Efficacy of heat treatments with water and fludioxonil for postharvest control of blue and gray molds on inoculated pears and fludioxonil residues in fruit

The residue levels of fludioxonil (FLU) were determined in pear cultivars Precoce di Fiorano, Coscia, and Spadona estiva after a 2-min dip in an aqueous mixture of FLU containing 300 or 100 mg/liter of active ingredient at 20 or 50 degrees C and after 12 days at 17 degrees C and 80% relative humidity (simulated shelf life conditions). The accumulation trend of FLU residues was determined in 'Precoce di Fiorano' pears after treatments with 25, 50, 100, or 200 mg/liter of active ingredient at 20 or 50 degrees C for 2 min or at 60 degrees C for 1 min. The efficacy of heat treatments with water and FLU was investigated on artificially inoculated 'Precoce di Fiorano', 'Coscia', and 'Spadona estiva' pears for the control of postharvest blue mold and gray mold caused by Penicillium expansum and Botrytis cinerea, respectively. Treatment with 300 mg/liter FLU at 20 degrees C resulted in residue levels similar to those from treatment with 100 mg/liter FLU at 50 degrees C in 'Coscia' fruit but in significantly lower residues in 'Precoce di Fiorano' and 'Spadona estiva' pears. Post-shelf life residues decreased in all cultivars, especially in 'Spadona estiva' pears treated with 300 mg/liter FLU at 20 degrees C. Residue levels of FLU in 'Precoce di Fiorano' pears treated at 20, 50, or 60 degrees C were correlated with fungicide dosage. When an equal rate was used, treatment at 50 degrees C resulted in a higher and a notably higher FLU deposition than that found under treatment at 60 and 20 degrees C, respectively. The in vitro tests showed that both pathogens were very sensitive to FLU, with MICs averaging 0.05 and 0.1 mg/liter for B. cinerea and P. expansum isolates, respectively. The 50% effective concentration ranged between 0.01 and 0.05 mg/liter for B. cinerea and between 0.05 and 0.1 mg/liter for P. expansum. In the in vivo trials, hot water treatment effectively reduced the incidence of both diseases during the first 4 to 8 days, depending on cultivar, dip temperature, and type of inoculum. However, as the incubation time proceeded, decay reduction was generally lower and the benefit of heat treatments was notably reduced or almost lost. In contrast, all treatments with FLU had a long-lasting effect. Treatments with heated FLU were more effective than those with unheated FLU; reduced concentrations of active ingredient were required to achieve a comparable control of blue and gray mold decay in these pears.     

Effect of water activity and temperature on competing abilities of common postharvest citrus fungi

The effect of temperature (4-30 degrees C) and water activity (a(w), 0.995-0.90) on the 'in vitro' interactions between Penicillium digitatum, Penicillium italicum and Geotrichum candidum were evaluated. The effect of temperature on growth of green and blue mould decays and their interactions on wounded oranges was also studied. The major competing abilities were observed at optimal conditions of temperature and a(w) for growth (25 degrees C and 0.995 a(w)), and no differences between growth rates when the fungi were growing alone or paired were observed in the other studied conditions. P. italicum and G. candidum were able to reduce the growth rate of P. digitatum when it was growing paired 'in vitro', suggesting that inhibitory metabolites were produced. In the 'in vivo' assays, growth rates of green mould were higher than those of blue mould at any temperature studied. However, at 4 degrees C, P. italicum began its rot development 1 week before P. digitatum. When these two pathogens were inoculated into the same wound at 25 degrees C, blue mould was practically inhibited. The difference between the results obtained in 'in vitro' and 'in vivo' assays suggests that other factors could interact with fungi, favoring the development of one pathogen to the detriment of the others.     

