Pear Surfaces Research Articles

Total Plate Count of Germs on Pear Surface Swabs During Washing with Fruit Washing Soap

The surface of the fruit is the first contamination of microorganisms on fruit with varying types and amounts. As many as 20% of cases of food poisoning caused by Salmonella typhi were recorded as a result of the consumption of fresh ready-to-eat products such as fruits. Washing the fruits that will be consumed is a good step, so a fruit washing soap product is used that can clean the fruits from these bacteria. Nonionic surfactants are cleaning agents found in fruit washing soaps that can remove bacteria on surfaces. The purpose of this study was to determine the difference in the total plate number of germs on the surface of pears when washing with fruit washing soap. The research method used in this research is descriptive method. The population is 50 soaps taken from 5 shops in the Harapan Baru market in Samarinda with different soap brands. The sample taken is 10% of the total population, namely 5 soaps. The sampling technique used purposive sampling. The study was carried out in July 2022. The method of examination used the examination of the TPC (Total Plate Count) with the pour plate method using PCA (Plate Count Agar) media. The data analysis used is univariate analysis which aims to explain the characteristics of each research variable by looking at the frequency distribution. The results showed that the number of bacteria before washing with fruit washing soap ranged from 4.4 x 100 CFU/cm2 to 1.4 x 101 CFU/cm2. Meanwhile, the number of bacteria after washing with fruit washing soap ranged from 0.4 x 100 CFU/cm2 to 3.4 x 100 CFU/cm2. The conclusion of this study is that there are differences in the number of total bacterial plate count on the surface of pears when washing with fruit washing soap.

The Biophysical Properties of the Fruit Cuticles of Six Pear Cultivars during Postharvest Ripening

Pears are abundant in bioactive compounds, which exert favorable effects on human health. The biophysical attributes of fruit cuticles are pivotal in determining fruit quality, storability, and susceptibility to mold growth. This study aimed to elucidate the biophysical properties of six pear cultivars, ‘Conference’, ‘Celina’, ‘Abate Fetel’, ‘Packham’s Triumph’, ‘Sweet Sensation’, and ‘Williams’. Two maturity stages, unripe and fully ripened, were investigated. Furthermore, the efficacy of trimethyl-chitosan-coated pear surfaces in preventing Penicillium expansum (P. expansum) growth was assessed. Basic maturity indices (CIE color, ethylene evolution, firmness, soluble solids), cuticle contact angle, roughness, and zeta potential were analyzed. Surface roughness was measured using an optical profilometer, hydrophobicity was measured via profilometry, and zeta potential was quantified using an electrokinetic analyzer. The ‘Celina’ cultivar exhibited the highest roughness, whereas ‘Williams’ had the lowest roughness. All the cultivars’ cuticles demonstrated hydrophilic characteristics, with contact angles ranging between 65° and 90°. For pH values exceeding 3.5, all pear surfaces exhibited a negative zeta potential. P. expansum growth was the slowest on the ‘Packham’s Triumph’ and ‘Conference’ cultivars. Treatment with trimethyl chitosan effectively inhibited P. expansum growth in the initial hours of incubation. In conclusion, diverse pear cultivars manifest distinct biophysical surface properties and varying susceptibility to P. expansum growth. The growth of P. expansum correlates positively with roughness, contact angle, and zeta potential. These differences can significantly impact shelf life potential and the overall postharvest quality of pears.

Ceratocystis fimbriata Causing Postharvest Fruit Rot of Pear in Punjab, Pakistan.

