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.     

Moulds, yeasts and aerobic plate counts in ginseng supplements

Forty six ginseng supplement samples including Siberian ginseng root, Chinese ginseng herb and root, and American ginseng root and extract were purchased from retail in the Washington, DC area and from Penn Herb Co. (Philadelphia, PA) and tested for mould and yeast (MY) contamination and the presence of aerobic mesophilic bacteria (APC). Results indicated that 100% of the Siberian ginseng samples were contaminated with fungi and bacteria. MY counts ranged from 8.0 x 10(2) to 1.4 x 10(3) cfu/g whereas the APCs were between 2.3 x 10(4) and 1.0 x 10(6) cfu/g. Most common fungi encountered in this commodity were Penicillium spp., Eurotium rubrum, E. chevalieri and Rhizopus spp. Seventy-eight percent of the Chinese ginseng herb samples were contaminated with fungi and 89% with bacteria at levels ranging between <100 and 6.0 x 10(4) and <100 and 1.2 x 10(6) cfu/g, respectively. Moulds commonly isolated were Alternaria alternata, Aspergillus niger, Aspergillus spp., Cladosporium spp., E. chevalieri, Penicillium spp. and Rhizopus spp. Fifty six percent of the Chinese ginseng root samples tested contained fungi (A. niger, Rhizopus spp. and yeasts), and 100% contained bacteria. Fungal counts ranged between <100 and 1.4 x 10(3) cfu/g and APCs were between 3.0 x 10(2) and 6.8 x 10(5) cfu/g. Forty-eight percent of the American ginseng root samples contained moulds and 30% showed bacterial contamination. MY counts were between <100 and 4.3 x 10(5) cfu/g whereas APCs were between <100 and 4.5 x 10(4) cfu/g. A. flavus was isolated from 9% and Penicillium spp. were recovered from 39% of the tested samples. This is the first report of A. flavus contamination in ginseng supplements. No moulds or yeasts were found in ginseng extract, but 50% of these samples contained bacteria at levels ranging between <100 and 1.0 x 10(3) cfu/g.     

Quantitative analysis of mycoflora on commercial domestic fruits in Japan

A comprehensive and quantitative analysis of the mycoflora on the surface of commercial fruit was performed. Nine kinds of fruits grown in Japan were tested. Overall fungal counts on the fruits ranged from 3.1 to 6.5 log CFU/g. The mean percentages of the total yeast counts were higher than those of molds in samples of apples, Japanese pears, and strawberries, ranging from 58.5 to 67.0%, and were lower than those of molds in samples of the other six fruits, ranging from 9.8 to 48.3%. Cladosporium was the most frequent fungus and was found in samples of all nine types of fruits, followed by Penicillium found in eight types of fruits. The fungi with the highest total counts in samples of the various fruits were Acremonium in cantaloupe melons (47.6% of the total fungal count), Aspergillus in grapes (32.2%), Aureobasidium in apples (21.3%), blueberries (63.6%), and peaches (33.6%), Cladosporium in strawberries (38.4%), Cryptococcus in Japanese pears (37.6%), Penicillium in mandarins (22.3%), and Sporobolomyces in lemons (26.9%). These results demonstrated that the mycoflora on the surfaces of these fruits mainly consists of common pre- and postharvest inhabitants of the plants or in the environment; fungi that produce mycotoxins or cause market diseases were not prominent in the mycoflora of healthy fruits. These findings suggest fruits should be handled carefully with consideration given to fungal contaminants, including nonpathogenic fungi, to control the quality of fruits and processed fruit products.     

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.     

进口鲜葡萄市场病害的检测与分析

对上海市场销售的进口葡萄进行了市场病害的检测,在原产于美国和智利的红地球葡萄（red-globe grape）中检出了链格孢（Alternaria spp）、灰霉（Botrytis cinerea）、芽枝霉（Cladosporium spp）和匐柄霉（Stemphulium sp）四个属的潜伏病原真菌,其中Alternaria spp在健康果实中的检出率高达65.8%,携带外来菌的可能性较大。同时进口红地球葡萄存在较严重的SO2伤害,在所检测的样品中有伤害症状的果粒占所检测果粒数的比率最高可达92%。     

Production of alternariol and alternariol methyl ether by Alternaria alternata grown on fruits at various temperatures

