Growth and mycotoxin production by food spoilage fungi under high carbon dioxide and low oxygen atmospheres

Patulin contamination of hard apple cider by Paecilomyces niveus and other postharvest apple pathogens: Assessing risk factors

Hard apple cider is considered to be a low-risk product for food spoilage and mycotoxin contamination due to its alcoholic nature and associated food sanitation measures. However, the thermotolerant mycotoxin-producing fungus Paecilomyces niveus may pose a significant threat to hard cider producers. P. niveus is known to infect apples (Malus xdomestica), and previous research indicates that it can survive thermal processing and contaminate finished apple juice with the mycotoxin patulin. To determine if hard apple cider is susceptible to a similar spoilage phenomenon, cider apples were infected with P. niveus or one of three patulin-producing Penicillium species and the infected fruits underwent benchtop fermentation. Cider was made with lab inoculated Dabinett and Medaille d'Or apple cultivars, and patulin was quantified before and after fermentation. Results show that all four fungi can infect cider apples and produce patulin, some of which is lost during fermentation. Only P. niveus was able to actively grow throughout the fermentation process. To determine if apple cider can be treated to hinder P. niveus growth, selected industry-grade sanitation measures were tested, including chemical preservatives and pasteurization. High concentrations of preservatives inhibited P. niveus growth, but apple cider flash pasteurization was not found to significantly impact spore germination. This study confirms that hard apple cider is susceptible to fungal-mediated spoilage and patulin contamination. P. niveus is an important concern for hard apple cider producers due to its demonstrated thermotolerance, survival in fermentative environments, and resistance to sanitation measures.

Photocatalytic titanium dioxide reduces postharvest decay of nectarine fruit packaged in different materials through modulating central carbon and energy metabolisms

The capacity of titanium dioxide (TiO2) photocatalysis photocatalytic reactor to prevent and control pathogen infection in nectarine fruit packed in laminated nylon/LDPE, low density polyethylene and microperforated LDPE films was evaluated. Results showed that TiO2 combined with microperforated LDPE packaging (TPL) exhibited superior inhibition of microbial growth, reducing total viable counts by 4.18 log CFU g-1 and yeast and mold counts by 3.20 log CFU g-1, compared to microperforated LDPE packaging alone. TiO2 photocatalysis primed the defense systems in nectarine fruit packed in microperforated LDPE, improving the activity of defense-related enzymes. Metabolomics analysis indicated that l-aspartate, oxaloacetate, and succinic acid involved in central carbon metabolism including the glycolysis and tricarboxylic acid cycle pathways, were significantly upregulated by TPL. TiO2 increased the activity of energy metabolism-related enzymes, adenosine triphosphate, adenosine diphosphate, and energy charge levels to provide adequate energy, thus reducing fruit decay.

Research progress on the application of different preservation methods for controlling fungi and toxins in fruit and vegetable

Fruits and vegetables are susceptible to fungal infections during picking, transportation, storage and processing, which have a high potential to produce toxins. Fungi and toxins can cause acute or chronic poisoning after entering the body. In the field of fruit and vegetable preservation, technologies such as temperature control, modified atmosphere, irradiation, application of natural or chemical preservatives, and edible films are commonly used. In practical applications, according to the types, physiological differences and actual needs of fruits and vegetables, suitable preservation methods can be selected to achieve the effect of preservation and control of fungi and toxins. The starting point of fresh-keeping technology is to delay post-harvest senescence of fruits and vegetables, inhibit the respiratory intensity, and control the reproduction of microorganisms, which is important to control the reproduction of fungi and the production of toxins. From the three directions of physical, chemical and biological means, the article analyses and explores the effects of different external factors on the production of toxins and the effects of different preservation techniques on fungal growth and toxin production in fruits and vegetables, in order to provide new ideas for the preservation of fruits and vegetables and the control of harmful substances in food.

Fungi under Modified Atmosphere-The Effects of CO2 Stress on Cell Membranes and Description of New Yeast Stenotrophomyces fumitolerans gen. nov., sp. nov

High levels of carbon dioxide are known to inhibit the growth of microorganisms. A total of twenty strains of filamentous fungi and yeasts were isolated from habitats with enriched carbon dioxide concentration. Most strains were derived from modified atmosphere packed (MAP) food products or mofettes and were cultivated under an atmosphere of 20% CO2 and 80% O2. The influence of CO2 on fungal cell membrane fatty acid profiles was examined in this study. Major changes were the increase in linolenic acid (C18:3 cis 9, 12, 15) and, additionally in most strains, linoleic acid (C18:2 cis 9, 12) with a maximum of 24.8%, at the expense of oleic (C18:1 cis 9), palmitic (C16:0), palmitoleic (C16:1 cis 9) and stearic acid (C18:0). The degree of fatty acid unsaturation increased for all of the strains in the study, which consequently led to lower melting temperatures of the cell membranes after incubation with elevated levels of CO2, indicating fluidization of the membrane and a potential membrane malfunction. Growth was reduced in 18 out of 20 strains in laboratory experiments and a change in pigmentation was observed in several strains. Two of the isolated strains, strain WT5 and strain WR1, were found to represent a hitherto undescribed yeast for which the new genus and species Stenotrophomyces fumitolerans (MB# 849906) is proposed.