Influence of post-harvest application rates of cyprodinil,treatment time and temperature on residue levels and efficacy in controlling green mould on ‘Valencia’ oranges

The effectiveness of heat treatments with water and cyprodinil in controlling post-harvest green mould caused by Penicillium digitatum was investigated on artificially inoculated ‘Valencia’ oranges. Residue levels of cyprodinil were determined in the oranges as a function of active ingredient concentration, temperature and treatment time. Cyprodinil residues were significantly dependent on treatment time when applied at 600 mg l^?1 and 20°C, but not when fruit were treated at 150–300 mg l^?1. The application of cyprodinil at 50 or 100 mg l^?1 at 55°C for 30 s produced similar residue levels, while residues increased when the application rate was 150 mg l^?1. Cyprodinil at 100 mg l^?1 and 60°C produced a significant increase in residues compared to treatment at 50 mg l^?1; no significant increase in residues was found when the application rate was raised from 100 to 150 mg l^?1. In comparison to treatments performed at 20°C, the application of a heated cyprodinil mixture resulted in significantly higher residues in fruit. All treatments with cyprodinil at 20°C similarly reduced green mould after 7 days of storage at 20°C. After 18 days, treatment with cyprodinil at 600 mg l^?1 for 30 s was more effective than at 150–300 mg l^?1. When dip time was extended to 90 or 180 s, treatment efficacy was positively related to fungicide concentration. Treatments with water at 55°C for 30 s were as effective as cyprodinil at 50–100 mg l^?1, but less effective than cyprodinil at 150 mg l^?1. After 7 days, treatment with water or cyprodinil at 50–150 mg l^?1 and 60°C were equally effective in controlling green mould; while, after 18 days, treatment with cyprodinil at 150 mg l^?1 was consistently more effective than at 50–100 mg l^?1 or hot water alone.     

Comparison of the activity of antifungal hexapeptides and the fungicides thiabendazole and imazalil against postharvest fungal pathogens

In this study, we evaluated the activity of short antimicrobial peptides against different fungal isolates that cause postharvest decay of fresh fruits. The previously identified hexapeptides PAF19, PAF26 and LfcinB4-9 inhibited the in vitro growth of isolates from Penicillium digitatum and P. italicum, and from Alternaria and Geotrichum genera, being no active against Rhizopus, Mucor and Aspergillus. The results extend our previous observations on the specific and distinct activity profiles of this class of antifungal peptides. In addition, peptide activities were compared with that of two fungicides used for citrus fruit preservation, thiabendazole (TBZ) and imazalil (IMZ). We observed a lack of correlation between peptide and fungicide sensitivity among different species. Importantly, P. digitatum and P. italicum isolates resistant to fungicides were susceptible to peptides and our data suggest that common multiple drug resistance mechanisms are not active against this class of peptides. The in vitro peptide inhibition was correlated with a retard of the decay caused by Penicillium on citrus fruits, and this effect was comparable for both fungicide-resistant and -sensitive isolates. Comparison of PAF26 and TBZ in vitro minimum inhibitory concentration (MIC) values and their in vivo effect on citrus decay indicated that PAF26 performed in vivo better than TBZ.     

Hot water and curing treatments reduce chilling injury and maintain post-harvest quality of 'Valencia' oranges

‘Valencia’ oranges [Citrus sinensis (L.) Osbeck] were harvested at optimal maturity and either dipped in hot water at 53 °C for 3 or 6 min or at 48 °C for 12 min or cured at 53 °C for 1 or 6 h or at 48 °C for 12 h. The fruits were not degreened, waxed or treated with any post‐harvest fungicides. All fruit samples were stored at 4 °C for 6 months following the treatments. Both hot water dip and curing treatments reduced chilling injury and decay when compared with the untreated control. The most effective treatments were curing of fruit at 53 °C for 6 h and at 48 °C for 12 h. Weight loss and juice yield were higher in cured fruits than those from other treatments, but the heat treatments had no consistent effects on titratable acid, soluble solids, ascorbic acid and peel colour. It was concluded that a pre‐storage hot water dip and curing at high temperatures might be beneficial in preventing chilling injury and decay of ‘Valencia’ oranges for 6 months of storage at 4 °C.     

