2.1. Materials and Measurement The experiment was carried out at the Biochemistry laboratory of the Department of Biochemistry, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh and Post Harvest Technology Division BARI Joydebpur, Gazipur, Bangladesh. Four released varieties and two advanced line of mustard (Brassica Campestries) namely BARI Sarisha-9, BARI Sarisha-12, BARI Sarisha-14, BARI Sarisha-15, Din-2 and BC2193 were collected from the Oilseeds Research Centre of BARI, Gazipur, Bangladesh. Seed were cleaned sun-dried and stored into plastic container in a cool place until used for the chemical analysis. All the chemicals used were collected from Merck (Germany), Wako Pure Chemicals Industries Ltd. and JHD (China). These chemicals were analytical, spectroscopic grade and were used without further purification unless otherwise specified. The sample was weighted by electric balance (KEY: JY-2003; China) and heated in a muffle furnace (Nebertherm: Mod-L9/11/c6; Germany). The amount of β-carotene and aflatoxin were determined by spectrophotometer (HALO BD-20S; Germany).
2.2. Determination of Physical Properties of Mustard Varieties and Rapeseed Seed were cleaned sun dried and stored into plastic container in a cool place until used for the chemical analysis. Therefore they are ready to be analyzed.
2.2.1. Determination of Grain Weight Grain weight was determined by thousand seed sample weighted by electric balance. Grain weight is a very important character of rapeseed and mustard, where highest consideration is one of the seed yield. This character has been found to vary widely from genotypes to genotypes and from the environment to environment.
2.2.2. Determination of Moisture and Dry Matter Dry Matter was determined by keeping weighted quantity of sample in a thermostat-controlled oven at 105ºC for 6 hours. The dry weight of each sample was taken in an electric balance. The percentage of the dry mater was then calculated.
2.3. Determination of Chemical Constant of Mustard Varieties and Rapeseed 2.3.1 Saponification Value At first, 2 g fat was taken in 250 ml round bottom flask and 25 ml, 0.5 N alcoholic potassium hydroxide solution added in same flask. The flask was fitted with a long air condenser and heated solution at reflux temperature about 30 minutes. Finally, the flask was cooled and added 1 ml of 1% phenolphthalein solution and titrate the excess of the alkali against standard 0.5 N HCl acid. At the same time and under similar conditions carry out a blank titration without fat (25 ml, 0.5 N same alcoholic KOH solution was taken in another round bottom flask and heated in a similar way and titrated, against 0.5 N acid). 1 ml of 0.5 N HCl acid was equivalent to 0.02805g of KOH.
2.3.2. Iodine Value 5 g of oil or fat was taken into 200 ml a glass stoppered bottle. 5 ml of CCl4 was added to dissolve this oil after 25 ml of Wij’s solution was added and to allow it at least 1 hour in a dark place. Then 5 ml of 10% potassium iodide solution and 50 ml water were added to each bottle and titrated against 0.1 N Na2S2O3 using starch solution as the indicator, near the end point of titration the colour of solution becomes pale yellow. Blue colour disappears which indicates the end point. At the same time and under similar conditions carry out a blank titration without oil or fat.
2.4. Determination of Chemical Characteristic and Aflatoxin Content of Mustard Varieties and Rapeseed The quantity of aflatoxin was examined by using a spectrophotometer [8]. For this purpose, the seeds of Brassica campestris were dried and put in polyethylene bags at 3 months. The quantity of β-carotene was examined by using a spectrophotometer. The recorded data for each character from the experiments was analyzed statistically to find out the variation resulting from experimental treatments using MASTAT package program. The mean for all the treatments were calculated and analysis of variance of characters under the study was performed by F test. The mean differences were evaluated by Least Significance Difference Test.