Prevalence and concentration of aflatoxin M1 and ochratoxin A in cheese: a global systematic review and meta-analysis and probabilistic risk assessment

Exposure to mycotoxins such as aflatoxins can endanger human health, especially infants and children. In this study, an attempt was made to retrieved studies related to the concentration of aflatoxin M1 (AFM1) and ochratoxin A (OTA). Search was performed in international databases such as Embase, PubMed, Scopus, and Web of Science for the period 1 January 2010 to 20 February 2023. Then, the pooled concentration in the defined subgroups was calculated using meta-analysis and the health risk assessment was conducted by margin of exposure (MOEs). Thirty-one scientific papers with 34 data reports (Sample size=2,277) were included in our study. The lowest and highest prevalence of AFM1 in cheese was related to El Salvador (12.18 %) and Serbia (100.00 %). The pooled prevalence of AFM1 was 49.85 %, 95 %CI (37.93-61.78 %). The lowest and highest prevalence of OTA in cheese was related to Türkiye (6.67 %) and Italy (44.21 %). The pooled prevalence of OTA was 35.64 %, 95 %CI (17.16-56.44 %). Health risk of AFM1 revealed that except Pakistan and Iran, MOE in the other countries was lower than 10,000 for adults and also except Pakistan, MOE for other countries was lower than 10,000 for children. Health risk of OTA revealed that except Greece, MOE in the other countries was higher than 10,000 for adults and also except Germany and Greece, MOE for other countries was higher than 10,000 for children. Therefore, it is recommended to conduct control plans to reduce the concentration of mycotoxins in cheese, especially AFM1.

Impact of carbon dioxide on the radial growth of fungi isolated from dairy environment

In dairy industry, filamentous fungi are used as adjunct cultures in fermented products for their technological properties but they could also be responsible for food spoilage and mycotoxin production. The consumer demands about free-preservative products has increased in recent years and lead to develop alternative methods for food preservation. Modified Atmosphere Packaging (MAP) can inhibit fungal growth and therefore increase the food product shelf-life. This study aimed to evaluate radial growth as a function of CO2 and more particularly carbonic acid for fourteen adjuncts and/or fungal spoiler isolated from dairy products or dairy environment by using predictive mycology tools. The impact of the different chemical species linked to CO2 (notably carbonic acid) were study because it was reported previously that undissociated carbonic acid impacted bacterial growth and bicarbonates ions were involved in modifications of physiological process of fungal cells. A significant diversity in the responses of selected strains was observed. Mucor circinelloides had the fastest growth rates (μ > 11 mm. day-1) while Bisifusarium domesticum, Cladosporium herbarum and Penicillium bialowiezense had the slowest growth rates (μ < 1 mm. day-1). Independently of the medium pH, the majority of strains were sensitive to total carbonic acid. In this case, it was not possible to conclude if CO2 active form was gaseous or aqueous so modeling were performed as a function of CO2 percentage. Only Geotrichum candidum and M. circinelloides strains were sensitive to undissociated carbonic acid. Among the fourteen strains, P. bialowiezense was the less sensitive strain to CO2, no growth was observed at 50% of CO2 only for this strain. M. lanceolatus was the less sensitive strain to CO2, the CO250 which reduce the growth rates by 50% was estimated at 138% of CO2. Low CO2 percentage improved the growth of Penicillium expansum, Penicillium roqueforti and Paecilomyces niveus. Mathematical models (without and with optimum) were suggested to describe the impact of CO2 percentage or undissociated carbonic acid concentration on fungal growth rate.

Impact of sodium chloride and carbon dioxide on conidial germination and radial growth of Penicillium camemberti

