2.2. Methods
2.2.1. Extraction Process. The onion skins were dried under
direct sunlight and grinded into small units with the help
of grinding machine. The wastages are removed using a fine
strainer and finally weight was taken. After drying, crushing,
and straining, the weight of 1 kg skins was found to be 805 gm.
The dried and crushed skin s were shown in Figure 2.
The color component was extracted from the skins in
aqueous extraction process. It was done by extracting fixed
quantity of crushed skins under pH 5 with a material to liquor
ratio of 1 : 10 (weight of crushed skins in g; amount of water
in mL) at boil for 60 min. In each process of extraction, the
mixture was cooled down and finally the dye extracts were
filtered accurately.