Mutations of β-tubulin codon 198 or 200 indicate thiabendazole resistance among isolates of Penicillium digitatum collected from citrus in Taiwan

Penicillium digitatum causes green mold on citrus, resulting in severe postharvest fruit decay and economic losses in many citrus-producing areas of the world. Forty isolates of P. digitatum were cultured from citrus groves, packinghouses, and local markets in Taiwan, and assessed quantitatively for their sensitivity to thiabendazole (TBZ) fungicide. Sensitivity assays using a 96-well microtiter plate revealed that, of 40 isolates examined, only one isolate collected from fruit produced in Taiwan and two isolates from Florida-imported citrus fruit were sensitive to TBZ. The concentration of TBZ causing a 50% growth reduction (EC(50)) was less than 1 μg/mL. The remaining 37 isolates could tolerate high concentrations of TBZ, with an EC(50) greater than 80 μg/mL. Overall, more than 97% of P. digitatum isolates tested in Taiwan were found to be resistant to TBZ. In vitro assays also revealed the ineffectiveness of TBZ for controlling a TBZ-resistant isolate on sweet oranges. A sequence analysis of β-tubulin genes revealed that all TBZ-resistant isolates displayed a single transversion point mutation, resulting in a change at either amino acid 198 (glutamic acid→glutamine) or 200 (phenylalanine→tyrosine). The repetitive use of a single fungicide over several decades has favored the selection and dominance of TBZ-resistant isolates of P. digitatum.     

Synergistic effect of fungicides on resistant strains of Penicillium italicum and Penicillium digitatum

In vitro and in vivo tests were carried out to study the inhibitory effect of mixtures of sodium orthophenylphenate, methyl-1-(butyl-carbamoyl)-2-benzimidazole ('Benomyl') and sodium orthophenylphenate, 2-(4-thiazolil)-benzimidazole ('Thiabendazole') on growth of strains of Penicillium italicum and P. digitatum resistant to sodium orthophenylphenate, 'Benomyl' and 'Thiabendazole'. 'In vitro' tests showed a synergistic effect of the mixtures; 10 ppm of sodium orthophenylphenate and 10 ppm of the benzimidazolic compound in most cases resulted in complete growth inhibition. Navel oranges inoculated with P. italicum spores showed no damage after 7 days of incubation at 25 degrees C and 80-90% relative humidity when treated with a mixture of 100 ppm of sodium orthophenylphenate and 100 ppm of Thiabendazole.     

Chemical and quality traits of ‘Olinda’ and ‘Campbell’ oranges after heat treatment at 44 or 46 °C for fruit fly disinfestation