Penicillium camemberti is a domesticated species adapted to the dairy environment, which is used as adjunct cultures to ripen soft cheeses. A recent population genomics analysis on P. camemberti revealed that P. camemberti is a clonal lineage with two varieties almost identical genetically but with contrasting phenotypes in terms of growth, color, mycotoxin production and inhibition of contaminants. P. camemberti variety camemberti is found on Camembert and Brie cheeses, and P. camemberti variety caseifulvum is mainly found on other cheeses like Saint-Marcellin and Rigotte de Condrieu. This study aimed to evaluate the impact of water activity (aw) reduced by sodium chloride (NaCl) and the increase of carbon dioxide (CO2) partial pressure, on conidial germination and growth of two varieties of P. camemberti: var. Camemberti and var. Caseifulvum. Mathematical models were used to describe the responses of P. camemberti strains to both abiotic factors. The results showed that these genetically distant strains had similar responses to increase in NaCl and CO2 partial pressure. The estimated cardinal values were very close between the strains although all estimated cardinal values were significantly different (Likelihood ratio tests, pvalue = 0.05%). These results suggest that intraspecific variability could be more exacerbated during fungal growth compared with conidial germination, especially in terms of macroscopic morphology. Indeed, var. Caseifulvum seemed to be more sensitive to an increase of CO2 partial pressure, as shown by the fungal morphology, with the occurrence of irregular outgrowths, while the morphology of var. Camemberti remains circular. These data could make it possible to improve the control of fungal development as a function of salt and carbon dioxide partial pressure. These abiotic factors could serve as technological barriers to prevent spoilage and increase the shelf life of cheeses. The present data will allow more precise predictions of fungal proliferation as a function of salt and carbon dioxide partial pressure, which are significant technological hurdles in cheese production.

Mycotoxins in soybean-based foods fermented with filamentous fungi: Occurrence and preventive strategies

Fermented soybean products are widely consumed worldwide, and their popularity is increasing. Filamentous fungi, such as Actinomucor, Aspergillus, Monascus, Mucor, Penicillium, Rhizopus, and Zymomonas, play critical roles in the fermentation processes of many soybean foods. However, besides producing essential enzymes for food fermentation, filamentous fungi can release undesirable or even toxic metabolites into the food. Mycotoxins are toxic secondary metabolites produced by certain filamentous fungi and may be detected during the food production process. Without effective prevention strategies, mycotoxin contamination in fermented soybean products poses a risk to human health. This review focused on the changes in mycotoxigenic fungal abundance and mycotoxin contamination at different stages during the production of soybean-based fermented foods, as well as effective strategies for preventing mycotoxin contamination in such products. Data from relevant studies demonstrated a tendency of change in the genera of mycotoxigenic fungi and types of mycotoxins (aflatoxins, alternariol, alternariol monomethyl ether, deoxynivalenol, fumonisins, ochratoxin A, rhizoxins, T-2 toxin, and zearalenone) present in the raw materials and the middle and final products. The applicability of traditional chemical and physical mitigation strategies and novel eco-friendly biocontrol approaches to prevent mycotoxin contamination in soybean-based fermented foods were discussed. The present review highlights the risks of mycotoxin contamination during the production of fermented soybean products and recommends promising strategies for eliminating mycotoxin contamination risk in soybean-based fermented foods.

The importance and mitigation of mycotoxins and plant toxins in Southeast Asian fermented foods

Fermented foods (ffs) and beverages are widely consumed in Southeast Asia (SEA) for their nutritional balance, flavor, and food security. They serve as vehicles for beneficial microorganisms performing a significant role in human health. However, there are still major challenges concerning the safety of ffs and beverages due to the presence of natural toxins. In this review, the common toxins found in traditional ffs in SEA are discussed with special reference to mycotoxins and plant toxins. Also, mitigation measures for preventing risks associated with their consumption are outlined. Ochratoxin, citrinin, aflatoxins were reported to be major mycotoxins present in SEA ffs. In addition, soybean-based ff food products were more vulnerable to mycotoxin contaminations. Common plant toxins recorded in ffs include cyanogenic glycosides, oxalates, phytates and saponins. Combined management strategies such as pre-harvest, harvest and post-harvest control and decontamination, through the integration of different control methods such as the use of clean seeds, biological control methods, fermentation, appropriate packaging systems, and controlled processing conditions are needed for the safe consumption of indigenous ffs in SEA.

Fine Identification and Classification of a Novel Beneficial Talaromyces Fungal Species from Masson Pine Rhizosphere Soil

Rhizosphere fungi have the beneficial functions of promoting plant growth and protecting plants from pests and pathogens. In our preliminary study, rhizosphere fungus JP-NJ4 was obtained from the soil rhizosphere of Pinus massoniana and selected for further analyses to confirm its functions of phosphate solubilization and plant growth promotion. In order to comprehensively investigate the function of this strain, it is necessary to ascertain its taxonomic position. With the help of genealogical concordance phylogenetic species recognition (GCPSR) using five genes/regions (ITS, BenA, CaM, RPB1, and RPB2) as well as macro-morphological and micro-morphological characters, we accurately determined the classification status of strain JP-NJ4. The concatenated phylogenies of five (or four) gene regions and single gene phylogenetic trees (ITS, BenA, CaM, RPB1, and RPB2 genes) all show that strain JP-NJ4 clustered together with Talaromyces brevis and Talaromyces liani, but differ markedly in the genetic distance (in BenA gene) from type strain and multiple collections of T. brevis and T. liani. The morphology of JP-NJ4 largely matches the characteristics of genes Talaromyces, and the rich and specific morphological information provided by its colonies was different from that of T. brevis and T. liani. In addition, strain JP-NJ4 could produce reduced conidiophores consisting of solitary phialides. From molecular and phenotypic data, strain JP-NJ4 was identified as a putative novel Talaromyces fungal species, designated T. nanjingensis.

