Postharvest Treatment Of Fruit Research Articles

Application of electrolysed water in post-harvest treatment of fruits and vegetables

Post-harvest losses in fruits and vegetables have triggered the interest of scientists to look for alternative methods for treatment of horticultural produce after harvest for inactivation of pathogens without causing any ill effects.

Development of Basil Essential Oil (BEO) as a Novel Alternative to Prolong the Storage of Tomato (Lycopersicum esculentum L.)

Antimicrobial compounds used as post-harvest treatment of fruit and vegetables can extend their shelf life by reducing the rate of microbial growth. Essential oils extracted from herbs or spices can also enhance shelf life due to their antimicrobial nature. Tomatoes harvested at consumption maturity were treated by spraying with aqueous solutions of basil essential oil (BEO) and glycerol in different concentrations (50, 100, 150, 200, 250 and 300 ppm) and stored by refrigeration at 8 ∘C and 85% relative humidity. The BEO used was obtained by extraction from indigenous crops of Ocimum basilicum and was analyzed by GC-MS for discerning of the constituents present in it. The main components identified in BEO were: eucalyptol, linalool, estragol, eugenol methyl-cinamate, trans-α-bergamotene, germacrene D, γ-cadinene and T-cadinol. During storage, in order to highlight the effect of the applied treatment, the following were determined: dry matter (DM), total soluble content (TSS), total phenols content (TP), antioxidant activity (AOA), color, weight loss and total number of aerobic mesophilic bacteria (AMB) during storage. It has been shown that spraying the fruit with solutions of different concentrations of BEO has significant effects on weight loss, DM, TSS, TP, AOA, color and TAMB, during storage. The lowest TP value was found in the control and the variant treated only with 2.5% aqueous glycerol solution (52.18 mg/100 g fw GAE) and the highest value in the variants treated with concentrations of 200, 250 and 300 ppm BEO (54.37, 55.00 and 57.81 mg GAE/100 g fw). The highest AOA values were found in the 300 ppm BEO-treated variant (119.23 μmol TE/100 g fw). Spraying tomatoes with aqueous solutions of glycerol 2.5% and BEO at a dose of 250 ppm prolongs their storage while maintaining their quality for fresh consumption.

Control of postharvest stem-end rot on mango by antifungal metabolites of Trichoderma pinnatum LS029-3

Mango stem-end rot caused by Lasiodiplodia theobromae is a destructive postharvest disease that seriously endangers the mango production process after picking. In this study, the antifungal activities of 10 Trichoderma isolates isolated from mango rhizosphere soil were tested against L. theobromae through dual-culture. To understand the mechanism of antifungal activity, volatile and non-volatile metabolites produced by these 10 strains were also tested. Among ten Trichoderma isolates, the highest antifungal activity was shown by non-volatile metabolites of Trichoderma LS029-3, which was identified as Trichoderma pinnatum by morphological and molecular characteristics. The concentration for 50% of maximal effect (EC50) of the crude extracts extracted by ethyl acetate from the fermentation broth of isolate LS029-3 on L. theobromae was 0.25 ± 0.03 g L−1. Scanning electron microscopy (SEM) showed that crude extracts could destroy the mycelium structure of L. theobromae at the 4 × EC50 concentration. Ten chemical constituents from crude extracts were identified by gas chromatography-mass spectrometry (GC-MS) among which three compounds (Z)-13-docosenamide (ACROS), Hexanedioic acid, bis(2-ethylhexyl) ester (DOA) and (Z)-9-Octadecenamide (MSDS) were the major constituents and could suppress fungal growth significantly. LS029-3 crude extracts significantly reduced severity and lesion area of mango stem-end rot disease, and maintained the hardness and color of the fruit by increasing the activity of mango defense enzyme (polyphenol oxidase, peroxidase, total phenol) and reducing the decline rate of superoxide dismutases enzyme, glutathione enzyme and ascorbic acid content, thereby slowing down fruit rot. Post-harvest treatment of fruits with protective chemicals is a serious concern, that is directly related to human health. This study provides a practical solution to control postharvest of stem-end rot disease on mango through a safe and effective biocontrol strategy. This study firstly reported the biocontrol effect of T. pinnatum metabolites on postharvest mango stem-end rot and maintain the quality of mango fruit.