Two toxigenic strains of the fungus Alternaria alternata (ATCC 56836 and ATCC 66868) were grown on surface-disinfected, fresh, ripe fruits and tested for the production of alternariol (AOH) and alternariol methyl ether (AME). Examined fruits included strawberries; red and green seedless grapes; concord grapes; red delicious, golden delicious, and gala apples; and blueberries. After inoculation, fruits were incubated at 4, 10 degrees C, or room temperature (approximately 21 degrees C) for up to 3 weeks. At weekly intervals, duplicate samples were analyzed for AOH and AME by using liquid chromatography. Results indicated that A. alternata and its metabolites were not a major problem in strawberries due to the presence of fast-growing molds like Rhizopus and Botrytis that outgrew and possibly inhibited Alternaria. Both Alternaria strains showed limited growth on apples, although fast-growing molds were not present after surface disinfection; AOH and AME were produced only by the ATCC 56836 strain on the golden delicious and gala varieties, (ranging from <0.1 to 5 microg/g and <0.1 to 14 microg/g for AOH and AME, respectively). Restricted growth of both strains without toxin production occurred in blueberries, whereas moderate growth and AOH (<0.1 to 3,336 microg/g) and AME (<0.1 to 1,716 microg/g) production took place in grapes.     

Moulds and yeasts in fresh and minimally processed vegetables, and sprouts

A limited survey of fresh and minimally processed vegetables, and sprouts was conducted in the Washington, DC area to determine if potentially toxigenic and pathogenic fungi were present in these commodities. Thirty-nine ready-to-eat salads, 29 whole fresh vegetables and 116 sprout samples (bean, alfalfa, broccoli, crunchy, garlic, spicy, onion, clover, lentil and multi-seed sprouts) were purchased from 13 local supermarkets and tested for yeast and mould counts as well as the presence of toxigenic moulds. Yeasts were the most prevalent organisms found in these samples, at levels ranging from less than 100 to 4.0x10(8) cfu/g. Mould counts generally ranged from less than 100 to 4.0x10(4) cfu/g. Two crunchy sprout samples, however, contained unusually high numbers of Penicillium (1.1x10(8) and 1.3x10(8) cfu/g), two alfalfa sprout samples contained Geotrichum populations about 10(6) cfu/g, and two alfalfa sprout samples had Cladosporium counts higher than 2.5x10(5) cfu/g. The most common moulds found in fresh and minimally processed vegetables were Cladosporium, Alternaria and Penicillium; less common was Geotrichum. The most frequently isolated moulds from sprouts were Alternaria, Cladosporium, Penicillium, and Phoma. Phoma was especially common in alfalfa sprouts. Fusarium, Rhizopus, Mucor, and Geotrichum were isolated less often.     

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.     

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.     

Specific fungi as the causative agents of the sporadic disintegration of sulphited strawberries

Summary. Fresh strawberries were inoculated with specific strawberry rotting fungi. When lesions of 1/4 - 1/2 in. diameter had developed on the fruits, they were added to sulphite-preserved strawberries to constitute 25% of the whole contents. Periodically the pulps were examined and breakdown estimated on a four point scale. of the ten species of fungi used only Rhizopus stolonifer, R. sexualis and Mucor sp. induced breakdown of the fruit to a puree-like consistency during storage. Two fungi failed to produce macerating activity and five failed to grow on the fruit before casual contaminants had outgrown them. Botrytis cinerea , the most common strawberry rotting fungus, did not cause breakdown. It is concluded that Rhizopus sp. and Mucor sp. are mainly responsible for the breakdown of sulphite-preserved strawberries and that the prevention of this trouble necessitates the exclusion of infected fruit. Practical recommendations for achieving this object are suggested. It is stressed that a major outbreak of this form of spoilage is still possible.     

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.     

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.     