Effect of in-package gas composition on growth and aflatoxin production of Aspergillus flavus in culture medium and red pepper

In this study, the effect of in-package gas composition on growth and aflatoxin production of toxigenic Aspergillus flavus was investigated. For this purpose, semi-dried red pepper samples and potato dextrose agar media with different pH values (3.5, 5.6, 7.0 and 9.0) were inoculated with A. flavus and packaged under different gas atmospheres (air, 100% N₂, 70% N₂ + 30% CO₂ and 100% CO₂). The growth of the fungus was monitored during storage at 25 °C for 8 days and the aflatoxin levels produced were determined at the end of storage. The highest growth rate was observed in the medium at pH 9.0 and the highest toxin production was in the medium at pH 5.6. Slowdowns up to 55.6% and 28.0% in the growth of A. flavus in the culture medium and red pepper were observed when packaging under 100% N₂ was employed. It was found that 70% N₂ + 30% CO₂ atmosphere was more effective than 100% N₂ in inhibiting the growth of A. flavus in red peppers; however, the difference between the aflatoxin levels produced in the samples packaged under these gas compositions was not significant (p > 0.05). CO₂ concentrations higher than 90% in the package were quite effective against A. flavus resulting in 60% and 99% reductions in the growth and aflatoxin production of the fungus in red pepper.

Multi-Mycotoxin Contamination of Maize Silages in Flanders, Belgium: Monitoring Mycotoxin Levels from Seed to Feed

Maize silage, which in Europe is the main feed for dairy cattle in winter, can be contaminated by mycotoxins. Mycotoxigenic Fusarium spp. originating from field infections may survive in badly sealed silages or re-infect at the cutting edge during feed-out. In this way, mycotoxins produced in the field may persist during the silage process. In addition, typical silage fungi such as Penicillium spp. and Aspergillus spp. survive in silage conditions and produce mycotoxins. In this research, 56 maize silages in Flanders were sampled over the course of three years (2016-2018). The concentration of 22 different mycotoxins was investigated using a multi-mycotoxin liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, and the presence of DNA of three Fusarium spp. (F. graminearum, F. culmorum and F. verticillioides) was analyzed in a selection of these samples using quantitative polymerase chain reaction (qPCR). Every maize silage contained at least two different mycotoxins. Nivalenol (NIV) and deoxynivalenol (DON) were the most prevalent (both in 97.7% of maize silages), followed by ENN B (88.7%). Concentrations often exceeded the EU recommendations for DON and zearalenone (ZEN), especially in 2017 (21.3% and 27.7% of the maize silages, respectively). No correlations were found between fungal DNA and mycotoxin concentrations. Furthermore, by ensiling maize with a known mycotoxin load in a net bag, the mycotoxin contamination could be monitored from seed to feed. Analysis of these net bag samples revealed that the average concentration of all detected mycotoxins decreased after fermentation. We hypothesize that mycotoxins are eluted, degraded, or adsorbed during fermentation, but certain badly preserved silages are prone to additional mycotoxin production during the stable phase due to oxygen ingression, leading to extremely high toxin levels.

Investigation of decontamination effect of argon cold plasma on physicochemical and sensory properties of almond slices

Cold plasma is a novel technology for surface decontamination. Almond slices can be contaminated with different microorganisms during their production. In the current research, the atmospheric argon plasma treatment (5, 10, 15, and 20 min) was used to decontamination of almond slices surface. Microbial load, Color, peroxide value, hardness, and sensory properties of slices was comprised with untreated samples (control). Descriptive sensory evaluation about color, flavor, crispiness, crunchiness, and hardness of almond slices were performed. According to the results of the microbial tests, Total count, molds and yeasts, and Staphylococcus aureus of almond surface decreased about 2.95 log cfu/g, 1.81 log cfu/g, and 2.72 log cfu/g after 20 min of plasma treatment, respectively, provided that microbial reduction increased more by increasing the treatment time. Coupled with the color evaluation, peroxide value and sensory attributes didn't change during plasma treatment. Having said that, the hardness of slices was changed by increasing treatment time. Furthermore, Principal Component Analysis and cluster analysis were performed for sensory evaluation. In light of the consumer's point of view, firstly 10 min and secondly 15 min plasma treatment can be more desirable.

Recent progress of the effect of environmental factors on Aspergillus flavus growth and aflatoxins production on foods

The contamination of Aspergillus flavus and subsequent aflatoxins (AFs) has been considered as one of the most serious food safety problems due to their acute and chronic adverse effects on humans and animals. This review collects the available information from recent years on the effect of the major environmental factors such as water activity (aw), temperature, CO2, and pH on the fungal growth, the expression of AFs-related genes, and AFs production by A. flavus on foods. In particular, the relationship between the relative expression of key regulatory (aflR and aflS) and structural genes (aflD, aflO, aflQ, etc.) and AFs production under different environmental conditions are collected and discussed. The information collected in this review can be used to design control strategies of A. flavus and AFs contamination in practical applications, primarily during storage and processing. These data suggest that integrating various post-harvest methods with synergistic functions may be more efficient for the control of A. flavus growth and AFs production, although the individual environmental factors alone have an impact.

