The practicality of using ozone with fruit and vegetables

Effect of plasma activated water on Escherichia coli disinfection and quality of kale and spinach

Plasma activated water (PAW) is one of the promising technologies for fresh food disinfection. In this study, PAW was generated by activating water under nonthermal plasma for 10, 20, 30, 45 and 60 min. The effectiveness of Escherichia coli inactivation by PAW treatment on kale and spinach samples was assessed. The differences between kale and spinach samples in terms of the product quality and nutritional characteristics upon PAW treatment was also investigated. Further, changes in leaf structure and surface morphology upon PAW treatment was also evaluated through FTIR cuticle analysis and SEM imaging of leaf surfaces. Results showed that, around 6 log CFU/g reduction in E. coli population was observed in PAW-45 min treatment. However, PAW treatment significantly reduced the total chlorophyll content in both kale and spinach. The total phenolic content, flavonoid content and ascorbic content were altered according to the PAW activation time. Further, kale and spinach behaved differently in terms of antioxidant activity and membrane electrolytic leakage values upon PAW treatment. Clear changes in the cuticular layer and the surface morphological characteristics of the leaf samples were observed after PAW which could be the reason for the significant differences between kale and spinach characteristics in response to PAW treatments.

Effects of Gaseous Ozone on Microbiological Quality of Andean Blackberries (Rubus glaucus Benth)

Andean blackberries are highly perishable due to their susceptibility to water loss, softening, mechanical injuries, and postharvest diseases. In this study, the antimicrobial efficacy of gaseous ozone against spoilage (mesophiles, psychrotrophs, and yeasts and molds) and pathogenic (E. coli, S. enterica, and B. cinerea) microorganisms was evaluated during 10 days of storage at 6 ± 1 °C. Respiration rate and mass loss were also determined. Ozone was applied prior to storage at 0.4, 0.5, 0.6, and 0.7 ppm, for 3 min. The best results were observed with the higher ozone dose, with initial maximum reductions of ~0.5, 1.09, and 0.46 log units for E. coli, S. enterica, and B. cinerea, respectively. For the native microflora, maximum reductions of 1.85, 1.89, and 2.24 log units were achieved on day 1 for the mesophiles, psychrotrophs, and yeasts and molds, respectively, and this effect was maintained throughout storage. In addition, the lower respiration rate and mass loss of the blackberries ozonated at 0.7 ppm indicate that this treatment did not induce physiological damage to the fruit. Gaseous O₃ could be effective in maintaining the postharvest quality of blackberries throughout refrigerated storage but higher doses could be advisable to enhance its antimicrobial activity.

Combination of ozone and ultrasonic-assisted aerosolization sanitizer as a sanitizing process to disinfect fresh-cut lettuce

Reduction of sanitizer dosage and development of non-immersion disinfection methods have become major focuses of research. Here, we examined the disinfection efficacy of combining gaseous ozone (4 and 8 ppm) with aerosolized oxidizing sanitizer [sodium hypochlorite (SH, 100 and 200 ppm)] and aerosolized organic acid [acetic acid (AA, 1% and 2%) and lactic acid (LA, 1% and 2%)]. Notably, 1% AA and 4 ppm gaseous ozone were ineffective for disinfecting Salmonella Typhimurium, and treatment with 1% AA + 8 ppm ozone caused browning of lettuce leaves and stimulated increases in aerobic mesophilic count (AMC), aerobic psychrotrophic count (APC), S. Typhimurium, and Escherichia coli O157:H7. Treatment with 2% LA + 8 ppm ozone resulted in the lowest S. Typhimurium, E. coli O157:H7, Listeria monocytogenes, AMC, APC, and molds and yeasts during storage (0-7 days at 4 °C). Quality analysis indicates that LA + 8 ppm ozone and SH + 8 ppm ozone did not negatively affect L*, a*, b*, polyphenolic content, weight loss, and sensory properties; however, the levels of two individual phenolic compounds (3,4-dihydroxybenzoic acid and vanillin), responsible for phenylpropanoid synthesis, were significantly increased after treatment with 2% LA + 8 ppm ozone. These findings provided insights into the use of LA combined with gaseous ozone for application in disinfecting fresh produce.

