Effects of ozone treatment on SOD activity and genes in postharvest cantaloupe

Effect of tropospheric ozone and its protectants on gas exchange parameters, antioxidant enzymes and quality of Garlic (Allium sativum. L)

An experimental study was conducted to assess the detrimental effect of ground-level ozone (O3) on garlic physiology and to find out appropriate control measures against ground-level O3, at TNAU-Horticultural Research farm, Udhagamandalam. Elevated ground ozone levels significantly decreased garlic leaf chlorophyll, photosynthetic rate, stomatal conductance, total soluble solids and pungency. The garlic chlorophyll content was highest in ambient ozone level and lowest in elevated ozone@200 ppb, highest stomatal conductance was recorded in ambient ozone with foliar spray of 3%Panchagavya, and the lowest was observed in elevated ozone@200 ppb. Since the elevated O3 had reduced in garlic photosynthetic rate significantly the lowest was observed in elevated O3@200 ppb and the highest photosynthetic rate was observed in ambient Ozone with foliar spray 3% of panchagavya after a week. The antioxidant enzymes of garlic were increased with increased concentration of tropospheric ozone. The highest catalase (60.97 µg of H2O2/g of leaf) and peroxidase (9.13 ΔA/min/g of leaf) concentration was observed at 200 ppb elevated ozone level. Garlic pungency content was highest in ambient ozone with foliar spray of 0.1% ascorbic acid and the lowest was observed under elevated O3@200 ppb. Highest total soluble solids were observed in ambient ozone with foliar spray of 3%Panchagavya and the lowest observed in elevated ozone@200 ppb. Thus, tropospheric ozone has a detrimental impact on the physiology of crops, which reduced crop growth and yield. Under elevated O3 levels, ascorbic acid performed well followed by panchagavya and neem oil. The antioxidant such as catalase and peroxidase had positive correlation among themselves and had negative correlation with chlorophyll content, stomatal conductance, photosynthetic rate, pungency and TSS. The photosynthetic rate has high positive correlation with chlorophyll content, pungency and TSS. Correlation analysis confirmed the negative effects of tropospheric ozone and garlic gas exchange parameters and clove quality. The ozone protectants will reduce stomatal opening by which the entry of O3 in to the cell will be restricted and other hand they also will alleviate ROS and allied stresses.

Single and combined toxicity of polystyrene nanoplastics and arsenic on submerged plant Myriophyllum verticillatum L

The contamination of nanoplastics (NPs) and heavy metals (HM) in water bodies has caused widespread concern, while their effects on submerged plants are poorly reported. Polystyrene nanoplastics (PSNPs) and arsenic (As) were used to assess their toxicity on Myriophyllum verticillatum L. via the orthogonal experiments. PSNPs significantly reduced the accumulation of As (17.24%-66.67%) in plant. Single As and high As-PSNPs treatments significantly inhibited plant growth, with a maximum reduction of 70.09% in the growth rate. The mineral nutrient content was significantly affected by PSNPs and As treatments. The antioxidant system was significantly inhibited, which was more pronounced in the roots. Similar findings were observed for soluble protein and soluble sugar. Some organic acids and amino acids showed down-regulation at high concentrations of As, leading to a decrease in the content of the mineral element and down-regulation of antioxidant enzyme synthesis. Furthermore, PSNPs could alleviate As toxicity under 0.1 mg/L As treatment but exacerbate As toxicity at 1 mg/L As dose. This study has important implications for the study of submerged plants exposed to co-contamination of microplastics and heavy metals, as well as the possible ecological risk assessment in freshwater.

Effect of Ozonation on the Mechanical, Chemical, and Microbiological Properties of Organically Grown Red Currant (Ribes rubrum L.) Fruit

Red currant fruits are a valuable source of micro- and macronutrients, vitamins, and chemical compounds with health-promoting properties, the properties of which change depending on the harvest date and the time and method of storage. This study analysed the effect of applying 10 ppm ozone gas for 15 and 30 min on the mechanical properties, chemical properties and microbiological stability of three organic-grown red currant fruit cultivars. Fruits harvested at the time of harvest maturity had significantly larger diameters and weights and lower water contents compared with fruits harvested seven days earlier, and the ozonation process, regardless of its harvesting date, reduced the physical parameters in question (diameter, weight, and water content). The ascorbic acid content of the ozonated fruit varied, with the highest decreases observed for fruit harvested 7 days before the optimal harvest date and stored for 15 days under refrigeration (an average decrease of 13.31% compared with the control fruit without ozonation). In general, the ozonation process had a positive effect on the variation of fruit antioxidant activity, with the highest average values obtained for fruit harvested 7 days before the optimum harvest date and stored for 15 days under refrigeration conditions; in addition, it also had an effect on reducing the development of microorganisms, including mesophilic aerobic bacteria, yeasts, and moulds, mainly for the cultivar 'Losan'.