Risk assessment for mycotoxin contamination in fish feeds in Europe

Mycotoxins are difficult to monitor continuously, and a tool to assess the risk would help to judge if there is a particular risk due to the inclusion of certain feed ingredients. For this, the toxin contents of 97 commercial fish feeds have been estimated, and the most prominent toxins in fish feed are calculated to be deoxynivalenol, zearalenone, fumonisins and enniatins. These pose a risk to fish well-being, as can be calculated by the Bayesian models for determining the critical concentrations 5% (CC5) for the different toxins. Besides fishmeal, wheat, soybean products and corn are regularly used as fish feed ingredients. The calculated scenarios show that fish are at high risk of toxin contamination if feed ingredients of low quality are chosen for feed production. Due to this, specific maximum allowable levels for several mycotoxins in fish feeds should be established.

Relationships between feeding and microbial faeces indices in dairy cows at different milk yield levels

A study was carried out to gain quantitative information on the diet-dependent faecal microbial biomass of dairy cows, especially on the biomass fractions of fungi, Gram-positive (G+) and Gram-negative (G-) bacteria. Groups of high-yield, low-yield and non-lactating cows were investigated at four different farms. A mean faecal microbial biomass C (MBC) concentration of 33.5 mg g-1 DM was obtained by the chloroform fumigation extraction method. This is similar to a mean microbial C concentration of 31.8 mg g-1 DM, which is the sum of bacterial C and fungal C, estimated by cell-wall derived muramic acid (MurN) and fungal glucosamine (GlcN), respectively. However, the response of these two approaches to the feeding regime was contradictory, due to feeding effects on the conversion values. The higher neutral detergent fibre (NDF) and acid detergent fibre (ADF) concentrations in the non-lactating group led to higher (P < 0.05) concentrations of cellulose and lignin in their faeces in comparison with the lactating cows. This change in faecal chemical composition in the non-lactating group was accompanied by usually higher ratios of G+/G- phospholipid fatty acids (PLFA), ergosterol/MBC and fungal C/bacterial C. Although bacteria dominate the faecal microbial biomass, fungi contribute a considerable mean percentage of roughly 20% to the faecal microbiome, according to PLFA and amino sugar data, which requires more attention in the future. Near-infra red spectroscopic estimates of organic N and C fractions of cow faeces were able to model microbial biomarkers successfully, which might be useful in the future to predict its N2O emission potential and fertilizer value.

Influence of oxygen exposure on fermentation process and sensory qualities of Sichuan pickle (paocai)

The physicochemical and microbial changes, volatile profile, texture and appearance were investigated in three groups of Sichuan pickles differing in oxygen exposure during a 64 day fermentation process.

Paecilomyces Rot: A New Apple Disease

Paecilomyces niveus is an important food spoilage fungus that survives thermal processing in fruit products, where it produces the mycotoxin patulin. Spoilage of products has been attributed to soil contamination; however, little is known about the ecology of this organism. In this study, orchard soils and culled apple fruit were surveyed and the ability of P. niveus to infect apple was tested on two popular apple varieties. P. niveus was found in 34% of sampled orchard soils from across New York. Completing Koch's postulates, P. niveus was demonstrated to cause postharvest disease in Gala and Golden Delicious apple. Symptoms of this disease, named Paecilomyces rot, resemble several other apple diseases, including black rot, bitter rot, and bull's-eye rot. External symptoms of Paecilomyces rot include brown, circular, concentrically ringed lesions, with an internal rot that is firm and cone-shaped. Both Gala and Golden Delicious apple fruit inoculated with P. niveus developed lesions ≥43 mm in size at 22 days after inoculation. There is some evidence that the size of lesions and rate of infection differ between Gala and Golden Delicious, which may indicate differing resistance to P. niveus. This work shows that P. niveus is common in New York orchard soil and can cause a novel postharvest fruit disease. Whether infected fruit can serve as an overlooked source of inoculum in heat-processed apple products requires further study.