The Effect of Surfactants of Microbial Origin on Phytopathogenic Microorganisms

Biodegradable non-toxic surfactants of microbial origin are multifunctional preparations, which due to antimicrobial activity are promising for use in crop production to control phytopathogenic microorganisms. Studies on the prospects of using microbial surfactants to control the number of phytopathogenic microorganisms are conducted in three directions: laboratory studies of antimicrobial activity of surfactants in vitro, determination of the effect of surfactants on phytopathogens in vegetative experiments in the process of plants growing in a laboratory or greenhouse, post-harvest treatment of fruits and vegetables with solutions of microbial surfactants to extend their shelf life. The review presents literature data on antimicrobial activity of surfactants against phytopathogenic bacteria and fungi in vitro. Antimicrobial activity of surfactants is evaluated by three main parameters: minimum inhibitory concentration, zones of growth retardation of test cultures on agar media and inhibition of growth of test cultures on agar or liquid media. The vast majority of available publications relate to the antifungal activity of surfactant lipopeptides and rhamnolipids, while data on the effect of these microbial surfactants on phytopathogenic bacteria (representatives of the genera Ralstonia, Xanthomonas, Pseudomonas, Agrobacterium, Pectobacterium) are few. The researchers determined the antimicrobial activity of either total lipopeptides extracted with organic solvents from the culture broth supernatant, or individual lipopeptides (iturin, surfactin, fengycin, etc.) isolated from a complex of surfactants, or culture broth supernatant. Lipopeptides synthesized by members of the genus Bacillus exhibit antimicrobial activity on phytopathogenic fungi of the genera Alternaria, Verticillium, Aspergillus, Aureobasidium, Botrytis, Rhizoctonia, Fusarium, Penicillium, Phytophora, Sclerotinia, Curvularia, Colletotrichum, etc. in sufficiently high concentrations. Thus, the minimum inhibitory concentrations of lipopeptides against phytopathogenic fungi are orders of magnitude higher (in average 0.04–8.0 mg/mL, or 40–8000 μg/mL) than against phytopathogenic bacteria (3–75 μg/mL). However, the antifungal activity of lipopeptidecontaining supernatants is not inferior by the efficiency to the activity of lipopeptides isolated from them, and therefore, to control the number of phytopathogenic fungi in crop production, the use of lipopeptidecontaining supernatants is more appropriate. Rhamnolipids synthesized by bacteria of the genus Pseudomonas are more effective antimicrobial agents comparing to lipopeptides: the minimum inhibitory concentrations of rhamnolipids against phytopathogenic fungi are 4–276 μg/mL, which is an order of magnitude lower than lipopeptides. In contrast to the data on the antifungal activity of rhamnolipids against phytopathogens, there are only a few reports in the literature on the effect of these surfactants on phytopathogenic bacteria, whilst the minimal inhibitory concentrations are quite high (up to 5000 μg/mL). The advantage of rhamnolipids as antimicrobial agents compared to lipopeptides is the high level of synthesis on cheap and available in large quantities industrial waste. Currently in the literature there is little information about the effect of surface-active sophorolipids of microbial origin on phytopathogenic fungi, and all these works are mainly about the antifungal activity of sophorolipids. We note that in contrast to surfactant lipopeptides and rhamnolipids, the effective concentration of most sophorolipids, which provides the highest antimicrobial activity against phytopathogens, is higher and reaches 10,000 μg/mL.

Obtention and characterization of a hybrid nanocomposite monolith by sol–gel process

A monolithic porous composite was synthesized by sol–gel process, containing the maximum and significant amount of bentonite that allows its use as a filter bed in aqueous effluents treatment. This process is able to apply on an industrial scale.The bentonite used was an efficient adsorbent for various contaminant molecules in aqueous media when is operated in a batch stirred tank, but presents difficulty in the separation stage of suspended particles. In this laboratory-scale work, cylindrical monoliths of 9cm length by 2cm diameter were made that can be used as a filter bed. The primary composite, silica-resin, was prepared by the sol–gel precursor mixture of the partially hydrolyzed tetraethylorthosilicate and a phenol-formaldehyde resin. Bentonite was added to the pre-gelling, obtaining the silica-resin-bentonite composite, made up the gel which is then dried and cured at 270°C. The different composites mineralogical and structurally were evaluated. The preliminary performance of the developed bentonite filter bed showed almost 90% adsorption of diphenylamine, a commercial agrochemical widely used as anti-antiscaldant in postharvest treatment of fruit, and showed that the bentonite conserves its adsorption capacity and controls the swelling of the interlayer space which encourages further research studies applied to water treatment.

