Postharvest Ultraviolet Radiation in Fruit and Vegetables: Applications and Factors Modulating Its Efficacy on Bioactive Compounds and Microbial Growth

Abstract

Ultraviolet (UV) radiation has been considered a deleterious agent that living organisms must avoid. However, many of the acclimation changes elicited by UV induce a wide range of positive effects in plant physiology through the elicitation of secondary antioxidant metabolites and natural defenses. Therefore, this fact has changed the original UV conception as a germicide and potentially damaging agent, leading to the concept that it is worthy of application in harvested commodities to take advantage of its beneficial responses. Four decades have already passed since postharvest UV radiation applications began to be studied. During this time, UV treatments have been successfully evaluated for different purposes, including the selection of raw materials, the control of postharvest diseases and human pathogens, the elicitation of nutraceutical compounds, the modulation of ripening and senescence, and the induction of cross-stress tolerance. Besides the microbicide use of UV radiation, the effect that has received most attention is the elicitation of bioactive compounds as a defense mechanism. UV treatments have been shown to induce the accumulation of phytochemicals, including ascorbic acid, carotenoids, glucosinolates, and, more frequently, phenolic compounds. The nature and extent of this elicitation have been reported to depend on several factors, including the product type, maturity, cultivar, UV spectral region, dose, intensity, and radiation exposure pattern. Even though in recent years we have greatly increased our understanding of UV technology, some major issues still need to be addressed. These include defining the operational conditions to maximize UV radiation efficacy, reducing treatment times, and ensuring even radiation exposure, especially under realistic processing conditions. This will make UV treatments move beyond their status as an emerging technology and boost their adoption by industry.

Conventional and non-conventional disinfection methods to prevent microbial contamination in minimally processed fruits and vegetables

“…Ultraviolet light (UV) provides a high intensity of light. It has been used in the food industry for several purposes like surface sterilization, fluid disinfestation, air treatment, waste treatment, and insect trapping ( Darré et al, 2022 ). This technology works with a wavelength range of 190–280 nm and results in germicidal and antimicrobial activities used to decontaminate water, fruits, and root vegetables ( Cutler & Zimmerman, 2011 ).…”

“…Several research reports suggest that UV light may stimulate the production of phenolic compounds such as ascorbic acid, glucosinolates, or carotenoids in fresh food. These effects keep the attention of researchers ( Darré et al, 2022 ). In this sense, the wavelength approved by the FDA is 254 nm to use in food products and juices (J.A.…”

Untitled

“…It also has use in air disinfection and has been reported to be able to inactivate the human SARS coronavirus. It can also trap insects and facilitate the degradation of unwanted molecules (Darré et al, 2022). Limited reviews on the effects of ultraviolet radiation on microbes exist.…”

Thermal and Non-Thermal Treatments to Preserve and Encourage Bioactive Compounds in Fruit- and Vegetable-Based Products

“…There are four papers within the first topic, dealing with the effect of thermal and non-thermal treatments on whole fruits [ 1 , 2 , 3 , 4 ]. The first study, by Bedrníček et al [ 1 ], investigated the influence of several thermally treated fresh garlic varieties (treated during ageing process—15 days with a temperature gradient ranging from 30 to 82 °C) on the physicochemical parameters of black garlic.…”

“…It was highlighted that the fresh garlic parameters did not correlate well with the properties of black garlic; therefore, they cannot be used for its quality prediction. The second study, a review by Darré et al [ 2 ], showed that ultraviolet radiation has been found to be a germicide and a potentially damaging agent; however, beneficial properties have also been reported in harvested commodities. UV treatments on whole fruit were shown to induce phytochemicals accumulation, including ascorbic acid, carotenoids, glucosinolates, and, more frequently, phenolic compounds.…”