The chemical and quality characteristics of ‘Olinda’ and ‘Campbell’ oranges (nucellar budlines from Valencia late cultivar) were evaluated after exposure to a fruit core temperature of 44 °C and held at 44 °C for 100 min or 46 °C and held at 46 °C for 50 min, subsequent storage at 6 °C for 2 weeks and an additional week of simulated marketing period (SMP) at 20 °C. Exposure to either heat treatment caused neither visible damage nor fruit softening. Fruit weight loss rate in ‘Olinda’ oranges was unaffected by treatment but was higher than control fruit in heat exposed ‘Campbell’ oranges after storage, though at the end of SMP differences between treated and untreated fruit were non-significant. While neither heat treatment affected decay incidence in ‘Olinda’ oranges, significantly less decay was found in heat treated ‘Campbell’ fruit compared to control fruit both during storage and SMP.The chemical analyses of flavedo tissue of ‘Olinda’ oranges revealed that there were no treatment differences in neutral sugars, soluble and insoluble pectins and calcium bound to insoluble pectin fraction. The calcium content bound to soluble pectin fractions increased following heat treatments. At the end of SMP there was a significant decrease of soluble pectin and a significant increase of calcium bound to insoluble pectins in flavedo from oranges of the 46 and 44 °C treatments.Following treatment at 46 °C ‘Olinda’ fruit had a significantly lower content of soluble solids concentration. However, differences in soluble solids concentration between treated and control fruit after storage and SMP were not significant.Post-treatment levels of ethanol in both cultivars were significantly higher than in non-treated fruit. During storage and SMP, significant increases of ethanol were detected in control fruits with respect to their initial levels, whereas a reverse trend occurred in fruit subjected to heat treatment. Upon termination of the heat treatment at 44 or 46 °C, mean taste scores of ‘Olinda’ oranges were lower than those of untreated fruit, while the taste of ‘Campbell’ oranges was adversely affected only by the 46 °C treatment. After storage and SMP, taste differences between treated and control fruit were not significant. Flavour scores were unaffected by the treatment at 44 °C. Following treatment at 46 °C flavour rating in ‘Olinda’ fruit was significantly lower than control fruit while after storage and SMP the differences in flavour scores between treated and untreated fruit were non significant. Heat treatment to a fruit core temperature of 44 °C for 100 min or 46 °C for 50 min can thus have important commercial applications as an alternative to toxic chemical fumigants or to longer and more expensive disinfestation treatments such as cold quarantine.     

桂枝提取物抑菌活性研究

以柑橘青、绿霉菌及猕猴桃灰霉菌等17种植物病原菌为指示菌,分别采用杯碟法、菌丝生长速率法对桂枝提取物的抑菌活性进行研究,结果表明桂枝提取物具有较广泛的抑菌谱,对这17种供试病原菌均表现出一定的抑制效果,其中对柑橘青、绿霉的抑菌圈大小分别为(32.67±0.23)mm和(30.50±0.17)mm,最小抑菌浓度(MIC)分别为3.125mg/mL和6.25mg/mL,最小杀菌浓度(MFC)分别为6.25mg/mL和12.5mg/mL,而在其他15种植物病原菌中,桂枝提取物对车前草穗枯菌的活性最强,半抑制浓度(EC50)为0.4386mg/mL,对其他病原菌的EC50为1~22mg/mL。      

Inactivation of conidia of Penicillium chrysogenum, P. digitatum and P. italicum by ethanol solutions and vapours

A fractional factorial design, 2(5-1) experiments, was used for assessing the influence of 5 factors: water activity, aw [0.7, 0.9], temperature, T ( degrees C) [10, 30], mode of application, A [liquid, vapour], ethanol concentration, E (% w/w) [5, 10] and time, t (d) [1, 4] on the inactivation of spores of Penicillium chrysogenum, P. digitatum and P. italicum. Survival was determined by germination at optimal conditions within 3d. The experimental response was log (N 0/Nt), where N 0 and Nt (spore ml(-1)) the concentrations of viable spores at t=0 and t respectively. By a decreasing order of sensitivity to ethanol, moulds were ranked as followed: P. digitatum, P. italicum and P. chrysogenum. A greater inactivation for P. digitatum, P. italicum, that were the most sensitive moulds to ethanol, was obtained by applying vapour rather than ethanol solution. The order of significance of the main factors depended upon the mould. The key factor for explaining inactivation of P. chrysogenum was water activity. But, temperature was the main factor for explaining inactivation of P. digitatum and P. italicum. In the more drastic conditions, (i.e., 0.7 aw, 30 degrees C, 10% w/w ethanol), all spores were inactivated by applying liquid solution for 4d.     

The storage life of packed shredded Iceberg lettuce dipped in glycine betaine solutions.

