Evaluation of antimicrobial and physical properties of edible film based on carboxymethyl cellulose containing potassium sorbate on some mycotoxigenic Aspergillus species in fresh pistachios.
Active packaging is a relatively novel concept of packaging that changes the conditions of the packaged food to extend its shelf-life and improve its safety. In this study; antimicrobial effects of carboxymethyl cellulose based-edible film containing potassium sorbate as an antimicrobial agent were studied against Aspergillus flavus (PTCC-5004); Aspergillus parasiticus (PTCC-5286) and Aspergillus parasiticus (PTCC-5018) by using agar diffusion assay. Results showed suitable inhibition effects against Aspergillus parasiticus (PTCC-5286) and Aspergillus flavus (PTCC-5004) in comparison with Aspergillus parasiticus (PTCC-5018). Pistachios were coated with this edible antimicrobial film containing three concentrations of sorbate (1; 0.5 and 0.25 g/100 mL film solution); all concentrations showed no growth of molds. Tensile strength values of films with potassium sorbate; decreased when compared to control; and film's flexibility; was 28.82 percent for 3 g/100 mL sorbate; while higher concentration of sorbate; decreased the flexibility. The water vapor permeability values (WVP) of films were determined to be 1.18 (g mm/m2 day kPa) for films plasticized with glycerol; without sorbate while WVP values for the films containing 1 and 2 g/100 mL sorbate increased to 3.77 and 15.5 (g mm/m2 day kPa); respectively. The observed glass transition temperature (TG) depression for these polymer blends was related to the plasticizer content (water; polyethylene; and glycerol); especially water.
Studies on contamination level of aflatoxins in some dried fruits and nuts of Pakistan
The occurrence of aflatoxins in dried fruits and nuts was surveyed in this study. One hundred and eighty samples of dried fruits and nuts were purchased from retail shops and local markets of different locations of NWFP and Northern areas of Pakistan. The samples were analyzed for total aflatoxins by immune affinity (IAC) clean-up with liquid chromatography and fluorescence detection. The results showed the percentage of contamination for total aflatoxins in the samples such as in; dried apricot (20%); dates (10%); dried figs (50%); dried mulberries (26%) and raisins (20%); while in apricot kernels (26%); almonds without shell (30%); walnuts with shell (40%); walnuts without shell (70%); peanut with shell (40%); peanuts without shell (50%); pistachios with shell (20%); pistachios without shell (50%) and pine nuts with shell (20%). The highest contamination levels of aflatoxins were found in one peanut sample (14.5 µg/kg) and one pistachio sample (14 µg/kg). Among all the contaminated samples; one dried apricot; three dried fig; one raisins; one apricot kernels; two walnuts with shell; three walnuts without shell; one peanuts with shell; two peanuts without shell and two pistachios without shell samples were above the suggested limit for total aflatoxins (4 µg/kg); set by EU regulations.
Farmers perceptions; knowledge and management of aflatoxins in groundnuts (Arachis hypogaea L.) in India
Aflatoxins; produced by the fungi Aspergillus flavus Link ex Fries and Aspergillus parasiticus Speare; are the major toxins affecting the quality of groundnuts (Arachis hypogaea L.) meant for human consumption. Groundnuts can be infected with aflatoxin -producing fungi pre-harvest; at harvest and post-harvest. This survey was conducted in Gujarat province in India in order to assess farmers and other stakeholders (extension staff and traders) perceptions and knowledge of aflatoxin contamination of groundnuts and to evaluate the agronomic and market practices used to manage it. The survey investigated the effects of the socioeconomic background of the farmers. The results showed that the socioeconomic and psychological characteristics; viz. education; caste; farm size; social participation; extension participation; market orientation; economic motivation; innovativeness and perception had positive and significant associations with farmers knowledge. The extension staff and traders had a good understanding of the problem and of the importance of managing aflatoxin contamination but farmers did not. Farmers who practised effective crop husbandry in order to increase production were unwittingly managing aflatoxin contamination to some extent. Their marketing practises showed that the problem of aflatoxin contamination was neglected at both the production and marketing stages. We suggest that extension agencies need to train farmers in the use of biological control agents; post-harvest management and identification of aflatoxin contamination. Partnerships need to be forged between research institutions; the departments of agriculture of various states; marketing agencies; NGOs; farmers groups; consumer groups; agrochemical manufacturers and other stakeholders in order to develop strategies for addressing the problem of aflatoxin contamination. Research highlights: Groundnut producers are indifferent to aflatoxin contamination. Knowledge of aflatoxins is influenced by socioeconomic and psychological characteristics. Aflatoxin contamination can be reduced by good agricultural practices (GAP). Premium price to contamination free groundnuts encourages farmers' to adopt GAP.