Pear (Pyrus communis) is an important deciduous fruit cultivated on a worldwide scale including Pakistan. During August 2021, a postharvest fruit rot disease was observed on several pears at various farmers market in Okara- a district of Punjab Province, Pakistan. The incidence of the disease varied from 7 to 20% with 35% disease severity. Necrotic spots (10 to 20 mm diameter) were first observed on the infected pear fruit. The spots enlarged gradually and developed into a brown, water-soaked and rotted lesion. Eventually, the whole fruit became soft, rotted and covered with a gray-brown mycelium. The isolates were obtained from the symptomatic tissues (n = 18) incubated on carrot discs that had been surface sterilized in 100-ppm streptomycin solution. After consistent sporulation of a fungus on the carrot discs, the ascospore masses formed at the tip of perithecia were transferred to malt extract agar (MEA). Primary conidia were cylindrical and hyaline (7 to 11 × 4 to 7 μm) and secondary conidia were hyaline and barrel-shaped (7 to 12 × 5 to 8 μm). Endoconidiophores with primary conidia were (12 to 27 × 2.6 to 5.5 μm). Perithecia produced on carrot discs were dark brown to black, and the base was 157 to 278 μm in diameter. Ascomatal necks were 512 to 656 µm long, dark brown to black, lighter in color at apices, tapering from base (23 to 45 μm diameter) to apex (13 to 24 μm diameter). Ostiolar hyphae were 41 to 79 μm long. Ascospores were hyaline, hat shaped, 3 to 4 μm long, and accumulated in a sticky matrix at the tips of perithecial necks. Mycelium was initially hyaline but became dark greenish brown after 7 days. Dark brown, thick-walled aleuroconidia (13 to 19.5 × 9 to 14 μm) appeared on culture plates after 2 months. Based on morphological characteristics, the fungus was identified as Ceratocystis fimbriata (Engelbrecht, 2005; Suwandi et al. 2021). To further confirm species identification, genomic DNA of two representative isolates (UO-05 and UO-06) was obtained using an extraction kit. The internal transcribed spacer (ITS) region was amplified using ITS1/4 (White et al. 1990). A BLAST search with GenBank accession nos. OR185451 and OR185456 indicated 99 to 100% identity with several C. fimbriata including type species (MH856050.1; KC493160.1; MT560374.1). Pathogenicity tests were conducted by inoculating nine disease-free pear (cv. Concord) fruit after disinfesting in 75% ethanol. A prepared spore suspension (1.0 × 106 spores/ml) was dropped on the wounds (a depth of 1 mm diameter) on the pear surface, which were made by a sterilized needle. 10 μl of a prepared spore suspension was dropped onto nine pears. Sterile water (10 μl) was dropped on the wounded sites of nine pear fruits as negative controls and all fruits were incubated in a growth chamber at 30/26°C (day/night, 90% relative humidity). Symptoms similar to those on the naturally infected fruits began after 4 to 5 days of inoculation, while controls remained healthy. The fungal isolates recovered from inoculated pears were morphologically identical to the C. fimbriata isolates originally recovered from symptomatic fruits fulfilling Koch's postulates. The pathogen has been reported to cause postharvest fruit rot of passion fruit and cucumber (Firmino et al. 2016; Li et al. 2019). To our knowledge, this is the first report of C. fimbriata causing fruit rot of pear in Punjab Province. The detection of this disease will help pear growers to take actions to monitor and prevent disease outbreak as well as develop an effective management practice when it occurs.

An Alternative Method to Evaluate Resistance to Pear Scab (Venturia nashicola).

Two pear cultivars with different degrees of resistance to Venturia nashicola were evaluated on the basis of a disease severity rating for pear scab resistance under controlled environmental condition. Two inoculation techniques were tested: the procedure for inoculation by dropping conidia suspension of V. nashicola; the procedure by deposition of agar plug on the abaxial surface of pear leaves. All tested cultivars resulted in blight symptoms on the inoculated leaves and became spread to uninoculated region or other leaves. Although both methods provide satisfactory infection of V. nashicola on pear leaves, the mycelial plug method of inoculation was more reliable than the spray inoculation method for the evaluation of pear scab disease resistance. The incubation period of V. nashicola in the resistant pear cultivar, Greensis was longer than that in the susceptible cultivar, Hwasan.

Spatial Frequency Domain Imaging System Calibration, Correction and Application for Pear Surface Damage Detection.

Spatial frequency domain imaging (SFDI) is a non-contact wide-field optical imaging technique for optical property detection. This study aimed to establish an SFDI system and investigate the effects of system calibration, error analysis and correction on the measurement of optical properties. Optical parameter characteristic measurements of normal pears with three different damage types were performed using the calibrated system. The obtained absorption coefficient μa and the reduced scattering coefficient μ’s were used for discriminating pears with different surface damage using a linear discriminant analysis model. The results showed that at 527 nm and 675 nm, the pears’ quadruple classification (normal, bruised, scratched and abraded) accuracy using the SFDI technique was 92.5% and 83.8%, respectively, which has an advantage compared with the conventional planar light classification results of 82.5% and 77.5%. The three-way classification (normal, minor damage and serious damage) SFDI technique was as high as 100% and 98.8% at 527 nm and 675 nm, respectively, while the classification accuracy of conventional planar light was 93.8% and 93.8%, respectively. The results of this study indicated that SFDI has the potential to detect different damage types in fruit and that the SFDI technique has a promising future in agricultural product quality inspection in further research.

