Investigation of the effects of reverse osmosis and ultrafiltration treatments on physicochemical, techno-functional, and rheological characteristics of liquid egg albumen and prepared meringue cookie batter

Membrane filtration has a promising advantage in the processing of egg products. In this study, liquid egg whites (LEW) were separately concentrated by using reverse osmosis (RO) and ultrafiltration (UF) techniques. The first aim of this research was to determine the effects of the concentration pre-treatments on the physico-chemical quality criteria (pH, relative whipping capacity, foaming stability, water holding capacity-WHC, colour) and the rheological behaviour (viscosity, oscillation) of LEW samples. The second aim of this research was to investigate the impact of the membrane pre-treatment on meringue's functional quality attributes such as meringue batter density and meringue batter colour values (L*, a*, b*). The average dry matter of LEW was increased from 12% to 23% by the concentration pre-treatment process (RO and UF), and water was removed from the LEW. In addition, the batter density of meringue cookie samples was 0.37 ± 0.01 g mL−1 in UF and RO. The differences between the pH and dry matter values of the ultrafiltration and reverse osmosis treated groups were found to be statistically similar, and it was observed that the elastic modulus (G′) increased with the increase in frequency in the rheological measurements. It has been determined that G′ is higher than G″ in all samples. An elastic/solid-like (G′ > G″) structural behaviour was determined while increasing the frequency value. It was determined that the WHC of LEW treated with RO was higher than of the group treated with UF. The results of the study showed that while reducing transportation and storage costs, the water content of >80% of LEW (raw material-the treated liquid egg white) removed by UF and RO applications can be suitable to produce meringue batter cookies (semi-finished product).