From the field to the table: ionizing radiation as a feasible postharvest treatment for fresh and dried plant foods
Conference Paper
Overview
Overview
abstract
Food irradiation is a treatment that involves subjecting in-bulk or packaged food to a controlled
dose of ionizing radiation, with a clearly defined goal. It has been used for disinfestation and
sanitization of food commodities and to retard postharvest ripening and senescence processes, being a
sustainable alternative to chemical agents 1 . Doses up to 10 kGy are approved by several international
authorities for not offering negative effects to food from a nutrition and toxicology point of view 2 .
However, the adoption of this technology for food applications has been a slow process due to some
misunderstandings by the consumer who often chooses non-irradiated foods. In this study, the effects
of the ionizing radiation treatment on physical, chemical and bioactive properties of dried herbs and its
suitability for preserving quality attributes of fresh vegetables during cold storage were evaluated.
The studied herbs, perennial spotted rockrose (Tuberaria lignosa (Sweet) Samp.) and common
mallow (Malva neglecta Wallr.) were freeze-dried and then irradiated up to 10 kGy in a Cobalt-60
chamber. The selected vegetables, watercress (Nasturtium officinale R. Br.) and buckler sorrel (Rumex
induratus Boiss. Reut.) were rinsed in tap water, packaged in polyethylene bags, submitted to
irradiation doses up to 6 kGy and then were stored at 4 C for a period of up to 12 days. Physical,
chemical and bioactive parameters of irradiated and non-irradiated samples were evaluated using
different methodologies the colour was measured with a colorimeter, individual chemical compounds
were analyzed by chromatographic techniques, antioxidant properties were evaluated using in vitro
assays based on different reaction mechanisms, and other quality analyses were performed following
official methods of analysis.
The irradiation treatment did not significantly affect the colour of the perennial spotted rockrose
samples, or its phenolic composition and antioxidant activity 3 . Medium doses preserved the colour
of common mallow and a low dose did not induce any adverse effect in the organic acids profile. The
green colour of the irradiated vegetables was maintained during cold storage but the treatment had
pros and cons in other quality attributes. The 2 kGy dose preserved free sugars and favoured
polyunsaturated fatty acids (PUFA) while the 5 kGy dose favoured tocopherols and preserved the
antioxidant properties in watercress samples. The 6 kGy dose was a suitable option for preserving
PUFA and the ω-6 ω-3 fatty acids ratio in buckler sorrel samples. This comprehensive experimental
work allowed selecting appropriate processing doses for the studied plant foods in order to preserve its
quality attributes and edibility.
