Effect of Ozone Exposure on Phytopathogenic Microorganisms on Stored Apples

Abstract

The aim of our study was to clarify the effect of ozone exposure on several phytopathogenic fungi on stored apple fruits under different storage conditions. The study was conducted at Bistrita, Romania, in the storehouse of an experimental apple orchard in 2002 and 2003. Two widely grown apple cultivars (‘Jonathan’ and ‘Golden Delicious’) were used. General microbial examination of the fruits was made during storage in order to identify the most important storage pathogens. Efficacy of six ozone treatments was evaluted on fruit decay caused by phytopathogenic fungi. Monthly observations (January, February, March and April) were made of the degree of decay and three measurements were assessed (disease frequency, disease intensity and degree of attack). Our results showed that the most important phytopathogenic fungi during storage was blue mold, caused by species of Penicillium. Disease frequency of apple fruits was very high on cv. ‘Jonathan’, much higher than on cv. ‘Golden delicious’. Ozone treatments (25 ppm ozone for 0.5 and 1.5 hours in November) caused significantly lower disease incidence on stored apple than all other ozone treatments. For longer storage, it seems that additional ozone treatments in February increased treatment efficacy. Cv. ‘Golden delicious’ seemed to be more resistant to storage diseases than cv. ‘Jonathan’ both on the untreated and treated fruits. The effect of the ozone treatments was also the most effective when 25 ppm ozone was applied for 0.5 and 1.5 hours in November.

The use of ozone to extend the shelf‐life and maintain quality of fresh produce

“…Ozone exposure decreased the disease incidence (% of fruit that show any degree of spoilage due to fungal infection) in apples treated with ozone at 25 ppm for 30–90 min, in grapes exposed to gaseous ozone at 200 ppm for 15 min or at 2500 ppm for 2 h, 5000 ppm for 1 h and 10 000 for 30 min . Similarly, decay of grapes was significantly reduced in produce continuously exposed to ozone at 100 ppb for up to 60 days, at 300 ppb over 7 weeks and in grapes continuously or intermittently (12 h per day) exposed to ozone at 2 ppm for 72 days, in tangerine exposed to gaseous ozone at 200 ppm for 4–6 h, in strawberries exposed to gaseous ozone at 1.5 ppm for 3 days, but not when the dose of ozone at 0.35 ppm for 3 days was too low to prevent decay of strawberries or in blueberries exposed to gaseous ozone at 450 ppb for 2 days .…”

Effectiveness of Ozone on Postharvest Conservation of Pear (Pyrus communis L.)

“…The high reactivity, penetrability and spontaneous decomposition to a nontoxic product (O 2 ) make ozone an alternative that enables food safety from a microbiological point of view, mainly because ozone has been classified as a GRAS (Generally Recognized as Safe) material in the United States and approved by the FDA (Food and Drug Administration) for direct contact with foods. Usually, low ozone concentrations and short contact times are needed to inactivate bacteria, fungi, yeasts, parasites and viruses, but the susceptibility of microorganisms to ozone varies, among other factors, with the physiological state of the culture, pH, temperature, humidity and the presence of additives [9][10][11][12][13][14][15][16][17].…”

Effects of Ozone Treatment on Botrytis cinerea and Sclerotinia sclerotiorum in Relation to Horticultural Product Quality

“…An experiment conducted by Puia and Oroian (2004) found that “Golden Delicious” apples were more resistant to storage diseases after ozone treatment. Ozone treatment was most effective when 25000 ppb ozone was applied for 0.5 or 1.5 h immediately after harvest and before storage.…”

“…Blueberries appear to be highly susceptible to fungal infection and after inoculation with B. cinerea spores, fruit rapidly developed decay at 20 • C. Another reason for the lack of ozone effect could be due to latent infection that occurred early in the growing season, and gaseous ozone is unable to penetrate the fruit tissue to kill the fungi. An experiment conducted by Puia and Oroian (2004) found that "Golden Delicious" apples were more resistant to storage diseases after ozone treatment. Ozone treatment was most effective when 25000 ppb ozone was applied for 0.5 or 1.5 h immediately after harvest and before storage.…”

“…In 2001, the Food and Drug Administration approved ozone for use on food (Federal Register 2001). In recent years, many findings have reported the effectiveness of ozone to reduce various species of bacteria and fungi in foods (Kim and others 1999, 2003; Perez and others 1999; Hildebrand and others 2001; Forney 2003; Puia and Oroian 2004). The different effectiveness among ozone treatments could result from different microbial species (Fan and others 2002, 2007), the method of ozone generation or different environmental factors (Kim and others 1999).…”