Post-harvest treatment of fruits and vegetables to extend their shelf life

Post-harvest treatment of fruits and vegetables to extend their shelf life

Towards a novel bioreactor technology for treating fungicide-rich wastewaters from the fruit packaging industry

The fruit processing industry is an important economic sector worldwide, whereas a wide range of plant pathogens affects the shelf life of fruits, resulting in great economic losses. Post-harvest fungicides are often applied in the fruit processing industry to address post-harvest infections. However, various fungicides have been reported to exhibit toxicity to aquatic and terrestrial non-target organisms. Thus, effective technological solutions are needed to treat fungicide-containing wastewaters generated by the fruit packaging industry. Regarding biological methods, few approaches have been explored to deplete high-strength fungicide-based wastewaters derived from the post-harvest treatment of fruits. Despite the application of post-harvest fungicides for several decades, we are still missing the implementation of a full-scale biobased system to treat fungicide-rich wastewater generated by the fruit-packaging industry. On the other hand, fixed and fluidized bed bioreactors compared to suspended solids systems result in higher removal efficiencies. Based on the advantages of such bioreactor technology and the recent findings regarding the depuration of post-harvest fungicides in these biosystems, immobilized cell bioreactors appear to be a promising biological approach to treat persistent fungicides present in fruit packaging wastewater. However, bioreactors technology scaling up for the biotreatment of fungicide-rich wastewaters from the fruit packaging industry is challenging. Towards this direction, “Minotaur”, a 3-year research project financed by EU and Greek funds, is on the way to develop a full-scale bioreactor technology for treating fungicide-based wastewaters.

An Analysis of the Published Literature on the Effects of Edible Coatings Formed by Polysaccharides and Essential Oils on Postharvest Microbial Control and Overall Quality of Fruit.

Consumers have shown increased concern about the importance of adopting regular fresh fruit consumption. Because fresh fruit are highly susceptible to postharvest decay, several studies have focused on the development of alternative technologies to extend their market period. The application of polysaccharides in combination with essential oils (EOs) to formulate edible coatings has been considered an innovative strategy to reduce postharvest losses in fruit. However, available studies have used different methodological procedures related to the production and application of these coatings on fruit, which could be potential influential factors on the achievement of the desired effects in coated fruit. This review summarized the studies focusing on the application of edible coatings formed by polysaccharides and EOs to preserve fruit, in addition to examine and discuss possible factors affecting their functionalities. The approach given in this review envisages to contribute to research in edible coatings formed by polysaccharides and EOs and help to their optimized application as a postharvest treatment of fruit. Despite of the different methods selected for use in experimental assays, data of available literature demonstrate that coatings formed by polysaccharides (that is, chitosan-the only polysaccharide used as an antimicrobial, cassava starch, flaxseed gum, gum arabic, hydroxypropylmethylcellulose, locust bean gum, mesquite gum, pectin, pullulan, and sodium alginate) and different EOs (or their individual constituents) are effective to reduce postharvest losses in fruit and generally do not adversely affected their physicochemical and sensory characteristics during storage.

Study on Intrinsic Factors Affecting Production Technology of Low Carbon Agriculture and Forestry Plants

The management of low-carbon agriculture and forestry plant farms is an important path to promote the development of agricultural industry. This study used binary logistic regression method to construct a logistic regression model of low-carbon agriculture and forestry plant production status. The various conditions of low-carbon agroforestry production were analysed. The various internal factors affecting the evaluation of the production status of low-carbon agroforestry plants and the farm production as well as production status were discussed and comprehensively evaluated. Six main influencing factors were summarized and analysed, which were seedling quality, seed market supervision, fruit and vegetable standardization, fruit and vegetable market supervision, fruit and vegetable market infrastructure, post-harvest treatment of fruits and vegetables, and the promotion of low carbon farmland and plant production.

