Mould and yeast flora in fresh berries, grapes and citrus fruits

Fresh fruits are prone to fungal contamination in the field, during harvest, transport, marketing, and with the consumer. It is important to identify fungal contaminants in fresh fruits because some moulds can grow and produce mycotoxins on these commodities while certain yeasts and moulds can cause infections or allergies. In this study, 251 fresh fruit samples including several varieties of grapes, strawberries, blueberries, raspberries, blackberries, and various citrus fruits were surface-disinfected, incubated at room temperature for up to 14 days without supplemental media, and subsequently examined for mould and yeast growth. The level of contamination (percent of contaminated items/sample) varied depending on the type of fruit. All raspberry and blackberry samples were contaminated at levels ranging from 33% to 100%, whereas 95% of the blueberry samples supported mould growth at levels between 10% and 100% of the tested berries, and 97% of strawberry samples showed fungal growth on 33-100% of tested berries. The most common moulds isolated from these commodities were Botrytis cinerea, Rhizopus (in strawberries), Alternaria, Penicillium, Cladosporium and Fusarium followed by yeasts, Trichoderma and Aureobasidium. Thirty-five percent of the grape samples tested were contaminated and supported fungal growth; the levels of contamination ranged from 9% to 80%. The most common fungi spoiling grapes were Alternaria, B. cinerea and Cladosporium. Eighty-three percent of the citrus fruit samples showed fungal growth at levels ranging from 25% to 100% of tested fruits. The most common fungi in citrus fruits were Alternaria, Cladosporium, Penicillium, Fusarium and yeasts. Less common were Trichoderma, Geotrichum and Rhizopus.     

Moulds and yeasts in fruit salads and fruit juices

Thirty-eight fruit salad samples including cantaloupe, citrus fruits, honeydew, pineapple, cut strawberries and mixed fruit salads, and 65 pasteurized fruit juice samples (apple, carrot, grapefruit, grape and orange juices, apple cider, and soy milk) were purchased from local supermarkets in the Washington, DC area and tested for fungal contamination. The majority of fruit salad samples (97%) were contaminated with yeasts at levels ranging from <2.0 to 9.72 log10 of colony forming units per gram (cfu/g). Frequently encountered yeasts were Pichia spp., Candida pulcherrima, C. lambica, C. sake, Rhodotorula spp., and Debaryomyces polymorphus. Low numbers of Penicillium spp. were found in pineapple salads, whereas Cladosporium spp. were present in mixed fruit and cut strawberry salads. Twenty-two per cent of the fruit juice samples tested showed fungal contamination. Yeasts were the predominant contaminants ranging from <1.0 to 6.83 log10 cfu/ml. Yeasts commonly found in fruit juices were C. lambica, C. sake, and Rhodotorula rubra. Geotrichum spp. and low numbers of Penicillium and Fusarium spp. (1.70 and 1.60 log10 cfu/ml, respectively) were present in grapefruit juice.     

Mycological survey of ripped service tree fruits (Sorbus domestica L.) with an emphasis on toxinogenic fungi

To investigate a possible incidence of microscopic fungi in ripped service tree (Sorbus domestica L.) fruits, a mycological survey was carried out during October-November 2003 in Slovakia. This rare kind of fruit is renowned for its significant curative actions in various human and animal diseases. The study revealed that all 24 surface sterilized fruits analysed were contaminated with fungi. The most dominant endogenous contaminant encountered was Cladosporium cladosporioides (Fres.) de Vries followed by Alternaria alternata (Fr.) Keissler and Penicillium expansum Link with 88%, 63% and 54% frequency, respectively. Furthermore, 24 other fungal species were associated with the fruits as well. P. expansum (40), P. carneum (Frisvad) Frisvad/Penicillium paneum Frisvad (35) and P. griseofulvum Dierckx (6) isolates recovered from the fruits were screened by an agar plug method for production of mycotoxin patulin, all with positive results. In addition, citrinin, griseofulvin and zearalenon production by appropriate species isolates were detected. Despite of a limited number of samples of the service tree fruits examined during this study, it was concluded that the ripening of service tree fruits is accompanied with the presence of typical rotting-fungi as well as of some others, which have not previously been reported in connection with fruit. Furthermore, it was suggested that the ripped service tree fruits should be considered as a potential source of significant fungal secondary metabolites including mycotoxins. Secondary metabolite profiles of the species identified during the study were included here.     

