Biological control of postharvest diseases of peach with Cryptococcus laurentii

Cryptococcus laurentii was evaluated for its activity in reducing postharvest gray mold decay, blue mold decay and Rhizopus decay of peach caused by Botrytis cinerea, Penicillium expansum and Rhizopus stolonifer respectively, and in reducing natural decay development of peach fruits. The concentrations of antagonist had significant effects on biocontrol effectiveness: the higher the concentrations of the antagonist, the lower the disease incidence. At concentrations of C. laurentii at 1 × 10⁹ CFU ml⁻¹, the gray mold decay was completely inhibited after 4 days incubation at 25 °C, while the control fruit had 50% decay, when inoculated with B. cinerea spores suspension of 1 × 10⁵ spores ml⁻¹; no complete control of the blue mold or Rhizopus mold was observed, when peach fruits were stored at 25 °C for 4 days (challenged with P. expansum) or 5 days (challenged with R. stolonifer) respectively, but the decay was distinctly prevented, the incidence of blue mold or Rhizopus mold was reduced by 78.6% or 80% respectively, compared with control, at challenged with P. expansum or R. stolonifer spores suspension of 5 × 10⁴ spores ml⁻¹, respectively. C. laurentii significantly reduced the natural development of decay and did not impair quality parameters of fruit following storage at 2 °C for 30 days followed by 20 °C for 7 days.     

Patulin accumulation in apples during postharvest: Effect of controlled atmosphere storage and fungicide treatments

The aim of this study was to assess the opportunities of Penicillium expansum to develop and produce patulin in apples under two different CA storage methods (LOW and U-LOW) at 1 °C. Differences in lesion diameter and patulin accumulation depending on CO₂ and O₂ partial pressure were studied. Further apple rot and patulin production during a three days post-storing stage at 20 °C was also monitored so that effect of further storage at room temperature could be assesed.Two lots of apples of Golden variety with different ripeness degrees were used. Half of each lot was fungicide treated. Apples were inoculated with patulin producer P. expansum strains and stored at 1 °C for either two month or 2.5 months at both LOW and U-LOW conditions. The extent of lesions and patulin accumulation both at the end of CA cold storage and after three days at 20 °C were assessed. CA storage conditions had strong significance in P. expansum growth on apples and factors such as fruit ripeness, fungicide treatment and time at the storage room had significant influence. In general, bigger lesions were observed under U-LOW than under LOW conditions, lesions being similar or bigger when increasing the storage time from 2 to 2.5 months. P. expansum grew faster in riper apples, although fungicide application was clearly more effective for ripe rather than for underripe apples. Although lesions were evident after both storage conditions, no patulin was detected. Increase of lesion when fruits were subsequently stored at 20 °C was evident in all cases and patulin was detected at this moment. No differences in patulin content were found at this stage between LOW and U-LOW stored apples.     

Octanal incorporated in postharvest wax of Satsuma mandarin fruit as a botanical fungicide against Penicillium digitatum

The antifungal activity of octanal against Penicillium digitatum, the causal agent of citrus green mold, was assessed by in vitro and in vivo experiments. In vitro assays results showed that the minimum inhibitory concentration and minimum fungicidal concentration (MFC) of octanal were 500 and 1000 μL/L, respectively. In vivo test results demonstrated that wax + octanal (WO; 2 × MFC) treatment but not WO (1 × MFC) treatment effectively inhibited the growth of P. digitatum after 6 d of storage at 25 ± 2 °C. The WO treatment remarkably increased the activities of antioxidant enzymes, such as catalase and superoxide dismutase, in Satsuma mandarin fruit. However, this treatment evidently decreased phenylalanine ammonia lyase activity and malondialdehyde content. The WO treatment also inhibited peroxidase activity and prevented hydrogen peroxide accumulation. Furthermore, the WO treatment did not impair the fruit quality parameters (vitamin C content, pH, coloration index, and total soluble solid content) of the tested fruit. This study provided theoretical data for the practical application of octanal to improve citrus fruit quality during postharvest storage.     