Quantitative SERS sensor based on self-assembled Au@Ag heterogeneous nanocuboids monolayer with high enhancement factor for practical quantitative detection.

Accurate and rapid quantitative detection of pesticide and pollutant levels in the actual sample can aid in protecting food security, environmental security, and human health. A high Raman enhancement factor and good repeatability of the surface-enhanced Raman spectroscopy (SERS) substrates are favorable to quantitative analysis. Herein, a quantitative SERS sensor based on constructed self-assembled plasmonic Au@Ag heterogeneous nanocuboids (Au@Ag NCs) monolayer was developed. The sensor was used to quantitatively detect the trace pesticides extracted from pear surfaces and pollutants in fishpond water. Densely packed Au@Ag NCs fabricated into large-scale monolayer films were chemically functionalized using 4-methyl-thiobenzoic acid (4-MBA) at the organic/aqueous interface, in which plentiful nanogaps contribute to increase hotspots. Their sharp corners and edges make the sensor have high SERS performance through providing abundant "hot spots." The obtained optically SERS-based sensor with uniform liquid-state interfacial nanoparticle arrays appeared to have nice SERS performance and uniformity using crystal violet (CV) as a probe molecule. In particular, the proposed SERS sensor was applied for quantitative detection of thiabendazole (TBZ) extracted from pear surfaces and malachite green (MG) in fishpond water down to levels of 0.0105nM and 0.87nM for SERS assay respectively. As a result, our proposed SERS quantitative detection strategy is quite preferred to on-site analysis and supervision of contaminant in food samples.

First Report of Phytophthora lacustris Causing a Fruit Rot of Bartlett Pear in North America

A major portion of Bartlett pears (Pyrus communis ‘Williams’) in the United States are produced in California. A fruit rot with symptoms similar to sprinkler rot caused by several Phytophthora spp. (Grove and Boal 1991) was observed in August 2017 and 2018 in an orchard in Ukiah Valley, Mendocino Co., California (N39°05′, W123°10′), where trees were irrigated by over-canopy sprinklers with water from the Russian River. Symptomatic pears were present throughout the canopy of trees, with ∼5% of fruit in the orchard affected. Symptoms initially appeared as small (5 to 10 mm in diameter), firm, light brown lesions with a diffuse margin on the exocarp. Lesions gradually expanded, covering 80 to 100% of the fruit surface, and darkened to almost black in color but remained firm. The mesocarp of infected fruit subsequently turned brown. To isolate the causal pathogen, the exocarp from 10 randomly collected infected fruit/year was removed aseptically, and 3 × 3 × 2-mm pieces of the mesocarp from the edge of lesions were placed onto a Phytophthora-selective agar medium (PARHFB-5% V8C; Hao et al. 2018). Colonies resembling a Phytophthora species consistently developed from every fruit after 5 to 7 days of incubation at 25°C in the dark. Two and four isolates obtained in 2017 and 2018, respectively, were further characterized. All isolates developed a similar petaloid mycelial growth pattern; sporangia, chlamydospores, hyphal swellings, or oospores were not observed on 5% V8C agar after 2 months. Abundant sporangia and zoospores, however, were produced in liquid culture following the protocol of Adaskaveg et al. (2015). All isolates produced nonpapillate, noncaducous sporangia from long (usually >300 μm) unbranched sporangiophores. Sporangia were mostly ovoid, varying in size (n = 60) from 38.0 to 56.0 μm (length) × 22.5 to 38.0 μm (width) (mean 43.5 × 28.6 μm) with a length/breadth ratio ranging from 1.14 to 1.83 (mean 1.52). Internal proliferation of sporangia was observed in all isolates. The sequences of ribosomal DNA internal transcribed spacers (ITS) 1 and 2 amplified with primers ITS6/ITS4 (Cooke et al. 2000) and cytochrome oxidase subunit 1 (cox 1) amplified with primers COXF4N/COXR4N (Kroon et al. 2004) of the six isolates were compared with sequences in GenBank. All were identified as Phytophthora lacustris Brasier, Cacciola, Nechw., Jung & Bakonyi based on 99% identity to the type strain P245 (Nechwatal et al. 2013; accession nos. AF266793 and JF896561 for ITS and cox 1 regions, respectively). ITS and cox 1 sequences were deposited in GenBank with accession numbers MN464235 and MN464236, and MN477337 and MN477338, for isolates 5721 and 5723, respectively. In two repeated pathogenicity tests, 30-µl drops of a zoospore suspension (1 × 10⁴ to 4 × 10⁴ zoospores/ml) of each of the six isolates of P. lacustris were pipetted onto the nonwounded surface of Bartlett pears (three drops per pear ∼15 mm apart). Fruit were placed into commercial fruit trays in enclosed plastic boxes in a randomized complete block design with two replicate fruit for each isolate and incubated at 25 ± 2°C and >95% relative humidity in the dark for 7 to 14 days. All six isolates caused brown lesions similar to those observed in the field. The pathogen was reisolated from all inoculated fruit and confirmed to be P. lacustris by ITS sequencing, completing Koch’s postulates. P. lacustris was previously isolated from necrotic roots of Alnus glutinosa, Prunus spp., Salix matsudana, and other tree species growing in flooded conditions (Nechwatal et al. 2013). It was also reported to cause a fruit rot of Bosc pear in Argentina (Sosa et al. 2015). This is the first report of P. lacustris causing a fruit rot of Bartlett pear in California. Because P. lacustris may be an opportunistic pathogen in wet habitats (Nechwatal et al. 2013) and has also been isolated from river water (Brazee et al. 2016), proper irrigation methods using pathogen-free water may effectively manage this disease.