Effect of stepwise humidity change on the release rate constant of 1-methylcyclopropene (1-MCP) in a cyclodextrin inclusion complex powder

The release behaviour of 1-methylcyclopropene (1-MCP) is important during postharvest treatment of fruit and vegetable. Effect of humidity and temperature on the release rate of 1-MCP in an α-cyclodextrin (α-CD) inclusion complex powder were investigated on the potential of direct application of 1-MCP inclusion complex powder and developing of functional packaging. The aim of this research was to study the release behaviour of 1-MCP from an inclusion complex powder under a stepwise humidity change. 1-MCP release experiments were conducted using a dynamic vapour sorption (DVS) system at different temperatures (40, 50, and 60 °C) with stepwise humidity changes (20% RH for 2 h to 40, 50, 60, and 80% RH for 2 h, respectively). The results showed that the release rate constant of 1-MCP from inclusion complex powders increased linearly with moisture concentration at 40, 50, and 60% RH. The highest release rate constant of 1-MCP was 1.5 × 10−3 s−1 for 80% RH at 60 °C. The activation energy at the highest humidity condition of 80% RH was 27.5 kJ/mol. The release rate constant of 1-MCP from the inclusion complex powders was well correlated with a first-order release rate equation. The results obtained showed that 1-MCP inclusion complex in α-CD has a potential as an active compound that could be incorporated into active packaging systems where storage condition below 60% RH is needed.

Improved the Shelf Life of Guava Fruits by Salicylic Acid against Postharvest Black Spot Disease

Guava fruit (Psidium guajava L.) is one of the most important popular fruits in the tropical and subtropical zones. It is a perishable and has a short postharvest shelf life at environment temperature due to climacteric ripening with changes in physicochemical properties; However, the most serious microorganisms attacked guava fruits are the fungi. Guava black spot (GBS) is a latent infection disease caused by the ascomycete fungal Phyllosticta capitalensis, that infect immature guava in the field. This postharvest decay can lead to significant economic losses. Since the commercial application of fungicides to control postharvest diseases found harmful to human and the ecosystems. Therefore, the search of finding alternative fungicides, safety and environmentally friendly strategy is a major aim of the researchers worldwide. Salicylic acid (SA) is one of the safe, natural compounds applied in the postharvest treatment of fruit. The present investigation aimed to evaluate the effect of different concentrations of SA on fungal growth in vitro and postharvest treatment of infected fruit to improve the shelf life of guava fruits. Guava fruit collected from local supermarket and measurement of disease incidence and severity (DI & DS%) carried out in the three seasons (2015-2017). SA at different concentrations assessed on mycelial linear growth inhibition (MLGI%) of P. capitalensis in vitro. Exogenous postharvest treatment of guava fruit with SA tested at five concentrations, three times of immersion and kept for three periods time of shelf life. DS% evaluated after three period time. Total soluble solids (TSS) and weight loss (WL) evaluated after three period time. SA concentrations at 6 mmol/L significant on MLGI of P. capitalensis in vitro. Postharvest treatment with SA at 3 mmol/L significantly reduced DS% on guava fruit, at three immersion time and after three periods of shelf life, compared to control. SA with a concentration at 4 mmol/L decreased TSS and WL after three periods of shelf life. Postharvest treatment with SA solutions had an overall positive effect on fruit quality of guava during shelf life. A decay incidence decreased, TSS and weight loss noticed in treated guava fruit compared to control. The present study demonstrated the efficacy and potential of SA solutions in preserving the shelf life of a highly perishable like guava fruits.

Characterization of the biodegradation, bioremediation and detoxification capacity of a bacterial consortium able to degrade the fungicide thiabendazole.

