| Synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), Vitamin E and ethoxyquin, have been commonly added to formulated animal feeds in order to delay discoloration and deterioration due to oxidation. However, these synthetic antioxidants have been limited in their applications as food additives because of potential health hazards. Specifically, synthetic antioxidants have been considered to be linked to various forms of cancer, most commonly kidney, liver and bladder cancer. In this work, value-added peptide antioxidants from rendering products were developed for use in potential aquaculture and pet food markets as natural antioxidant substitutes for synthetic antioxidants. The antioxidant peptides developed from the rendering protein were studied based on obtaining the hydrolysates fractions, together with evaluation antioxidant properties, ultrafiltration and analysis sequence of identified peptide.;In the initial studies, three typical rendering proteins (poultry meal, fish meal and premium pet meal) characteristic compositions of three rendering proteins were investigated, including moisture content, ash content, fat content, and protein content. Then, the antioxidant capacity of three alkaline rendering proteins hydrolysates, including poultry meal hydrolysates, fish meal hydrolysates and premium pet meal hydrolysates, were examined. The antioxidant activities of alkaline hydrolysates were evaluated using five methods including two based on the free radical scavenging capacity (DPPH, ABTS radical scavenging assay and one oxygen radical absorbance capacity (ORAC) assay). Hydrophobic antioxidant capacities of alkaline hydrolysates were determined by beta-Carotene Linoleic Acid System. Oxidation Stability Index (OSI) was used to evaluated the anti-lipid oxidation ability.;The antioxidant peptides developed from proteolytic hydrolysis of premium pet meal were the analyzed using Response surface optimization, Ultra-Filtration and LC-MS. The optimum hydrolysis condition on temperature, enzyme to substrate ratio, and the hydrolysis time were obtained by Response Surface Methodology (RSM). Abilities of scavenging ABT•+ free radicals and degree of the hydrolysis were employed as indicators of Response surface methodology. Under the optimum hydrolysis conditions, the proteolytic hydrolysates fractions were separated by the ultrafiltration to obtain different molecular weight proteolytic hydrolysates fractions. During this process, the antioxidant capacity was also evaluated by the ABTS•+ scavenging free radical assay. For the last step, peptides less than 1000Da peptide that were derived from premium pet meal were identified using LC-MS, indicating of the possible amino acid sequences of Leu-Thr-Cys or Iso-Thr-Cys and His-Cys. |
