Analysis of some chemical and biological contaminants during wheat milling

Mycotoxigenic fungi, mycotoxins, pesticides and heavy metals were estimated in wheat, flour, bran, shorts and wheat germ. Samples were collected from different commercial milling lines in Great Cairo Governorate. Results showed that the most frequently isolated fungi were Aspergillus, Pencillium and Fusarium. The highest total fungal count was recorded in bran [14.3 x 10[-3] cfu] followed by shorts [11.9 x 10[3] cfu] and wheat germ [10.1 x 10[3] cfu] comparable with that of flour [3.1 x 10[3] cfu]. Nevertheless, the aflatoxins [AFs] were not detected in all collected samples. Ochratoxin A [OTA] was detected in 40%, 30%, 30%, 26.7% and 13.3% of bran, shorts, wheat germ, wheat and flour, respectively. The mean concentration of OTA in wheat was 4.15 ppb and it was 3 ppb in flour which considered lower than the permissible limits being 5 Pb. The obtained results indicated that heptachlor and o. p-DDE were the major pesticides contaminant in wheat and milling fractions and the highest mean level of heptachlor was detected in bran 0.017 ppm, whereas it was 0.033 ppm of o. p-DDE in shorts. The highest mean levels of lead [Pb] and cadmium [Cd] were found in shorts [0.482 and 0.097 ppm, respectively], while the lowest level of Pb [0.194 ppm] and Cd [0.034 ppm] were detected in flour

Improving method for the detection of aflatoxins in green coffee beans

The extraction and clean-up of aflatoxins [AFs] in green coffee beans were performed according to two official methods and an improved method. The TLC and HPLC techniques were used in the detection and determination of AFs in the final extracts. The results indicated that the AOAC method for green coffee beans failed to separate the four aflatoxins from a zone of pigmentation that masks the area of aflatoxins B[2]G[1] and G[2]. Aflatoxin B1, was the only spot that appear clearly. Also, the AOAC method for the detection of aflatoxins in cocoa beans failed to separate the pigmentation that mask the area of where aflatoxins spots should appear. The improved method seems to remove the interference compounds and aflatoxins spots appear clearly. The percentage recoveries for total aflatoxins were detected by HPLC and recorded 46.1%, 13.9% and 74.6% for AOAC for green coffee beans, AOAC for cocoa beans and the improved methods, respectively

Effect of variety, locality and processing of coffee beans on the detection and determination of aflatoxins

The effect of variety [Arabica and Robusta], locality of cultivation [Brazilian, Ethiopian and Colombian] of the same variety [Arabica] and processing [decaffeination and roasting] on the detection and determination of aflatoxins in coffee beans were studied. Using the AOAC method for the detection of aflatoxins in green coffice beans could not succeed to overcome the masked material that covered AFB[2], G[1] and G[2] in all samples under study and AFB[1] was the only spot that appeared on the TLC. Due to roasting of coffee beans, the interference material with aflatoxins increased and even AFB[1] could not be detected by the AOAC method. An improved procedure which uses silver nitrate to get rid of caffeine and related compounds, succeeded to remove the interference materials due to the coffee beans matrix and aflatoxins spots were separated clearly. However, this method failed to remove the interference materials that masked the area of aflatoxins in roasted coffee beans completely. HPLC was tested as an alternative technique for the detection of aflatoxins. The HPLC chromatogram of green coffee beans using the AOAC method showed unidentified intensity peaks and low recovery was obtained. The HPLC coupled with the improved procedure of extraction showed that the unidentified peaks due to the matrix of green and decaffeinated coffee beans were eliminated. However, it failed to overcome the problems of the roasted coffee beans especially in the area of AFG[1]. An obvious effect of cultivation locality on the matrix of green coffee beans was observed. This effect also appeared in the recovery percentage of aflatoxins. Also, this locality effect did not allow to reach a solid conclusion for the effect of variety

Inhibitory effect of some essential oils and food additives on aflatoxins production by Aspergillus parasiticus on yellow corn during storage

Nine essential oils, two food additives and salicylic acid were evaluated for their inhibitory effect against activity of Aspergillus parasiticus. In vitro studies, the highest growth reduction of A. parasiticus was recorded when oils of geranium, lemon grass and rose added to the growth medium at concentrations above 0.5%, while the same effect was noticed at 2% of lime shell oil and 3% of peppermint, garlic and onion oils. Also, potassium sorbate [0.07%], sodium benzoate [0.09%] and salicylic acid [0.8%] were able to cause 100% growth reduction of A. parasiticus on growth medium. In vivo studies, the highest inhibition of fungal growth [9624%, 93.98%, 94.73%, 54.28% and 67.42%] and aflatoxins production [100%] were recorded on inoculated stored grains of yellow corn, treated with potassium sorbate, sodium benzoate and salicylic acid as well as geranium and rose oils at concentrations as 0.28, 0.36, 3.2,6 and 6%, respectively. Obtained results in the present study led to conclude that essential oils of germinum, rose and flood additives as potassium sorbate and sodium benzoate in addition to salaicylic acid could be used as preventing and inhibiting factors against mould contamination and aflatoxins production in food and foodstuffs during storage. These agents are considered inexpensive, safe, easily applied and not hazard to human health and environment