Rocket or arugula (Eruca sativa Mill.) is widely appreciated for its numerous beneficial compounds for human health, such as vitamins A and C, folic acid, carotenoids, flavonoids and glucosinolates. Its short shelf life of approximately 8–12 days when stored under proper conditions (0°C and 100% RH) makes it necessary to use a combination of preservation methods (sanitization, temperature, relative humidity, atmospheric composition) to ensure product quality, especially during commercial distribution when the temperature rises and the relative humidity is variable.
Scientists from Chile and Uruguay have evaluated the synergic effect of UV-C irradiation (0.34 to 20.13 kJ/m2), as an alternative sanitizer method, combined with subsequent high O2 atmosphere (>85%) packaging on: the respiration rate, atmospheric composition, microbiological growth and nutritional quality of fresh-cut rocket stored at 5°C for 10 days.
All treatments under increased O2 levels showed a reduction in the respiration rate throughout the cold storage.
UV-C radiation enabled an initial reduction of about 1 and 1.5 log units on mesophilic and psychrotrophic counts, respectively. However, this treatment was not effective for mold control. In addition, a noticeable increase occurred in the total antioxidant capacity and polyphenol content without affecting the visual appearance of the leaves.
Scientists concluded that high UV-C doses of 15.14 and 20.13 kJ/m2 combined with a high O2 atmosphere present a viable alternative for the quality maintenance of fresh-cut rocket leaves. These UV-C doses enabled the initial reduction of the populations of psychrotrophic, mesophilic and Enterobacteriaceae microbes.
However, the high microbial load recorded in the raw material highlights the importance of an integrated management from the culturing step to ensure low microorganism levels at the beginning of the minimal process. This enables UV-C to be a successful disinfection method that is complementary to others and to be a way to increase antioxidant compound levels in vegetal tissues, which constitutes an advantage over other methods. In addition, these doses did not affect the appearance and color parameters of the products.
Finally, UV-C radiation can be applied by a cheap and simple chamber with a relative low maintenance cost being a feasible alternative to small industry.
Study was first published online last June 25th 2015 at:
http://onlinelibrary.wiley.com/doi/10.1111/jfs.12202/abstract
Source: Ana Cecilia Silveira, Andrea Baeza, Victor Hugo Escalona, ‘Effect of ultraviolet-c radiation combined with unconventional atmosphere packaging on the quality of fresh-cut arugula (Eruca sativa Mill.)’, 2015, Journal of Food Safety, doi: 10.1111/jfs.12202
Contacts:
Victor Hugo Escalona
Centro de Estudio Postcosecha, Departamento de Produccion Agrıcola, Facultad de Ciencias Agronomicas, Universidad de Chile,
Santa Rosa11315, La Pintana,
PO Box 1004, Santiago, Chile
Ph.: +56 2 29785841/23
Email: vescalona@uchile.cl