Rapid nondestructive detection of mixed pesticides residues on fruit surface using SERS combined with self-modeling mixture analysis method

Mixed pesticides are usually applied to agricultural products to enhance agricultural production. However, their presence in the environment and food poses serious health risks to humans. Therefore, rapid and reliable detection methods for mixed pesticides residues are in need to minimize potential health hazards. Herein, a nondestructive and sensitive strategy was developed to determine thiram and thiabendazole (TBZ) mixture on fruit surface using surface-enhanced Raman spectroscopy (SERS) technology coupled with interfacial self-assembly gold nanorods (Au NRs) array substrates together with self-modelling mixture analysis (SMA) method. Firstly, a large area high-density Au NRs array was fabricated by organic-aqueous interfacial self-assembly to serve as a sensitive SERS substrate for simultaneously screening of thiram and TBZ on the fruit surface. Then, an SMA method was employed to identify and separate the Raman spectrum for each pesticide from the Raman spectra of the pesticides mixture on the contaminated fruit surface. Results showed that using SERS technique with the SMA method, qualitative and quantitative analyses of a single component from the spectra of the mixture were simultaneously realized, and the resolved pure spectrum of each pesticide was presented. The limits of detection (LOD) of pesticides on the surface of apple, tomato and pear were 0.041, 0.029 and 0.047 ng/cm2 for thiram, and 0.79, 0.76 and 0.80 ng/cm2 for TBZ, respectively. It was anticipated that the proposed SERS detection approach combined with SMA methods should pave the way for detecting multi-analytes in practical applications for agriculture and food safety inspection.

Effect of natural light on the phenolic compounds contents and coloration in the peel of ‘Xiyanghong’ (Pyrus bretschneideri×Pyrus communis)

Pear (Pyrus) is one of the most important fruit trees in the world. As an important pear cultivar, ‘Xiyanghong’ (P. bretschneideri × P. communis) is widely cultivated. However, its red skin is commonly occurred in the light exposed part, which restrictes its commercial value. Here, to investigate the effect of natural light on coloration and the phenolic compounds of the ‘Xiyanghong’ peel, the bag surface of bagged pears was cut to expose the peel to natural light, and exposed peel versus bagged peel were compared. The results showed that the exposed peel started to be colored in red at 57 days after full bloom (DAFB) and kept in red until the final stage, while the bagged peel was not colored among all stages. Anthocyanin content of exposed skin was significantly higher than that of bagged skin at the 57 DAFB and the following two stages. This similar higher level in exposed skin was also observed in the contents of other five phenolic compounds, including syringic acid, gallic acid, procyanidin B2, quercetin-3-galactoside, and quercetin-3-rutinoside. In addition, the expression of pathway genes, PAL, CHS, CHI, F3H, DFR, ANS, and UFGT, correlated highly with anthocyanin accumulation. And the expression of regulative genes MYB10, bHLH3, and light response gene HY5 were also with a consistent trend at 57 DAFB. These results will contribute to an improved understanding of the mechanism of red pears response for light, and will aid development of new cultivation techniques to improve coloration and quality of pear.

