Abu Saleh Mostafa Kamal
Dept. of Botany, Jahangirnagar University, Savar, Dhaka.
Abul Khair
Dept. of Botany, Jahangirnagar University, Savar, Dhaka.
Mamtaz Dawlatana
IFST:BCSIR; Dr.Qudrat-I-Khuda road, Dhaka-1205.Bangladesh.
M Tariqul Hassan
IFST:BCSIR; Dr.Qudrat-I-Khuda road, Dhaka-1205.Bangladesh.
Fauzia Begum
IFST:BCSIR; Dr.Qudrat-I-Khuda road, Dhaka-1205.Bangladesh.
Matiur Rahim
IFST:BCSIR; Dr.Qudrat-I-Khuda road, Dhaka-1205.Bangladesh.
Mushrooms, Oyster, Button, Aflatoxins, DDT, Heptachlor; Pesticide residue.
Dept. of Botany, Jahangirnagar University, Savar, Dhaka
Food Safety and Security
Collection of samples: Fresh-cut Oyster mushrooms (Pleurotus ostreatus) are collected as of third flash from the Cropping room of IFST, BCSIR, Dhaka. The substrates were sawdust (FM1) and paddy straw (FM2) respectively. The sizes of mushrooms are in between 5 to 11cm in diameter on an average 8cm, and did not require use of pesticide in both of pre-harvest or postharvest stages. Oven dried mushroom powder (MP1), mushroom soup powder (MP2) and recently developed Mushroom-Juice (MJ) are collected from the same laboratory as processed mushrooms. The canned (M;GM) White button mushrooms (Agaricus spp) were imported and collected randomized from mega shops of Dhaka city considered to be processed /preserved foods. Total seven categories of samples are collected and three replicates of each sample are analyzed. Instruments/Apparatus Detection and quantification of Aflatoxins, Ochratoxcins were performed with a High Performance Liquid Chromatograph (HPLC), Agilent1200, G1316A, CULCOM, German. Heptachlor and DDT were analyzed using Gas- Chromatography (GC-14B Shimadzu) with an electron capture detector (ECD), a manual sampler and solution software. Syringe (10μl;Hamilton co.). Concerned instruments/apparatus are rinsed with acetone prior to use. Reagents Acetone, diethyl ether, dimethyl formamide saturated with petroleum ether, n-hexane, petroleum ether (30-60OC), petroleum ether (30-60OC) saturated with dimethyl formamide, eluting mixture I (petroleum ether+diethyl ether 94:6v/v), standard solutions, eosin solution (2 mg in 100 ml), sodium sulfate solution (2g/100ml NaSo4 10 H2O), sodium sulfate anhydrous (heated for at least 2 hour at 550OC), florisil 60-100 mesh (heated for at least 2 hour at 550OC, cool and stored in tightly stopper- container, prior to use was heated for at least 5 hour at 130OC, cool and add 5% w/w water, the mixture was shaken for at least 20 min and was stored in a container for at least 10 hour), cotton wool. Chemicals, reagents and solvents used for the analysis were procured form MERCK, Germany. DDT and heptachlor standards were obtained from Sigma Chemicals. Sample preparation: All the samples were blended while comminuting was avoided by brief chopping for several times. Titration was done with 25 g of sample and sodium sulfate to get dry powdery mixture, with the aid of an extraction thimble; the powdary mixture exhaustively with Petroleum Ether in Soxhlet apparatus. Concentrate and dilute to 25ml with petroleum ether saturated with dimethyl formamide (Hans and Zeumer, 1987). Clean up Preparation of injecting solution and clean up was performed according to the method described by Hans and Zeumer (1987). Procedure for aflatoxins: To get injecting solution, the required amount of fresh-cut mushrooms or mushroombased food products were weighted and then blended with the help of high-speed blender fitted with proof glass jar and explosion-proof mater to make slurry. Procedure for DDT and heptachlor The DDT and heptachlor residues were analyzed by GC- 148, Shimadzu with an electron capture detector (ECD), a manual sampler and GC solution software. A column of 3.1m X 3.2 mm; I. D glass spiral; stationary phase silicon OV 17, 5%, aging 300OC, support chromosorb-W-AWDMCS, mesh 80/100,1μm film thickness was used for the chromatographic separation of insecticides. The temperature was fixed for the injector at 250OC, column at 280OC, detector at 280OC. The carrier gas was nitrogen with a 60 ml/min-flow rate. 1.0 μl sample was injected for each run and the running time was 25min. Standards peak were identified by injecting high concentration of the standard (0.5 ppm and 0.25ppm) and the retention time for DDT and heptachlor were determined. Then calibration was done at 3 points (25 ppb, 50 ppb and 100ppb) by composite stock standard solution. GC system was calibrated using external standard technique. Individual standard stock solution (100mg/l) was prepared by weighing appropriate amounts of Teflon-lined screw cap and dissolving the weighed standard in HPLC grade hexane. Stock standard solution was used to prepare primary dilution standards. Appropriate volume of each individual stock solution was taken in a volumetric flask and mixed the solutions to obtain composite stock standard solution.
Bangladesh J. Sci. Ind. Res. 44(2), 193-198, 2009
Journal