Ultraviolet-C light inactivation of Penicillium expansum on fruit surfaces

Understanding the influence of fruit surface morphology on ultraviolet-C (UV-C 254 nm) inactivation of microorganisms is required for designing effective treatment systems. In this study, we analyzed UV-C inactivation of Penicillium expansum that was inoculated onto the surface of organic fruits. Results show that maximum reductions of 1.8 (apple), 2.4 (cherry), 2.6 (strawberry) and 2.8 (raspberry) log CFU/g were observed after 1.2, 2.1, 3.3, and 3.3 kJ/m² of UV-C doses, respectively. The UV doses required to reduce 2 log CFU/g of P. expansum population on apples, cherries, strawberries, and raspberries estimated with the Weibull equation were 1.03, 1.28, 1.39, and 1.61 kJ/m², respectively. Findings also show that the hydrophobic nature of raspberries, along with high surface roughness, resulted in a lower inactivation rate of P. expansum. This study shows that UV-C effectively reduces P. expansum populations on fresh fruit surfaces; however, the efficacy of treatment is dependent on fruit surface morphology.     

Biotransformation of patulin to hydroascladiol by Lactobacillus plantarum

Growth of Penicillium expansum, an ubiquitous mould found in stored fruit globallyt, was significantly restricted by exposure to 48 h cell-free supernatant of two strains of Lactobacillus plantarum (p < 0.001). In addition, the biotransformation of patulin, a toxic secondary metabolite formed by P. expansum, on exposure to L. plantarum cells and cell-free supernatant highlights the potential of this GRAS microbe as a biocontrol agent. Up to 80% of patulin was biotransformed following a 4 h incubation with 10¹⁰ cells ml⁻¹ (37 °C) forming E- and Z-ascladiol. The formation of these products was more pronounced at elevated pH and cell density. Exposure to cell free supernatant or sonicated cells resulted in complete patulin biotransformation with heat treatment inhibiting this effect. The ascladiol isomers were then further transformed over a 4-week cell-free incubation (4 °C) into the novel metabolite hydroascladiol (5-(2-hydroxyethyl)-4-(hydroxymethyl) furan-2(5H)-one) which produced a 2 amu difference across the main tandem mass fragments (113.1, 129.0, 139.0), compared to ascladiol (111.1, 127.0, 137.0). This suggests hydroascladiol could be a better biomarker of initial patulin levels in some food commodities. The in vitro biotransformation data and resistance of L. plantarum to highly elevated concentrations of patulin (≥100 μg ml⁻¹) suggest L. plantarum is a potential candidate for food preservation or remediation strategies and future work with fruit products is proposed.     

Control of citrus blue mold by the antagonist yeast Pichia guilliermondii Z1: Compatibility with commercial fruit waxes and putative mechanisms of action

Pichia guilliermondii strain Z1, which was previously proven to be effective against blue mold of citrus fruit, has been further tested in controlled conditions to determine whether the yeast, as an alternative for synthetic fungicides, would be compatible with other postharvest practices used commercially. In particular, commercial fruit waxes can reduce their survival and effectiveness. The commercial fruit waxes tested, in combination at 20% with strain Z1, included microcrystalline, ester gum, candelilla, beeswax, montan, paraffin, rice bran, rosin maleic, carnauba, shellac, and one mixture shellac plus carnauba. Beeswax, paraffin, rosin maleic, carnauba, and shellac increased significantly strain Z1 survival in Petri dish assays. Candelilla, beeswax, rice bran, rosin maleic, carnauba, shellac, and shellac–carnauba mixture did not significantly reduce the strain Z1 yield on orange fruit surfaces compared to other waxes. With the exception of rosin maleic wax, none of the commercial fruit waxes or mixture increased significantly the ability of the formulated product of strain Z1 to control the postharvest pathogen Penicillium italicum on wounded orange fruit. When the formulated product of strain Z1 was used in combination with beeswax, strain Z1 retained the same efficacy. In contrast, microcrystalline, ester gum, candelilla, montan, paraffin, rice bran, carnauba, shellac, and shellac-carnauba mixture significantly reduced the effectiveness of the formulated product of strain Z1. No antibiosis was detected for strain Z1 against P. italicum. Strain Z1 inhibited the spore germination for the low juice concentration (up to 5%) when compared to the control. However, the addition of fresh juice after antagonist removal allowed the restoration of the germination of P. italicum spores; suggesting the possibility of competition for nutrients in the biocontrol activity of strain Z1. The study demonstrates the potential commercial application of strain Z1 with beeswax and rosin maleic wax for postharvest control of citrus blue mold. As biocontrol relies on competition for nutrients, an enriched formulation with nutrients is needed for reliable antifungal activity of this yeast strain.     