Influence of ozone treatment on functional and rheological characteristics of food products: an updated review

In this milieu, ozone technology has emerged as an avant-garde non-thermal mode of disinfection with potential applications in the food industry. This eco-friendly technology has a comprehendible adeptness in replacing alternative chemical sanitizers and is recognized as a generally safe disinfectant for fruits and vegetables. Several researchers have been focusing on the biochemical impacts of ozone on different quantitative and qualitative aspects of fruits and vegetables. A collection of those works is presented in this review highlighting the effect of ozone on the functional, antioxidant, and rheological properties of food. This can be a benevolent tool for discovering the processing states of ozone applications and ensuing influence on safety and quality attributes of previously studied foods and opening further research areas. It extends shelf life and never leaves any harmful residues on the product since it decomposes to form oxygen. It was seen that the impact on a specific property of food was dependent on the ozone concentration and treatment time, and the adverse effects of ozone exposure can be alleviated once the processing conditions are optimized. The present review can be used as a baseline for designing different food processing operations involving ozone.

Ozone treatment promotes physicochemical properties and antioxidant capacity of fresh-cut red pitaya based on phenolic metabolism

Pitaya is an important fresh-cut product in the global fruit market. The health benefits of fresh-cut red pitaya fruit are attributed to its unique phenolic content and other antioxidants, but the fruit is highly susceptible to spoilage which causes a decline in nutritional quality. In this study, we monitored changes in quality and phenolic compounds of pitaya fruit treated with gaseous ozone during storage at 8 ± 2^°C for 4 days. Compared with the control group, ozone treatment was an effective strategy for preserving quality by controlling the growth of microorganisms, preventing weight loss and softening, and improving the content of soluble solids and titratable acids. The results showed that ozone induced the accumulation of phenolic compounds while maintaining the quality. The content of phenolic compounds in fresh-cut pitaya was positively correlated with antioxidant activity. Ultra-performance liquid chromatography-electrospray tandem mass spectrometry was used to fingerprint the phenolic metabolites and metabolomic analysis identified 26 phenolic compounds. The majority of these were phenylpropanoids, and the key metabolic pathways were phenylpropane metabolism and flavonoid synthesis. This study illustrated the mechanism by which of ozone prolongs the shelf life of fresh-cut pitaya fruit and validated ozone as a valuable phenolic inducer and regulator of antioxidant activity, positively influencing the potential health benefits of fresh-cut products.

Differential Responses of Antioxidative System during the Interaction of Soursop Fruits (Annona muricata L.) and Nectria haematococca at Postharvest Storage

Soursop fruit (Annona muricata L.) production is diminished by the attack of pathogens such as Nectria haematococca. However, the fruit-pathogen interaction at the biochemical and molecular levels is still unknown. The objective of this study was to analyze the response of the soursop fruit to the presence of N. haematococca during postharvest storage. Soursop fruits were inoculated with the pathogen and total phenolic compounds, antioxidant capacity by Ferric reducing/antioxidant power (FRAP), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS•+), and 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH•), as well as enzymatic activity and transcript levels of polyphenol oxidase (PPO) and superoxide dismutase (SOD), were evaluated at 1, 3, and 5 days of storage. The noninoculated fruits were the controls of the experiment. The highest total phenol content was recorded on day one in the inoculated fruits. FRAP, ABTS, and DPPH activity presented the highest values on day three in the control fruits. Inoculated fruits recorded the highest PPO activity on day five and a five-fold induction in the PPO transcript on day three. SOD activity showed a decrease during the days of storage and 10-fold induction of SOD transcript on day three in the inoculated fruits. Principal component analysis showed that total phenols were the variable that contributed the most to the observed variations. Furthermore, a positive correlation between total phenols and SOD activity, PPO expression, and SOD expression, as well as between DPPH and FRAP, was recorded. The results showed a differential response in antioxidant capacity, enzymatic activity, and gene expression during the interaction of soursop fruits-N. haematococca at postharvest storage.