Thiabendazole (TBZ) is a persistent fungicide used in the post-harvest treatment of fruits. Its application results in the production of contaminated effluents which should be treated before their environmental discharge. In the absence of efficient treatment methods in place, biological systems based on microbial inocula with specialized degrading capacities against TBZ could be a feasible treatment approach. Only recently the first bacterial consortium able to rapidly transform TBZ was isolated. This study aimed to characterize its biodegradation, bioremediation and detoxification potential. The capacity of the consortium to mineralize 14C-benzyl-ring labelled TBZ was initially assessed. Subsequent tests evaluated its degradation capacity under various conditions (range of pH, temperatures and TBZ concentration levels) and relevant practical scenarios (simultaneous presence of other postharvest compounds) and its bioaugmentation potential in soils contaminated with increasing TBZ levels. Finally cytotoxicity assays explored its detoxification potential. The consortium effectively mineralized the benzoyl ring of the benzimidazole moiety of TBZ and degraded spillage level concentrations of the fungicide in aqueous cultures (750mg L-1) and in soil (500mgkg-1). It maintained its high degradation capacity in a wide range of pH (4.5-7.5) and temperatures (15-37°C) and in the presence of other pesticides (ortho-phenylphenol and diphenylamine). Toxicity assays using the human liver cancer cell line HepG2 showed a progressive decrease in cytotoxicity, concomitantly with the biodegradation of TBZ, pointing to a detoxification process. Overall, the bacterial consortium showed high potential for future implementation in bioremediation and biodepuration applications.

Substantiation of the choice of optimal concentrations of active ingredients of the antioxidant composition for fruit treatment before storage

The object of this research is the technological process of refrigerated storage of fruit products. In order to reduce the level of losses during normal refrigeration, a technological audit is carried out to solve this problem by applying antioxidant compositions for post-harvest treatment of fruits. The aim of research is development of a new antioxidant composition and optimization of its composition. The use of this composition for post-harvest treatment of fruits contributes to the extension of their shelf life and the reduction of the level of daily loss. The treatment with antioxidant compositions (AOC) was performed in storage facilities by immersing them in pre-prepared working solutions. Exposure – 10 seconds. The fruit was dried by ventilation. Options for treatment: K – control, option 1 – DL – a mixture of dimethyl sulfoxide, ionol and lecithin. The following concentrations of active substances were studied: distinol 0–0.048 %, lecithin 0–6 %. The effectiveness of exposure to various concentrations of active substances is determined by the average level of daily loss of fruit during storage, consisting of the sum of mass losses and losses caused by microbiological diseases and functional disorders, referred to the number of days of storage. The following concentrations of active substances in the developed antioxidant composition are established by optimization: apple and pear fruits storage – distinol concentration is 0.041...0.042 %, the lecithin concentration is 2.9 %. Plum fruits storage, respectively: distinol – 0.022 %, lecithin – 3.4 %.

Control of Rhizopus soft rot and quality responses in plums (Prunus domestica L.) coated with gum arabic, oregano and rosemary essential oils

This study evaluated the efficacy of coatings comprising gum arabic (GA) and essential oils from Origanum vulgare L. (OVEO) and Rosmarinus officinalis L. (ROEO) to control Rhizopus soft rot and quality of plums (Prunus domestica L.) during storage at room (25°C; 12 days) and cold (12°C; 24 days) temperatures. GA (1 mg/ml) and OVEO (0.25 μl/ml) or OVEO (0.06 μl/ml) plus ROEO (0.25 μl/ml) inhibited the mycelial growth, spore germination and sporulation of R. stolonifer. GA-OVEO and GA-OVEO-ROEO coatings delayed the occurrence of soft rot and decreased the rotted plums at the end of storage compared to GA alone. Plums coated with GA-OVEO and GA-OVEO-ROEO exhibited greater firmness decreased weight loss and lower decrease of sugars and phenolics at the end of storage compared to uncoated plums. GA-OVEO and GA-OVEO-ROEO coatings enhanced the color and flavor, while GA-OVEO coating affected negatively the aftertaste of plums. GA-OVEO-ROEO coating is a promising postharvest treatment for plums. Practical applications In plums, the reduction of postharvest quality losses resulting from decay caused by Rhizopus stolonifer contamination or by the ripening process is a major goal of postharvest technology, which increase attention to use environmental friendly methods as postharvest treatment of fruit. Edible coatings can reduce the use of synthetic fungicides, thus are in agreement with the increased consumer's demand by products obtained with the minimum quantities of synthetic products. Gum arabic is largely used in food industry, however underexplored as coating component, particularly in combination with natural antifungal substances such as essential oils. Edible coatings containing essential oils are considered environmentally friendly technologies because these substances when incorporated in polissacharydes can be released on surfaces of fruit and increase the storage time. This study evaluated coatings containing reduced amounts of oregano and rosemary essential oils in combination as postharvest treatment to control Rhizopus soft rot in plums (Prunus domestica), as well as their effects on the quality attributes of this fruit during storage. The tested coatings are presented as alternative technologies to control soft rot and preserve the quality of plums during storage.

