Manufacture of Toman Fish Protein (Channa micropeltes) Isolate with Different pH Methods using Star Fruit (Averrhoa bilimbi) Acid

Abstract

Toman fish (Channa micropeltes) is a type of freshwater fish that belongs to the genus Channa which is the largest size compared to the others and has high protein. This study aims to obtain the isolate of toman fish protein (Channa micropeltes) by the method of pH regulation using star fruit acid. Wuluh star fruit acid is used as a substitute for HCl in making fish protein isolates to reduce pH. This research method uses a Completely Randomized Design (CRD). The treatments consisted of (P1 = pH 4, P2 = pH 5, P3 = pH 6). The results showed that star fruit acid can replace HCl as a protein precipitant and P1 (pH 4) obtained the most isolates, namely an average protein content of 91.64% (db), a moisture content of 1.67%, ash content of 2.06 % (db), fat content of 2.74% (db), yield of 88.46%, and total amino acid composition of 61.30%, where the type of amino acid that dominates is glutamic acid (12.30%). Glutamic acid amino acid is the one that influences a lot in giving pH isoelectric point, in the treatment of P1 with pH 4 making isolates of toman fish protein to be the best treatment, because glutamic acid has an isoelectric point of 3.22 which is the closest to pH 4 plus also the pH of isoelectric point from other amino acids.