Identification of fungal contamination and determination of mycotoxigenic molds by micellar electrokinetic capillary chromatography in smoked paprika

The purpose of this work was to analyze the fungal contamination in smoked and unsmoked paprika processed from different cultivars of pepper and to investigate the ability of these and other mycotoxigenic molds to grow and synthesize mycotoxins in smoked paprika. Eighteen mycotoxins were evaluated using micellar electrokinetic capillary chromatography. No relevant differences were found in fungal contamination between smoked and unsmoked paprika. The number of yeasts obtained was low, ranging from 0.4 to 3.29 log CFU g(-1); most of the yeast strains were identified as Cryptococcus spp. followed by Candida spp. All mold counts were <4 log CFU g(-1). Aspergillus, Cladosporium, Penicillium, and Fusarium were the predominant hyphomycete genera. Six mycotoxins were identified in the extracts of several strains isolated from paprika and incubated on malt extract agar. Penicillium expansum followed by Penicillium citrinum and Penicillium raistrickii were the dominant mycotoxigenic fungi isolated. Most of themycotoxin-producing fungi produced detectable amounts of mycotoxins when grown on paprika agar.     

一次性灌胃不同水果汁对大鼠外周血抗氧化力影响的研究

目的:观察不同抗氧化力水果汁对大鼠外周血抗氧化活性的影响。方法:以FRAP法测定水果汁的抗氧化活性,以灌胃法观察不同水果制汁后对大鼠外周血抗氧化活性的影响。取山楂、猕猴桃、石榴、草莓、苹果、梨果肉制汁后灌胃,连续动态观察大鼠外周血抗氧化力的变化。结果:测定的6种水果汁抗氧化活性排序依次为山楂、猕猴桃、石榴、草莓、红香蕉苹果、水晶梨。灌胃4g抗氧化力较强的山楂、猕猴桃、石榴制汁,大鼠外周血抗氧化力均显著增强,与对照组相比有显著性差别(P<0.01);抗氧化力较弱的红富士苹果和水晶梨制汁灌胃后外周血抗氧化力无变化;灌胃2g水果制汁后变化趋势与4g相同,但与对照组比较无显著差别。结论:在体外具有较强抗氧化力的水果汁对大鼠外周血抗氧化力影响较为显著,但抗氧化力较弱水果汁该作用较弱。     

Mold growth on strawberries and cherries during storage at 25 degrees C

Mold species that grew on the surface of retailed strawberries (10 packs, 211 strawberries) and cherries (18 packs, 441 cherries) during storage at 25 degrees C were isolated and identified to evaluate the state of mold growth. Mold growth was observed on 208 (98.6%) of the 211 strawberries and 193 (43.8%) of the 441 cherries. The mold species most frequently isolated from strawberries was Botrytis cinerea, being observed in 81.0% of the strawberries examined, followed by Cladosporium and Alternaria alternata. The mold most frequently isolated from cherries was Alternaria (28.7%), followed by Penicillium, Botrytis, and Cladosporium. The frequency of cherries on which mold growth was observed varied among packs. Mold tended to grow more often in the areas of the fruits in contact with adjacent fruits.     

