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We investigated a reproductive flock of Zatorska geese. The birds were divided into four groups: three-year-old ganders (n=10), and one-, two-, and three-year-old layers (n=30). Mature feathers were collected from the birds between July and September (i.e., after breeding). Before collection, the feathers and down were evaluated to determine their maturity. The quantitative composition of each sample of feathers was evaluated manually. The evaluated quality traits of the feathers were turbidity of an aqueous extract, acidity, oxygen index number, and fat content. The data were analyzed using the SAS statistical package with multivariate analysis of variance for repeated measures. The weight of feathers collected from all three gatherings was the highest for the three-year-old ganders. In subsequent gatherings, the weight of the collected feathers tended to increase. There was a statistically significant difference in down composition between the first and the subsequent two gatherings in all age-groups of geese. Neither the age nor the gender of the birds had an effect on the quantity of down obtained, which was 80-85 g. The turbidity of the feather extract was lowest for feathers collected in the first gathering. For the layers, the turbidity of the feather extract was lowest in feathers obtained from the one-year-old birds. The feathers ranged from slightly acidic to neutral, with pH values between 5.9 and 7.2. The fat content was lowest in feathers collected in the first gathering (2.4-2.7%), and tended to increase in subsequent gatherings. There was no statistically significant difference in the oxygen index number between individual gatherings, or between the three-years-old layers and the ganders.

The aim of this study was to optimize and characterize Flavourzyme hydrolysis conditions for the preparation of antioxidant peptides from duck meat, using response surface methodology. The results indicated that optimal Flavourzyme hydrolysis conditions for preparation of antioxidant peptides from duck protein were a temperature of 50.19°C, pH 5.45, and a reaction time of 1.03 h. Compared to non-hydrolyzed duck meat, Flavourzyme hydrolysis significantly improved the hydroxyl-radical scavenging, DPPH radical-scavenging, ferrous ion-chelating, reducing, and ABTS radical cation-scavenging activities of duck meat. Therefore, Flavourzyme can be regarded as an effective hydrolytic enzyme for the preparation of antioxidant peptides from duck meat.