The effects of glycine betaine dip, packaging method, and storage time on the sensory quality of shredded Iceberg lettuce were first modeled using a statistical experimental design, followed by a second storage test verifying the effect of the glycine betaine treatment. Shredded lettuce was dipped in 0 to 100 mg/liter active chlorine solution and then in 0 to 1.0 mol/liter glycine betaine solution, packed in 25 microm oriented polypropylene film, 250 g per package, and stored at 5 degrees C for 8 days. Models with good predictability were created suggesting that the glycine betaine dip helped retain sensory quality, especially appearance (P < 0.05). The models also suggested that washing periods over 60 s were not needed and that the microperforation of packages should not exceed 0.31 mm2 per package. The modeled positive effect on sensory quality was verified in the second storage test (P < 0.05). The optimum glycine betaine concentration was 0.2 mol/liter. Chlorination of the first dip particularly retained appearance of packed lettuce.     

Fungal decay and shelf life of oranges coated with chitosan and bergamot, thyme, and tea tree essential oils

Chitosan coatings, containing or not essential oils (bergamot, thyme and tea tree oil), were applied to oranges (cv. Navel Powell). Antifungal effect was evaluated by applying coatings before and after inoculating the fruit with Penicillium italicum CECT 2294 (10(5) spores/mL), preventive and curative treatments, respectively. The effect of coatings on the quality parameters (acidity, pH, soluble solids, juice percentage, weight loss, firmness, color parameters, and respiration rate) was controlled for the different oranges samples throughout the cold storage time. Preventive antimicrobial treatments with coatings containing tea tree oil were the most effective with a reduction of the microbial growth (expressed as the percentage of infected samples) of 50%, as compared to the uncoated samples. The coatings did not lead to any relevant changes in the development of the sample quality parameters throughout the cold storage, except for a slightly reduced loss of both weight and firmness when the coatings contained bergamot oil. Practical Applications: Results of this study are a useful tool for the development of new environmental friendly and healthier commercial applications in the control of the main postharvest fungal decay of citrus fruits.     

生物源保鲜剂枯草芽孢杆菌对锦橙贮藏病菌敏感性和保鲜效果

研究了生物源保鲜剂枯草芽孢杆菌对锦橙采后主要病菌的毒性及对锦橙果实的贮藏保鲜效果。结果表明:枯草芽孢杆菌可湿性粉剂对青霉菌和绿霉病的毒性较大,EC50值分别为7.4970μg/m L和8.8832μg/m L。保鲜结果表明:枯草芽孢杆菌可湿性粉剂2000倍液对青霉病、绿霉病、炭疽病等总病害均有较好的防治效果,比对照药剂250g/L咪鲜胺乳油667倍液效果好。在15~45d时,枯草芽孢杆菌可湿性粉剂各处理对锦橙的失重率没有影响;贮藏到60d后,对失重率有一定的影响,枯草芽孢杆菌2000倍液对果实品质的影响和清水对照比较没有差异性,并且对外观色泽和口感没有负面影响。总的来说:枯草芽孢杆菌可湿性粉剂2000倍液对锦橙储藏保鲜效果较好。      

Combining Pantoea agglomerans (CPA-2) and curing treatments to control established infections of Penicillium digitatum on lemons

The effectiveness of the strain CPA-2 of Pantoea agglomerans alone or in combination with a curing treatment at 33 degrees C for 65 h to control green mold was evaluated on lemons stored at ambient temperature and in cold storage. An application of P. agglomerans at 2 x 10(8) CFU/ml effectively reduced green mold incidence on recently inoculated lemons stored at temperatures from 5 to 25 degrees C. Moreover, a 30-s immersion of lemons in a P. agglomerans suspension at 2 x 10(8) CFU/ml significantly reduced green mold incidence, even when delayed up to 15 h after inoculation with Penicillium digitatum at either 20 degrees C or while in cold storage. However, it failed to control established infections of P. digitatum of more than 24 h. Curing P. agglomerans-treated lemons at 33 degrees C for 65 h completely controlled 24-h-old infections on artificially inoculated lemons stored at 20 degrees C for 14 days and on naturally infected lemons stored at 10 degrees C for 3 weeks plus 7 additional days at 20 degrees C. When applied before curing, population growth of P. agglomerans in wounds was similar to that within wounds of control fruits at 20 degrees C. In contrast, when it was applied immediately after curing treatment, P. agglomerans populations within wounds did not increase.     