Occurrence, distribution and contamination levels of heat-resistant moulds throughout the processing of pasteurized high-acid fruit products

Heat-resistant moulds (HRMs) are well known for their ability to survive pasteurization and spoil high-acid food products, which is of great concern for processors of fruit-based products worldwide. Whilst the majority of the studies on HRMs over the last decades have addressed their inactivation, few data are currently available regarding their contamination levels in fruit and fruit-based products. Thus, this study aimed to quantify and identify heat-resistant fungal ascospores from samples collected throughout the processing of pasteurized high-acid fruit products. In addition, an assessment on the effect of processing on the contamination levels of HRMs in these products was carried out. A total of 332 samples from 111 batches were analyzed from three processing plants (=three processing lines): strawberry puree (n = 88, Belgium), concentrated orange juice (n = 90, Brazil) and apple puree (n = 154, the Netherlands). HRMs were detected in 96.4% (107/111) of the batches and 59.3% (197/332) of the analyzed samples. HRMs were present in 90.9% of the samples from the strawberry puree processing line (1-215 ascospores/100 g), 46.7% of the samples from the orange juice processing line (1-200 ascospores/100 g) and 48.7% of samples from the apple puree processing line (1-84 ascospores/100 g). Despite the high occurrence, the majority (76.8%, 255/332) of the samples were either not contaminated or presented low levels of HRMs (<10 ascospores/100 g). For both strawberry puree and concentrated orange juice, processing had no statistically significant effect on the levels of HRMs (p > 0.05). On the contrary, a significant reduction (p < 0.05) in HRMs levels was observed during the processing of apple puree. Twelve species were identified belonging to four genera - Byssochlamys, Aspergillus with Neosartorya-type ascospores, Talaromyces and Rasamsonia. N. fumigata (23.6%), N. fischeri (19.1%) and B. nivea (5.5%) were the predominant species in pasteurized products. The quantitative data (contamination levels of HRMs) were fitted to exponential distributions and will ultimately be included as input to spoilage risk assessment models which would allow better control of the spoilage of heat treated fruit products caused by heat-resistant moulds.

Mould spoilage of foods and beverages: Using the right methodology

Fungal spoilage of products manufactured by the food and beverage industry imposes significant annual global revenue losses. Mould spoilage can also be a food safety issue due to the production of mycotoxins by these moulds. To prevent mould spoilage, it is essential that the associated mycobiota be adequately isolated and accurately identified. The main fungal groups associated with spoilage are the xerophilic, heat-resistant, preservative-resistant, anaerobic and psychrophilic fungi. To assess mould spoilage, the appropriate methodology and media must be used. While classic mycological detection methods can detect a broad range of fungi using well validated protocols, they are time consuming and results can take days or even weeks. New molecular detection methods are faster but require good DNA isolation techniques, expensive equipment and may detect viable and non-viable fungi that probably will not spoil a specific product. Although there is no complete and easy method for the detection of fungi in food it is important to be aware of the limitation of the methodology. More research is needed on the development of methods of detection and identification that are both faster and highly sensitive.

Diversity and Control of Spoilage Fungi in Dairy Products: An Update

Fungi are common contaminants of dairy products, which provide a favorable niche for their growth. They are responsible for visible or non-visible defects, such as off-odor and -flavor, and lead to significant food waste and losses as well as important economic losses. Control of fungal spoilage is a major concern for industrials and scientists that are looking for efficient solutions to prevent and/or limit fungal spoilage in dairy products. Several traditional methods also called traditional hurdle technologies are implemented and combined to prevent and control such contaminations. Prevention methods include good manufacturing and hygiene practices, air filtration, and decontamination systems, while control methods include inactivation treatments, temperature control, and modified atmosphere packaging. However, despite technology advances in existing preservation methods, fungal spoilage is still an issue for dairy manufacturers and in recent years, new (bio) preservation technologies are being developed such as the use of bioprotective cultures. This review summarizes our current knowledge on the diversity of spoilage fungi in dairy products and the traditional and (potentially) new hurdle technologies to control their occurrence in dairy foods.

Effects of iron and boron combinations on the suppression of Fusarium wilt in banana

The effects of mineral nutrient on banana wilt disease, which are the result of a competitive relationship between host plants and pathogens, can affect the interactions of plants with microorganisms. To investigate the mineral nutrient effect, hydroponic experiments were conducted in glasshouse containing combinations of low, medium, and high iron (Fe) and boron (B) concentrations, followed by pathogen inoculation. High Fe and B treatment significantly reduced the disease index and facilitated plants growth. With increasing Fe and B concentrations, more Fe and B accumulated in plants. High Fe and B treatment dramatically reduced the Fusarium oxysporum conidial germination rate and fungal growth compared with the other two treatments, contributing to decreased numbers of the pathogen on infected plants. Furthermore, High Fe and B treatment decreased the fusaric acid production of F. oxysporum in vitro and also increased the mannitol content of the plants, which in turn decreased the phytotoxin production of infected plants and finally reduced the disease index due to the virulence factor of phytotoxin. Taken together, these results indicate that Fe and B play a multifunctional role in reducing the severity of diseases by affecting the growth of F. oxysporum and the responses between plants and pathogens.