Comparing the effectiveness of chitosan and nanochitosan coatings on the quality of refrigerated silver carp fillets

The coating effects of chitosan and chitosan nanoparticles on the quality of silver carp (Hypophthalmicthys molitrix) fillets during refrigerated storage at 4 °C were compared. Solutions of Chitosan (2%, w/v) and nanochitosan (2%, w/v) were used for the coating. The control and the coated fish samples were analyzed periodically for microbiological (total mesophilic and psychrotrophic count), physicochemical (pH, TVB-N, TBARS), and sensory attributes. The results indicated that both chitosan and nanochitosan coating were effective for the preservation of silver carp fillets during refrigerated storage. However, nanochitosan exhibited higher antimicrobial activity than chitosan during the storage period. Furthermore, nanochitosan showed a stronger ability to inhibit the TVB-N content than chitosan. Therefore, to extend the shelf life and delay the deterioration of fresh silver carp fillets during refrigerated storage, nanochitosan coating is more effective.     

Growth or penetration of Salmonella into citrus fruit is not facilitated by natural-light labels

In natural-light labeling of fruits and vegetables, the desired information is etched onto the produce surface using a low-energy carbon dioxide laser beam (10,600 nm). Etched characters are formed by surface depressions in the epidermis that may facilitate entrance of decay and pathogenic organisms. The objective of this study was to determine the effects of natural-light labeling and different postharvest treatments on Salmonella populations' ability to survive/grow and penetrate into citrus fruit. A five-strain cocktail of Salmonella was spot inoculated onto Valencia orange in different application sequences with wax and natural-light etching. Samples were stored at 10, 26 °C, or combinations of both, for up to 42 days. Etched peels and corresponding juices were extracted from whole oranges following storage and enumerated for Salmonella. No set of conditions involving natural-light labeling promoted the growth of Salmonella on the fruit surface or resulted in the detection of Salmonella from the juice of sound fruit. Survival of Salmonella populations on the peel surface did not differ between any of the treatment and control samples. In all cases, Salmonella declined between 1.5 and 3.0 log CFU/orange after 30 days, with faster decline noted at 10 °C. Based on the data obtained from all treatments and under conditions extremely unfavorable and unrealistic in terms of fruit storage, natural-light labeling citrus fruit peels and subsequent waxing in any order did not allow for the growth or influence the natural decline of Salmonella populations on citrus fruit surfaces, or movement into juices, as compared to controls.     

Studying the effect of combining two nonconventional treatments,gamma irradiation and the application of an edible coating,on the postharvest quality of tamarillo (Solanum betaceum Cav.) fruits

The effect of the combination of gamma irradiation with gamma rays and a commercial edible coating, Sta-Fresh 2505, on the postharvest quality of golden-yellow and purple-red tamarillo (Solanum betaceum Cav.) fruits was studied. Irradiation and edible coating were used because these are technologies that fulfill the consumer trend to buy fresh fruits while assuring food safety and prolonging shelf life.Weight loss, pH, firmness, soluble solids content, respiration rate, pulp appearance, sensory hardness, aroma, and off-flavor were analyzed. The irradiated fruits and the irradiated fruits with edible coating were stored up to 10 weeks at 5 °C and 90% RH plus 7 days at 20 °C and 80% relative humidity (RH), to simulate shelf life. The combination of the edible coating and irradiation at 500 Gy maintained the postharvest properties of the fruit. Weight loss was reduced up to 48% compare to the control. Firmness and appearance were 70 and 40% higher than the control, respectively. The respiration rate was 30% lower than the control. The combination of gamma irradiation and edible coating had a synergetic effect on the postharvest quality of tamarillo.     

