The significance of critical processing steps in the production of dried egg albumen powder on gel textural and foaming properties

The purpose of the present work was to study the variation in egg albumen functional properties as a function of seven selected processing steps from the initially raw liquid albumen to the final dried egg albumen powder. Albumen samples in six replicates were analysed for dry matter, pH, glucose, triglycerides, albumen gel properties (ie textural stress and Hencky strain, water- and protein-binding capacity and gel colour L*, a*, b*), foaming properties (ie overrun, stability against drainage and bubble breakdown) and surface tension. The gel texture and water-holding capacity significantly decreased during the processing steps from raw albumen through storage, centrifugation and ion exchange, whereas the final drypasteurisation resulted in increased gel properties. Covalently linked protein polymers formed during the dry-pasteurisation, as revealed by SDSPAGE, may explain this improvement. The foam overrun increased twofold during the three final steps of ultrafiltration, spray-drying and drypasteurisation compared with the raw albumen; however, the foam stability decreased, ie drainage and foam volume breakdown rates increased. The surface pressure increase was positively correlated with the foam overrun. This paper reveals at which processing steps the control of functional properties of egg albumen powder can take place.