Microbial quality and presence of moulds in Kuflu cheese

The chemical and microbial qualities, including fungal flora, of 30 samples of Kuflu cheese randomly purchased from different markets in Turkey were investigated. The gross composition of the cheese samples ranged between 37.65-53.65% moisture, 6.21-40.09% fat-in-dry matter, 4.70-10.07% salt-in-moisture and 26.18-44.85% protein. The mean pH value of the cheeses was 6.29+/-0.28 and pH values ranged from 5.52 to 7.22. Variations between the samples in terms of their gross composition suggested a lack of quality standards in cheesemilk, cheesemaking procedure and ripening conditions. The levels of main microbial groups including total mesophilic and coliform bacteria, yeasts and moulds and the presence of some potentially pathogenic microorganisms (E. coli, Salmonella spp. and Staphylococcus aureus) were determined. The high numbers of all microbial groups and presence of potentially pathogenic organisms in the cheese samples suggested that the production and maturation of Kuflu cheese should be improved by better hygiene. Moulds at the cheese surface were isolated and identified. A total of 24 different mould species were detected and the genus most frequently isolated was Penicillium spp. which represented 70.25% of total isolates. Penicillium commune, P. roqueforti and P. verrucosum were the most abundant species in the cheeses sampled. The other dominant fungal groups were Geotrichum candidum, Penicillium expansum and P. chrysogenum. Other genera isolated from the cheese were Acremonium, Alternaria, Aspergillus, Cladosporium, Geotrichum, Mucor, Rhizopus and Trichoderma. The potentially toxigenic species, including some Penicillum spp. and Aspergillus flavus, were also detected.     

Molecular Identification of Spoilage Fungi Isolated from Fruit and Vegetables and Their Control with Chitosan

This study investigated fungal spoilage of fruits and vegetables in Saudi Arabia. Activities of cell wall degrading enzymes in fungal isolates were measured. We evaluated the fungicidal activities of chitosan against spoilage fungi. Thirty-three fungal species belonged to 21 fungal genera were collected during this study. ITS sequencing results showed that Alternaria tenuissima, Fusarium chlamydosporum, Penicillium sumatrens, Rhizopus stolonifera, and Trichoderma harzianum were the most common species. The diversity of cell wall degrading enzyme produced by the spoilage fungi revealed that xylanase was the most widely distributed enzyme in fungi followed by amylase and cellulase. Some strains of Macrophomina phaseolina, Trichoderma harzianum, Trichoderma asperellum, Aspergillus niger and Alternaria consortialis showed the highest enzymes activities among tested fungi. Four different concentrations of chitosan (20, 30, 50, and 100 mg/L) were investigated against 22 fungal species. All investigated concentrations of chitosan showed highly significant reduction in the average of radial growth of all tested fungi.     

汾酒大曲可培养真菌多样性的初步分析

从汾酒大曲中分离出81株真菌,并对这81株菌进行了基于rDNA序列的分子生物学鉴定.结果表明,在汾酒大曲中分布有6个属的霉菌和4个属的酵母菌,其中扣囊腹膜孢酵母是优势酵母菌种,伞枝犁头霉和匍枝根霉是优势霉菌菌种.     

Mycotoxins in fruits,fruit juices,and dried fruits

This review gives an overview of the presence of mycotoxins in fruits. Although several mycotoxins occur in nature, very few (aflatoxins, ochratoxin A, patulin, Alternaria toxins) are regularly found in fruits. It has been shown that the presence of fungi on fruits is not necessarily associated with mycotoxin contamination. The formation of mycotoxins depends more on endogenous and environmental factors than fungal growth does. Mycotoxins may remain in fruits even when the fungal mycelium has been removed. Depending on the fruit and the mycotoxin, the diffusion of mycotoxins into the sound tissues of fruits may occur. The influence of the selection and storage of fruits and the influence of different processing steps involved in the production of fruit juices and dried fruits on possible mycotoxin contamination is described. It is shown that the careful selection, washing, and sorting of fruits is the most important factor in the reduction of mycotoxin contamination during the production of fruit juices. The processing of fruits does not result in the complete removal of mycotoxins.     

Ochratoxigenic species from Spanish wine grapes

The ochratoxigenic mycobiota of grapes belonging to representative wine regions located along the Mediterranean coast of Spain at different developmental stages was identified. During the development of the berries, the occurrence of Aspergillus spp. increased while the percentage of berries contaminated by non-ochratoxin A (OTA) producing species such as Alternaria spp. and Cladosporium spp. decreased. Penicillium verrucosum, the only confirmed Penicillium spp. that is able to produce OTA, was not isolated. The contamination by OTA-producing species comes from the surface of the berries and not from the inner fruit. Black aspergilli were predominant among the different Aspergillus spp. isolated. All the Aspergillus carbonarius isolates were able to produce OTA at different concentrations. None of the isolates belonging to Aspergillus niger aggregate and to Aspergillus japonicus var. aculeatus were able to produce OTA. These results are a strong evidence of the contribution of A. carbonarius in the OTA contamination in wine grapes, mainly at the last developmental stages of the berries.     

