma (CP) technology has been displayed to overcome many of the insufficiency of regular decontamination strategies in the food industry, with slight damage to the quality of products and high efficiency. Although several physical procedures have shown acceptable results in the decontamination of fungi and degradation of mycotoxins in many foods, to date there are few published works on the effects of simultaneous application of UV radiation and CP on foods, particularly pistachios in is available. Hence, the intention of this investigation was to assess the effect of combination of UV radiation and CP on the physicochemical attributes and shelf life of dried pistachios during the storage period.