Effects of integrated treatment of nonthermal UV-C light and different antimicrobial wash on Salmonella enterica on plum tomatoes

The aim of this study was to evaluate inactivation of inoculated Salmonella enterica on whole tomato surface exploiting integration of nonthermal ultraviolet light (UV-C) treatment with antimicrobial wash. The effect of combined treatment on background microflora (aerobic mesophilic, and yeast and mold), during storage at ambient temperature (22 °C) for 21 days was also determined. A bacterial cocktail containing three serotypes of S. enterica (S. Newport H1275, S. Stanley H0558, and S. Montevideo G4639) was used based on their association with produce-related outbreaks. Tomatoes were spot inoculated using approximately 100 μL of inocula to achieve cell population of about 10⁷ CFU/tomato. An inoculated tomato was initially treated with a low (0.6 kJ/m²) dose of UV-C light (253.7 nm) followed by immersion in selected sanitizing solution (700 ml) to wash under mild agitation (ca. 250 rpm) for 2 min at room temperature (22 °C). Inactivation efficacy of combined treatments varied widely depending on the sanitizer property. Combined UV-C plus aqueous ozone (1 ppm) provided 3.13 ± 0.47 log CFU/fruit Salmonella reduction which was significantly lower (p < 0.05) compared to the rest of the combination treatments; whereas the treatment of UV-C followed by immersion in a novel antimicrobial preparation ‘HEN’, formulated mixing hydrogen peroxide, EDTA and nisin provided the best log reduction (4.71 ± 0.25 log CFU/fruit). Organic acids (1%) or their binary mixtures, hydrogen peroxide (3%), and HEN provided greater than 4.0 log reductions for UV-C treated tomatoes. Treatments were effective in controlling native microbial loads as the total aerobic mesophilic organisms and the population of yeast and mold remained significantly (p < 0.05) low during storage compared to control. Findings from this study provide safe and effective post harvest intervention strategies for produce industry as an alternative to current chlorine based wash. These results may also help researchers design future decontamination studies.     

Combination of nisin and ε-polylysine with chitosan coating inhibits the white blush of fresh-cut carrots

Effects of the combination of nisin and ε-polylysine with chitosan coating on quality maintenance and white blush inhibition were investigated in fresh-cut carrots. Fresh-cut carrots were treated with 1% lactic acid solution (v/v), 1% chitosan solution (w/v), or 1% chitosan solution containing 64 μg/mL nisin and 250 μg/mL ε-polylysine (LA + CH + Nisin + ε-PL). The samples were packed in polyethylene plastic bags and stored at 4 °C for 9 days. Changes in sensory attributes, physicochemical indices, respiration rate, microbiological counts and white blush were measured. Results showed that LA + CH + Nisin + ε-PL significantly (P < 0.05) inhibited respiration rate, decline of ascorbic acid and growth of microorganism (yeast and mold, total viable counts, total coliforms counts, Staphylococcus aureus and Pseudomonas spp.), and increased total phenol content and phenylalanine ammonialyse (PAL) activity compared with the control after 9-day storage. It was also strongly effective in inhibiting the white blush of fresh-cut carrots. Furthermore, LA + CH + Nisin + ε-PL significantly (P < 0.05) reduced the lignin synthesis in fresh-cut carrots by inhibiting the cinnamate-4-hydroxylase (C4H) and 4-coumarate-CoA ligase (4CL) activity, as well as Dc4CL and DcC4H gene expression. Our results may provide some basis for the use of the combination of nisin and ε-polylysine with chitosan coating as an alternative preservation method for fresh-cut carrots.     

