Induced oxidation and addition of antioxidant before enzymatic hydrolysis of heads of rainbow trout (Oncorhynchus mykiss) – effect on the resulting oil and protein fraction

Abstract

The effect of freshness of heads of rainbow trout ( Onchorhynchus mykiss ) for hydrolysing fish protein was investigated. To simulate storage and transportation, hydrogen peroxide and iron was added to minced heads to induce oxidation in the raw material prior to one week of storage. The effect of antioxidant in retarding oxidative changes during hydrolysis or to the raw material was investigated by adding butylated hydroxy toluene (BHT) prior to hydrolysis or storage. Enzymatic hydrolysis was carried out using bromelain and papain. The oil fraction was separated from the water soluble proteins, and the soluble phase was freeze dried. Both the oil fraction and protein fraction from enzymatic hydrolysis was affected by oxidative state of raw material. FFA was significantly higher in those FPH made from raw material added pro-oxidants, addition of antioxidant did not affect the level of FFA. The solubility of proteins in dried fish protein hydrolysates (FPH) decreased significantly when using oxidized raw material. Although addition of antioxidant improved the solubility, it was still significantly lower compared to those FPHs not added pro-oxidants. The FPH with decreased solubility also had higher levels of carbonyl groups which indicate protein oxidation. However, the oxidative state of raw material did not affect fatty acid composition in oil fraction or the amino acid composition in the FPH.

Physicochemical and functional properties of rainbow trout (Oncorhynchus mykiss) hydrolysate

“…The proximate composition of rainbow trout raw material and the obtained FPH is shown in Table 1 . Proximate parameters displayed similar values in regard to dry matter, ash, lipid and protein content in rainbow trout as reported in previous studies [ 5 , 31 , 32 ].…”

“…and fish processing rest raw materials are good sources of high-quality protein compounds that may be used for human consumption [ 4 ]. Enzymatic hydrolysis is normally carried out under moderate conditions of pH and temperature [ 5 ]. The full utilization of fish raw material, including side-streams and by-products, would also help to increase the amount of high-quality protein ingredients, which may be used as a source of bioactive peptides with a number of functional and health-promoting properties [ 4 ].…”

Freezing and frozen storage of aquatic products: mechanism and regulation of protein oxidation

“…Amino acids located in the myosin tail of silver carp fillets were found to be highly susceptible to oxidation, while the gill-cutting halo method was found to be more susceptible to oxidation in vitro due to structural disruptions caused by the stress response (Zhang et al, 2021). Moreover, it was also demonstrated that the addition of hydrogen peroxide and iron to chopped rainbow trout heads induced protein oxidation (Kvangarsnes et al, 2021).…”

Recent advances in the effects of protein oxidation on aquatic products quality: mechanism and regulation

“…Metal ion‐induced protein oxidation exposes specific binding sites, and the generated free radicals attack these sites, which in turn cause oxidative denaturation of the protein. Experiments have confirmed that protein oxidation can be induced by the incorporation of hydrogen peroxide and iron (Kvangarsnes et al ., 2021).…”