Improving quality of greenhouse tomato (Solanum lycopersicum L.) by pre- and postharvest applications of hexanal-containing formulations

From harvest to consumption, tomato (Solanum lycopersicum L.) fruit are exposed to several exogenous factors that enhance product deterioration. Phospholipase D is a key enzyme involved in membrane deterioration that occurs during fruit ripening and senescence. Hexanal, an inhibitor of phospholipase D has been successfully used for pre- and postharvest treatment of fruit, vegetables and flowers. In this study, effectiveness of pre- and postharvest application of an aqueous hexanal formulation and an enhanced freshness formulation (EFF) containing hexanal and other ingredients were evaluated by monitoring changes in quality parameters during postharvest storage of greenhouse tomatoes. Tomatoes subjected to preharvest spray with EFF containing 1mM hexanal twice a week had better colour, and firmness than untreated fruit and hexanal formulation treated fruit. EFF treated tomatoes also showed low hue angle values indicative of enhanced red colour. Preharvest spray with 1mM hexanal twice a week resulted in higher levels of ascorbic acid and soluble solids in fruit than those subjected to EFF treatment, and the control. Postharvest dip application of harvested tomatoes in 2mM hexanal as EFF resulted in enhanced brightness and hue angle values, reduced red colour, increased fruit firmness and ascorbic acid content after 21 days of storage, indicative of better quality. The results suggest that hexanal has the potential to enhance shelf-life and quality of greenhouse tomatoes.

An innovative combined water ozonisation/O3-atmosphere storage for preserving the overall quality of two globe artichoke cultivars

Abstract Effects of ozonised water, gaseous ozone exposure, and their combined treatments on microbiological and qualitative parameters of two globe artichoke cultivars (Violet de Provence and Romanesco clone C3) were studied during storage at 4 °C. At the end of this period, microbial counts were significantly lowered. Considering the qualitative parameters, ozone can be successfully applied to cv. Romanesco clone C3 without significantly increasing the respiration rate, while it could determine the acceleration of senescence in Violet de Provence heads. The storage under ozone-enriched atmosphere improved the initial polyphenol content in Violet de Provence, while for Romanesco clone C3 it seemed to be opportune to interrupt the ozonisation within the 4th day of storage for preventing excessive losses of polyphenol content. The ascorbic acid reduction, for both cultivars, was significantly increased by postharvest treatments with gaseous ozone suggesting to reduce, also in this case, the exposure days to the gas. Industrial relevance The globe artichoke is a herbaceous crop native to the Mediterranean basin, which gives an important contribution both to agricultural economy and to human health due to the high content of promoting nutrients. Unfortunately, globe artichoke heads are very perishable because of their high respiratory activity, susceptibility to weight loss, and microbial decay. In particular, fungal decay is one of the main factors affecting the postharvest quality of globe artichoke and, so far, it is controlled by the application of chemical fungicides. However, resistance phenomena in microbial populations, growing public health and environmental concerns are urging for the use of alternative treatments. Among them, ozone is one of the most promising technologies from the health and environmental points of view for its spontaneous decomposition to non-toxic product. In addition, it has emerged as a potential antimicrobial agent in the post-harvest treatment of fruits and vegetables and is able to decompose pesticides and chemical residues. On the other side, the effect of ozone treatments on other qualitative parameters, including the level of antioxidant compounds, is highly dependent on the commodity and storage conditions. In this view, the combined water ozonisation/O 3 -atmosphere storage represents innovative and applicable postharvest treatments for globe artichoke, whose exposure time and concentrations need to be customized for each cultivar.

Antifungal and Antipatulin Activity of Gluconobacter Oxydans Isolated from Apple Surface

Fungicides are the most common agents used in postharvest treatment of fruit and are the most effective against blue mould, primarily caused by Penicillium expansum. Alternatively, blue mould can be treated with antagonistic microorganisms naturally occurring on fruit, such as the bacterium Gluconobacter oxydans. The aim of this study was to establish the antifungal potential of the G. oxydans 1J strain isolated from apple surface against Penicillium expansum in culture and apple juice and to compare it with the efficiency of a reference strain G. oxydans ATCC 621H. The highest antifungal activity of G. oxydans 1J was observed between days 3 and 9 with no colony growth, while on day 12, P. expansum colony diameter was reduced to 42.3% of the control diameter. Although G. oxydans 1J did not fully inhibit mould growth, it showed a high level of efficiency and completely prevented patulin accumulation in apple juice.