Microbiological evaluation of an edible antimicrobial coating on minimally processed carrots

This work aimed to develop an edible antimicrobial coating based on a starch–chitosan matrix to evaluate its effect on minimally processed carrot by means of microbiological analyses. Coatings based on 4% yam starch (w/w) + 2% glycerol (w/w) and coatings based on 4% yam starch (w/w) + 2% glycerol (w/w) + chitosan in 0.5% and 1.5% concentrations were prepared. Samples of minimally processed carrot slices were immersed into these coatings. All the samples were placed in expanded polystyrene trays, wrapped in polyvinylchloride film and stored at 10 °C/15 days. During storage, all the samples had counting <100 CFU/g for Staphylococcus aureus and <3 MPN/g for Escherichia coli. Starch + 0.5% chitosan coating controlled the growth of mesophilic aerobes, yeasts and molds and psychrotrophs during the first five days of storage, ultimately presenting reductions of only 0.64, 0.11 and 0.16 log cycles, respectively, compared to the control. Starch + 1.5% chitosan coated samples showed reductions in mesophilic aerobes, mold and yeast and psychrotrophic counting of 1.34, 2.50 and 1.30 log cycles, respectively, compared to the control. The presence of 1.5% chitosan in the coatings inhibited the growth of total coliforms and lactic acid bacteria throughout the storage period. The use of edible antimicrobial yam starch and chitosan coating is a viable alternative for controlling microbiological growth in minimally processed carrot.     

Effects of UV-C treatment on inactivation of Salmonella enterica and Escherichia coli O157:H7 on grape tomato surface and stem scars,microbial loads,and quality

The purpose of this study was to investigate the effectiveness of ultraviolet-C (UV-C) light inactivation as affected by the location of pathogens on the surface and at stem scars of whole grape tomatoes. A mixed bacterial cocktail containing a three strain mixture of Escherichia coli O157:H7 (C9490, E02128 and F00475) and a three serotype mixture of Salmonella enterica (S. Montevideo G4639, S. Newport H1275, and S. Stanley H0558) were used. Tomatoes were spot inoculated using approximately 100 μL of inocula to achieve a population of about 10^7±1 CFU/tomato. Additionally, the effects of treatment on color, texture, lycopene content, and background microbial loads during post UV-C storage at 4 °C for 21 days were determined. Results showed that UV-C doses of 0.60–6.0 kJ/m² resulted in 2.3–3.5 log CFU per fruit reduction of E. coli O157:H7 compared to 2.15–3.1 log CFU per fruit reduction for Salmonella on the surfaces. Under the same conditions, log reductions achieved at stem scar were 1.7–3.2 logs CFU for E. coli O157:H7 and 1.9–2.8 logs CFU for Salmonella. The treatment was effective in controlling native microbial loads during storage at 4 °C as the total aerobic mesophilic organisms (PCA) and anaerobic lactic acid bacteria (LAB) counts of treated tomatoes were significantly (p < 0.05) lower during storage compared to the control group and the yeast and mold populations were reduced significantly below the detection limit. Furthermore, the firmness of tomato and its color was not affected by the UV-C doses during storage. UV-C radiation could potentially be used for sanitizing fresh tomatoes and extending shelf-life. The results of this study indicate that the specific location of pathogens on the produce influences the effectiveness of UV-C treatment, which should be taken into consideration for the design of UV-C systems for produce sanitization.     

Assessment of Penicillium expansum and Escherichia coli transfer from poplar crates to apples

Poplar crates are widely used in contact with foodstuffs. One of the major markets for poplar crates is apple packaging. As a direct food contact material, wood is subject to European regulation n° 1935/2004, which requires no negative effect of material or packaging on foodstuffs. This study aims to quantify the transfer of Penicillium expansum conidia and Escherichia coli from poplar specimens to Golden apples. This [microorganisms-poplar-Golden apple] model was developed taking into account realistic parameters with extreme and usual conditions. Poplar specimens were artificially contaminated with P. expansum and E. coli. They were then put in contact with apples and stored in a climatic room for up to one week. Both wood specimens and apples were analyzed to assess the survival of microorganisms on wood specimens and the proportion of microorganism transfer to apples. Whereas P. expansum conidia survived but did not grow on wood specimens, E. coli mortality was observed after one hour of contact with wood. The proportion of both microorganisms transferred to apples was less than 0.25%. The impact of wood moisture content, contact time between wood and apples, and apple supply variability on the transfer levels were studied. The hygroscopic properties of wood were discussed. The low and reproducible transfer levels observed demonstrate that poplar is a safe packaging material for apples.     