微波和臭氧处理对果脯的杀菌效果及品质变化分析

该研究探究了微波与臭氧处理对四种果脯优势霉菌芽枝状枝孢霉（Cladosporium velox）、暗黄青霉（Penicillium citreonigrum）、菌核青霉（Penicillium sclerotiorum）、细极链格孢（Alternariate nuissima）的抑菌效果及果脯理化品质的影响。结果表明,微波与臭氧处理均可显著抑制霉菌生长,抑菌率随微波功率,微波时间,臭氧通入时间增加而增大。当微波功率为630 W,微波时间为20 s时,四种霉菌抑菌率最高均达到100%。当通入臭氧10 min时,抑菌效果最佳,芽枝状枝孢霉、暗黄青霉、菌核青霉、细极链格孢的抑菌率分别达到73.17%、80.87%、83.33%、91.02%。微波和臭氧处理均对果脯理化品质具有一定影响,随着随微波功率,微波时间,臭氧通入时间增加,果脯水分含量、水分活度、总糖含量和色差值均呈下降趋势。研究结果为微波和臭氧技术在果脯杀菌中的应用提供了理论支撑和参考依据。     

Antifungal Coatings on Fresh Strawberries (Fragaria × ananassa) to Control Mold Growth During Cold Storage

ABSTRACT: Chitosan (2%) -based or hydroxypropyl methylcellulose (HPMC) (1%) -based coatings were applied on fresh strawberries to evaluate their antifungal efficacies against Cladosporium sp. and Rhizopus sp. Potassium sorbate (PS) was also incorporated into coating formulas to evaluate any additional inhibitory effects on mold inhibition. Strawberries were inoculated with Cladosporium sp. or Rhizopus sp. at a level of approximately 10³ log colony-forming units (CFU) /g, coated with 2% chitosan, 2% chitosan containing 0.3% PS, or 1% HPMC containing 0.3% PS, and stored at about 5°C and about 50% RH up to 23 d for enumeration of mold, yeast, total aerobes, and coli forms. To assess antifungal activity of the coating materials in vitro, coating solutions were embedded into agar plates and the diameters of radial mold growth were measured after inoculation. In addition, weight loss of coated strawberries and water vapor permeability of the coatings were measured. No significant combined inhibitory effects between chitosan and PS on fungal growth on fresh strawberries were detected. However, significant combined inhibition activity was observed in in vitro testing when PS was formulated into chitosan. Antifungal activity of chitosan against Cladosporium sp. and Rhizopus sp. was not affected by the autoclaving process of coating solutions. Coating treatment also reduced total aerobic count, coliforms, and weight loss of strawberries during storage. Hence, chitosan can be used as a natural antimicrobial coating on fresh strawberries to control the growth of fungi, thus extending shelf-life of the fruits.     

MICROBIOLOGICAL AND CHEMICAL PROPERTIES OF IRRADIATED MANGO

Fourteen fungal species belonging to five genera , Aspergillus, Cladosporium, Penicillium, Fusarium and Scoplariopsis were isolated from the surface of mango fruits , (Mangifera indica L.) variety "Zebda". Mycotoxin production by isolated molds was tested in Czapek-Dox broth as well as mango pulp. The irradiation decimal reduction doses (D₁₀ values) of the molds were determined in either physiological saline solution or mango pulp. The effects of ionizing radiation in combination with hot water-dipping (55C/5 min) on shelf-life extension and the microbiological, chemical, rheological and organoleptic properties of mango fruit (at mature green stage) stored at 12°C and 80–85% relative humidity were determined. Results showed that Zebda mango irradiated with doses of 1.0 kGy can be stored 50 days at 12°C without any undesirable changes to measured nutrient and sensory quality when compared to unirradiated mangoes refrigerated for 25 days.     

Concentration of morpholine residues in major fruits and juices and its dietary exposure in China

Morpholine is a common chemical used as emulsifier in the preparation of wax coatings for some fruit to help them remain fresh and protect against insects and fungal contamination. It has been reported that morpholine has acute toxic effects on rodents. In the present study, morpholine concentrations were analysed in fruits (citrus fruits, apples, strawberries and grapes) and juices (apple juice and orange juice) in order to determine dietary exposure among the Chinese population. A total of 732 fruit and juice samples were collected during 2015–2016, which covered major foods in China. Fruit and juice consumption data were taken from China National Nutrient and Health Survey (2002) and include data from 16,407 fruit or juice consumers. It was found that mean dietary exposure to morpholine residues from fruits and/or juices for general Chinese consumers and children 2–6 years old were 0.42 and 1.24 µg/kg bw/day, respectively. The 97.5% intake in general Chinese consumers and children 2–6 years old were 2.25 and 6.90 µg/kg bw/day, respectively. The primary food sources of the morpholine dietary intake of general Chinese consumers were citrus fruits (57.4%) and apples (40.8%). These findings suggested that dietary exposure to morpholine in the Chinese population was lower than the acceptable daily intake of morpholine, and there are no health concerns.     