己醛熏蒸对脐橙果实侵染性病害和生理性病害的影响

以脐橙为原料,研究了不同剂量的己醛熏蒸对采后脐橙果实常见侵染性病害和生理性病害的影响。果实损伤接种的实验结果表明,与对照组相比,先己醛熏蒸后接种病原菌对脐橙果实采后侵染性病害的控病效果不显著;而先接种病原菌后己醛熏蒸对侵染性病害的控制效果与己醛剂量有关。50、100 μL/L己醛熏蒸能显著降低果实青霉病、绿霉病、炭疽病的发病率和病斑直径,其中100 μL/L的己醛效果最好。同时100 μL/L的己醛也可以显著抑制脐橙果实自然发病率的上升。果实生理性病害的研究表明,低剂量（50、100 μL/L）己醛熏蒸与对照相比差异不显著,而高剂量（150 μL/L）的己醛熏蒸会促进酚类物质的氧化,造成果皮的褐变和塌陷,加重果实生理性病害的发生。     

不同发育期椪柑精油对意大利青霉和指状青霉的抑制作用

对不同发育期（7、8、9和10月）的椪柑（CitrusreticulataBlanco）果皮精油进行GC-MS分析,共鉴定出柠檬烯（47.28%～58.40%）、γ-松油烯（8.27%～13.23%）、β-芳樟醇（3.48%～7.86%）、β-月桂烯（6.24%～7.50%）、α-蒎烯（5.07%～6.05%）、β-蒎烯（2.30%～3.45%）和辛醛（2.04%～2.48%）等50种萜烯类化合物。椪柑果皮精油及其所含的6种潜在抑菌组分（柠檬醛、辛醛、壬醛、癸醛、β-芳樟醇和α-松油醇）的体外抑菌实验结果表明:不同发育期椪柑果皮精油对意大利青霉（Penicillium italicum）的抑制作用要强于指状青霉（P.digitatum）;潜在抑菌组分中柠檬醛和辛醛对意大利青霉的抑菌效果最好,壬醛和辛醛对指状青霉的抑菌效果最好。柠檬醛和辛醛对意大利青霉的最小抑菌浓度（MIC）、壬醛和辛醛对指状青霉的MIC均为0.50μL/mL;β-芳樟醇和α-松油醇对意大利青霉和指状青霉的MIC均为2.00μL/mL。      

MONILINIA AND RHIZOPUS DECAY CONTROL DURING CONTROLLED RIPENING OF FREESTONE PEACHES FOR CANNING

ABSTRACT— Decay was controlled when freestone peach fruit, harvested at various stages of maturity ranging from green to straw-color, were dipped in 50% 2,6-dichloro-4-nitroaniline (DCNA) at 1–1/2 and 4 lb/100 gal water and ripened for 5–17 days at 20°C and 90% R.H. Treated fruit had less than 10% decay while untreated fruit developed as much as 61% decay during this period. Regardless of treatment, straw-blush and full-blush fruit held for only 3 days did not develop decay. The most commonly occurring fungus pathogens, Monilinia fructicola and Rhizopus stolonifer, were controlled with these treatments. Postharvest DCNA plus captan dip treatments gave more effective decay control than from preharvest field sprays. Concentrations of DCNA or DCNA plus captan required for Monilinia decay control, suggested by preliminary laboratory tests on fruit, were verified by these commercial-size experiments.     