First Report on Mould and Mycotoxin Contamination of Pistachios Sampled in Algeria
Mycotoxin contamination of pistachios represents a serious food safety hazard. The aim of this study was to evaluate fungal contamination and aflatoxin (AF) and ochratoxin A (OTA) occurrence in pistachio sampled in Algeria and to study the mycotoxigenic capacities of the isolates. A total of 31 pistachio samples were collected from retail outlets from different regions of Algeria. The most frequently found fungi were Penicillium spp. (38%); Aspergillus section Nigri (30%) and A. flavus (22%). A total of 56.5% of A. flavus isolates were able to produce AFB(1) and AFB(2). No A. section Nigri uniseriate isolate was OTA producer; whereas OTA production capacity was detected in 33.3% of the A. section Nigri biseriate. At least one of the potentially ochratoxigenic species was found in 64.5% of samples. Despite the high number of pistachio samples containing AFs and OTA-producing isolates; only two samples contained AFs (always below the EU maximum tolerable level) and only one sample showed OTA contamination. This is the first report on the occurrence of toxigenic moulds and mycotoxins in pistachios from Algerian market.
Correlation between aflatoxin contamination and various USDA grade categories of shelled almonds
The California almond industry is interested in determining if there is a correlation between aflatoxin contamination and almonds classified into various U.S. Department of Agriculture (USDA) grades. A 12 000 g sample was taken from each of 50 lots of shelled almonds. The almonds in each sample were then partitioned into five USDA grades: high quality (HQ); insect damage (ID); mold damage (MOD); mechanical damage (MED); and other defects (OD). Across all 50 samples; kernels in the HQ grade accounted for 83.7% of the kernel mass and 3.2% of the aflatoxin mass. Conversely; kernels in the remaining four damage grades (ID; MOD; MED; and OD) accounted for 16.3% of the kernel mass and 96.8% of the aflatoxin mass. ID kernels had the highest risk for aflatoxin contamination. Almonds in the ID grade accounted for 76.3% of the total aflatoxin mass and 7.2% of the kernel mass. Regression equations were developed to predict the aflatoxin concentration in each 12 000 g sample by measuring the aflatoxin mass in one or more of the four damage grades. Regression equations demonstrated that aflatoxin mass only in the insect damaged kernels was also an effective way to predict the aflatoxin concentration in each 12 000 g sample.
Detoxification of Aflatoxin B1 and Patulin by Enterococcus faecium strains
Aim of the present study was to investigate the detoxification of aflatoxin B1 and patulin from aqueous solution by probiotic culture of Enterococcus faecium M74 and commercial culture of E. faecium EF031. The effect of the bacterial viability; incubation time and pH of the medium on the binding ability was tested. Also; binding stability was determined by washing the bacteria-mycotoxin complexes with phosphate buffer saline. Both M74 and EF031 strains have ability to remove aflatoxin B1 and patulin. While M74 remove 19.3 to 30.5% of aflatoxin B1 and 15.8 to 41.6% of patulin; EF031 remove 23.4 to 37.5% of aflatoxin B1 and 19.5 to 45.3% of patulin throughout a 48 h incubation period. The removal of aflatoxin B1 and patulin was the highest at pH 7.0 and 4.0; respectively. The stability of the aflatoxin B1 and patulin complexes formed with the bacterial strains was found to be high. The viability of the bacteria did not have any significant effect on the detoxification of aflatoxin B1 and patulin. Detoxification properties of E. faecium could represent new strategies for a possible application in the human diet and animal feed.
Indicators for early identification of re-emerging mycotoxins
The aim of this study was to select the most important indicators for early identification of re-emerging mycotoxins in wheat; maize; peanuts and tree nuts. The study was based on a holistic approach and; consequently; potential indicators were evaluated not only from the food production chain but also from other influential sectors. The study comprised a literature review followed by an expert judgement study. The expert study consisted of a series of individual interviews and a workshop. It used a panel of 25 experts from the Netherlands. The selected indicators for the model commodity wheat included relative humidity; temperature; transport and storage conditions; crop rotation; crop variety; tillage practice; and drying of the kernel. For maize; peanuts and tree nuts; the first three indicators were found to be most important. The results of this study will be used in the development of models for early identification of re-emerging mycotoxins in wheat; maize; peanuts and tree nuts. Such models may be useful for risk managers from feed and food industry and/or governmental authorities to facilitate pro-active feed and/or food safety management.