On-farm biopurification systems for the depuration of pesticide wastewaters: recent biotechnological advances and future perspectives

Point source contamination of natural water resources by pesticides constitutes a serious problem and on-farm biopurification systems (BPS) were introduced to resolve it. This paper reviews the processes and parameters controlling BPS depuration efficiency and reports on recent biotechnological advances which have been used for enhancing BPS performance. Biomixture composition and water management are the two factors which either individually or through their interactions control the depuration performance of BPS. Which process (biodegradation or adsorption) will dominate pesticides dissipation in BPS depends on biomixture composition and the physicochemical properties of the pesticides. Biotechnological interventions such as augmentation with pesticide-degrading microbes or pesticide-primed matrices have resulted in enhanced biodegradation performance of BPS. Despite all these advancement in BPS research, there are still several issues which should be resolved to facilitate their full implementation. Safe handling and disposal of the spent biomixture is a key practical issue which needs further research. The use of BPS for the depuration of wastewaters from post-farm activities such as postharvest treatment of fruits should be a priority research issue considering the lack of alternative treatment systems. However, the key point hampering optimization of BPS is the lack of fundamental knowledge on BPS microbiology. The use of advanced molecular and biochemical methods in BPS would shed light into this issue in the future.

Microarray analysis of ripening-regulated gene expression and its modulation by 1-MCP and hexanal

Hexanal, an inhibitor of phospholipase D, has been successfully applied for the pre- and post-harvest treatment of fruits, vegetables and flowers. Changes in gene expression induced by hexanal and the ethylene antagonist 1-MCP, were analyzed by microarray using TOM2 tomato oligo-array containing approximately 12000 unigenes. Mature green tomato fruits were treated with 1-MCP and hexanal, RNA isolated after 10 days of storage, and labeled cDNA synthesized for microarray analysis. A large variation in gene expression profile was observed in 1-MCP-treated fruits. Genes for ethylene biosynthetic pathway enzymes such as ACC- synthase/oxidase, ethylene receptor and ethylene response factors were heavily down-regulated in 1-MCP-treated fruits. In addition, genes for key enzymes involved in cell wall degradation and carotenoid development pathways were down-regulated. Hexanal treatment significantly down-regulated ACC-synthase, and to a lesser extent, other components of ethylene signal transduction. By contrast to MCP-treated fruits, hexanal-treated fruits gradually ripened and showed higher levels of lycopene and β-carotene. GC-MS analysis of volatiles showed a higher level of major volatile components in hexanal-treated fruits. Similarities in the modulation of gene expression by hexanal and 1-MCP suggest that hexanal, in addition to being a PLD inhibitor, may also act as a weak ethylene inhibitor.

Use of a solid mixture containing diethylenetriamine/nitric oxide (DETANO) to liberate nitric oxide gas in the presence of horticultural produce to extend postharvest life

Postharvest treatment of fruit and vegetables with a low concentration of nitric oxide gas can extend postharvest life but application of nitric oxide by release from a gas cylinder is not feasible for many horticultural situations. This paper reports on development of a solid mixture to generate nitric oxide gas in the presence of horticultural produce. The solid NO-donor compound, diethylenetriamine/nitric oxide (DETANO) was found to quantitatively liberate nitric oxide in the presence of a range of acidic substances including citric acid. A solid mixture of DETANO and citric acid with wheat starch added as a filler and moisture absorbent in the ratio of 1:10:20 was found to be stable for at least six months when stored in dry air. However, in humid air, absorption of moisture from the atmosphere led to reaction of DETANO with citric acid and the evolution of nitric oxide gas. When the dry mixture was placed in a container with strawberry and mushroom, the moisture given off by produce activated the mixture and resulted in a similar extension in postharvest life as achieved by direct fumigation with nitric oxide gas. Commercial use of such a solid mixture could be through tablets or sachets which are more manageable in a farm or packing house than gas fumigation.