Determination of Chlorpyrifos in Pears by Raman Spectroscopy with Random Forest Regression Analysis

Pesticide detection has been a long-running concern within the agricultural industry. Therefore, rapid and accurate detection techniques are required. Raman spectroscopy is favored by scientists due to the rapid detection without the need for the pretreatment or destruction of samples. However, the accuracy of the quantitative analysis that is based on Raman spectra is related to the detection model and analysis algorithm. In this study, random forest regression (RFR) was employed to construct a quantitative detection model that correlated the Raman spectral intensity of chlorpyrifos at 341 cm−1 and the chlorpyrifos concentration remaining on the pear surface. RFR performs better than partial least square regression (PLSR). The correlation coefficient (R2) of RFR was 0.9003 and 0.8495 for the training and test sets, respectively. In particular, the R2 value of the test sets was significantly higher than for PLSR (R2 of 0.6985). The intensity of the Raman spectra at 341 cm−1 was improved by four-fold using 100 nm gold nanoparticles. The results show that Raman spectroscopy combined with RFR achieves the rapid and accurate quantitative determination of pesticide residues.

High-efficiency texture coding and synthesis on point-based pear surface

© 2017 IOS Press and the authors. The fruit images on points cloud acquired by the current 3D scanner from field will appear a visible seams, inconvenient data acquisition or taking large space due to unorganized background. We give a SAOW method to cope with the space efficiency and realistic effects of texture synthesis on pear point model. At first, a point-quadtree is proposed to simplify the pear image division. Then, an adaptive multi-granularity morton coding scheme are presented to optimizing the memory space of pear image. At last, weighted oversampling mixing method is mainly focused on texture quality of pear surface. As shown in the experiment results, our adaptive division makes the memory space decline dramatically about 90.7% than non-division and 92.9% than general division respectively; adaptive code scheme helps to reduce the memory to 72.1% of ordinary morton code; weighted oversampling keeps the mixed texture more real and smoothly than current methods.

Development of fruit diseases of microbial origin during storage at treatment with antioxidant compositions

Present study addresses scientific substantiation of appropriateness of conducting after-harvesting treatment with antioxidant compositions for preventing the development of pathogenic microflora on the surface of fruits during long-term storage. We examined the fruits of apple of the varieties Idared, Golden Delicious, Simirenko Renet, the fruits of pear of the varieties Victoria, Izyuminka Crimea and Cure, the fruits of plum of the varieties Voloshka, Stanley, and Ugorka Italian. The fruits were treated by immersion in the following antioxidant compositions: ACM is a mixture of dimethylsulfoxide, ionol and polyethylene glycols; AARL is a mixture of ascorbic acid, rutine and lecithin; DL is a mixture of dimethylsulfoxide, ionol and lecithin. Control fruits were treated with water. Exposure is 10 seconds. Storage was maintained at a temperature of 0±1 oC, at relative air humidity 90–95 %. It was established that during preparation of fruits for storing, the largest mean population of epiphytic microflora was registered on the surface of plums and pears with medium term of ripening. The species composition of epiphytic microflora was dominated by spores of mesophilic aerobic and facultative anaerobic microorganisms. Their mean population on the surface of apples was 9.6•103 cfu/g, on the surface of plums – 18•103 cfu/g. Treating all kinds of fruit with AOC significantly decreased speed of growth of both MAFAnM and micromycetes. It is shown that the application of composition reduced the level of daily losses from microbiological diseases over the entire period of storage by 2...3.5 times. The largest positive effect was obtained when applying the composition based on dystynol and lecithin. By performing a multi-factor analysis, it was revealed that the level of daily losses from microbiological diseases during storage was affected by the dominant influence of factors of generic features of fruit raw materials (factor A) and treatment with antioxidant compositions (factor D). The shares of influence are, respectively, 24 and 21 %

Cellulose Nanocrystal Reinforced Chitosan Coatings for Improving the Storability of Postharvest Pears Under Both Ambient and Cold Storages.