Gaseous ozone to preserve quality and enhance microbial safety of fresh produce: Recent developments and research needs

Fresh fruits and vegetables are highly perishable and are subject to large postharvest losses due to physiological (senescence), pathologic (decay), and physical (mechanical damage) factors. In addition, contamination of fresh produce with foodborne human pathogens has become a concern. Gaseous ozone has multiple benefits including destruction of ethylene, inactivation of foodborne and spoilage microorganisms, and degradation of chemical residues. This article reviews the beneficial effects of gaseous ozone, its influence on quality and biochemical changes, foodborne human pathogens, and spoilage microorganisms, and discusses research needs with an emphasis on fruits. Ozone may induce synthesis of a number of antioxidants and bioactive compounds by activating secondary metabolisms involving a wide range of enzymes. Disparities exist in the literature regarding the impact of gaseous ozone on quality and physiological processes of fresh produce, such as weight loss, ascorbic acid, and fruit ripening. The disparities are complicated by incomplete reporting of the necessary information, such as relative humidity and temperatures at which ozone measurement and treatment were performed, which is needed for accurate comparison of results among studies. In order to fully realize the benefits of gaseous ozone, research is needed to evaluate the molecular mechanisms of gaseous ozone in inhibiting ripening, influence of relative humidity on the antimicrobial efficacy, interaction between ozone and the cuticle of fresh produce, ozone signaling pathways in the cells and tissues, and so forth. Possible adverse effects of gaseous ozone on quality of fresh produce also need to be carefully evaluated for the purpose of enhancing microbial and chemical safety of fresh produce.

Effect of Red Cabbage Sprouts Treating with Organic Acids on the Content of Polyphenols, Antioxidant Properties and Colour Parameters

In recent years, there has been a great deal of consumer interest in consuming vegetables in the form of sprouts, characterized by high nutritional value. The disadvantage of sprouts is the loss of bioactive compounds during storage and the relatively short shelf life, due to the fact that they are a good medium for microorganisms, especially yeasts and molds. The aim of the study was to compare the content of polyphenols, antioxidant properties, color and microbiological quality of red cabbage sprouts preserved by the use of mild organic acids: Citric, ascorbic, lactic, acetic and peracetic. In the study, the content of polyphenols and antioxidant properties of sprouts was examined using the spectrophotometric method, instrumental color measurement was done using an “electronic eye” and the content of mold, yeast and the total number of mesophilic microorganisms was determined using the plate inoculation method. Taking into account the content of polyphenols and the antioxidant potential of sprouts, it was found that the addition of all organic acids contributed to the preservation of the tested compounds during their 14-day storage under refrigerated conditions, depending on the type of organic acid used, from 71 to 86% for polyphenols and from 75 to 96% for antioxidant properties. The best results were obtained by treating the sprouts with peracetic acid and ascorbic acid, respectively, at a concentration of 80 ppm and 1%. The conducted research on the possibility of extending the storage life and preserving the bioactive properties of fresh sprouts showed that the use of peracetic acid in the form of an aqueous solution during pre-treatment allows to reduce the content of microorganisms by one logarithmic order. Ascorbic acid did not reduce the content of microorganisms in the sprout samples tested. Considering the content of bioactive ingredients, as well as the microbiological quality of fresh sprouts, it can be said that there is a great need to use mild organic acids during the pre-treatment of sprouts in order to maintain a high level of health-promoting ingredients during their storage, which may also contribute to their prolongation durability.

A Review into the Effectiveness of Ozone Technology for Improving the Safety and Preserving the Quality of Fresh-Cut Fruits and Vegetables

In recent years, consumers have become increasingly aware of the nutritional benefits brought by the regular consumption of fresh fruits and vegetables, which reduces the risk of health problems and disease. High-quality raw materials are essential since minimally processed produce is highly perishable and susceptible to quality deterioration. The cutting, peeling, cleaning and packaging processes as well as the biochemical, sensorial and microbial changes that occur on plant tissue surfaces may accelerate produce deterioration. In this regard, biological contamination can be primary, which occurs when the infectious organisms directly contaminate raw materials, and/or by cross-contamination, which occurs during food preparation processes such as washing. Among the many technologies available to extend the shelf life of fresh-cut products, ozone technology has proven to be a highly effective sterilization technique. In this paper, we examine the main studies that have focused on the effects of gaseous ozone and ozonated water treatments on microbial growth and quality retention of fresh-cut fruit and vegetables. The purpose of this scientific literature review is to broaden our knowledge of eco-friendly technologies, such as ozone technology, which extends the shelf life and maintains the quality of fresh produce without emitting hazardous chemicals that negatively affect plant material and the environment.