Antifungal activity of chitosan and its application to control post‐harvest quality and fungal rotting of Tankan citrus fruit (Citrus tankan Hayata)

In this study, the antifungal activity of chitosan A (MW = 92.1 kDa) and B (MW = 357.3 kDa), with 94.2% N‐deacetylation were examined at various concentrations against fungi including Penicillium digitatum, Penicillium italicum, Botrydiplodia lecanidion and Botrytis cinerea. The effectiveness of these chitosans to control the post‐harvest quality of Tankan fruit, a popular sub‐tropical citrus fruit, was investigated. It was found that chitosan, depending on type and concentration, caused 25.0–90.5% growth inhibition on test organisms after 5 days of cultivation at 24 °C. Chitosan treatment significantly reduced (P < 0.05) the percentage decay of Tankan fruit during storage at 24 °C. After 42 days of storage at 13 °C, chitosan‐coated Tankan fruits were firmer, exhibited less decay and weight loss, and showed higher titratable acidity, ascorbic acid, and total soluble solids than the control fruit. Weight loss of Tankan fruits decreased as the concentration of chitosan was increased. On the other hand, chitosan A, regardless of concentration tested, was found to be more effective in retaining the firmness, titratable acidity and water content, total solid content and ascorbic acid content of Tankan fruits than chitosan B. Copyright © 2006 Society of Chemical Industry     

Decontamination of strawberries using batch and continuous chlorine dioxide gas treatments

Efficacy of chlorine dioxide (ClO2) gas in reducing Escherichia coli O157:H7 and Listeria monocytogenes on strawberries was determined using batch and continuous flow ClO2 gas treatment systems. Effects of continuous ClO2 gas treatment on total aerobic plate count, color, and residual ClO2 and chlorite on strawberries were also evaluated. Strawberries were spot inoculated with 7 to 8 log CFU per strawberry of each pathogen (E. coli O157:H7 and L. monocytogenes), stored for 1 day at 4 degrees C, and treated at 22 degrees C and 90 to 95% relative humidity with 0.2 to 4.0 mg/liter ClO2 gas for 15 or 30 min using a batch treatment system or with 0.6, 1.8, and 3.0 mg/liter for 10 min using a continuous treatment system. Surviving microbial populations were determined using a membrane-transfer plating recovery method. Increased ClO2 gas concentrations resulted in increased log reductions of each pathogen for both the batch and continuous systems. A batch treatment of strawberries with 4 mg/liter ClO2 for 30 min and continuous treatment with 3 mg/liter ClO2 for 10 min achieved greater than a 5-log reduction for both E. coli O157:H7 and L. monocytogenes. After continuous exposure to 3.0 mg/liter ClO2 gas for 10 min followed by 1 week of storage at 4 degrees C, no aerobic microorganisms were detected and the color of the strawberry surface did not change significantly (P > 0.05). Residues of ClO2 and chlorite on strawberries after the treatment were 0.19 +/- 0.33 mg ClO2 per kg and 1.17 +/- 2.02 mg Cl2 per kg, respectively, whereas after 1 week of storage no ClO2 residues were detected and residual chlorite levels were down to 0.07 +/- 0.12 mg Cl2 per kg. These results suggest that ClO2 gas treatment is an effective decontamination technique for improving the safety of strawberries while extending shelf life.     

Combined effects of potassium sorbate,hot water and thiabendazole against green mould of citrus fruit and residue levels

Postharvest treatments of potassium sorbate only controlled recently established infections of Penicillium digitatum on Femminello siracusano lemons but did not confer any persistent protection. The loss of efficacy of potassium sorbate to control green mould decay was related to its irregular deposition on the fruit surface, as revealed by environmental scanning electron microscopy of oranges, and to the brief persistence of potassium sorbate residues. When treatment was done at 53 °C, the co-application of potassium sorbate with thiabendazole reduced thiabendazole residues in Moro and Sanguinello oranges, compared to thiabendazole treatment alone. However, treatment efficacy against two isolates of P. digitatum (thiabendazole-sensitive and thiabendazole-resistant) notably improved, indicating that potassium sorbate and hot water potentiated thiabendazole activity. Potassium sorbate residues remarkably decreased during fruit storage and were not affected by the co-application of thiabendazole.