FUNGAL BIOTA ISOLATED FROM SPANISH CHEESES

Fungal biota, with special reference to the genus Penicillium, was studied in 52 samples of commercial cheeses (10 fresh, 17 semiripened and 25 ripened) made from different types of milk (cow, ewe, goat and mixed) produced in southern Spain. In 41 of the total of cheeses analyzed (79%) molds were isolated. Penicillium was identified in 63% of the samples , Mucor spp. in 27% , Geotrichum candidum in 17% and Cladosporium herbarum in 10%; eleven other fungal genera were detected ranging from 2 to 4%. Thirty-five species of Penicillium were analyzed with the following distribution: 7 in fresh cheese, 16 in semiripened cheese and 30 in ripened cheese. The incidence of Penicillium spp. was also greater in the cheeses with a higher degree of ripeness, i.e. 20% in fresh cheese, 71% in the semiripened and 76% in the ripened cheese.     

果脯蜜饯中霉菌污染情况及污染菌相调查

对杭州市部分超市随机抽取的10种果脯蜜饯中霉菌污染情况及污染菌相调查显示：10种果脯蜜饯的霉菌总数超标率达100％。污染的霉菌有14个菌属,优势菌群为曲霉属,占总数的62．53％,其次为青霉属,占总数的18．56％。     

Fungal spoilage of bottled mineral water

The occurrence of filamentous fungi together with bacteriological parameters was assessed in 126 samples of still bottled mineral water of eight different commercial brands in Argentina. In spoiled samples with visible mycelium growth, the most frequently isolated fungal species were Penicillium citrinum, P. glabrum, other Penicillium species, Cladosporium cladosporioides and Alternaria alternata. In unspoiled samples, the genera found were Penicillium, Cladosporium, Rhizopus, Aspergillus and Phoma. Only three of the 126 samples failed to meet the required microbiological standards because they were found to contain faecal streptococci.     

Evaluation of Penicillium expansum isolates for aggressiveness, growth and patulin accumulation in usual and less common fruit hosts

Experiments were carried out in vivo and in vitro with four isolates of Penicillium expansum (I 1, E 11, C 28 and I 12) to evaluate their aggressiveness, growth and patulin accumulation in both usual (pears and apples) and less common hosts (apricots, peaches, strawberries and kiwifruits) of the pathogen. The 75% of isolates showed the ability to cause blue mould in all tested hosts. In particular, C 28 and I 1 were the most and the least aggressive isolates, respectively (52.9 and 10.6% infection and 20.7 and 15.4 mm lesion diameters). ‘Candonga’ strawberries and ‘Pinkcot’ apricots showed the largest lesion diameters (29.8 and 25.3 mm), followed by ‘Conference’ pears, ‘Spring Crest’ peaches and ‘Abate Fetel’ pears. With the exception of ‘Candonga’ strawberries, the formation of colonies and mycelial growth of P. expansum isolates on fruit puree agar media (PAMs) was stimulated in comparison to a standard growth medium (malt extract agar, MEA). Two of the most aggressive isolates in our assays (I 12 and C 28) showed the greatest accumulation of patulin both in vitro and in vivo, while the least aggressive isolate (I 1) produced patulin only in a few growth media and cvs. Patulin concentration on fruit PAMs was higher than patulin detected in infected fruit tissues. Apple PAMs were the more favorable substrates for patulin accumulation in vitro (maximum concentration 173.1 and 74.1 μg/mL in ‘Pink Lady and ‘Golden Delicious’ PAMs, respectively) and ‘Pink Lady’ apples inoculated with the isolate E 11 showed the greatest accumulation of patulin in the whole in vivo assay (33.9 μg/mL). However, infected tissue of cv Golden Delicious showed lower average accumulation of patulin (1.7 μg/mL) than that of cv Pink Lady (19.1 μg/mL), and no significant differences in patulin concentrations were found among ‘Golden Delicious’ apples and tested cvs of pears, kiwifruits and strawberries. Peaches were highly susceptible to patulin accumulation, showing average concentrations of 27.4 and 18.6 μg/mL in vitro and in vivo, respectively. Apricots were also consistently positive for patulin accumulation, both in vitro (average values of 20.1 μg/mL) and in vivo (average values of 9.4 μg/mL). Our study showed the potential of some less common hosts of P. expansum (in particular peaches and apricots) to support patulin production, indicating that a steady monitoring of patulin contamination should be carried out in fruit substrates other than apples and pears.     