Comparative transcriptomic analysis of cantaloupe melon under cold storage with ozone treatment

Ozone treatment was found to delay the postharvest cantaloupe melon decay and improve its intrinsic quality during the cold storage. The transcriptomes of cantaloupe peel and pulp in response to ozone treatment were investigated to reveal the mechanisms using a high-throughput RNA sequencing approach. Results showed that 570 and 313 differentially expressed genes were identified in peel and pulp, respectively. According to these identified genes, the gene ontology and pathway enrichment analysis indicated that the ozone treatment could maintain the firmness of the cantaloupe by changing pectin metabolites and reduction of the ethylene production by regulating relevant genes especially in the peel. The total flavonoid content changes in peel and pulp related to the regulation of phenylalanine ammonia lyase, 4-coumarate-CoA ligase and P450 family genes which further leading to the inhibition of phenylalanine metabolic pathway in peel but promotion of secondary metabolism in pulp. The qRT-PCR results were in accordance with our RNA sequencing results which validated the conclusions. The present study for the first time reveals the mechanism of cantaloupe in response to ozone treatment at a transcriptome level which is of importance for cantaloupe storage.

A Review of Hygienization Methods of Herbal Raw Materials

This article reviews various decontamination methods of herbal raw materials in Poland. These are the physical and chemical treatments of plant raw materials that remove mineral and microbiological impurities to ensure food safety. There is increasing use of herbal raw materials, and it is important to understand various methods that can be used for hygienization. Techniques used ensure the removal of mechanical impurities and elimination of microorganisms in a plant material. Depending on the method of choice, certain microorganisms are removed to a varying degree, and at the same time, there is a partial loss of the health-promoting properties of the plants subjected to the hygienization. Therefore, there is need to decide on optimal methods for hygienization of herbs that both reduce microbial contamination to the maximum extent and minimize the decrease in valuable ingredients contained in the herbs. Ozonization of plant raw materials is an effective method of removing microbiological contamination from most herbs. A good solution is also to use hybrid methods. In our literature review, ozone is very often mentioned as an effective disinfectant for herbs and spices. However, there is no information about the effect of ozone use on the substances contained in herbs and spices.

Effect of ozone treatment on the phenylpropanoid biosynthesis of postharvest strawberries

Ozone treatment at a suitable concentration can improve the antioxidant capacity of postharvest fruits. However, few studies have examined the antioxidant bioactive compounds in ozone-treated postharvest strawberries, especially in relation to proteomics. In this study, the total phenol content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC) were used as the main antioxidant compound indicators and unlabeled proteomics was used to study the metabolism of phenylpropanoids in postharvest strawberries (Jingtaoxiang) treated with different concentrations of ozone (0, 1, 3, and 5 ppm) throughout the duration of storage. The results showed that the postharvest strawberries treated with 5 ppm ozone concentration exhibited improved accumulation of total phenols, flavonoids and anthocyanins in the antioxidant bioactive compounds, which was beneficial to the expression of phenylpropanoid metabolism-related proteins over the whole storage period compared with the other three groups. The results of proteomics were consistent with the changes in the key metabolites of phenylpropanoids, which indicated that ozone treatment at a suitable concentration aids the accumulation of TPC, TAC and TFC by promoting the key proteins associated with phenylpropanoid metabolism.

Chlorfenapyr Residue in Sweet Persimmon from Farm to Table

The use of the pesticide chlorfenapyr has been increasing over time, with a consequent wider application to crops. However, there is limited information available on the amount and safety of the residues it leaves on crops. The amount of chlorfenapyr residues in sweet persimmon (Diospyros kaki L.) at both the pre- and postharvest stages were investigated in this study by calculating its biological half-life. The half-life at the preharvest stage was 8.8 days, shorter than that found during the storage periods at 4 and 20°C, when the half-lives were 11.0 and 23.9 days, respectively. In addition, peeling and washing after harvesting reduced residue content. The majority of the chlorfenapyr residues in sweet persimmon were found in the peel of the fruit, with the pulp containing less than 25% of the total. Thus, peeling effectively removed chlorfenapyr residues and diminished the residues below the limit of quantification in the pulp. In addition, washing with 1.0% alcohol and 0.2% Tween 20 solutions effectively removed 47.8 and 55.6% of the residues, respectively. Furthermore, a 1.0% alcohol solution showed high reduction efficiency for other hydrophobic pesticides, such as dimethomorph and fluquinconazole, up to 78.0%. Chlorfenapyr residues in sweet persimmon can be effectively reduced via storage or peeling and washing practices or a combination of them.