REDUCTION OF FUNGI AND MYCOTOXINS FORMATION IN SEEDS BY GAMMA-RADIATION

Ninety samples of maize, chick-peas and groundnut seeds collected from the Egyptian market were found to be heavily contaminated by molds. Alternaria, Aspergillus, Cladosporium, Eurotium, Fusarium, Mucor, Penicillium and Rhizopus were the most common fungal genera isolated from nondisinfected seeds . Aspergillus alutaceus, A. flavus, Fusarium verticillioides and F. oxysporum were isolated from all surface-disinfected seeds and were reported to produce ochratoxin A, aflatoxin B₁ and zearalenone, respectively. Irradiation at a dose 4.0 kGy reduced the mold growth greatly relative to unirradiated controls. There was no growth at dose 5.0 kGy. On the basis of the radiation survival data, the decimal reduction values D₁₀ for A. alutaceus, A. flavus and F. verticilliodies were 0.70. 2.10 and 0.93 kGy in maize. A dose of 5 kGy inhibited the toxigenic molds and mycotoxin formation in seeds. Aflatoxin B₁ and ochratoxin A were detected in maize and chick-peas, whereas zearalenone was detected in maize samples. Application of radiation at a dose of 6.0 kGy detoxified aflatoxin B₁ by 74.3–76.7%, ochratoxin A by 51.3–96.2% and zearalenone by about 78%.     

CONTAMINATION OF GRAINS BY MYCOTOXIN-PRODUCING MOLDS AND MYCOTOXINS AND CONTROL BY GAMMA IRRADIATION

Ninety random grain samples were collected and analyzed for mycotoxins, and the effect of gamma irradiation on the production of mycotoxins in grains was studied. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium, Alternaria, Scopulariopsis and Cladosporium were the most common fungal genera isolated from grains. Aspergillus flavus, Aspergillus niger, Aspergillus candidus, Aspergillus ochraceus, Penicillium citrinum, Penicillium expansum, Penicillium citreonigrum, Penicillium purpurogenum, Penicillium griseofulvum and Penicillium verrucosumwere the most common Aspergillus and Penicillium species in grains. Out of 120 Aspergillus and Penicillium isolates, 80 were mycotoxin producers. Analysis of grains revealed the occurrence of aflatoxin B₁ ochratoxin A, cycolopiazonic acid and citrinin. Of the 90 samples, 67 were positive for one or more mycotoxin. Irradiation of grains at dose of 2.0 and 4.0 kGy decreased significantly the total fungal counts compared with unirradiated controls. After 100 days of storage at room temperature, the unirradiated grains were contaminated with high concentrations of mycotoxins as compared with irradiated 4.0‐kGy samples. Mycotoxin production in grains decreased with increasing irradiation doses and was not detected at 6.0 kGy over 100 days of storage.     

Occurrence of pathogenic fungal species in Tunisian vineyards

Mycotoxins are secondary metabolites produced by filamentous fungi detected in food, such are grapes. OTA was evaluated in ten handle musts from different Tunisian vineyard. This mycotoxin was found at levels 1.1 mug/L to 4.3 mug/L. A survey was conducted to assess the contamination of the Tunisian vineyard with pathogenic fungal species, in particular those responsible of the OTA production. The results were evaluated for the first time in parcels cultivated in the North, in the Centre and in the South of the country. Italia Muscate and Superior Seedless varieties were concerned at three developmental stages of the berry, setting, veraison and maturity. Carigon variety was used as positive control for musts contaminating by OTA. The main fungal species isolated were Aspergillus spp. (33.32%), Botrytis cinerea (23.32%), Alternaria spp. (12.80%), Cladosporium spp. (10.59%) and Penicillium spp. (8.3%). The isolates of the Aspergillus genus were identified as Aspergillus niger aggregate (77%), Aspergillus carbonarius (15%) and Aspergillus flavus (8%). Their presence was characterized by a significant decrease in the Centre during the veraison and a slight increase in the North and the South during the maturity stage. Furthermore, when comparing Superior Seedless and Italia Muscate cultivated in the same area, the aspergilli were particularly less abundant at the setting stage in the case of Superior Seedless. There is no correlation between the OTA amount in musts and the contamination by Aspergillus species in different vineyards and for grape varieties studied.