Agata Marzec

Correlations between Vitelline Membrane Strength and Selected Physical Parameters of Poultry Eggs

Abstract The aim of this study was to evaluate the strength of vitelline membrane and its correlation with other morphological traits and the viscosity of egg yolk of different poultry species: goose, turkey, Muscovy duck, chicken, guinea fowl and Japanese quail. Vitelline membrane strength (VMS) was defined as work and force after the deformation of yolk at 6 mm. Bird species affected the VMS of egg yolk. The lowest strength was measured for the vitelline membrane of goose egg yolk. There were no apparent differences in the strength of vitelline membrane for ducks, guinea fowl, chickens and Japanese quail. In contrast, the vitelline membrane of turkey egg yolk appeared to be of the highest strength. Statistically significant positive correlations were observed between VMS and yolk index, while there was no correlation between the weight of the eggs and egg yolk. The work deformation of yolk was positively correlated with the viscosity of poultry egg yolk.

Rehydration properties of hybrid method dried fruit enriched by natural components

Abstract The aim of the study was to determine the impact of osmotic pre-dehydration and drying of fruit on the rehydration properties of dried fruit. Herein, the effect of fruit juice, applied as a natural enriching substance was very important. In addition, the properties of dried fruits obtained through combined air-drying and subsequent microwave-vacuum drying with ‘puffing’ effect were similar to the freeze-dried fruits, but showed other rehydration properties. As raw material, frozen strawberry (Honeoye variety) and fresh apples (Idared variety) were used in the study. The apples and partially defrosted strawberries were prior dehydrated in solutions of sucrose and a mixture of sucrose with chokeberry juice concentrate at 50°C for 2 h. Next, the fruit samples were dried by one of two ways: air-drying (50°C, 5 h) and microwavevacuum drying for about 360 s; and freeze-drying (30°C, 63 Pa, 24 h). The rehydration was carried out in distilled water (20°C, 5 h). The osmotic pre-dehydration hindered fruit drying process. The impact of drying method became particularly evident while examining the kinetics of rehydration. During the rehydration of the pre-dehydrated dried fruit a slower hydration could be observed. Freeze-dried strawberries absorbed 2-3 times more water than those dried by the ‘puffing’ effect.