Studies on Some Mycotoxin and Mycotoxigenic Fungi in Different Types of Processed Peanuts in Egypt

Abstract

Peanut are considered an important crop which grown in Egypt for local consumption, industry raw or as processed peanut products and export to European markets. Peanuts are greatly appreciated by consumers but are very susceptible to aflatoxigenic fungi contamination. This indicates that there is a potential hazard of aflatoxins contamination in Egyptian processed peanuts and that require resistance to this fungus. This study monitored the moisture content (MC),the population of fungal flora, aflatoxigenic fungi and aflatoxins contamination present in total eighty samples representing four peanut products raw and processed peanuts(roasted, salted and lebanese with spices). These samples were collected from supermarkets and small shops in five different governorates of Egypt (Cairo, Suez, Menoufia of north Delta and Fayoum and Luxor of south Delta) during one year from winter 2013 to autumn 2014. As well ten powder spices (clove, black pepper, cinnamon, peppermint, thyme, cardamom, cumin, ginger, onions and fenugreek) were used for antifungal and anti aflatoxigenic activity against Aspergillus flavus at different concentrations 4,7,10 mg/ml. Results showed that moisture content (MC) in peanut samples was detected, most of the samples had < 9.3 MC%, also moisture content of raw peanut samples were higher than lebanese with spices followed by salted peanuts and the lowest MC% in roasted peanut. Raw peanut samples had the highest moisture content (MC%) 16.66±0.75 in Suez governorate in winter season. Fungal flora associated with raw peanut and peanut products yielded 3771fungal isolates belonging to four fungal genera: Aspergillus spp.(55.23%), Penicillium spp.(19.51%)Fusarium spp.(13.94%) and Rhizopus spp.(11.29%).The Suez governorate samples had the highest contamination percentage of fungi (62.5%) whereas Luxor governorate samples had the lowest (43.75%).For peanut products ,raw peanut samples were the highest of fungal population (92.1%) followed by lebanese with spices (75.4%) whereas salted peanut samples were the lowest fungal population (48.75%). Spring season had the highest fungal contamination (77.5%) while, autumn had the lowest fungal contamination (60.0%).It was noticed that Aspergillus spp was the highest percentage. Results indicated that A.niger was the highest contamination percentage of A.spp. A.niger (48.68%) followed by A.flavus (19.73%), A.parasiticus (17.57%), A.oryzae (8.83%) and A.oryzae var effusus (5.18%). Test of aflatoxigenic fungi using thin layer chromatography (TLC) showed that 64 isolates of A.flavus gave positive reaction with AFB1 and AFB2, while96 isolate of A.parasiticus produced AFB1, AFB2, AFG1 and AFG2. The results indicated that 33(41.25%) of total 80 peanut samples were aflatoxins positive, with concentrations range from (3.77 to 871.9μg/kg). Furthermore, the numbers of contaminated samples with each of AFB1 and AFB2 were 33(41.25%), G1 18(22.5%) and G2 19(23.75%). It was noticed that raw peanut had the highest average concentration value of total aflatoxins total AFs 112.21 μg/kg and roasted peanut had the lowest total AFs 26.7. As well autumn season had the highest of total AFs 85.7 μg/kg, while the spring season had the lowest total AFs 49.92 μg/kg. Also Suez province had the highest average concentration value of total AFs 97.2 μg/kg and Luxor province had the lowest total AFs 38.26 μg/kg. The results recorded that clove powder is the most effective spice which completely inhibited A. flavus growth and aflatoxins production in broth media, on the other hand onion and fenugreek had no antifungal effect on mycelial growth and aflatoxins production, while cinnamon, thyme and peppermint inhibited aflatoxins production at 4,7 and 10mg/ml concentrations in broth media, and spices of each black pepper, cardamom, cumin and ginger inhibited aflatoxins production at 10mg/ml only. Results recorded that the minimum inhibitory concentration (MIC) of clove was at 3mg/ml. As well the effect of spices (clove, cinnamon, thyme and peppermint) on A. flavus growth in raw peanut seeds showed that the fungal growth was noticed at all the concentrations (4, 7 and 10 mg/g) but it was weak at 10mg/g of clove. Aflatoxins production were inhibited at 10mg/g of spices (clove, cinnamon, thyme and peppermint also, 7mg/g of clove and cinnamon inhibited aflatoxins production. While at 7mg/g of peppermint and thyme reduced the aflatoxins production till 22.3 and 30 μg/kg, respectively. At 4 mg/g of spices concentration (clove, cinnamon, peppermint and thyme) aflatoxins production were reduced to 20, 40, 43.8 and 50 μg/kg respectively in peanuts for 7 days.