Effect of ultraviolet irradiation on postharvest quality and composition of tomatoes: a review

Abstract

Ultraviolet (UV) irradiation has recently emerged as a possible alternative to currently used postharvest phytosanitary treatments. Research has also highlighted other benefits associated with UV irradiation in postharvest technology. This review presents the effects of UV irradiation on postharvest and nutritional quality of tomatoes. The application of UV irradiation on tomatoes is discussed including its effect on biological (respiration rate, ethylene production and microbial growth), physico-chemical (firmness, colour, total soluble solids and titratable acidity) and nutritional (vitamins, carotenoids, phenolic and antioxidants) quality. UV-treated tomatoes have shown resistance to microbial growth and decay. Although UV irradiation reduces the loss of vitamin C during storage, the loss of vitamin E remains a concern. UV treatments lead to higher antioxidant capacity, flavonoids and phenolic content. UV irradiation significantly reduced carotenoids in certain cultivars. Based on the literature reviewed, the success of UV irradiation treatments is cultivar-dependent. While improved retention of phytochemicals has been reported in UV-C treated fruit, increased losses have been reported in certain cultivars. Research efforts on the development of cultivar-specific UV irradiation protocols are warranted. The effect of harvest maturity and seasonal differences in the efficacy of UV treatments is required to be investigated.

Effect of UV-C Hormesis in Regulating Anthracnose Disease and Postharvest Quality of Tomato

“…Gallic acid was the most abundant phenolic compound in tomato fruit, and usually it increases during storage (Mditshwa et al, 2017). In our study, treated fruits of both varieties, have higher total phenolic content compared to non-treated fruits (data not shown).…”

“…It could enhance the phytoalexin production, the induction of phenylalanine amonia lyase (PAL) and the induction of pathogenesis-related (PR) proteins (chitinases and β-1, 3-endoglucanases) (Shama and Alderson, 2005). This supports that UV can be responsible in mediating these gradual biochemical defence responses (Mditshwa et al, 2017) in the peel of UV irradiated fruit.…”

“…Fruit softening could arise from one of the three mechanisms: loss of turgor; degradation of starch; or breakdown of the fruit cell walls due to fungal attack. UV-C reduces cell wall degradation of the pericarp (Mditshwa et al, 2017). Previous research has shown that UV-C significantly inhibits cellulase, polygalacturonase and pectin-methyl-esterase activities, the key cell wall degrading enzymes, resulting in higher firmness retention (Bu et al, 2013).…”

“…The accumulation of reactive oxygen species (ROS), microbial growth, cell wall degrading enzymes and higher respiration rate are the prominent changes leading to a quality loss in tomato fruit. These changes in turn lead to texture loss, weight loss, physiological disorders and decay (Mditshwa et al, 2017;Wills et al, 2007). According to the results, UV-C treatment has shown higher firmness retention compared to the untreated fruits.…”

“…After UV-C treatments, enzymes like phenylalanine ammonia lyase (PAL) can get activated. It acts as a catalyst for the synthesis of phenolic compounds such as phenylpropanoids, coumarins and flavonoids (Mditshwa et al, 2017).…”