Chitosan combined with calcium chloride impacts fresh-cut honeydew melon by stabilising nanostructures of sodium-carbonate-soluble pectin

Effects of chitosan, calcium chloride, and their combination on preventing quality and safety deterioration of postharvest fresh-cut honeydew melon at 7 °C were investigated. Treatments of all these three delayed weight loss, improved firmness, delayed colour changes and moderately inhibited microbial growth. Interestingly, combined treatment of chitosan and calcium chloride was the most effective, leading to 40% less weight loss, 45% (3.70 N) increase in firmness, less overall colour difference, and more than 0.5 log CFU/g inhibition on mesophilic and psychrotropic growths on day 13 of storage as compared to control group. In addition, these treatments also inhibited degradation of pectin chains. Nanostructural analysis of fruit pectin via atomic force microscopy (AFM) indicated that firmness was closely related to the nanostructure of sodium carbonate-soluble pectin (SSP). Short and narrow SSP chains were observed more in samples with less firmness. We conclude that edible coating of chitosan combined with calcium chloride treatment synergistically extends the shelf-life of fresh-cut honeydew melon by maintaining the integrity of SSP via interactions between SSP and calcium ions or protonated chitosan groups.     

Synergistic action between fractions of essential oils from Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris against Penicillium expansum

Penicillium expansum is a mould that causes the rotting of several fruits and vegetables, especially apples onto which it also synthesizes some dangerous mycotoxins. The degree of synergism between fractions of essential from Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris was evaluated against two mycotoxin producing strains of P. expansum. The antifungal activity determined by dilution method and expressed as a Number of Decimal Reduction of the colony forming units per ml (NDR cfu) showed that the essential oils extracted from O. gratissimum was significantly (P < 0.05) more active against P. expansum than those extracted from C. citratus and T. vulgaris. Fractions enriched with oxygenated terpenes were significantly (P < 0.05) more active than their respective essential oils, whereas most of the fractions enriched with terpene hydrocarbons, were significantly (P < 0.05) less active. The fungicidal activity of mixtures of fractions from the same essential oils or from two different essential oils showed that there exist synergistic, additive and antagonistic effects between fractions of the three essential oils tested against both fungal strains. The synergistic effects observed could be exploited in order to maximize the antimicrobial activity of essential oils and to minimize the concentrations of essential oil required to produce a given antimicrobial effect without any alteration of the food test.     

High pressure processing,thermal processing and freezing of ‘Camarosa’ strawberry for the inactivation of polyphenoloxidase and control of browning

Polyphenoloxidase (PPO) is an enzyme present in strawberry (Fragaria ananassa) which causes undesirable fruit browning, especially if the fruit is cut in pieces or processed into puree. High Pressure Processing (HPP) is an emerging non-thermal food preservation technology with minimum impact on the food original sensory, functional and nutritional properties. As an alternative to conventional freezing/frozen storage of strawberry, the inactivation of PPO in ‘Camarosa’ strawberry puree by HPP (200 MPa and 600 MPa), thermal processing (29–71 °C) and their combination was attempted for 5 and 15 min processing times. The effect of conventional thermal processing and freezing/frozen storage (−18 °C and −70 °C) for 1 month on PPO was also investigated in puree and whole fruit. Room temperature processing at 600 MPa for 5 min and 15 min resulted in 35% and 82% PPO inactivation, respectively. A 5 min process of 600 MPa in combination with mild heat (40–60 °C) resulted in 9–65% residual activity as opposed to 44–100% with exclusively thermal processing. 200 MPa had minor effect on PPO. Thermal preservation of puree than whole fruit is preferable, whereas frozen storage of whole fruit than puree is better for avoiding strawberry browning. ‘Camarosa’ strawberry PPO is less resistant to pressure inactivation and more appropriate for HPP technology than ‘Elsanta’, ‘Aroma’ and ‘Festival’ strawberry cultivars.     