Potential ochratoxin A producers from wine grapes in Argentina and Brazil

The aim was to identify the normal mycoflora in wine grapes from Argentina and Brazil. We collected 50 grapes samples from Malbec and Chardonnay varieties in each country during the 1997-98 harvest. Yeasts were a major component of the fungal population, and the most frequent genera of filamentous fungi isolated were: Aspergillus, Penicillium and Botrytis. Other genera identified (in decreasing order) were: Phythophthora, Moniliella, Alternaria and Cladosporium. From grapes, the mean frequency of filamentous fungi ranged from 1.3 × 10⁴ to 5.4 × 10⁶ CFUg^-1. We isolated 48 Aspergillus niger strains from Argentinian grape, of which eight could produce ochratoxin A. Sixteen of 53 A. niger strains from Brazilian grapes produced ochratoxin A. The results indicate that similar mycobiota were isolated from Argentinian and Brazilian wine grapes and there could be ochratoxin A production in this substrate.     

Incidence of heat-resistant fungi in Nsukka, southern Nigeria

A total of 42 soil samples collected from different parts of Nsukka, Southern Nigeria, and 20 freshly plucked mango fruits were screened for the presence of heat-resistant fungi. Each soil sample, suspended in sterile water, and washings from each mango fruit were separately heated at 70 degrees C for 1 h before plating on double-strength potato dextrose agar containing chloramphenicol and incubating at approx. 28 degrees C. Approximately 98% of all soil samples and 17% of mango fruits contained heat-resistant fungi which were identified as Neosartorya fischeri, N. fischeri var. spinosa, Aspergillus flavus, Penicillium citrinum and Paecilomyces varioti which has not been reported in tropical soil. Neosartorya spp. were predominant and occurred in all positive samples. Fungal counts ranged from non-detectable to 200 colony-forming units per 10 g of soil. Most isolates appeared to grow faster at 35 degrees C than at 30 degrees C and 40 degrees C.     

Contamination of freshly harvested Bambara groundnut (Vigna subterranea) seed from Mpumalanga,South Africa,with mycotoxigenic fungi

Freshly harvested Bambara groundnut (BGN) is occasionally consumed raw and can potentially become infected with mycotoxingenic field fungi. In this study, BGN samples were obtained from 12 farms in three districts of Mpumalanga in South Africa. Eight pooled samples were screened for multi-mycotoxin contamination using Ultra Performance Liquid-Chromatography tandem mass spectrometry (UPLC-MS/MS). To identify mycoflora, 12 samples were screened using conventional and molecular methods. Selected potential mycotoxin producing isolates were screened for mycotoxins using UPLC-MS/MS. No mycotoxins were detected on the freshly harvested BGN samples, but they were infected with various mycotoxin producing fungal species namely Aspergillus flavus (50%), Penicillium citrinum (25%), Penicillium oxalicum (17%), Penicillium citreoviridin (0.8%), and Fusarium verticillioides (0.8%). Following screening of selected fungal cultures, aflatoxin B₁ (0.4, 0.45 and 0.4 ppm) and fumonisin B₁ (0.7 ppm) were detected from A. flavus and F. verticillioides, respectively. Identification of mycotoxigenic fungi on freshly harvested BGN presents a potential health risk.     