Analysis of genes early expressed during Aspergillus flavus colonisation of hazelnut
Aflatoxins contamination by Aspergillus flavus is a matter of great concern for oil rich crops among which hazelnuts represent economically important agricultural commodities of Mediterranean countries; mainly used as mixed nuts or as ingredients in the bakery and confectionery industries. Since the biosynthetic pathway of aflatoxin biosynthesis has been elucidated in detail; expression analysis of the genes along the pathway can provide a thorough insight into the molecular mechanisms of toxin production and regulation. In the present work; we carried out a transcriptional analysis of the main genes belonging to aflatoxin biosynthetic cluster of A. flavus; namely the two regulatory genes aflR and aflS and the five structural genes aflD; aflM; aflO; aflP; and aflQ. The analysis was carried out at different stages of fungal growth on two different media: hazelnut agar medium and YES medium. The transcripts of all the genes paralleled the synthesis of aflatoxin and both were detected starting around 36h in YES medium; and 72h in hazelnut agar medium. Significantly; the amount of aflatoxin produced was about one order lower in hazelnut agar compared to YES medium. The expression of two genes encoding a lipase and a metalloprotease; potentially involved in lipid and protein catabolism; was also monitored during fungal growth. Noteworthy; the expression of the metalloprotease gene appeared to be specific for the hazelnut medium; whereas the lipase gene was expressed in both media. Finally; we verified the expression profiles of three genes encoding fatty acid dioxygenases/diol synthases involved in the biosynthesis of fungal oxylipins; namely ppoA; ppoB; ppoC. Recent findings have pointed out the importance of fungal oxylipins in fungal growth/mycotoxin production and our results indicated that all the three ppo genes are expressed during A. flavus growth on hazelnut medium. In particular; ppoB appeared to be specifically expressed in this medium. This study reports for the first time on the expression profiles of genes belonging to the biosynthetic cluster and genes potentially involved in the regulation of fungal secondary metabolism during A. flavus colonisation of hazelnuts.
Biocontrol of Aspergillus flavus on peanut kernels by use of a strain of marine Bacillus megaterium
A strain of marine Bacillus megaterium isolated from the Yellow Sea of East China was evaluated for its activity in reducing postharvest decay of peanut kernels caused by Aspergillus flavus in in vitro and in vivo tests. The results showed that the concentrations of antagonist had a significant effect on biocontrol effectiveness in vivo: when the concentration of the washed bacteria cell suspension was used at 1x10(9)CFU/ml; the percentage rate of rot of peanut kernels was 31.67%+/-2.89%; which was markedly lower than that treated with water (the control) after 7days of incubation at 28 degrees C. The results also showed that unwashed cell culture of B. megaterium was as effective as the washed cell suspension; and better biocontrol was obtained when longer incubation time of B. megaterium was applied. When the incubation time of B. megaterium was 60-h; the rate of decay declined to 41.67%+/-2.89%. Furthermore; relative to the expression of 18S rRNA; the mRNA abundances of aflR gene and aflS gene in the experiment group were 0.28+/-0.03 and 0.024+/-0.005 respectively; indicating that this strain of B. megaterium could significantly reduce the biosynthesis of aflatoxins and expression of aflR gene and aflS gene (p<0.01). To the best of our knowledge; this is a first report demonstrating that the marine bacterium B. megaterium could be used as a biocontrol agent against postharvest fungal disease caused by A. flavus.
Increased aflatoxin contamination of dried figs in a drought year
Dried figs (4917 samples) destined for export from Turkey to the European Union were collected between September and December during the very dry crop year of 2007 and tested for aflatoxins B(1); B(2); G(1) and G(2) by immunoaffinity column clean-up and reverse-phase high-performance liquid chromatography (RP-HPLC). While 32% of the samples contained detectable levels of total aflatoxins; 9.8% of them exceeded the European Union limits. Aflatoxin levels were in the range of 0.2-259.46 microg kg(-1) and 2.04-259.46 microg kg(-1) for all samples and samples that exceeded the limits; respectively. A substantial increase in the incidence of aflatoxins was observed in 2007 compared with previous years; most likely due to the drought stress; high temperatures and low relative humidity encountered during the period from January to September of that year. In 2007; the mean temperature was 1-2 degrees C higher; there was 300 mm less total rain; and the mean relative humidity was 10-15% lower than in 2002-06. The average concentration of individual aflatoxins present in the samples was quantified to determine whether the drought conditions promoted certain types of aflatoxins. Among the contaminated samples; aflatoxin B(1) occurred in 97% of the contaminated samples; followed by G(1) in 47%; B(2) in 24%; and G(2) in 6% of samples. Concentrations of individual aflatoxins exhibited great variability among the samples but were not significantly different from those reported in previous studies; which were conducted under conditions without drought and high temperatures.