Effect of Ozone Application on Postharvest Quality and Microbiological State of “Zaghloul” Date Palm Fruits

Abstract

The postharvest quality of 'Zaghloul' date palm cultivar was investigated to study the effects of ozone on weight loss rate, electrolyte leakage (EL), total soluble solids (TSS), titratable acidity (TA), ascorbic acid, total phenol content and antioxidant activity at harvest and during cold storage at 0 ± 1°C for up to 30 days. Moreover, the study aimed to elucidate the efficiency of ozone application on controlling microbial growth. The fruits were exposed to 150 ppb ozone (O 3) by using ozone generator (biofresh OZ80, UK).The results indicated that ozone application reduced the yeasts and molds and mesophilic aerobic bacteria compared to control. Ozone treated fruits had higher weight loss than control but the differences were not significant. However, Ozone treated fruit showed lower total soluble solid, electrolyte leakage, and rutab% compared to non-ozone treated ones. Ozone treated fruits had higher ascorbic acid and total phenol contents as well as antioxidant activity, while did not significantly affect fruit titratable acidity. Thus, ozone application could be an effective strategy for maintaining post-harvest quality of dates and provide a longer storage life.

Effects of Postharvest Gaseous Ozone Treatment on Quality Attributes and Extending Storage Life of Fresh Cut ‘Hass' Avocado Fruits

“…Ozone treatments were more effective in keeping the ascorbic acid level of avocado slices stable throughout storage. These results are similar to those achieved by Pérez et al [30] on strawberries; Ladaniya [31] on lime; Barboni et al [32] on kiwifruit and Khalil [33] on Zaghloul date palm; EL-Hadidy [25] on Washington Navel orange since ozone gas treatments delayed the degradation of ascorbic acid content and increased its concentration in the fruit at cold storage conditions. Klopotek et al [34]; Allende et al [35]; Alwi and Ali [36] explained the increase in ascorbic acid content of fruits exposed to O3 to the high oxidative capacity of ozone generate toxic molecular species, that acting as a potent phytotoxic agent, causing activation of the fruit defense system (anti-oxidative system) that promotes the biosynthesis of ascorbic acid from the carbohydrate pool [30,37] to avoid the oxidative activity caused by ozone.…”

“…These results are in agreement with the previous reports by Kumar et al [45]; Ayón-Reyna et al [29] about pineapple, who found that phenolic compounds uses as substrates by the PPO, produced compounds that provoke the browning in the pineapple slices surface. These findings are in line with Cayuela et al [28] on grapes; Alothman et al [46] on banana and pineapple fresh cut; Minas et al [47] on kiwi and Khalil [33] on 'Zaghloul' date palm, since all of them concluded that ozone treatment induced higher total phenolic contents. Besides, Ali et al [48] reported that a higher increase in content of total phenolic was detected in response to ozone at 1.5-5 ppm for 96 h in papaya when compared with the control fruits in nonozonized environment.…”

Phytosanitary ozone treatment for guava infested with Bactrocera zonata and mandarin infested with Ceratitis capitata (Diptera: Tephritidae)

“…The ascorbic acid content of avocado slices was better stabilized during storage with ozone treatments. These outcomes are comparable to those attained by Pérez et al (1999) on strawberries, Ladaniya (2004) on lime, Barboni et al, (2010) on kiwi fruit, and Khalil (2016) on Zaghloul date palm, as well as EL-Hadidy (2017) on Washington Navel orange. This is because ozone gas treatments delayed ascorbic acid content degradation and increased its concentration in the fruit under cold storage conditions.…”

The Influence of Ozonation Carried Out during Vegetation on the Content of Selected Bioactive Phytochemicals and the Microbiological Load of Tubers of Raphanus sativus var. sativus

“…Moreover, ozone fumigation reduces the number of Gram-positive and -negative bacteria, as well as their spores [62,63]. There are a number of scientific reports in the literature that ozone reduces the number of mesophilic aerobic bacteria during storage of asparagus [43], rhubarb [22], marjoram [39], groats corn [64], or date palm fruit [65]. Moreover, ozone gas reduces the number of yeasts and molds on strawberry fruit [66,67], citrus fruits [68], dried figs [69], and berries [70].…”