鱿鱼丝加工中真菌菌相变化规律及优势真菌的分离鉴定

为减少鱿鱼丝加工过程中真菌污染,提高鱿鱼丝产品的质量,将传统的微生物鉴定技术与5.8S r DNA-ITS序列分析法相结合,并通过系统发育树分析,探索鱿鱼丝加工过程中真菌菌相变化规律及优势菌株。结果表明,在鱿鱼丝加工过程中,不同阶段样品中真菌数量差异显著(p0.05),在加工终点(即烘干包装后)时真菌数量高达2.61 log cfu/g,其中调味和烘干包装阶段是真菌污染的主要环节。加工终点的鱿鱼丝中分离出6种酵母菌和4种霉菌,经测序并通过National Center for Biotechnology Information(NCBI)数据库比对,确定它们分别属于假丝酵母属(Candida sp.)、隐球酵母属(Cryptococcus sp.)、座囊菌属(Dothideomycetes sp.)、胶红酵母属(Rhodotorula sp.)、丝孢酵母属(Trichosporon sp.)、茎点霉属(Phoma sp.)、青霉属(Penicillium sp.)、曲霉属(Aspergillus sp.)、枝孢霉属(Cladosporium sp.)。其中,青霉菌(M-03)和假丝酵母菌(Y-04)为鱿鱼丝加工过程中的优势菌,在加工终点时的数量分别为1.85 log cfu/g和2.15 log cfu/g。     

Fungal population and distribution of aflatoxigenic fungi in commercial almond powder products

The fungal population and distribution of aflatoxin-producing fungi in 30 samples of imported almond powder products purchased from retail markets were examined in this study. Total counts of fungi ranged from under 1.0 x 10 colony-forming units (CFU)/g to 8.5 x 10(3) CFU/g as determined with the dilution plating technique. The predominant fungi in the mould-contaminated almond samples were Aspergillus niger, A. flavus and the related species, Penicillium, Cladosporium and Rhizopus. Aflatoxin-producing ability in the isolates of A. flavus and related fungi were tested by thin layer chromatography using 2% yeast extract and 15% sucrose broth culture. Four different aflatoxigenic fungi were detected in the isolates; aflatoxins B1 and B2 were produced by some strains of A. flavus and A. parvisclerotigenus, and aflatoxins B1, B2, G1, G2 were produced by all tested strains of A. parasiticus and A. nomius. Identification of the strains was based on morphological and metabolic characters.     

Whole wheat and white wheat flour— the mycobiota and potential mycotoxins

Mold growth has detrimental effects on the quality of flour and may result in mycotoxin contamination. The search for potential mycotoxins—almost 400 are known—is time-consuming and expensive. However, detailed knowledge about the mycobiota and especially the toxin producing fungi enables the effective search for these toxic fungal metabolites. Therefore, a whole wheat flour and a white wheat flour (type 405) were investigated for their total qualitative as well as quantitative mycobiota. Overall, 51 species belonging to 14 different genera could be isolated. Total fungal counts of the whole wheat flour amounted to 1833 molds while the white wheat flour contained 1730 cfu 2 g⁻¹. The mycobiota of both flours was dominated by Aspergillus spp. accounting for 84% and 77·3% of the isolations, respectively. Fungi of the genus Penicillium spp. occurred only to a minor degree: 8% of the isolations in whole wheat flour and 15% in white wheat flour. Aspergillus candidus was the most frequently encountered mold.Penicillium aurantiogriseum , Cladosporium cladosporioides, A. flavus, Eurotium herbariorum,P. griseofulvum , P. brevicompactum and P. viridicatum were isolated to a lesser degree. From the 3563 identified fungi 93·3% (32 species) belong to the group of toxigenic molds.