Microemulsification of clove essential oil improves its in vitro and in vivo control of Penicillium digitatum

Clove essential oil (CEO) is a promising alternative to chemical fungicides for postharvest decay control. However, relatively high concentrations required for in vivo microbial growth inhibition limit its application. Hence, this study aimed to strengthen the antifungal activity of CEO by loading it in microemulsion system. Two CEO microemulsions (ME-1, CEO/ethanol/Tween 80 = 1:2:7; ME-2, CEO/ethanol/Tween 80 = 1:3:6) were evaluated their antifungal activity against Penicillium digitatum in vitro and in navel oranges. Microemulsification of CEO caused a reduction of MIC (minimum inhibitory concentration) from 0.50 μl/ml to 0.25 μl/ml, while the MFC (minimum fungicidal concentration) remained unchanged at 0.50 μl/ml, indicating enhancement of only fungistatic activity. The decay incidence of navel oranges treated with ME-1 and ME-2 was significantly (p < 0.05) reduced by 34.51% and 20.93%, respectively, in comparison to that of pure oil treatment after 5 days' storage at 25 °C. In the vapor phase, CEO microemulsions had the best control of lesion diameter and decay development. Additionally, the improved antifungal activity of CEO microemulsions may be related to their stronger ability to suppress spore germination and germ tube elongation of P. digitatum. The enhanced control of postharvest green mold of navel oranges by CEO after microemulsification can broaden its application in food industry.     

Improved control of postharvest decay in Chinese bayberries by a combination treatment of ethanol vapor with hot air

The effect of ethanol vapor treatment (EVT, 250 or 500 μL L^?1 for 3 h) alone or in combination with hot air treatment (HAT, 48 °C for 3 h) on postharvest decay and microbial loads in Chinese bayberries was investigated. Treatment with ethanol vapor or hot air alone both resulted in significantly lower decay incidence caused by Verticicladiella abietina, Penicillium citrinum or Trichoderma viride compared with the control. The combined treatment of 500 μL L^?1 ethanol vapor with hot air showed the lowest incidence of fruit decay caused by these pathogens. This treatment also significantly inhibited spore germination and germ tube elongation of the pathogens in vitro than EVT or HAT alone. Meanwhile, the combined treatment exhibited the lowest natural decay incidence and microbial loads on Chinese bayberries without impairing fruit quality. These results suggest the usefulness of the combined treatment for reducing fruit decay in Chinese bayberries.     

Antifungal effect of poly(lactic acid) films containing thymol and R-(-)-carvone against anthracnose pathogens isolated from avocado and citrus

Biodegradable antifungal films were developed to be used for controlling postharvest anthracnose pathogens. Two antifungal compounds, thymol and R-(-)-carvone, were incorporated into poly(lactic acid) (PLA)-based polymer at 10, 15 and 20% (w/w). Antifungal activity of the pure compounds and the antifungal films against Colletotrichum gloeosporioides isolated from avocado and citrus was evaluated at 12 and 25 °C using vapor diffusion assays. The results indicated that the colony diameter was affected by the vapor concentration of the antifungal compounds in the headspace. At 12 °C, 20% thymol showed complete growth reduction of avocado isolate, while at 25 °C, 15 and 20% thymol showed complete growth reduction of both avocado and citrus isolates. The PLA films incorporated with 15% R-(-)-carvone and 20% thymol were the most effective at 12 °C in suppressing the mycelial growth of the avocado and citrus C. gloeosporioides isolates, respectively, whereas the film incorporated with 20% thymol had the highest antifungal activity against both anthracnose isolates at 25 °C. The inhibitory effect of the antifungal films against anthracnose isolates was correlated to the vapor concentration of the antifungal compounds remaining in the headspace of the Petri dish. Antifungal packaging films can potentially be used to control postharvest pathogens of fresh produce.