Optimization of decolorization process and its effect on flavor of sardine fish head protein peptide

ObjectiveTo improve the color and flavor of enzymatically prepared sardine fish head protein peptide (SFHP).MethodsThe optimal absorption wavelength of the SFHP solution was determined using a spectrophotometer. The effects of three decolorizing agents, including their dosage, decolorization time, and temperature, on the decolorization efficiency of SFHP were investigated. A plate-and-frame filtration pilot-scale test was conducted to validate the decolorizing and filtration-enhancing effects of the decolorizing agents. Flavor profiles before and after decolorization were analyzed using an electronic nose (E-nose) and electronic tongue (E-tongue).ResultsThe optimal absorption wavelength of the SFHP solution was 220 nm. The optimal decolorization conditions were determined as 1% activated carbon dosage, 1 h-decolorization time, and 40 ℃. Under these conditions, the decolorization rate reached 36.2%, with a protein loss rate of 8%. Key odor-active compounds in SFHP included aldehydes, chlorides, amines, and ketones. After decolorization, the bitterness of the SFHP was significantly reduced. The proportion of bitter amino acids decreased from 72.60% to 60.04%, and the content of bitter nucleotides (inosine and hypoxanthine) decreased from (24.85±1.14) mg/mL and (10.14±0.77) mg/mL to (10.66±1.60) mg/mL and (6.90±0.47) mg/mL, respectively.ConclusionThe use of activated carbon for decolorization effectively reduced the levels of bitter amino acids, bitter nucleotides, and aldehyde compounds in SFHP. This approach effectively improved the SFHP flavor by enhancing the umami and sweet flavors while decreasing the bitterness.