Occurrence, prevention and remediation of toxigenic fungi and mycotoxins in silage: a review

Ruminants are considered to be less sensitive towards mycotoxins than monogastric animals because rumen microbiota have mycotoxin-detoxifying capacities. Therefore the effect of mycotoxins towards ruminants has been studied to a lesser extent compared with monogastric animals. Worldwide, a high proportion of the ruminant diet consists of silages made of forage crops (i.e. all parts of the crop above the stubble are harvested). In practice, silages are often contaminated with multiple mycotoxins. Exposure to a cocktail of mycotoxins can hamper animal production and have severe health consequences. In this article the different aspects associated with mycotoxin contamination of silage are reviewed 'from seed to feed'. An overview is given on the occurrence of toxigenic fungal species and their concomitant mycotoxins in forage crops before and after ensiling. The mycotoxin load of visually non-mouldy samples and mouldy hot spots within the same silo is also compared. Subsequently, this review delves into different problem-solving strategies. A logical first step is prevention of mould growth and mycotoxin production in the field, during harvest and during ensiling. If prevention should fail, several remediation strategies are available. These are listed, mainly focusing on the possibilities of microbial degradation of mycotoxins in vivo in silage. © 2015 Society of Chemical Industry.

Inactivation of Byssochlamys nivea ascospores in strawberry puree by high pressure, power ultrasound and thermal processing

Byssochlamys nivea is a mold that can spoil processed fruit products and produce mycotoxins. In this work, high pressure processing (HPP, 600 MPa) and power ultrasound (24 kHz, 0.33 W/mL; TS) in combination with 75°C for the inactivation of four week old B. nivea ascospores in strawberry puree for up to 30 min was investigated and compared with 75°C thermal processing alone. TS and thermal processing can activate the mold ascospores, but HPP-75°C resulted in 2.0 log reductions after a 20 min process. For a 10 min process, HPP-75°C was better than 85°C alone in reducing B. nivea spores (1.4 vs. 0.2 log reduction), demonstrating that a lower temperature in combination with HPP is more effective for spore inactivation than heat alone at a higher temperature. The ascospore inactivation by HPP-thermal, TS and thermal processing was studied at different temperatures and modeled. Faster inactivation was achieved at higher temperatures for all the technologies tested, indicating the significant role of temperature in spore inactivation, alone or combined with other physical processes. The Weibull model described the spore inactivation by 600 MPa HPP-thermal (38, 50, 60, 75°C) and thermal (85, 90°C) processing, whereas the Lorentzian model was more appropriate for TS treatment (65, 70, 75°C). The models obtained provide a useful tool to design and predict pasteurization processes targeting B. nivea ascospores.

Anaerobic digestion of food waste using yeast

Fermentative breakdown of food waste seems a plausible alternative to feeding food waste to pigs, incineration or garbage disposal in tourist areas. We determined the optimal conditions for the fermentative breakdown of food waste using yeast (Saccharomyces cerevisiae) in incubations up to 30days. Yeast efficiently broke down food waste with food waste loadings as high as 700g FW/l. The optimum inoculation was ≈46×10(6)cells/l of culture with a 40°C optimum (25-40°C). COD and BOD were reduced by ≈30-50%. Yeast used practically all the available sugars and reduced proteins and lipids by ≈50%. Yeast was able to metabolize lipids much better than expected. Starch was mobilized after very long term incubations (>20days). Yeast was effective in breaking down the organic components of food waste but CO2 gas and ethanol production (≈1.5%) were only significant during the first 7days of incubations.

Molecular identification of isolated fungi, microbial and heavy metal contamination of canned meat products sold in Riyadh, Saudi Arabia

Several studies have shown that canned meat products may be contaminated with fungal elements, bacteria and even heavy metals which may occur during the transportation, storage and handling processes. We conducted this study to determine the fungal, microbial and heavy metal contents of canned meats in Saudi Arabia. Of the 13 canned meat samples studied, Aspergillus and Penicillium were found in more than 70% of the total samples. Sequences of Penicillium species isolated from meat samples generated a phylogenetic tree which shows that the studied isolates were clustered in four groups. No bacterial contamination was noted in all of the samples. Nine of the 13 samples had iron concentrations above the permissible limit. All samples had zinc and copper levels below the maximum permissible limit. Four samples had cadmium levels above the maximum permissible level. All samples had levels of lead above the maximum permissible levels. These results indicate that fungal elements and higher levels of heavy metals such as lead and cadmium can be found in canned meat products. This may pose as a real danger to consumers, since canned meat products are readily accessible and convenient in Saudi Arabia.