Cellulose nanocrystal (CNC, 0%, 5%, and 10% w/w, in chitosan, dry basis) reinforced 2% chitosan aqueous coatings were evaluated for delaying the ripening and quality deterioration of postharvest green D'Anjou (Pyrus communis L.) and Bartlett (Pyrus communis L.) pears during 3 wk of ambient storage (20 ± 2 °C and 30 ± 2% RH) or 5 mo of cold storage (-1.1 °C and 90% RH), respectively. Ethylene and CO2 production, color, firmness, and internal fruit quality were monitored during both storage conditions. Moisture and gas barrier, antibacterial activity, and surface morphology of the derived films were also evaluated to investigate the mechanisms of delayed fruit ripening and quality deterioration. In the ambient storage study, the 5% CNC reinforced chitosan coating significantly (P < 0.05) delayed green chlorophyll degradation of pear peels, prevented internal browning, reduced senescence scalding, and improved retained fruit firmness. During cold storage, the 5% CNC reinforced chitosan coating showed a competitive effect on delaying fruit postharvest quality deterioration compared to a commercial product (Semperfresh™, Pace International, Wapato, Wash., U.S.A.). The 5% CNC coating strongly adhered to the pear surface, provided a superior gas barrier and a more homogenous matrix in comparison with the other coatings tested. Hence, it was effective in delaying ripening and improving the storability of postharvest pears during both ambient and cold storage.

真珠層に発生する軽微な劣化現象である "うろこ" の成因と対策

真珠層に発生する軽微な劣化現象である "うろこ" の成因と対策

Visible and Near-Infrared Hyper-Spectral Imaging for the Identification of the Type of Wax on Pears

This article presents a method for rapid, credible and noninvasive identification of the type of wax on pears using hyper-spectral imaging (HSI) in the visible and near-infrared (Vis–NIR) range (400–1,026 nm). The successive projection algorithm (SPA) was used to select the most effective wavelengths for wax type identification within a calibration set of 108 pears. This set was used to build identification models based on Multiple Linear Regression (MLR) and Linear Discrimination Analysis (LDA) using the relative reflectance values of the effective wavelengths. A prediction set of 72 pears was used to verify the reliability of the models and the results of both models were compared. SPA–LDA was found to be a better model than SPA–MLR, with an identification accuracy of 99.07% for calibration and 95.83% for the prediction sets. This demonstrates that Vis–NIR HSI is a potential candidate for wax type identification in a rapid, credible and noninvasive way. Practical Applications In the international markets and packing houses, many traders will wax the surface of pears to ensure they have a fresh appearance. Most traders use edible wax, but to reduce the cost, some unscrupulous traders may use industrial wax which is harmful to people's health. In recent years, a growing number of food products contain pears, such as Perry, sweetened pear pulp and dried pear. Therefore, it is crucial that the safety of the pear's surface can be ensured. In this study, the relative reflectance values of 11 effective wavelengths were selected by the Successive Projection Algorithm (SPA) as the independent variables of Linear Discrimination Analysis (LDA) based on hyper-spectral imaging (HSI), and the obtained 11 effective wavelengths can be developed into an on-line multi-spectral system for food safety detection. This method allows nondestructive identification of the type of wax on pears and can automatically focus during the detection process.

Effect of postharvest practices on the culturable filamentous fungi and yeast microbiota associated with the pear carpoplane

Information regarding the filamentous fungi and yeast microbiota on pear surfaces is limited when compared to other fruits such as grapes and apples. The effect of commercial postharvest practices on pear fruit surface microbiota and species composition is not known, particularly in terms of the presence of postharvest pathogens and potential biocontrol microorganisms. Pear fruit were collected at harvest in the orchards of four commercial farms, after harvest at a communal pack house following chlorine drenching and after modified atmosphere storage. Microbiological analysis showed that during season one the fungal populations on pears from the four farms were significantly lower after CA storage when compared to populations of orchard pears, however during season two, the opposite trend was observed. The yeast populations were either significantly higher or similar after CA storage compared to the orchard pear counts during both seasons. Commercial drenching led to either an increase or reduction in the filamentous fungi and yeast populations, however a definite trend could not be observed. The postharvest practices decreased the number of viable morphologically different yeast and filamentous fungal species. A total of 16 yeast and 24 filamentous fungal species were isolated. A 76% dominance of Ascomycetes was observed. Known postharvest pathogens Penicilium commune and Penicillium crysogenum were present after CA storage. Potential known biocontrol organisms included Aureobasidium pullulans, Cryptococcus sp. and Sporobolomyces roseus. Knowledge generated could contribute to development of commodity-specific supply-chain management systems and biocontrol strategies based on scientific data to reduce pear fruit losses and for quality control purposes.

