Use of UV-C and Gaseous Ozone as Sanitizing Agents for Keeping the Quality of Fresh-Cut Rocket (Eruca sativa mill)

Abstract

The effects of UV-C radiation doses (5, 10 and 20 kJ/m 2 ) and gaseous ozone doses (1, 2 and 5 ppm) on microbial growth and quality parameters of fresh-cut rocket (Eruca vesicaria subsp. Sativa) leaves throughout 12 days at 5C were investigated. As control, washing with water was used. Sensory attributes (general appearance, decay, color and odor), headspace gas composition, some chemical characteristics (chlorophyll a and b, total chlorophyll and total carotenoids) and microbial counts throughout shelf-life were studied. Fresh-cut rocket was not adversely affected by the UV-C and ozone treatment, maintaining the sensory quality during cold storage. The 20 kJ UV-C/m 2 treatment was found to be better than the chlorine and gaseous ozone treatments, in terms of reducing the microbial load in fresh-cut rocket during 8 days of storage at 5C. PRACTICAL APPLICATIONSThe information provided in this study shows that the treatment with UV-C radiation and gaseous ozone treatment represent a novel technology that could be useful to the industry, allowing surface decontamination of fresh-cut rocket to be achieved while maintaining their overall quality. Its applications can easily be applied in industry.

Combined Effect of UV-C and Ozone on Bioactive Compounds and Microbiological Quality of Fresh-Cut Rocket Leaves

“…The changes that were registered of the partial pressures of the O 2 and CO 2 gases during storage inside the MAP packages are showed in Figure 2. Due to the respiratory activity of the vegetable, O 2 levels decreased while those of CO 2 increased both in the control and in the treatments [26,27]. From day-1 to day-12 storage, the partial pressures of the gases at equilibrium for all samples were 7-8 kPa O 2 and 3-4 kPa CO 2 at 5°C.…”

“…The following treatments were applied: T 1 (control): 0; T 2 (O 3 ): 2.5 mg/L for 10 min O 3 ; T 3 (UV-C): 25 kJ/m 2 UV-C (380 s) of UV-C dose (the exposure time was calculated according to the radiation intensity); T 4 (UV-C + O 3 ): combination of T 2 + T 3 . Both the UV-C doses and O 3 gaseous concentrations were selected in accordance with the results of preliminary experiments carried out by the authors with minimally processed rocket leaves [26,28]. UV-C treatment was applied in a reflective stainless-steel chamber equipped with 6 unfiltered germicidal lamps (254.7 nm, TUV 36W/G36, Philips, Amsterdam, The Netherlands), on its topside and 6 at its bottom.…”

“…The ozone concentration within the chamber was recorded via an ozone analyzer (Gas Alert Extreme O 3 -BW Technology, Honeywell, Canada). These UV-C and O 3 equipment's used in this work is fully described in Gutiérrez et al [26].…”

“…An eight-membered trained panel (aged between 24-64) performed the sensory evaluation of the samples on days 1, 4, 8 and 12 of storage using a 9-point scale for overall visual quality and decay as follows: 9 = excellent, 7 = good, 5 = acceptable (limit of acceptability), 3 = poor and 1 = extremely poor. Color and odor were evaluated using a 5-point scale, that is, 5 = full characteristic of the product, 3 = acceptable (limit of acceptability) and 1 = no characteristic, as indicated by Gutiérrez et al [26].…”

“…So, postharvest treatments with UV-C and O 3 could be a technological alternative for the decontamination of the surface of fresh-cut rocket leaves, maintaining their general quality [26]. On the other hand, Martínez-Hernández et al [27] reported that the combined application of sanitizing treatments could have a synergistic effect that allows a greater microbial reduction in the products.…”