Filamentous Fungi and Mycotoxins in Cheese: A Review

Important fungi growing on cheese include Penicillium, Aspergillus, Cladosporium, Geotrichum, Mucor, and Trichoderma. For some cheeses, such as Camembert, Roquefort, molds are intentionally added. However, some contaminating or technological fungal species have the potential to produce undesirable metabolites such as mycotoxins. The most hazardous mycotoxins found in cheese, ochratoxin A and aflatoxin M1, are produced by unwanted fungal species either via direct cheese contamination or indirect milk contamination (animal feed contamination), respectively. To date, no human food poisoning cases have been associated with contaminated cheese consumption. However, although some studies state that cheese is an unfavorable matrix for mycotoxin production; these metabolites are actually detected in cheeses at various concentrations. In this context, questions can be raised concerning mycotoxin production in cheese, the biotic and abiotic factors influencing their production, mycotoxin relative toxicity as well as the methods used for detection and quantification. This review emphasizes future challenges that need to be addressed by the scientific community, fungal culture manufacturers, and artisanal and industrial cheese producers.

Predicting and preventing mold spoilage of food products

This article is a review of how to quantify mold spoilage and consequently shelf life of a food product. Mold spoilage results from having a product contaminated with fungal spores that germinate and form a visible mycelium before the end of the shelf life. The spoilage can be then expressed as the combination of the probability of having a product contaminated and the probability of mold growth (germination and proliferation) up to a visible mycelium before the end of the shelf life. For products packed before being distributed to the retailers, the probability of having a product contaminated is a function of factors strictly linked to the factory design, process, and environment. The in-factory fungal contamination of a product might be controlled by good manufacturing hygiene practices and reduced by particular processing practices such as an adequate air-renewal system. To determine the probability of mold growth, both germination and mycelium proliferation can be mathematically described by primary models. When mold contamination on the product is scarce, the spores are spread on the product and more than a few spores are unlikely to be found at the same spot. In such a case, models applicable for a single spore should be used. Secondary models can be used to describe the effect of intrinsic and extrinsic factors on either the germination or proliferation of molds. Several polynomial models and gamma-type models quantifying the effect of water activity and temperature on mold growth are available. To a lesser extent, the effect of pH, ethanol, heat treatment, addition of preservatives, and modified atmospheres on mold growth also have been quantified. However, mold species variability has not yet been properly addressed, and only a few secondary models have been validated for food products. Once the probability of having mold spoilage is calculated for various shelf lives and product formulations, the model can be implemented as part of a risk management decision tool.

The effect of cocoa fermentation and weak organic acids on growth and ochratoxin A production by Aspergillus species

The acidic characteristics of cocoa beans have influence on flavor development in chocolate. Cocoa cotyledons are not naturally acidic, the acidity comes from organic acids produced by the fermentative microorganisms which grow during the processing of cocoa. Different concentrations of these metabolites can be produced according to the fermentation practices adopted in the farms, which could affect the growth and ochratoxin A production by fungi. This work presents two independent experiments carried out to investigate the effect of some fermentation practices on ochratoxin A production by Aspergillus carbonarius in cocoa, and the effect of weak organic acids such as acetic, lactic and citric at different pH values on growth and ochratoxin A production by A. carbonarius and Aspergillus niger in culture media. A statistical difference (ρ<0.05) in the ochratoxin A level in the cured cocoa beans was observed in some fermentation practices adopted. The laboratorial studies demonstrate the influence of organic acids on fungal growth and ochratoxin A production, with differences according to the media pH and the organic acid present. Acetic acid was the most inhibitory acid against A. carbonarius and A. niger. From the point of view of food safety, considering the amount of ochratoxin A produced, fermentation practices should be conducted towards the enhancement of acetic acid, although lactic and citric acids also have an important role in lowering the pH to improve the toxicity of acetic acid.

Influence of package, type of apple juice and temperature on the production of patulin by Byssochlamys nivea and Byssochlamys fulva

Although the production of patulin in apple fruits is mainly by Penicillium expansum, there is no information on the ability of heat resistant moulds that may survive pasteurization to produce this mycotoxin in juice packages during storage and distribution. In this study, the production of patulin by Byssochlamys spp (Byssochlamys nivea FRR 4421, B. nivea ATCC 24008 and Byssochlamys fulva IOC 4518) in cloudy and clarified apple juices packaged in laminated paperboard packages or in polyethylene terephthalate bottles (PET) and stored at both 21 degrees C and 30 degrees C, was investigated. The three Byssochlamys strains were able to produce patulin in both cloudy and clarified apple juices. Overall, the lower the storage temperature, the lower the patulin levels and mycelium dry weight in the apple juices (p<0.05). The greatest variations in pH and degrees Brix were observed in the juices from which the greatest mycelium dry weights were recovered. The maximum levels of patulin recovered from the juices were ca. 150 microg/kg at 21 degrees C and 220 microg/kg at 30 degrees C. HPLC-UV, HPCL-DAD and mass spectrometry analyses confirmed the ability of B. fulva IOC 4518 to produce patulin. Due to the heat resistance of B. nivea and B. fulva and their ability to produce patulin either in PET bottles or in laminated paperboard packages, the control of contamination and the incidence of these fungi should be a matter of concern for food safety. Control measures taken by juice industries must also focus on controlling the ascospores of heat resistant moulds.