Abstract:
This research aimed to extract protein hydrolyzate from chrome leather scraps by the chemical method in combination with alkaline protease and extracted protein hydrolyzate was used for earthworm manure. The mixed solution of 3 percent w/w sodium hydroxide, 5 percent w/w magnesium oxide and 5 percent w/w calcium oxide were used as extracting chemicals. After extraction, chrome leather scraps and extracted protein hydrolyzate were utilized as a food ingredient for E. eugeniae earthworm. The growth of earthworm, the weight of earthworm manure, nitrogen content and chromium content of different flooring materials were determined both before and after the experiment. The results showed that (1) the quantity of protein hydrolyzate from chrome leather scraps was 183.20±4.36 mg/L and (2) chrome leather scraps and protein hydrolyzate could be used as a food ingredient and manure production for the earthworm. The chromium content found in both flooring materials after the experiment (40 days) was less than 300 mg/kg. It was shown that alkaline protease is specific for peptide bond cleaving to make protein smaller resulting in chromium removal from leather scraps because of the precipitation of chromium oxide in alkaline solution. Therefore, protein hydrolyzate extracted from chrome leather scrap was a suitable in protein source for earthworm growth, reducing the disposal cost, conserving the environment and guiding the earthworm manure production."