GREEN DISCOLORATION OF FATTENED GOOSE LIVER Factors and mechanisms influencing green discoloration in vacuum-packed frozen fattened goose liver.

Surface discoloration, particularly green discoloration in vacuum-packed frozen fattened goose liver, is a common quality defect, adversely affecting product acceptability. Therefore, the aim of the study was to investigate the effects of evisceration timing and frozen storage on green discoloration (Trial I), and to use controlled chemical induction models to assess potential contribution of sulfhemoglobin formation (Trial II). Force-fed male Greylag Landaise geese (n=60) were randomly selected and allocated to two experimental groups. After slaughter and initial processing, 50% of the birds were immediately eviscerated. Remaining half of the carcasses was eviscerated after 8 h cooling. Hemoglobin content was determined. Livers were vacuum-packed, frozen, color was measured. Livers were stored at -18°C for 35 d. Surface color was measured every 7 d. After storage, elemental analysis was conducted, amino acid profile analysis was performed and hydrogen sulfide was investigated. Artificial induction of green discoloration was attempted. Results of Trial I showed that under conditions of study, surface color was significantly affected by evisceration timing (P<0.001). Liver surface removed by cold evisceration turned green by 21 d. Elemental analysis resulted in significant difference (Fe, K and Mn). Amino acid analysis did not reveal significant differences. Hydrogen sulfide was confirmed in greened livers. Artificial induction of surface greening (Trial II) was successfully executed by application of H2O2+SO2. These findings suggest that delayed evisceration promotes conditions favorable for sulfhemoglobin formation, providing a plausible mechanistic explanation for green discoloration, likely through the interaction of hydrogen sulfide with residual hemoglobin under low oxygen conditions.