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 swere 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.