Reduction of Escherichia coli O157:H7 and naturally present microbes on fresh-cut lettuce using lactic acid and aqueous ozone

Lactic acid (LA) is an effective sanitizer for disinfection of fresh produce. Tap water is generally used to wash disinfected fresh produce because sanitizer residues negatively affect the quality and organoleptic properties of the produce. However, tap water is ineffective for secondary disinfection compared with sanitizers. Thus, we propose a disinfection method using LA plus aqueous ozone (AO), an oxidizing sanitizer that does not lead to secondary residue. We compared the proposed method of 1% LA (90 s) plus 1 mg L⁻¹ AO (30 s) or 2 mg L⁻¹ AO (30 s) with the traditional method of 100 ppm chlorine (120 s) or 1% LA (120 s) plus tap water (30 s) and 2 mg L⁻¹ AO (150 s). Microbial analysis showed that LA plus AO led to the greatest reductions in microbes (Escherichia coli O157:H7, aerobic mesophilic counts, aerobic psychrophilic counts, moulds, and yeasts) during storage (0–5 days at 5 °C). Quality analysis (colour, sensory qualities, electrolyte leakage, polyphenolic content, and weight loss) showed that LA + AO did not cause additional quality loss compared with tap water treatment. These results indicate that the hurdle technology proposed (LA plus AO) has a good potential for use in fresh produce disinfection.

Lactic acid plus aqueous ozone is an effective hurdle technology for fresh produce disinfection.

Maintaining postharvest quality of cold stored 'Hass' avocados by altering the fatty acids content and composition with the use of natural volatile compounds - methyl jasmonate and methyl salicylate

BACKGROUND

Low temperatures are often used to reduce metabolic processes and extend the storage life of fruit; however, in the case of avocado, a temperature below 3 °C will often result in the development of physiological disorders associated with chilling injury. The objective of this study was to investigate the ability of methyl jasmonate (MeJA) and methyl salicylate (MeSA) vapours to alleviate chilling injury in 'Hass' avocado fruit kept at 2 °C for 21 days followed by 6-7 days of shelf-life at 20 °C, simulating supply chain conditions.

RESULTS

The incidence and severity of chilling injury were significantly reduced in MeJA- and MeSA-exposed fruit, especially at 100 µmol L^-1 . The mechanism involved improved membrane integrity via alteration of the fatty acid content and composition, down-regulation of LOX gene expression and reduced activity of lipoxygenase.

CONCLUSION

MeJA and MeSA have the potential for being used with 'Hass' avocado fruit shipped at low temperature to reduce its susceptibility to chilling injury. © 2017 Society of Chemical Industry.

Evaluation of the effectiveness of ozone as a sanitizer for fish experimentally contaminated with Salmonella sp

Abstract Salmonellosis is a major public health problem related to food contamination and ensuing food poisoning. Brazilian resolution RDC nº 12/2001 of the Brazilian National Health Surveillance Agency (ANVISA) established the absence of Salmonella in 25 g of fish for consumption. However, the significant increase in the occurrence of fish contamination by Salmonella and other pathogenic bacteria shows that the currently applied strategies are not sufficient and that, in addition to the implementation of good health practices, the application of new sanitizer technologies in the fish industry is also necessary. In this context, the present study evaluated the effectiveness of ozone in an aqueous medium as a sanitizer for Salmonella contaminated fish. The experiment was carried out using a completely randomized design with eight treatments and five replicates, giving a total of 40 experimental units. Each sample consisted of three fishes, totalizing 120 fishes. The treatments consisted of different combinations of temperature and water-dissolved ozone (O3) concentrations (21 °C × 0.35 ppm; 20 °C × 0.45 ppm; 21 °C × 0.60 ppm; 20 °C × 0.80 ppm; 19 °C × 1.7 ppm; 6 × 5.1 ppm; 4 °C × 7.2 ppm; and 2 °C × 9.1 ppm). Colossoma macropomum (Tambaqui) samples were experimentally infected with Salmonella typhymurium (ATCC 14028) and immersed in water with the different treatments. After three minutes, the fish samples were collected and subjected to qualitative Salmonella analyses. The ozone tests were not efficient in eradicating Salmonella under the experimental conditions presented here, indicating the need for the identification of effective sanitizers in order to meet the determinations of Brazilian law.