Ultraviolet-C light inactivation of Escherichia coli O157:H7 and Listeria monocytogenes on organic fruit surfaces

This study investigated UV-C light inactivation of Escherichia coli O157:H7 and Listeria monocytogenes on the surface of organic apples, pears, strawberries, red raspberries and cantaloupes. Fruit surfaces spot inoculated with cocktail strains of E. coli O157:H7 and L. monocytogenes were exposed to UV-C doses up to 11.9kJ/m2 at 23°C. Fruit surface roughness, contact angle, and surface energy were determined and correlated with UV-C inactivation kinetics.Results demonstrate that bacterial pathogens on fruit surfaces respond differently to UV-C light exposure. E. coli O157:H7 on apple and pear surfaces was reduced by 2.9 and 2.1logCFU/g, respectively when treated with UV-C light at 0.92kJ/m2 (60s). For berries, the reduction of E. coli O157:H7 was lower with 2.0 (strawberry) and 1.1logCFU/g (raspberry) achieved after UV-C treatment at 7.2kJ/m2 (8min) and at 10.5kJ/m2 (12min), respectively. Similarly, a higher reduction of L. monocytogenes was observed on apple (1.6logCFU/g at 3.75kJ/m2) and pear (1.7logCFU/g at 11.9kJ/m2) surfaces compared to cantaloupe and strawberry surfaces (both achieved 1.0logCFU/g at 11.9kJ/m2). L. monocytogenes shows more resistance than E. coli O157:H7. Inactivation rates were higher for less hydrophobic fruits with smoother surfaces (apples and pears) as compared to fruits with rougher surfaces (cantaloupe, strawberry and raspberry). Findings indicate that UV-C light can effectively reduce E. coli O157:H7 and L. monocytogenes populations on fruit and berry surfaces. However, surface characteristics influence the efficacy of UV-C light.

Preparatory work for the pest categorisation of three bacteria listed in the annexes of the Council directive 2000/29/EC Erwinia amylovora Winslow et al. Xylophilus ampelinus (Panagopoulos) Willems et al. Clavibacter michiganensis subsp. insidiosus(McCulloch) Davis et al

Preparatory work for the pest categorisation of three bacteria listed in the annexes of the Council directive 2000/29/EC Erwinia amylovora Winslow et al. Xylophilus ampelinus (Panagopoulos) Willems et al. Clavibacter michiganensis subsp. insidiosus(McCulloch) Davis et al

UV-C light inactivation kinetics of Penicillium expansum on pear surfaces: Influence on physicochemical and sensory quality during storage

UV-C inactivation kinetic data of Penicillium expansum on intact and wounded pear disks were determined. P. expansum conidia (0.5mL, 1.6×107CFU/mL) were spot inoculated onto intact and wounded pear tissue with skin (excised disks), treated with UV-C doses ranging 0.101–3.06kJ/m2 at 23°C and surviving conidia were enumerated. Changes in selected physicochemical parameters and sensory quality following UV-C treatment of whole pears were determined immediately after treatment, and 4 and 8 weeks of storage at 4°C. A greater UV-C intensity was required for similar inactivation levels of P. expansum populations on wounded pear disks (3.1kJ/m2 for 2.7log reduction) compared to intact pear disks (1.7kJ/m2 for 2.8log reduction). No significant difference in % weight loss, or soluble solids content and texture was observed between UV-C treated and untreated pears. However, browning was observed on UV-C treated pear surfaces after 4 and 8 weeks along with changes in flavor and texture. An increase in consumer preference was noticed for the untreated control pears after 4 weeks storage.

Estimation of Pear Ripeness by Hyperspectral Laser Scatter Imaging

Abstract The purpose of this research is to analyse relationships between pear ripeness and subsurface scattering, Tested sample was pear ( Pyrus communis L., “Doyenne du Comice”). Soluble solids content and firmness were measured as indices of pear ripeness. Dispersed light in the range from 450 nm to 1000 nm in 5 nm intervals was irradiated at 1 mm diameter spot on pear surface. Light scattering around the spot was captured by a CCD camera. Area and mean diameter of the scattering region in each wavelength image were measured by image-processing. Relationships between the ripeness and the area or mean diameter were analysed by PLS (partial least squares) and PCR (principal component regression) methods. The results showed that the correlation coefficient between the measured and estimated ripeness was 0.653 for soluble solids content and 0.609 for firmness when the scattering images were measured on peel.